Lab 5

GNUmakefile

@@ -141,6 +141,7 @@ include boot/Makefrag
 include kern/Makefrag
 include lib/Makefrag
 include user/Makefrag
+include fs/Makefrag
 
 
 CPUS ?= 1
@@ -149,6 +150,8 @@ QEMUOPTS = -drive file=$(OBJDIR)/kern/kernel.img,index=0,media=disk,format=raw -
 QEMUOPTS += $(shell if $(QEMU) -nographic -help | grep -q '^-D '; then echo '-D qemu.log'; fi)
 IMAGES = $(OBJDIR)/kern/kernel.img
 QEMUOPTS += -smp $(CPUS)
+QEMUOPTS += -drive file=$(OBJDIR)/fs/fs.img,index=1,media=disk,format=raw
+IMAGES += $(OBJDIR)/fs/fs.img
 QEMUOPTS += $(QEMUEXTRA)
 
 .gdbinit: .gdbinit.tmpl

conf/lab.mk

@@ -1,2 +1,2 @@
-LAB=4
+LAB=5
-PACKAGEDATE=Mon Oct 8 21:31:51 PDT 2018
+PACKAGEDATE=Wed Oct 24 20:44:37 EDT 2018

fs/Makefrag

@@ -0,0 +1,77 @@
+
+OBJDIRS += fs
+
+FSOFILES := 		$(OBJDIR)/fs/ide.o \
+			$(OBJDIR)/fs/bc.o \
+			$(OBJDIR)/fs/fs.o \
+			$(OBJDIR)/fs/serv.o \
+			$(OBJDIR)/fs/test.o \
+
+USERAPPS := 		$(OBJDIR)/user/init
+
+FSIMGTXTFILES :=	fs/newmotd \
+			fs/motd
+
+
+USERAPPS :=		$(USERAPPS) \
+			$(OBJDIR)/user/cat \
+			$(OBJDIR)/user/echo \
+			$(OBJDIR)/user/init \
+			$(OBJDIR)/user/ls \
+			$(OBJDIR)/user/lsfd \
+			$(OBJDIR)/user/num \
+			$(OBJDIR)/user/forktree \
+			$(OBJDIR)/user/primes \
+			$(OBJDIR)/user/primespipe \
+			$(OBJDIR)/user/sh \
+			$(OBJDIR)/user/testfdsharing \
+			$(OBJDIR)/user/testkbd \
+			$(OBJDIR)/user/testpipe \
+			$(OBJDIR)/user/testpteshare \
+			$(OBJDIR)/user/testshell \
+			$(OBJDIR)/user/hello \
+			$(OBJDIR)/user/faultio \
+
+FSIMGTXTFILES :=	$(FSIMGTXTFILES) \
+			fs/lorem \
+			fs/script \
+			fs/testshell.key \
+			fs/testshell.sh
+
+
+FSIMGFILES := $(FSIMGTXTFILES) $(USERAPPS)
+
+$(OBJDIR)/fs/%.o: fs/%.c fs/fs.h inc/lib.h $(OBJDIR)/.vars.USER_CFLAGS
+	@echo + cc[USER] $<
+	@mkdir -p $(@D)
+	$(V)$(CC) -nostdinc $(USER_CFLAGS) -c -o $@ $<
+
+$(OBJDIR)/fs/fs: $(FSOFILES) $(OBJDIR)/lib/entry.o $(OBJDIR)/lib/libjos.a user/user.ld
+	@echo + ld $@
+	$(V)mkdir -p $(@D)
+	$(V)$(LD) -o $@ $(ULDFLAGS) $(LDFLAGS) -nostdlib \
+		$(OBJDIR)/lib/entry.o $(FSOFILES) \
+		-L$(OBJDIR)/lib -ljos $(GCC_LIB)
+	$(V)$(OBJDUMP) -S $@ >$@.asm
+
+# How to build the file system image
+$(OBJDIR)/fs/fsformat: fs/fsformat.c
+	@echo + mk $(OBJDIR)/fs/fsformat
+	$(V)mkdir -p $(@D)
+	$(V)$(NCC) $(NATIVE_CFLAGS) -o $(OBJDIR)/fs/fsformat fs/fsformat.c
+
+$(OBJDIR)/fs/clean-fs.img: $(OBJDIR)/fs/fsformat $(FSIMGFILES)
+	@echo + mk $(OBJDIR)/fs/clean-fs.img
+	$(V)mkdir -p $(@D)
+	$(V)$(OBJDIR)/fs/fsformat $(OBJDIR)/fs/clean-fs.img 1024 $(FSIMGFILES)
+
+$(OBJDIR)/fs/fs.img: $(OBJDIR)/fs/clean-fs.img
+	@echo + cp $(OBJDIR)/fs/clean-fs.img $@
+	$(V)cp $(OBJDIR)/fs/clean-fs.img $@
+
+all: $(OBJDIR)/fs/fs.img
+
+#all: $(addsuffix .sym, $(USERAPPS))
+
+#all: $(addsuffix .asm, $(USERAPPS))
+

fs/bc.c

@@ -0,0 +1,151 @@
+
+#include "fs.h"
+
+// Return the virtual address of this disk block.
+void*
+diskaddr(uint32_t blockno)
+{
+	if (blockno == 0 || (super && blockno >= super->s_nblocks))
+		panic("bad block number %08x in diskaddr", blockno);
+	return (char*) (DISKMAP + blockno * BLKSIZE);
+}
+
+// Is this virtual address mapped?
+bool
+va_is_mapped(void *va)
+{
+	return (uvpd[PDX(va)] & PTE_P) && (uvpt[PGNUM(va)] & PTE_P);
+}
+
+// Is this virtual address dirty?
+bool
+va_is_dirty(void *va)
+{
+	return (uvpt[PGNUM(va)] & PTE_D) != 0;
+}
+
+// Fault any disk block that is read in to memory by
+// loading it from disk.
+static void
+bc_pgfault(struct UTrapframe *utf)
+{
+	void *addr = (void *) utf->utf_fault_va;
+	uint32_t blockno = ((uint32_t)addr - DISKMAP) / BLKSIZE;
+	int r;
+
+	// Check that the fault was within the block cache region
+	if (addr < (void*)DISKMAP || addr >= (void*)(DISKMAP + DISKSIZE))
+		panic("page fault in FS: eip %08x, va %08x, err %04x",
+		      utf->utf_eip, addr, utf->utf_err);
+
+	// Sanity check the block number.
+	if (super && blockno >= super->s_nblocks)
+		panic("reading non-existent block %08x\n", blockno);
+
+	// Allocate a page in the disk map region, read the contents
+	// of the block from the disk into that page.
+	// Hint: first round addr to page boundary. fs/ide.c has code to read
+	// the disk.
+	//
+	// LAB 5: you code here:
+
+	// Clear the dirty bit for the disk block page since we just read the
+	// block from disk
+	if ((r = sys_page_map(0, addr, 0, addr, uvpt[PGNUM(addr)] & PTE_SYSCALL)) < 0)
+		panic("in bc_pgfault, sys_page_map: %e", r);
+
+	// Check that the block we read was allocated. (exercise for
+	// the reader: why do we do this *after* reading the block
+	// in?)
+	if (bitmap && block_is_free(blockno))
+		panic("reading free block %08x\n", blockno);
+}
+
+// Flush the contents of the block containing VA out to disk if
+// necessary, then clear the PTE_D bit using sys_page_map.
+// If the block is not in the block cache or is not dirty, does
+// nothing.
+// Hint: Use va_is_mapped, va_is_dirty, and ide_write.
+// Hint: Use the PTE_SYSCALL constant when calling sys_page_map.
+// Hint: Don't forget to round addr down.
+void
+flush_block(void *addr)
+{
+	uint32_t blockno = ((uint32_t)addr - DISKMAP) / BLKSIZE;
+
+	if (addr < (void*)DISKMAP || addr >= (void*)(DISKMAP + DISKSIZE))
+		panic("flush_block of bad va %08x", addr);
+
+	// LAB 5: Your code here.
+	panic("flush_block not implemented");
+}
+
+// Test that the block cache works, by smashing the superblock and
+// reading it back.
+static void
+check_bc(void)
+{
+	struct Super backup;
+
+	// back up super block
+	memmove(&backup, diskaddr(1), sizeof backup);
+
+	// smash it
+	strcpy(diskaddr(1), "OOPS!\n");
+	flush_block(diskaddr(1));
+	assert(va_is_mapped(diskaddr(1)));
+	assert(!va_is_dirty(diskaddr(1)));
+
+	// clear it out
+	sys_page_unmap(0, diskaddr(1));
+	assert(!va_is_mapped(diskaddr(1)));
+
+	// read it back in
+	assert(strcmp(diskaddr(1), "OOPS!\n") == 0);
+
+	// fix it
+	memmove(diskaddr(1), &backup, sizeof backup);
+	flush_block(diskaddr(1));
+
+	// Now repeat the same experiment, but pass an unaligned address to
+	// flush_block.
+
+	// back up super block
+	memmove(&backup, diskaddr(1), sizeof backup);
+
+	// smash it
+	strcpy(diskaddr(1), "OOPS!\n");
+
+	// Pass an unaligned address to flush_block.
+	flush_block(diskaddr(1) + 20);
+	assert(va_is_mapped(diskaddr(1)));
+
+	// Skip the !va_is_dirty() check because it makes the bug somewhat
+	// obscure and hence harder to debug.
+	//assert(!va_is_dirty(diskaddr(1)));
+
+	// clear it out
+	sys_page_unmap(0, diskaddr(1));
+	assert(!va_is_mapped(diskaddr(1)));
+
+	// read it back in
+	assert(strcmp(diskaddr(1), "OOPS!\n") == 0);
+
+	// fix it
+	memmove(diskaddr(1), &backup, sizeof backup);
+	flush_block(diskaddr(1));
+
+	cprintf("block cache is good\n");
+}
+
+void
+bc_init(void)
+{
+	struct Super super;
+	set_pgfault_handler(bc_pgfault);
+	check_bc();
+
+	// cache the super block by reading it once
+	memmove(&super, diskaddr(1), sizeof super);
+}
+

fs/fs.c

@@ -0,0 +1,456 @@
+#include <inc/string.h>
+#include <inc/partition.h>
+
+#include "fs.h"
+
+// --------------------------------------------------------------
+// Super block
+// --------------------------------------------------------------
+
+// Validate the file system super-block.
+void
+check_super(void)
+{
+	if (super->s_magic != FS_MAGIC)
+		panic("bad file system magic number");
+
+	if (super->s_nblocks > DISKSIZE/BLKSIZE)
+		panic("file system is too large");
+
+	cprintf("superblock is good\n");
+}
+
+// --------------------------------------------------------------
+// Free block bitmap
+// --------------------------------------------------------------
+
+// Check to see if the block bitmap indicates that block 'blockno' is free.
+// Return 1 if the block is free, 0 if not.
+bool
+block_is_free(uint32_t blockno)
+{
+	if (super == 0 || blockno >= super->s_nblocks)
+		return 0;
+	if (bitmap[blockno / 32] & (1 << (blockno % 32)))
+		return 1;
+	return 0;
+}
+
+// Mark a block free in the bitmap
+void
+free_block(uint32_t blockno)
+{
+	// Blockno zero is the null pointer of block numbers.
+	if (blockno == 0)
+		panic("attempt to free zero block");
+	bitmap[blockno/32] |= 1<<(blockno%32);
+}
+
+// Search the bitmap for a free block and allocate it.  When you
+// allocate a block, immediately flush the changed bitmap block
+// to disk.
+//
+// Return block number allocated on success,
+// -E_NO_DISK if we are out of blocks.
+//
+// Hint: use free_block as an example for manipulating the bitmap.
+int
+alloc_block(void)
+{
+	// The bitmap consists of one or more blocks.  A single bitmap block
+	// contains the in-use bits for BLKBITSIZE blocks.  There are
+	// super->s_nblocks blocks in the disk altogether.
+
+	// LAB 5: Your code here.
+	panic("alloc_block not implemented");
+	return -E_NO_DISK;
+}
+
+// Validate the file system bitmap.
+//
+// Check that all reserved blocks -- 0, 1, and the bitmap blocks themselves --
+// are all marked as in-use.
+void
+check_bitmap(void)
+{
+	uint32_t i;
+
+	// Make sure all bitmap blocks are marked in-use
+	for (i = 0; i * BLKBITSIZE < super->s_nblocks; i++)
+		assert(!block_is_free(2+i));
+
+	// Make sure the reserved and root blocks are marked in-use.
+	assert(!block_is_free(0));
+	assert(!block_is_free(1));
+
+	cprintf("bitmap is good\n");
+}
+
+// --------------------------------------------------------------
+// File system structures
+// --------------------------------------------------------------
+
+
+
+// Initialize the file system
+void
+fs_init(void)
+{
+	static_assert(sizeof(struct File) == 256);
+
+	// Find a JOS disk.  Use the second IDE disk (number 1) if available
+	if (ide_probe_disk1())
+		ide_set_disk(1);
+	else
+		ide_set_disk(0);
+	bc_init();
+
+	// Set "super" to point to the super block.
+	super = diskaddr(1);
+	check_super();
+
+	// Set "bitmap" to the beginning of the first bitmap block.
+	bitmap = diskaddr(2);
+	check_bitmap();
+	
+}
+
+// Find the disk block number slot for the 'filebno'th block in file 'f'.
+// Set '*ppdiskbno' to point to that slot.
+// The slot will be one of the f->f_direct[] entries,
+// or an entry in the indirect block.
+// When 'alloc' is set, this function will allocate an indirect block
+// if necessary.
+//
+// Returns:
+//	0 on success (but note that *ppdiskbno might equal 0).
+//	-E_NOT_FOUND if the function needed to allocate an indirect block, but
+//		alloc was 0.
+//	-E_NO_DISK if there's no space on the disk for an indirect block.
+//	-E_INVAL if filebno is out of range (it's >= NDIRECT + NINDIRECT).
+//
+// Analogy: This is like pgdir_walk for files.
+// Hint: Don't forget to clear any block you allocate.
+static int
+file_block_walk(struct File *f, uint32_t filebno, uint32_t **ppdiskbno, bool alloc)
+{
+       // LAB 5: Your code here.
+       panic("file_block_walk not implemented");
+}
+
+// Set *blk to the address in memory where the filebno'th
+// block of file 'f' would be mapped.
+//
+// Returns 0 on success, < 0 on error.  Errors are:
+//	-E_NO_DISK if a block needed to be allocated but the disk is full.
+//	-E_INVAL if filebno is out of range.
+//
+// Hint: Use file_block_walk and alloc_block.
+int
+file_get_block(struct File *f, uint32_t filebno, char **blk)
+{
+       // LAB 5: Your code here.
+       panic("file_get_block not implemented");
+}
+
+// Try to find a file named "name" in dir.  If so, set *file to it.
+//
+// Returns 0 and sets *file on success, < 0 on error.  Errors are:
+//	-E_NOT_FOUND if the file is not found
+static int
+dir_lookup(struct File *dir, const char *name, struct File **file)
+{
+	int r;
+	uint32_t i, j, nblock;
+	char *blk;
+	struct File *f;
+
+	// Search dir for name.
+	// We maintain the invariant that the size of a directory-file
+	// is always a multiple of the file system's block size.
+	assert((dir->f_size % BLKSIZE) == 0);
+	nblock = dir->f_size / BLKSIZE;
+	for (i = 0; i < nblock; i++) {
+		if ((r = file_get_block(dir, i, &blk)) < 0)
+			return r;
+		f = (struct File*) blk;
+		for (j = 0; j < BLKFILES; j++)
+			if (strcmp(f[j].f_name, name) == 0) {
+				*file = &f[j];
+				return 0;
+			}
+	}
+	return -E_NOT_FOUND;
+}
+
+// Set *file to point at a free File structure in dir.  The caller is
+// responsible for filling in the File fields.
+static int
+dir_alloc_file(struct File *dir, struct File **file)
+{
+	int r;
+	uint32_t nblock, i, j;
+	char *blk;
+	struct File *f;
+
+	assert((dir->f_size % BLKSIZE) == 0);
+	nblock = dir->f_size / BLKSIZE;
+	for (i = 0; i < nblock; i++) {
+		if ((r = file_get_block(dir, i, &blk)) < 0)
+			return r;
+		f = (struct File*) blk;
+		for (j = 0; j < BLKFILES; j++)
+			if (f[j].f_name[0] == '\0') {
+				*file = &f[j];
+				return 0;
+			}
+	}
+	dir->f_size += BLKSIZE;
+	if ((r = file_get_block(dir, i, &blk)) < 0)
+		return r;
+	f = (struct File*) blk;
+	*file = &f[0];
+	return 0;
+}
+
+// Skip over slashes.
+static const char*
+skip_slash(const char *p)
+{
+	while (*p == '/')
+		p++;
+	return p;
+}
+
+// Evaluate a path name, starting at the root.
+// On success, set *pf to the file we found
+// and set *pdir to the directory the file is in.
+// If we cannot find the file but find the directory
+// it should be in, set *pdir and copy the final path
+// element into lastelem.
+static int
+walk_path(const char *path, struct File **pdir, struct File **pf, char *lastelem)
+{
+	const char *p;
+	char name[MAXNAMELEN];
+	struct File *dir, *f;
+	int r;
+
+	// if (*path != '/')
+	//	return -E_BAD_PATH;
+	path = skip_slash(path);
+	f = &super->s_root;
+	dir = 0;
+	name[0] = 0;
+
+	if (pdir)
+		*pdir = 0;
+	*pf = 0;
+	while (*path != '\0') {
+		dir = f;
+		p = path;
+		while (*path != '/' && *path != '\0')
+			path++;
+		if (path - p >= MAXNAMELEN)
+			return -E_BAD_PATH;
+		memmove(name, p, path - p);
+		name[path - p] = '\0';
+		path = skip_slash(path);
+
+		if (dir->f_type != FTYPE_DIR)
+			return -E_NOT_FOUND;
+
+		if ((r = dir_lookup(dir, name, &f)) < 0) {
+			if (r == -E_NOT_FOUND && *path == '\0') {
+				if (pdir)
+					*pdir = dir;
+				if (lastelem)
+					strcpy(lastelem, name);
+				*pf = 0;
+			}
+			return r;
+		}
+	}
+
+	if (pdir)
+		*pdir = dir;
+	*pf = f;
+	return 0;
+}
+
+// --------------------------------------------------------------
+// File operations
+// --------------------------------------------------------------
+
+// Create "path".  On success set *pf to point at the file and return 0.
+// On error return < 0.
+int
+file_create(const char *path, struct File **pf)
+{
+	char name[MAXNAMELEN];
+	int r;
+	struct File *dir, *f;
+
+	if ((r = walk_path(path, &dir, &f, name)) == 0)
+		return -E_FILE_EXISTS;
+	if (r != -E_NOT_FOUND || dir == 0)
+		return r;
+	if ((r = dir_alloc_file(dir, &f)) < 0)
+		return r;
+
+	strcpy(f->f_name, name);
+	*pf = f;
+	file_flush(dir);
+	return 0;
+}
+
+// Open "path".  On success set *pf to point at the file and return 0.
+// On error return < 0.
+int
+file_open(const char *path, struct File **pf)
+{
+	return walk_path(path, 0, pf, 0);
+}
+
+// Read count bytes from f into buf, starting from seek position
+// offset.  This meant to mimic the standard pread function.
+// Returns the number of bytes read, < 0 on error.
+ssize_t
+file_read(struct File *f, void *buf, size_t count, off_t offset)
+{
+	int r, bn;
+	off_t pos;
+	char *blk;
+
+	if (offset >= f->f_size)
+		return 0;
+
+	count = MIN(count, f->f_size - offset);
+
+	for (pos = offset; pos < offset + count; ) {
+		if ((r = file_get_block(f, pos / BLKSIZE, &blk)) < 0)
+			return r;
+		bn = MIN(BLKSIZE - pos % BLKSIZE, offset + count - pos);
+		memmove(buf, blk + pos % BLKSIZE, bn);
+		pos += bn;
+		buf += bn;
+	}
+
+	return count;
+}
+
+
+// Write count bytes from buf into f, starting at seek position
+// offset.  This is meant to mimic the standard pwrite function.
+// Extends the file if necessary.
+// Returns the number of bytes written, < 0 on error.
+int
+file_write(struct File *f, const void *buf, size_t count, off_t offset)
+{
+	int r, bn;
+	off_t pos;
+	char *blk;
+
+	// Extend file if necessary
+	if (offset + count > f->f_size)
+		if ((r = file_set_size(f, offset + count)) < 0)
+			return r;
+
+	for (pos = offset; pos < offset + count; ) {
+		if ((r = file_get_block(f, pos / BLKSIZE, &blk)) < 0)
+			return r;
+		bn = MIN(BLKSIZE - pos % BLKSIZE, offset + count - pos);
+		memmove(blk + pos % BLKSIZE, buf, bn);
+		pos += bn;
+		buf += bn;
+	}
+
+	return count;
+}
+
+// Remove a block from file f.  If it's not there, just silently succeed.
+// Returns 0 on success, < 0 on error.
+static int
+file_free_block(struct File *f, uint32_t filebno)
+{
+	int r;
+	uint32_t *ptr;
+
+	if ((r = file_block_walk(f, filebno, &ptr, 0)) < 0)
+		return r;
+	if (*ptr) {
+		free_block(*ptr);
+		*ptr = 0;
+	}
+	return 0;
+}
+
+// Remove any blocks currently used by file 'f',
+// but not necessary for a file of size 'newsize'.
+// For both the old and new sizes, figure out the number of blocks required,
+// and then clear the blocks from new_nblocks to old_nblocks.
+// If the new_nblocks is no more than NDIRECT, and the indirect block has
+// been allocated (f->f_indirect != 0), then free the indirect block too.
+// (Remember to clear the f->f_indirect pointer so you'll know
+// whether it's valid!)
+// Do not change f->f_size.
+static void
+file_truncate_blocks(struct File *f, off_t newsize)
+{
+	int r;
+	uint32_t bno, old_nblocks, new_nblocks;
+
+	old_nblocks = (f->f_size + BLKSIZE - 1) / BLKSIZE;
+	new_nblocks = (newsize + BLKSIZE - 1) / BLKSIZE;
+	for (bno = new_nblocks; bno < old_nblocks; bno++)
+		if ((r = file_free_block(f, bno)) < 0)
+			cprintf("warning: file_free_block: %e", r);
+
+	if (new_nblocks <= NDIRECT && f->f_indirect) {
+		free_block(f->f_indirect);
+		f->f_indirect = 0;
+	}
+}
+
+// Set the size of file f, truncating or extending as necessary.
+int
+file_set_size(struct File *f, off_t newsize)
+{
+	if (f->f_size > newsize)
+		file_truncate_blocks(f, newsize);
+	f->f_size = newsize;
+	flush_block(f);
+	return 0;
+}
+
+// Flush the contents and metadata of file f out to disk.
+// Loop over all the blocks in file.
+// Translate the file block number into a disk block number
+// and then check whether that disk block is dirty.  If so, write it out.
+void
+file_flush(struct File *f)
+{
+	int i;
+	uint32_t *pdiskbno;
+
+	for (i = 0; i < (f->f_size + BLKSIZE - 1) / BLKSIZE; i++) {
+		if (file_block_walk(f, i, &pdiskbno, 0) < 0 ||
+		    pdiskbno == NULL || *pdiskbno == 0)
+			continue;
+		flush_block(diskaddr(*pdiskbno));
+	}
+	flush_block(f);
+	if (f->f_indirect)
+		flush_block(diskaddr(f->f_indirect));
+}
+
+
+// Sync the entire file system.  A big hammer.
+void
+fs_sync(void)
+{
+	int i;
+	for (i = 1; i < super->s_nblocks; i++)
+		flush_block(diskaddr(i));
+}
+

fs/fs.h

@@ -0,0 +1,49 @@
+#include <inc/fs.h>
+#include <inc/lib.h>
+
+#define SECTSIZE	512			// bytes per disk sector
+#define BLKSECTS	(BLKSIZE / SECTSIZE)	// sectors per block
+
+/* Disk block n, when in memory, is mapped into the file system
+ * server's address space at DISKMAP + (n*BLKSIZE). */
+#define DISKMAP		0x10000000
+
+/* Maximum disk size we can handle (3GB) */
+#define DISKSIZE	0xC0000000
+
+struct Super *super;		// superblock
+uint32_t *bitmap;		// bitmap blocks mapped in memory
+
+/* ide.c */
+bool	ide_probe_disk1(void);
+void	ide_set_disk(int diskno);
+void	ide_set_partition(uint32_t first_sect, uint32_t nsect);
+int	ide_read(uint32_t secno, void *dst, size_t nsecs);
+int	ide_write(uint32_t secno, const void *src, size_t nsecs);
+
+/* bc.c */
+void*	diskaddr(uint32_t blockno);
+bool	va_is_mapped(void *va);
+bool	va_is_dirty(void *va);
+void	flush_block(void *addr);
+void	bc_init(void);
+
+/* fs.c */
+void	fs_init(void);
+int	file_get_block(struct File *f, uint32_t file_blockno, char **pblk);
+int	file_create(const char *path, struct File **f);
+int	file_open(const char *path, struct File **f);
+ssize_t	file_read(struct File *f, void *buf, size_t count, off_t offset);
+int	file_write(struct File *f, const void *buf, size_t count, off_t offset);
+int	file_set_size(struct File *f, off_t newsize);
+void	file_flush(struct File *f);
+int	file_remove(const char *path);
+void	fs_sync(void);
+
+/* int	map_block(uint32_t); */
+bool	block_is_free(uint32_t blockno);
+int	alloc_block(void);
+
+/* test.c */
+void	fs_test(void);
+

fs/fsformat.c

@@ -0,0 +1,244 @@
+/*
+ * JOS file system format
+ */
+
+// We don't actually want to define off_t!
+#define off_t xxx_off_t
+#define bool xxx_bool
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#undef off_t
+#undef bool
+
+// Prevent inc/types.h, included from inc/fs.h,
+// from attempting to redefine types defined in the host's inttypes.h.
+#define JOS_INC_TYPES_H
+// Typedef the types that inc/mmu.h needs.
+typedef uint32_t physaddr_t;
+typedef uint32_t off_t;
+typedef int bool;
+
+#include <inc/mmu.h>
+#include <inc/fs.h>
+
+#define ROUNDUP(n, v) ((n) - 1 + (v) - ((n) - 1) % (v))
+#define MAX_DIR_ENTS 128
+
+struct Dir
+{
+	struct File *f;
+	struct File *ents;
+	int n;
+};
+
+uint32_t nblocks;
+char *diskmap, *diskpos;
+struct Super *super;
+uint32_t *bitmap;
+
+void
+panic(const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+	fputc('\n', stderr);
+	abort();
+}
+
+void
+readn(int f, void *out, size_t n)
+{
+	size_t p = 0;
+	while (p < n) {
+		ssize_t m = read(f, out + p, n - p);
+		if (m < 0)
+			panic("read: %s", strerror(errno));
+		if (m == 0)
+			panic("read: Unexpected EOF");
+		p += m;
+	}
+}
+
+uint32_t
+blockof(void *pos)
+{
+	return ((char*)pos - diskmap) / BLKSIZE;
+}
+
+void *
+alloc(uint32_t bytes)
+{
+	void *start = diskpos;
+	diskpos += ROUNDUP(bytes, BLKSIZE);
+	if (blockof(diskpos) >= nblocks)
+		panic("out of disk blocks");
+	return start;
+}
+
+void
+opendisk(const char *name)
+{
+	int r, diskfd, nbitblocks;
+
+	if ((diskfd = open(name, O_RDWR | O_CREAT, 0666)) < 0)
+		panic("open %s: %s", name, strerror(errno));
+
+	if ((r = ftruncate(diskfd, 0)) < 0
+	    || (r = ftruncate(diskfd, nblocks * BLKSIZE)) < 0)
+		panic("truncate %s: %s", name, strerror(errno));
+
+	if ((diskmap = mmap(NULL, nblocks * BLKSIZE, PROT_READ|PROT_WRITE,
+			    MAP_SHARED, diskfd, 0)) == MAP_FAILED)
+		panic("mmap %s: %s", name, strerror(errno));
+
+	close(diskfd);
+
+	diskpos = diskmap;
+	alloc(BLKSIZE);
+	super = alloc(BLKSIZE);
+	super->s_magic = FS_MAGIC;
+	super->s_nblocks = nblocks;
+	super->s_root.f_type = FTYPE_DIR;
+	strcpy(super->s_root.f_name, "/");
+
+	nbitblocks = (nblocks + BLKBITSIZE - 1) / BLKBITSIZE;
+	bitmap = alloc(nbitblocks * BLKSIZE);
+	memset(bitmap, 0xFF, nbitblocks * BLKSIZE);
+}
+
+void
+finishdisk(void)
+{
+	int r, i;
+
+	for (i = 0; i < blockof(diskpos); ++i)
+		bitmap[i/32] &= ~(1<<(i%32));
+
+	if ((r = msync(diskmap, nblocks * BLKSIZE, MS_SYNC)) < 0)
+		panic("msync: %s", strerror(errno));
+}
+
+void
+finishfile(struct File *f, uint32_t start, uint32_t len)
+{
+	int i;
+	f->f_size = len;
+	len = ROUNDUP(len, BLKSIZE);
+	for (i = 0; i < len / BLKSIZE && i < NDIRECT; ++i)
+		f->f_direct[i] = start + i;
+	if (i == NDIRECT) {
+		uint32_t *ind = alloc(BLKSIZE);
+		f->f_indirect = blockof(ind);
+		for (; i < len / BLKSIZE; ++i)
+			ind[i - NDIRECT] = start + i;
+	}
+}
+
+void
+startdir(struct File *f, struct Dir *dout)
+{
+	dout->f = f;
+	dout->ents = malloc(MAX_DIR_ENTS * sizeof *dout->ents);
+	dout->n = 0;
+}
+
+struct File *
+diradd(struct Dir *d, uint32_t type, const char *name)
+{
+	struct File *out = &d->ents[d->n++];
+	if (d->n > MAX_DIR_ENTS)
+		panic("too many directory entries");
+	strcpy(out->f_name, name);
+	out->f_type = type;
+	return out;
+}
+
+void
+finishdir(struct Dir *d)
+{
+	int size = d->n * sizeof(struct File);
+	struct File *start = alloc(size);
+	memmove(start, d->ents, size);
+	finishfile(d->f, blockof(start), ROUNDUP(size, BLKSIZE));
+	free(d->ents);
+	d->ents = NULL;
+}
+
+void
+writefile(struct Dir *dir, const char *name)
+{
+	int r, fd;
+	struct File *f;
+	struct stat st;
+	const char *last;
+	char *start;
+
+	if ((fd = open(name, O_RDONLY)) < 0)
+		panic("open %s: %s", name, strerror(errno));
+	if ((r = fstat(fd, &st)) < 0)
+		panic("stat %s: %s", name, strerror(errno));
+	if (!S_ISREG(st.st_mode))
+		panic("%s is not a regular file", name);
+	if (st.st_size >= MAXFILESIZE)
+		panic("%s too large", name);
+
+	last = strrchr(name, '/');
+	if (last)
+		last++;
+	else
+		last = name;
+
+	f = diradd(dir, FTYPE_REG, last);
+	start = alloc(st.st_size);
+	readn(fd, start, st.st_size);
+	finishfile(f, blockof(start), st.st_size);
+	close(fd);
+}
+
+void
+usage(void)
+{
+	fprintf(stderr, "Usage: fsformat fs.img NBLOCKS files...\n");
+	exit(2);
+}
+
+int
+main(int argc, char **argv)
+{
+	int i;
+	char *s;
+	struct Dir root;
+
+	assert(BLKSIZE % sizeof(struct File) == 0);
+
+	if (argc < 3)
+		usage();
+
+	nblocks = strtol(argv[2], &s, 0);
+	if (*s || s == argv[2] || nblocks < 2 || nblocks > 1024)
+		usage();
+
+	opendisk(argv[1]);
+
+	startdir(&super->s_root, &root);
+	for (i = 3; i < argc; i++)
+		writefile(&root, argv[i]);
+	finishdir(&root);
+
+	finishdisk();
+	return 0;
+}
+

fs/ide.c

@@ -0,0 +1,112 @@
+/*
+ * Minimal PIO-based (non-interrupt-driven) IDE driver code.
+ * For information about what all this IDE/ATA magic means,
+ * see the materials available on the class references page.
+ */
+
+#include "fs.h"
+#include <inc/x86.h>
+
+#define IDE_BSY		0x80
+#define IDE_DRDY	0x40
+#define IDE_DF		0x20
+#define IDE_ERR		0x01
+
+static int diskno = 1;
+
+static int
+ide_wait_ready(bool check_error)
+{
+	int r;
+
+	while (((r = inb(0x1F7)) & (IDE_BSY|IDE_DRDY)) != IDE_DRDY)
+		/* do nothing */;
+
+	if (check_error && (r & (IDE_DF|IDE_ERR)) != 0)
+		return -1;
+	return 0;
+}
+
+bool
+ide_probe_disk1(void)
+{
+	int r, x;
+
+	// wait for Device 0 to be ready
+	ide_wait_ready(0);
+
+	// switch to Device 1
+	outb(0x1F6, 0xE0 | (1<<4));
+
+	// check for Device 1 to be ready for a while
+	for (x = 0;
+	     x < 1000 && ((r = inb(0x1F7)) & (IDE_BSY|IDE_DF|IDE_ERR)) != 0;
+	     x++)
+		/* do nothing */;
+
+	// switch back to Device 0
+	outb(0x1F6, 0xE0 | (0<<4));
+
+	cprintf("Device 1 presence: %d\n", (x < 1000));
+	return (x < 1000);
+}
+
+void
+ide_set_disk(int d)
+{
+	if (d != 0 && d != 1)
+		panic("bad disk number");
+	diskno = d;
+}
+
+
+int
+ide_read(uint32_t secno, void *dst, size_t nsecs)
+{
+	int r;
+
+	assert(nsecs <= 256);
+
+	ide_wait_ready(0);
+
+	outb(0x1F2, nsecs);
+	outb(0x1F3, secno & 0xFF);
+	outb(0x1F4, (secno >> 8) & 0xFF);
+	outb(0x1F5, (secno >> 16) & 0xFF);
+	outb(0x1F6, 0xE0 | ((diskno&1)<<4) | ((secno>>24)&0x0F));
+	outb(0x1F7, 0x20);	// CMD 0x20 means read sector
+
+	for (; nsecs > 0; nsecs--, dst += SECTSIZE) {
+		if ((r = ide_wait_ready(1)) < 0)
+			return r;
+		insl(0x1F0, dst, SECTSIZE/4);
+	}
+
+	return 0;
+}
+
+int
+ide_write(uint32_t secno, const void *src, size_t nsecs)
+{
+	int r;
+
+	assert(nsecs <= 256);
+
+	ide_wait_ready(0);
+
+	outb(0x1F2, nsecs);
+	outb(0x1F3, secno & 0xFF);
+	outb(0x1F4, (secno >> 8) & 0xFF);
+	outb(0x1F5, (secno >> 16) & 0xFF);
+	outb(0x1F6, 0xE0 | ((diskno&1)<<4) | ((secno>>24)&0x0F));
+	outb(0x1F7, 0x30);	// CMD 0x30 means write sector
+
+	for (; nsecs > 0; nsecs--, src += SECTSIZE) {
+		if ((r = ide_wait_ready(1)) < 0)
+			return r;
+		outsl(0x1F0, src, SECTSIZE/4);
+	}
+
+	return 0;
+}
+

fs/lorem

@@ -0,0 +1,12 @@
+Lorem ipsum dolor sit amet, consectetur
+adipisicing elit, sed do eiusmod tempor
+incididunt ut labore et dolore magna
+aliqua. Ut enim ad minim veniam, quis
+nostrud exercitation ullamco laboris
+nisi ut aliquip ex ea commodo consequat.
+Duis aute irure dolor in reprehenderit
+in voluptate velit esse cillum dolore eu
+fugiat nulla pariatur. Excepteur sint
+occaecat cupidatat non proident, sunt in
+culpa qui officia deserunt mollit anim
+id est laborum.

fs/motd

@@ -0,0 +1,4 @@
+This is /motd, the message of the day.
+
+Welcome to the JOS kernel, now with a file system!
+

fs/newmotd

@@ -0,0 +1,2 @@
+This is the NEW message of the day!
+

fs/script

@@ -0,0 +1,5 @@
+echo This is from the script.
+cat lorem | num | cat
+echo These are my file descriptors.
+lsfd -1
+echo This is the end of the script.

fs/serv.c

@@ -0,0 +1,345 @@
+/*
+ * File system server main loop -
+ * serves IPC requests from other environments.
+ */
+
+#include <inc/x86.h>
+#include <inc/string.h>
+
+#include "fs.h"
+
+
+#define debug 0
+
+// The file system server maintains three structures
+// for each open file.
+//
+// 1. The on-disk 'struct File' is mapped into the part of memory
+//    that maps the disk.  This memory is kept private to the file
+//    server.
+// 2. Each open file has a 'struct Fd' as well, which sort of
+//    corresponds to a Unix file descriptor.  This 'struct Fd' is kept
+//    on *its own page* in memory, and it is shared with any
+//    environments that have the file open.
+// 3. 'struct OpenFile' links these other two structures, and is kept
+//    private to the file server.  The server maintains an array of
+//    all open files, indexed by "file ID".  (There can be at most
+//    MAXOPEN files open concurrently.)  The client uses file IDs to
+//    communicate with the server.  File IDs are a lot like
+//    environment IDs in the kernel.  Use openfile_lookup to translate
+//    file IDs to struct OpenFile.
+
+struct OpenFile {
+	uint32_t o_fileid;	// file id
+	struct File *o_file;	// mapped descriptor for open file
+	int o_mode;		// open mode
+	struct Fd *o_fd;	// Fd page
+};
+
+// Max number of open files in the file system at once
+#define MAXOPEN		1024
+#define FILEVA		0xD0000000
+
+// initialize to force into data section
+struct OpenFile opentab[MAXOPEN] = {
+	{ 0, 0, 1, 0 }
+};
+
+// Virtual address at which to receive page mappings containing client requests.
+union Fsipc *fsreq = (union Fsipc *)0x0ffff000;
+
+void
+serve_init(void)
+{
+	int i;
+	uintptr_t va = FILEVA;
+	for (i = 0; i < MAXOPEN; i++) {
+		opentab[i].o_fileid = i;
+		opentab[i].o_fd = (struct Fd*) va;
+		va += PGSIZE;
+	}
+}
+
+// Allocate an open file.
+int
+openfile_alloc(struct OpenFile **o)
+{
+	int i, r;
+
+	// Find an available open-file table entry
+	for (i = 0; i < MAXOPEN; i++) {
+		switch (pageref(opentab[i].o_fd)) {
+		case 0:
+			if ((r = sys_page_alloc(0, opentab[i].o_fd, PTE_P|PTE_U|PTE_W)) < 0)
+				return r;
+			/* fall through */
+		case 1:
+			opentab[i].o_fileid += MAXOPEN;
+			*o = &opentab[i];
+			memset(opentab[i].o_fd, 0, PGSIZE);
+			return (*o)->o_fileid;
+		}
+	}
+	return -E_MAX_OPEN;
+}
+
+// Look up an open file for envid.
+int
+openfile_lookup(envid_t envid, uint32_t fileid, struct OpenFile **po)
+{
+	struct OpenFile *o;
+
+	o = &opentab[fileid % MAXOPEN];
+	if (pageref(o->o_fd) <= 1 || o->o_fileid != fileid)
+		return -E_INVAL;
+	*po = o;
+	return 0;
+}
+
+// Open req->req_path in mode req->req_omode, storing the Fd page and
+// permissions to return to the calling environment in *pg_store and
+// *perm_store respectively.
+int
+serve_open(envid_t envid, struct Fsreq_open *req,
+	   void **pg_store, int *perm_store)
+{
+	char path[MAXPATHLEN];
+	struct File *f;
+	int fileid;
+	int r;
+	struct OpenFile *o;
+
+	if (debug)
+		cprintf("serve_open %08x %s 0x%x\n", envid, req->req_path, req->req_omode);
+
+	// Copy in the path, making sure it's null-terminated
+	memmove(path, req->req_path, MAXPATHLEN);
+	path[MAXPATHLEN-1] = 0;
+
+	// Find an open file ID
+	if ((r = openfile_alloc(&o)) < 0) {
+		if (debug)
+			cprintf("openfile_alloc failed: %e", r);
+		return r;
+	}
+	fileid = r;
+
+	// Open the file
+	if (req->req_omode & O_CREAT) {
+		if ((r = file_create(path, &f)) < 0) {
+			if (!(req->req_omode & O_EXCL) && r == -E_FILE_EXISTS)
+				goto try_open;
+			if (debug)
+				cprintf("file_create failed: %e", r);
+			return r;
+		}
+	} else {
+try_open:
+		if ((r = file_open(path, &f)) < 0) {
+			if (debug)
+				cprintf("file_open failed: %e", r);
+			return r;
+		}
+	}
+
+	// Truncate
+	if (req->req_omode & O_TRUNC) {
+		if ((r = file_set_size(f, 0)) < 0) {
+			if (debug)
+				cprintf("file_set_size failed: %e", r);
+			return r;
+		}
+	}
+	if ((r = file_open(path, &f)) < 0) {
+		if (debug)
+			cprintf("file_open failed: %e", r);
+		return r;
+	}
+
+	// Save the file pointer
+	o->o_file = f;
+
+	// Fill out the Fd structure
+	o->o_fd->fd_file.id = o->o_fileid;
+	o->o_fd->fd_omode = req->req_omode & O_ACCMODE;
+	o->o_fd->fd_dev_id = devfile.dev_id;
+	o->o_mode = req->req_omode;
+
+	if (debug)
+		cprintf("sending success, page %08x\n", (uintptr_t) o->o_fd);
+
+	// Share the FD page with the caller by setting *pg_store,
+	// store its permission in *perm_store
+	*pg_store = o->o_fd;
+	*perm_store = PTE_P|PTE_U|PTE_W|PTE_SHARE;
+
+	return 0;
+}
+
+// Set the size of req->req_fileid to req->req_size bytes, truncating
+// or extending the file as necessary.
+int
+serve_set_size(envid_t envid, struct Fsreq_set_size *req)
+{
+	struct OpenFile *o;
+	int r;
+
+	if (debug)
+		cprintf("serve_set_size %08x %08x %08x\n", envid, req->req_fileid, req->req_size);
+
+	// Every file system IPC call has the same general structure.
+	// Here's how it goes.
+
+	// First, use openfile_lookup to find the relevant open file.
+	// On failure, return the error code to the client with ipc_send.
+	if ((r = openfile_lookup(envid, req->req_fileid, &o)) < 0)
+		return r;
+
+	// Second, call the relevant file system function (from fs/fs.c).
+	// On failure, return the error code to the client.
+	return file_set_size(o->o_file, req->req_size);
+}
+
+// Read at most ipc->read.req_n bytes from the current seek position
+// in ipc->read.req_fileid.  Return the bytes read from the file to
+// the caller in ipc->readRet, then update the seek position.  Returns
+// the number of bytes successfully read, or < 0 on error.
+int
+serve_read(envid_t envid, union Fsipc *ipc)
+{
+	struct Fsreq_read *req = &ipc->read;
+	struct Fsret_read *ret = &ipc->readRet;
+
+	if (debug)
+		cprintf("serve_read %08x %08x %08x\n", envid, req->req_fileid, req->req_n);
+
+	// Lab 5: Your code here:
+	return 0;
+}
+
+
+// Write req->req_n bytes from req->req_buf to req_fileid, starting at
+// the current seek position, and update the seek position
+// accordingly.  Extend the file if necessary.  Returns the number of
+// bytes written, or < 0 on error.
+int
+serve_write(envid_t envid, struct Fsreq_write *req)
+{
+	if (debug)
+		cprintf("serve_write %08x %08x %08x\n", envid, req->req_fileid, req->req_n);
+
+	// LAB 5: Your code here.
+	panic("serve_write not implemented");
+}
+
+// Stat ipc->stat.req_fileid.  Return the file's struct Stat to the
+// caller in ipc->statRet.
+int
+serve_stat(envid_t envid, union Fsipc *ipc)
+{
+	struct Fsreq_stat *req = &ipc->stat;
+	struct Fsret_stat *ret = &ipc->statRet;
+	struct OpenFile *o;
+	int r;
+
+	if (debug)
+		cprintf("serve_stat %08x %08x\n", envid, req->req_fileid);
+
+	if ((r = openfile_lookup(envid, req->req_fileid, &o)) < 0)
+		return r;
+
+	strcpy(ret->ret_name, o->o_file->f_name);
+	ret->ret_size = o->o_file->f_size;
+	ret->ret_isdir = (o->o_file->f_type == FTYPE_DIR);
+	return 0;
+}
+
+// Flush all data and metadata of req->req_fileid to disk.
+int
+serve_flush(envid_t envid, struct Fsreq_flush *req)
+{
+	struct OpenFile *o;
+	int r;
+
+	if (debug)
+		cprintf("serve_flush %08x %08x\n", envid, req->req_fileid);
+
+	if ((r = openfile_lookup(envid, req->req_fileid, &o)) < 0)
+		return r;
+	file_flush(o->o_file);
+	return 0;
+}
+
+
+int
+serve_sync(envid_t envid, union Fsipc *req)
+{
+	fs_sync();
+	return 0;
+}
+
+typedef int (*fshandler)(envid_t envid, union Fsipc *req);
+
+fshandler handlers[] = {
+	// Open is handled specially because it passes pages
+	/* [FSREQ_OPEN] =	(fshandler)serve_open, */
+	[FSREQ_READ] =		serve_read,
+	[FSREQ_STAT] =		serve_stat,
+	[FSREQ_FLUSH] =		(fshandler)serve_flush,
+	[FSREQ_WRITE] =		(fshandler)serve_write,
+	[FSREQ_SET_SIZE] =	(fshandler)serve_set_size,
+	[FSREQ_SYNC] =		serve_sync
+};
+
+void
+serve(void)
+{
+	uint32_t req, whom;
+	int perm, r;
+	void *pg;
+
+	while (1) {
+		perm = 0;
+		req = ipc_recv((int32_t *) &whom, fsreq, &perm);
+		if (debug)
+			cprintf("fs req %d from %08x [page %08x: %s]\n",
+				req, whom, uvpt[PGNUM(fsreq)], fsreq);
+
+		// All requests must contain an argument page
+		if (!(perm & PTE_P)) {
+			cprintf("Invalid request from %08x: no argument page\n",
+				whom);
+			continue; // just leave it hanging...
+		}
+
+		pg = NULL;
+		if (req == FSREQ_OPEN) {
+			r = serve_open(whom, (struct Fsreq_open*)fsreq, &pg, &perm);
+		} else if (req < ARRAY_SIZE(handlers) && handlers[req]) {
+			r = handlers[req](whom, fsreq);
+		} else {
+			cprintf("Invalid request code %d from %08x\n", req, whom);
+			r = -E_INVAL;
+		}
+		ipc_send(whom, r, pg, perm);
+		sys_page_unmap(0, fsreq);
+	}
+}
+
+void
+umain(int argc, char **argv)
+{
+	static_assert(sizeof(struct File) == 256);
+	binaryname = "fs";
+	cprintf("FS is running\n");
+
+	// Check that we are able to do I/O
+	outw(0x8A00, 0x8A00);
+	cprintf("FS can do I/O\n");
+
+	serve_init();
+	fs_init();
+        fs_test();
+	serve();
+}
+

fs/testshell.sh

@@ -0,0 +1,7 @@
+echo hello world | cat
+cat lorem
+cat lorem |num
+cat lorem |num |num |num |num |num
+lsfd -1
+cat script
+sh <script

grade-lab5

@@ -0,0 +1,112 @@
+#!/usr/bin/env python
+
+from gradelib import *
+
+r = Runner(save("jos.out"),
+           stop_breakpoint("readline"))
+
+def matchtest(parent, name, *args, **kw):
+    def do_test():
+        r.match(*args, **kw)
+    test(5, name, parent=parent)(do_test)
+
+@test(5, "internal FS tests [fs/test.c]")
+def test_fs():
+    r.user_test("hello")
+matchtest(test_fs, "fs i/o",
+          "FS can do I/O")
+matchtest(test_fs, "check_bc",
+          "block cache is good")
+matchtest(test_fs, "check_super",
+          "superblock is good")
+matchtest(test_fs, "check_bitmap",
+          "bitmap is good")
+matchtest(test_fs, "alloc_block",
+          "alloc_block is good")
+matchtest(test_fs, "file_open",
+          "file_open is good")
+matchtest(test_fs, "file_get_block",
+          "file_get_block is good")
+matchtest(test_fs, "file_flush/file_truncate/file rewrite",
+          "file_flush is good",
+          "file_truncate is good",
+          "file rewrite is good")
+
+@test(10, "testfile")
+def test_testfile():
+    r.user_test("testfile")
+matchtest(test_testfile, "serve_open/file_stat/file_close",
+          "serve_open is good",
+          "file_stat is good",
+          "file_close is good",
+          "stale fileid is good")
+matchtest(test_testfile, "file_read",
+          "file_read is good")
+matchtest(test_testfile, "file_write",
+          "file_write is good")
+matchtest(test_testfile, "file_read after file_write",
+          "file_read after file_write is good")
+matchtest(test_testfile, "open",
+          "open is good")
+matchtest(test_testfile, "large file",
+          "large file is good")
+
+@test(10, "spawn via spawnhello")
+def test_spawn():
+    r.user_test("spawnhello")
+    r.match('i am parent environment 00001001',
+            'hello, world',
+            'i am environment 00001002',
+            'No runnable environments in the system!')
+
+@test(5, "Protection I/O space")
+def test_faultio():
+    r.user_test("spawnfaultio")
+    r.match('TRAP')
+
+@test(10, "PTE_SHARE [testpteshare]")
+def test_pte_share():
+    r.user_test("testpteshare")
+    r.match('fork handles PTE_SHARE right',
+            'spawn handles PTE_SHARE right')
+
+@test(5, "PTE_SHARE [testfdsharing]")
+def test_fd_share():
+    r.user_test("testfdsharing")
+    r.match('read in child succeeded',
+            'read in parent succeeded')
+
+@test(10, "start the shell [icode]")
+def test_icode():
+    r.user_test("icode")
+    r.match('icode: read /motd',
+            'This is /motd, the message of the day.',
+            'icode: spawn /init',
+            'init: running',
+            'init: data seems okay',
+            'icode: exiting',
+            'init: bss seems okay',
+            "init: args: 'init' 'initarg1' 'initarg2'",
+            'init: running sh',
+            '\$ ')
+
+@test(15)
+def test_testshell():
+    r.user_test("testshell", timeout=60)
+    r.match("shell ran correctly")
+
+def gen_primes(n):
+    rest = range(2, n)
+    while rest:
+        yield rest[0]
+        rest = [n for n in rest if n % rest[0]]
+
+@test(10)
+def test_primespipe():
+    r.user_test("primespipe", stop_on_line("[0-9]{4}$"), timeout=120)
+    primes = set(gen_primes(1000))
+    nonprimes = set(range(1000)) - primes
+    r.match(no=["%d$" % np for np in nonprimes],
+            *["%d$" % p for p in primes])
+
+run_tests()

inc/args.h

@@ -0,0 +1,82 @@
+#ifndef JOS_INC_ARGS_H
+#define JOS_INC_ARGS_H
+
+struct Argstate;
+
+// JOS command-line parsing functions.
+
+// Initializes the Argstate buffer from argc and argv.
+// (Note: it is safe to use a 'const char **' for argv.)
+void argstart(int *argc, char **argv, struct Argstate *args);
+
+// Returns the next flag in the argument list,
+// or -1 if there are no more flags.
+//
+// Flags stop at a non-flag (anything that doesn't start with '-'),
+// at the end of the argument list, before "-", or after "--",
+// whichever comes first.  Any "--" argument is not returned.
+//
+// Consumes arguments from the argc/argv array passed in to argstart.
+// If you argstart with an argc/argv array of ["sh", "-i", "foo"],
+// the first call to argnext will return 'i' and change the array to
+// ["sh", "foo"].  Thus, when argnext returns -1, the argc/argv array
+// contains just the non-flag arguments.
+int argnext(struct Argstate *);
+
+// Returns the next value for the current flag, or 0 if it has no value.
+// For example, given an argument list ["-fval1", "val2", "val3"],
+// a call to argnext() will return 'f', after which repeated calls to
+// argnextvalue will return "val1", "val2", and "val3".
+// Consumes arguments from the argc/argv array.
+char *argnextvalue(struct Argstate *);
+
+// Returns the current flag's value, or 0 if it has no value.
+// Behaves like argnextvalue, except that repeated calls to argvalue will
+// return the same value.
+char *argvalue(struct Argstate *);
+
+// Example:
+//
+//	#include <inc/lib.h>
+//
+//	void
+//	umain(int argc, char **argv)
+//	{
+//		int i;
+//		struct Argstate args;
+//
+//		argstart(&argc, argv, &args);
+//		while ((i = argnext(&args)) >= 0)
+//			switch (i) {
+//			case 'r':
+//			case 'x':
+//				cprintf("'-%c' flag\n", i);
+//				break;
+//			case 'f':
+//				cprintf("'-f %s' flag\n", argvalue(&args));
+//				break;
+//			default:
+//				cprintf("unknown flag\n");
+//			}
+//
+//		for (i = 1; i < argc; i++)
+//			cprintf("argument '%s'\n", argv[i]);
+//	}
+//
+// If this program is run with the arguments
+// ["-rx", "-f", "foo", "--", "-r", "duh"]
+// it will print out
+//	'-r' flag
+//	'-x' flag
+//	'-f foo' flag
+//	argument '-r'
+//	argument 'duh'
+
+struct Argstate {
+	int *argc;
+	const char **argv;
+	const char *curarg;
+	const char *argvalue;
+};
+
+#endif

inc/env.h

@@ -41,6 +41,7 @@ enum {
 // Special environment types
 enum EnvType {
 	ENV_TYPE_USER = 0,
+	ENV_TYPE_FS,		// File system server
 };
 
 struct Env {

inc/error.h

@@ -17,6 +17,15 @@ enum {
 	E_IPC_NOT_RECV	,	// Attempt to send to env that is not recving
 	E_EOF		,	// Unexpected end of file
 
+	// File system error codes -- only seen in user-level
+	E_NO_DISK	,	// No free space left on disk
+	E_MAX_OPEN	,	// Too many files are open
+	E_NOT_FOUND	, 	// File or block not found
+	E_BAD_PATH	,	// Bad path
+	E_FILE_EXISTS	,	// File already exists
+	E_NOT_EXEC	,	// File not a valid executable
+	E_NOT_SUPP	,	// Operation not supported
+
 	MAXERROR
 };
 

inc/fd.h

@@ -0,0 +1,58 @@
+// Public definitions for the POSIX-like file descriptor emulation layer
+// that our user-land support library implements for the use of applications.
+// See the code in the lib directory for the implementation details.
+
+#ifndef JOS_INC_FD_H
+#define JOS_INC_FD_H
+
+#include <inc/types.h>
+#include <inc/fs.h>
+
+struct Fd;
+struct Stat;
+struct Dev;
+
+// Per-device-class file descriptor operations
+struct Dev {
+	int dev_id;
+	const char *dev_name;
+	ssize_t (*dev_read)(struct Fd *fd, void *buf, size_t len);
+	ssize_t (*dev_write)(struct Fd *fd, const void *buf, size_t len);
+	int (*dev_close)(struct Fd *fd);
+	int (*dev_stat)(struct Fd *fd, struct Stat *stat);
+	int (*dev_trunc)(struct Fd *fd, off_t length);
+};
+
+struct FdFile {
+	int id;
+};
+
+struct Fd {
+	int fd_dev_id;
+	off_t fd_offset;
+	int fd_omode;
+	union {
+		// File server files
+		struct FdFile fd_file;
+	};
+};
+
+struct Stat {
+	char st_name[MAXNAMELEN];
+	off_t st_size;
+	int st_isdir;
+	struct Dev *st_dev;
+};
+
+char*	fd2data(struct Fd *fd);
+int	fd2num(struct Fd *fd);
+int	fd_alloc(struct Fd **fd_store);
+int	fd_close(struct Fd *fd, bool must_exist);
+int	fd_lookup(int fdnum, struct Fd **fd_store);
+int	dev_lookup(int devid, struct Dev **dev_store);
+
+extern struct Dev devfile;
+extern struct Dev devcons;
+extern struct Dev devpipe;
+
+#endif	// not JOS_INC_FD_H

inc/fs.h

@@ -0,0 +1,116 @@
+// See COPYRIGHT for copyright information.
+
+#ifndef JOS_INC_FS_H
+#define JOS_INC_FS_H
+
+#include <inc/types.h>
+#include <inc/mmu.h>
+
+// File nodes (both in-memory and on-disk)
+
+// Bytes per file system block - same as page size
+#define BLKSIZE		PGSIZE
+#define BLKBITSIZE	(BLKSIZE * 8)
+
+// Maximum size of a filename (a single path component), including null
+// Must be a multiple of 4
+#define MAXNAMELEN	128
+
+// Maximum size of a complete pathname, including null
+#define MAXPATHLEN	1024
+
+// Number of block pointers in a File descriptor
+#define NDIRECT		10
+// Number of direct block pointers in an indirect block
+#define NINDIRECT	(BLKSIZE / 4)
+
+#define MAXFILESIZE	((NDIRECT + NINDIRECT) * BLKSIZE)
+
+struct File {
+	char f_name[MAXNAMELEN];	// filename
+	off_t f_size;			// file size in bytes
+	uint32_t f_type;		// file type
+
+	// Block pointers.
+	// A block is allocated iff its value is != 0.
+	uint32_t f_direct[NDIRECT];	// direct blocks
+	uint32_t f_indirect;		// indirect block
+
+	// Pad out to 256 bytes; must do arithmetic in case we're compiling
+	// fsformat on a 64-bit machine.
+	uint8_t f_pad[256 - MAXNAMELEN - 8 - 4*NDIRECT - 4];
+} __attribute__((packed));	// required only on some 64-bit machines
+
+// An inode block contains exactly BLKFILES 'struct File's
+#define BLKFILES	(BLKSIZE / sizeof(struct File))
+
+// File types
+#define FTYPE_REG	0	// Regular file
+#define FTYPE_DIR	1	// Directory
+
+
+// File system super-block (both in-memory and on-disk)
+
+#define FS_MAGIC	0x4A0530AE	// related vaguely to 'J\0S!'
+
+struct Super {
+	uint32_t s_magic;		// Magic number: FS_MAGIC
+	uint32_t s_nblocks;		// Total number of blocks on disk
+	struct File s_root;		// Root directory node
+};
+
+// Definitions for requests from clients to file system
+enum {
+	FSREQ_OPEN = 1,
+	FSREQ_SET_SIZE,
+	// Read returns a Fsret_read on the request page
+	FSREQ_READ,
+	FSREQ_WRITE,
+	// Stat returns a Fsret_stat on the request page
+	FSREQ_STAT,
+	FSREQ_FLUSH,
+	FSREQ_REMOVE,
+	FSREQ_SYNC
+};
+
+union Fsipc {
+	struct Fsreq_open {
+		char req_path[MAXPATHLEN];
+		int req_omode;
+	} open;
+	struct Fsreq_set_size {
+		int req_fileid;
+		off_t req_size;
+	} set_size;
+	struct Fsreq_read {
+		int req_fileid;
+		size_t req_n;
+	} read;
+	struct Fsret_read {
+		char ret_buf[PGSIZE];
+	} readRet;
+	struct Fsreq_write {
+		int req_fileid;
+		size_t req_n;
+		char req_buf[PGSIZE - (sizeof(int) + sizeof(size_t))];
+	} write;
+	struct Fsreq_stat {
+		int req_fileid;
+	} stat;
+	struct Fsret_stat {
+		char ret_name[MAXNAMELEN];
+		off_t ret_size;
+		int ret_isdir;
+	} statRet;
+	struct Fsreq_flush {
+		int req_fileid;
+	} flush;
+	struct Fsreq_remove {
+		char req_path[MAXPATHLEN];
+	} remove;
+
+	// Ensure Fsipc is one page
+	char _pad[PGSIZE];
+};
+
+#endif /* !JOS_INC_FS_H */

inc/lib.h

@@ -17,6 +17,9 @@
 #include <inc/memlayout.h>
 #include <inc/syscall.h>
 #include <inc/trap.h>
+#include <inc/fs.h>
+#include <inc/fd.h>
+#include <inc/args.h>
 
 #define USED(x)		(void)(x)
 
@@ -46,6 +49,7 @@ int	sys_env_destroy(envid_t);
 void	sys_yield(void);
 static envid_t sys_exofork(void);
 int	sys_env_set_status(envid_t env, int status);
+int	sys_env_set_trapframe(envid_t env, struct Trapframe *tf);
 int	sys_env_set_pgfault_upcall(envid_t env, void *upcall);
 int	sys_page_alloc(envid_t env, void *pg, int perm);
 int	sys_page_map(envid_t src_env, void *src_pg,
@@ -75,7 +79,43 @@ envid_t	ipc_find_env(enum EnvType type);
 envid_t	fork(void);
 envid_t	sfork(void);	// Challenge!
 
+// fd.c
+int	close(int fd);
+ssize_t	read(int fd, void *buf, size_t nbytes);
+ssize_t	write(int fd, const void *buf, size_t nbytes);
+int	seek(int fd, off_t offset);
+void	close_all(void);
+ssize_t	readn(int fd, void *buf, size_t nbytes);
+int	dup(int oldfd, int newfd);
+int	fstat(int fd, struct Stat *statbuf);
+int	stat(const char *path, struct Stat *statbuf);
 
+// file.c
+int	open(const char *path, int mode);
+int	ftruncate(int fd, off_t size);
+int	remove(const char *path);
+int	sync(void);
+
+// pageref.c
+int	pageref(void *addr);
+
+
+// spawn.c
+envid_t	spawn(const char *program, const char **argv);
+envid_t	spawnl(const char *program, const char *arg0, ...);
+
+// console.c
+void	cputchar(int c);
+int	getchar(void);
+int	iscons(int fd);
+int	opencons(void);
+
+// pipe.c
+int	pipe(int pipefds[2]);
+int	pipeisclosed(int pipefd);
+
+// wait.c
+void	wait(envid_t env);
 
 /* File open modes */
 #define	O_RDONLY	0x0000		/* open for reading only */

inc/partition.h

@@ -0,0 +1,33 @@
+#ifndef JOS_INC_PARTITION_H
+#define JOS_INC_PARTITION_H
+#include <inc/types.h>
+
+/*
+ * This file contains definitions for x86 partition tables, and comes from
+ * Mike Mammarella.
+ */
+
+// Offset of 1st partition descriptor in a partition sector
+#define PTABLE_OFFSET		446
+// 2-byte partition table magic number location and value
+#define PTABLE_MAGIC_OFFSET	510
+#define PTABLE_MAGIC		"\x55\xAA"
+
+// Partition type constants
+#define PTYPE_JOS_KERN		0x27	// JOS kernel
+#define PTYPE_JOSFS		0x28	// JOS file system
+// Extended partition identifiers
+#define PTYPE_DOS_EXTENDED	0x05
+#define PTYPE_W95_EXTENDED	0x0F
+#define PTYPE_LINUX_EXTENDED	0x85
+
+struct Partitiondesc {
+	uint8_t boot;
+	uint8_t chs_begin[3];
+	uint8_t type;
+	uint8_t chs_end[3];
+	uint32_t lba_start;
+	uint32_t lba_length;
+};
+
+#endif

inc/syscall.h

@@ -12,6 +12,7 @@ enum {
 	SYS_page_unmap,
 	SYS_exofork,
 	SYS_env_set_status,
+	SYS_env_set_trapframe,
 	SYS_env_set_pgfault_upcall,
 	SYS_yield,
 	SYS_ipc_try_send,

kern/Makefrag

@@ -76,6 +76,24 @@ KERN_BINFILES +=	user/idle \
 			user/pingpong \
 			user/pingpongs \
 			user/primes
+# Binary files for LAB5
+KERN_BINFILES +=	user/faultio\
+	      		user/spawnfaultio\
+	      		user/testfile \
+			user/spawnhello \
+			user/icode \
+			fs/fs
+
+# Binary files for LAB5
+KERN_BINFILES +=	user/testpteshare \
+			user/testfdsharing \
+			user/testpipe \
+			user/testpiperace \
+			user/testpiperace2 \
+			user/primespipe \
+			user/testkbd \
+			user/testshell
+
 KERN_OBJFILES := $(patsubst %.c, $(OBJDIR)/%.o, $(KERN_SRCFILES))
 KERN_OBJFILES := $(patsubst %.S, $(OBJDIR)/%.o, $(KERN_OBJFILES))
 KERN_OBJFILES := $(patsubst $(OBJDIR)/lib/%, $(OBJDIR)/kern/%, $(KERN_OBJFILES))

kern/console.c

@@ -102,6 +102,9 @@ serial_init(void)
 	(void) inb(COM1+COM_IIR);
 	(void) inb(COM1+COM_RX);
 
+	// Enable serial interrupts
+	if (serial_exists)
+		irq_setmask_8259A(irq_mask_8259A & ~(1<<IRQ_SERIAL));
 }
 
 

kern/env.c

@@ -258,7 +258,7 @@ env_alloc(struct Env **newenv_store, envid_t parent_id)
 	env_free_list = e->env_link;
 	*newenv_store = e;
 
-	cprintf("[%08x] new env %08x\n", curenv ? curenv->env_id : 0, e->env_id);
+	// cprintf("[%08x] new env %08x\n", curenv ? curenv->env_id : 0, e->env_id);
 	return 0;
 }
 
@@ -353,6 +353,9 @@ void
 env_create(uint8_t *binary, enum EnvType type)
 {
 	// LAB 3: Your code here.
+
+	// If this is the file server (type == ENV_TYPE_FS) give it I/O privileges.
+	// LAB 5: Your code here.
 }
 
 //
@@ -372,7 +375,7 @@ env_free(struct Env *e)
 		lcr3(PADDR(kern_pgdir));
 
 	// Note the environment's demise.
-	cprintf("[%08x] free env %08x\n", curenv ? curenv->env_id : 0, e->env_id);
+	// cprintf("[%08x] free env %08x\n", curenv ? curenv->env_id : 0, e->env_id);
 
 	// Flush all mapped pages in the user portion of the address space
 	static_assert(UTOP % PTSIZE == 0);

kern/init.c

@@ -47,14 +47,20 @@ i386_init(void)
 	// Starting non-boot CPUs
 	boot_aps();
 
+	// Start fs.
+	ENV_CREATE(fs_fs, ENV_TYPE_FS);
+
 #if defined(TEST)
 	// Don't touch -- used by grading script!
 	ENV_CREATE(TEST, ENV_TYPE_USER);
 #else
 	// Touch all you want.
-	ENV_CREATE(user_primes, ENV_TYPE_USER);
+	ENV_CREATE(user_icode, ENV_TYPE_USER);
 #endif // TEST*
 
+	// Should not be necessary - drains keyboard because interrupt has given up.
+	kbd_intr();
+
 	// Schedule and run the first user environment!
 	sched_yield();
 }

kern/pmap.c

@@ -84,6 +84,8 @@ static void check_page_installed_pgdir(void);
 // If we're out of memory, boot_alloc should panic.
 // This function may ONLY be used during initialization,
 // before the page_free_list list has been set up.
+// Note that when this function is called, we are still using entry_pgdir,
+// which only maps the first 4MB of physical memory.
 static void *
 boot_alloc(uint32_t n)
 {

kern/sched.c

@@ -21,7 +21,8 @@ sched_yield(void)
 	//
 	// If no envs are runnable, but the environment previously
 	// running on this CPU is still ENV_RUNNING, it's okay to
-	// choose that environment.
+	// choose that environment. Make sure curenv is not null before
+	// dereferencing it.
 	//
 	// Never choose an environment that's currently running on
 	// another CPU (env_status == ENV_RUNNING). If there are

kern/syscall.c

@@ -55,10 +55,6 @@ sys_env_destroy(envid_t envid)
 
 	if ((r = envid2env(envid, &e, 1)) < 0)
 		return r;
-	if (e == curenv)
-		cprintf("[%08x] exiting gracefully\n", curenv->env_id);
-	else
-		cprintf("[%08x] destroying %08x\n", curenv->env_id, e->env_id);
 	env_destroy(e);
 	return 0;
 }
@@ -107,6 +103,22 @@ sys_env_set_status(envid_t envid, int status)
 	panic("sys_env_set_status not implemented");
 }
 
+// Set envid's trap frame to 'tf'.
+// tf is modified to make sure that user environments always run at code
+// protection level 3 (CPL 3), interrupts enabled, and IOPL of 0.
+//
+// Returns 0 on success, < 0 on error.  Errors are:
+//	-E_BAD_ENV if environment envid doesn't currently exist,
+//		or the caller doesn't have permission to change envid.
+static int
+sys_env_set_trapframe(envid_t envid, struct Trapframe *tf)
+{
+	// LAB 5: Your code here.
+	// Remember to check whether the user has supplied us with a good
+	// address!
+	panic("sys_env_set_trapframe not implemented");
+}
+
 // Set the page fault upcall for 'envid' by modifying the corresponding struct
 // Env's 'env_pgfault_upcall' field.  When 'envid' causes a page fault, the
 // kernel will push a fault record onto the exception stack, then branch to

kern/trap.c

@@ -190,6 +190,9 @@ trap_dispatch(struct Trapframe *tf)
 	// interrupt using lapic_eoi() before calling the scheduler!
 	// LAB 4: Your code here.
 
+	// Handle keyboard and serial interrupts.
+	// LAB 5: Your code here.
+
 	// Unexpected trap: The user process or the kernel has a bug.
 	print_trapframe(tf);
 	if (tf->tf_cs == GD_KT)

lib/Makefrag

@@ -16,7 +16,17 @@ LIB_SRCFILES :=		$(LIB_SRCFILES) \
 			lib/fork.c \
 			lib/ipc.c
 
+LIB_SRCFILES :=		$(LIB_SRCFILES) \
+			lib/args.c \
+			lib/fd.c \
+			lib/file.c \
+			lib/fprintf.c \
+			lib/pageref.c \
+			lib/spawn.c
 
+LIB_SRCFILES :=		$(LIB_SRCFILES) \
+			lib/pipe.c \
+			lib/wait.c
 
 LIB_OBJFILES := $(patsubst lib/%.c, $(OBJDIR)/lib/%.o, $(LIB_SRCFILES))
 LIB_OBJFILES := $(patsubst lib/%.S, $(OBJDIR)/lib/%.o, $(LIB_OBJFILES))

lib/args.c

@@ -0,0 +1,73 @@
+#include <inc/args.h>
+#include <inc/string.h>
+
+void
+argstart(int *argc, char **argv, struct Argstate *args)
+{
+	args->argc = argc;
+	args->argv = (const char **) argv;
+	args->curarg = (*argc > 1 && argv ? "" : 0);
+	args->argvalue = 0;
+}
+
+int
+argnext(struct Argstate *args)
+{
+	int arg;
+
+	args->argvalue = 0;
+
+	// Done processing arguments if args->curarg == 0
+	if (args->curarg == 0)
+		return -1;
+
+	if (!*args->curarg) {
+		// Need to process the next argument
+		// Check for end of argument list
+		if (*args->argc == 1
+		    || args->argv[1][0] != '-'
+		    || args->argv[1][1] == '\0')
+			goto endofargs;
+		// Shift arguments down one
+		args->curarg = args->argv[1] + 1;
+		memmove(args->argv + 1, args->argv + 2, sizeof(const char *) * (*args->argc - 1));
+		(*args->argc)--;
+		// Check for "--": end of argument list
+		if (args->curarg[0] == '-' && args->curarg[1] == '\0')
+			goto endofargs;
+	}
+
+	arg = (unsigned char) *args->curarg;
+	args->curarg++;
+	return arg;
+
+    endofargs:
+	args->curarg = 0;
+	return -1;
+}
+
+char *
+argvalue(struct Argstate *args)
+{
+	return (char*) (args->argvalue ? args->argvalue : argnextvalue(args));
+}
+
+char *
+argnextvalue(struct Argstate *args)
+{
+	if (!args->curarg)
+		return 0;
+	if (*args->curarg) {
+		args->argvalue = args->curarg;
+		args->curarg = "";
+	} else if (*args->argc > 1) {
+		args->argvalue = args->argv[1];
+		memmove(args->argv + 1, args->argv + 2, sizeof(const char *) * (*args->argc - 1));
+		(*args->argc)--;
+	} else {
+		args->argvalue = 0;
+		args->curarg = 0;
+	}
+	return (char*) args->argvalue;
+}
+

lib/console.c

@@ -15,11 +15,114 @@ cputchar(int ch)
 int
 getchar(void)
 {
+	unsigned char c;
 	int r;
-	// sys_cgetc does not block, but getchar should.
+
-	while ((r = sys_cgetc()) == 0)
+	// JOS does, however, support standard _input_ redirection,
-		sys_yield();
+	// allowing the user to redirect script files to the shell and such.
+	// getchar() reads a character from file descriptor 0.
+	r = read(0, &c, 1);
+	if (r < 0)
 		return r;
+	if (r < 1)
+		return -E_EOF;
+	return c;
 }
 
 
+// "Real" console file descriptor implementation.
+// The putchar/getchar functions above will still come here by default,
+// but now can be redirected to files, pipes, etc., via the fd layer.
+
+static ssize_t devcons_read(struct Fd*, void*, size_t);
+static ssize_t devcons_write(struct Fd*, const void*, size_t);
+static int devcons_close(struct Fd*);
+static int devcons_stat(struct Fd*, struct Stat*);
+
+struct Dev devcons =
+{
+	.dev_id =	'c',
+	.dev_name =	"cons",
+	.dev_read =	devcons_read,
+	.dev_write =	devcons_write,
+	.dev_close =	devcons_close,
+	.dev_stat =	devcons_stat
+};
+
+int
+iscons(int fdnum)
+{
+	int r;
+	struct Fd *fd;
+
+	if ((r = fd_lookup(fdnum, &fd)) < 0)
+		return r;
+	return fd->fd_dev_id == devcons.dev_id;
+}
+
+int
+opencons(void)
+{
+	int r;
+	struct Fd* fd;
+
+	if ((r = fd_alloc(&fd)) < 0)
+		return r;
+	if ((r = sys_page_alloc(0, fd, PTE_P|PTE_U|PTE_W|PTE_SHARE)) < 0)
+		return r;
+	fd->fd_dev_id = devcons.dev_id;
+	fd->fd_omode = O_RDWR;
+	return fd2num(fd);
+}
+
+static ssize_t
+devcons_read(struct Fd *fd, void *vbuf, size_t n)
+{
+	int c;
+
+	if (n == 0)
+		return 0;
+
+	while ((c = sys_cgetc()) == 0)
+		sys_yield();
+	if (c < 0)
+		return c;
+	if (c == 0x04)	// ctl-d is eof
+		return 0;
+	*(char*)vbuf = c;
+	return 1;
+}
+
+static ssize_t
+devcons_write(struct Fd *fd, const void *vbuf, size_t n)
+{
+	int tot, m;
+	char buf[128];
+
+	// mistake: have to nul-terminate arg to sys_cputs,
+	// so we have to copy vbuf into buf in chunks and nul-terminate.
+	for (tot = 0; tot < n; tot += m) {
+		m = n - tot;
+		if (m > sizeof(buf) - 1)
+			m = sizeof(buf) - 1;
+		memmove(buf, (char*)vbuf + tot, m);
+		sys_cputs(buf, m);
+	}
+	return tot;
+}
+
+static int
+devcons_close(struct Fd *fd)
+{
+	USED(fd);
+
+	return 0;
+}
+
+static int
+devcons_stat(struct Fd *fd, struct Stat *stat)
+{
+	strcpy(stat->st_name, "<cons>");
+	return 0;
+}
+

lib/exit.c

@@ -4,6 +4,7 @@
 void
 exit(void)
 {
+	close_all();
 	sys_env_destroy(0);
 }
 

lib/fd.c

@@ -0,0 +1,320 @@
+#include <inc/lib.h>
+
+#define debug		0
+
+// Maximum number of file descriptors a program may hold open concurrently
+#define MAXFD		32
+// Bottom of file descriptor area
+#define FDTABLE		0xD0000000
+// Bottom of file data area.  We reserve one data page for each FD,
+// which devices can use if they choose.
+#define FILEDATA	(FDTABLE + MAXFD*PGSIZE)
+
+// Return the 'struct Fd*' for file descriptor index i
+#define INDEX2FD(i)	((struct Fd*) (FDTABLE + (i)*PGSIZE))
+// Return the file data page for file descriptor index i
+#define INDEX2DATA(i)	((char*) (FILEDATA + (i)*PGSIZE))
+
+
+// --------------------------------------------------------------
+// File descriptor manipulators
+// --------------------------------------------------------------
+
+int
+fd2num(struct Fd *fd)
+{
+	return ((uintptr_t) fd - FDTABLE) / PGSIZE;
+}
+
+char*
+fd2data(struct Fd *fd)
+{
+	return INDEX2DATA(fd2num(fd));
+}
+
+// Finds the smallest i from 0 to MAXFD-1 that doesn't have
+// its fd page mapped.
+// Sets *fd_store to the corresponding fd page virtual address.
+//
+// fd_alloc does NOT actually allocate an fd page.
+// It is up to the caller to allocate the page somehow.
+// This means that if someone calls fd_alloc twice in a row
+// without allocating the first page we return, we'll return the same
+// page the second time.
+//
+// Hint: Use INDEX2FD.
+//
+// Returns 0 on success, < 0 on error.  Errors are:
+//	-E_MAX_FD: no more file descriptors
+// On error, *fd_store is set to 0.
+int
+fd_alloc(struct Fd **fd_store)
+{
+	int i;
+	struct Fd *fd;
+
+	for (i = 0; i < MAXFD; i++) {
+		fd = INDEX2FD(i);
+		if ((uvpd[PDX(fd)] & PTE_P) == 0 || (uvpt[PGNUM(fd)] & PTE_P) == 0) {
+			*fd_store = fd;
+			return 0;
+		}
+	}
+	*fd_store = 0;
+	return -E_MAX_OPEN;
+}
+
+// Check that fdnum is in range and mapped.
+// If it is, set *fd_store to the fd page virtual address.
+//
+// Returns 0 on success (the page is in range and mapped), < 0 on error.
+// Errors are:
+//	-E_INVAL: fdnum was either not in range or not mapped.
+int
+fd_lookup(int fdnum, struct Fd **fd_store)
+{
+	struct Fd *fd;
+
+	if (fdnum < 0 || fdnum >= MAXFD) {
+		if (debug)
+			cprintf("[%08x] bad fd %d\n", thisenv->env_id, fdnum);
+		return -E_INVAL;
+	}
+	fd = INDEX2FD(fdnum);
+	if (!(uvpd[PDX(fd)] & PTE_P) || !(uvpt[PGNUM(fd)] & PTE_P)) {
+		if (debug)
+			cprintf("[%08x] closed fd %d\n", thisenv->env_id, fdnum);
+		return -E_INVAL;
+	}
+	*fd_store = fd;
+	return 0;
+}
+
+// Frees file descriptor 'fd' by closing the corresponding file
+// and unmapping the file descriptor page.
+// If 'must_exist' is 0, then fd can be a closed or nonexistent file
+// descriptor; the function will return 0 and have no other effect.
+// If 'must_exist' is 1, then fd_close returns -E_INVAL when passed a
+// closed or nonexistent file descriptor.
+// Returns 0 on success, < 0 on error.
+int
+fd_close(struct Fd *fd, bool must_exist)
+{
+	struct Fd *fd2;
+	struct Dev *dev;
+	int r;
+	if ((r = fd_lookup(fd2num(fd), &fd2)) < 0
+	    || fd != fd2)
+		return (must_exist ? r : 0);
+	if ((r = dev_lookup(fd->fd_dev_id, &dev)) >= 0) {
+		if (dev->dev_close)
+			r = (*dev->dev_close)(fd);
+		else
+			r = 0;
+	}
+	// Make sure fd is unmapped.  Might be a no-op if
+	// (*dev->dev_close)(fd) already unmapped it.
+	(void) sys_page_unmap(0, fd);
+	return r;
+}
+
+
+// --------------------------------------------------------------
+// File functions
+// --------------------------------------------------------------
+
+static struct Dev *devtab[] =
+{
+	&devfile,
+	&devpipe,
+	&devcons,
+	0
+};
+
+int
+dev_lookup(int dev_id, struct Dev **dev)
+{
+	int i;
+	for (i = 0; devtab[i]; i++)
+		if (devtab[i]->dev_id == dev_id) {
+			*dev = devtab[i];
+			return 0;
+		}
+	cprintf("[%08x] unknown device type %d\n", thisenv->env_id, dev_id);
+	*dev = 0;
+	return -E_INVAL;
+}
+
+int
+close(int fdnum)
+{
+	struct Fd *fd;
+	int r;
+
+	if ((r = fd_lookup(fdnum, &fd)) < 0)
+		return r;
+	else
+		return fd_close(fd, 1);
+}
+
+void
+close_all(void)
+{
+	int i;
+	for (i = 0; i < MAXFD; i++)
+		close(i);
+}
+
+// Make file descriptor 'newfdnum' a duplicate of file descriptor 'oldfdnum'.
+// For instance, writing onto either file descriptor will affect the
+// file and the file offset of the other.
+// Closes any previously open file descriptor at 'newfdnum'.
+// This is implemented using virtual memory tricks (of course!).
+int
+dup(int oldfdnum, int newfdnum)
+{
+	int r;
+	char *ova, *nva;
+	pte_t pte;
+	struct Fd *oldfd, *newfd;
+
+	if ((r = fd_lookup(oldfdnum, &oldfd)) < 0)
+		return r;
+	close(newfdnum);
+
+	newfd = INDEX2FD(newfdnum);
+	ova = fd2data(oldfd);
+	nva = fd2data(newfd);
+
+	if ((uvpd[PDX(ova)] & PTE_P) && (uvpt[PGNUM(ova)] & PTE_P))
+		if ((r = sys_page_map(0, ova, 0, nva, uvpt[PGNUM(ova)] & PTE_SYSCALL)) < 0)
+			goto err;
+	if ((r = sys_page_map(0, oldfd, 0, newfd, uvpt[PGNUM(oldfd)] & PTE_SYSCALL)) < 0)
+		goto err;
+
+	return newfdnum;
+
+err:
+	sys_page_unmap(0, newfd);
+	sys_page_unmap(0, nva);
+	return r;
+}
+
+ssize_t
+read(int fdnum, void *buf, size_t n)
+{
+	int r;
+	struct Dev *dev;
+	struct Fd *fd;
+
+	if ((r = fd_lookup(fdnum, &fd)) < 0
+	    || (r = dev_lookup(fd->fd_dev_id, &dev)) < 0)
+		return r;
+	if ((fd->fd_omode & O_ACCMODE) == O_WRONLY) {
+		cprintf("[%08x] read %d -- bad mode\n", thisenv->env_id, fdnum);
+		return -E_INVAL;
+	}
+	if (!dev->dev_read)
+		return -E_NOT_SUPP;
+	return (*dev->dev_read)(fd, buf, n);
+}
+
+ssize_t
+readn(int fdnum, void *buf, size_t n)
+{
+	int m, tot;
+
+	for (tot = 0; tot < n; tot += m) {
+		m = read(fdnum, (char*)buf + tot, n - tot);
+		if (m < 0)
+			return m;
+		if (m == 0)
+			break;
+	}
+	return tot;
+}
+
+ssize_t
+write(int fdnum, const void *buf, size_t n)
+{
+	int r;
+	struct Dev *dev;
+	struct Fd *fd;
+
+	if ((r = fd_lookup(fdnum, &fd)) < 0
+	    || (r = dev_lookup(fd->fd_dev_id, &dev)) < 0)
+		return r;
+	if ((fd->fd_omode & O_ACCMODE) == O_RDONLY) {
+		cprintf("[%08x] write %d -- bad mode\n", thisenv->env_id, fdnum);
+		return -E_INVAL;
+	}
+	if (debug)
+		cprintf("write %d %p %d via dev %s\n",
+			fdnum, buf, n, dev->dev_name);
+	if (!dev->dev_write)
+		return -E_NOT_SUPP;
+	return (*dev->dev_write)(fd, buf, n);
+}
+
+int
+seek(int fdnum, off_t offset)
+{
+	int r;
+	struct Fd *fd;
+
+	if ((r = fd_lookup(fdnum, &fd)) < 0)
+		return r;
+	fd->fd_offset = offset;
+	return 0;
+}
+
+int
+ftruncate(int fdnum, off_t newsize)
+{
+	int r;
+	struct Dev *dev;
+	struct Fd *fd;
+	if ((r = fd_lookup(fdnum, &fd)) < 0
+	    || (r = dev_lookup(fd->fd_dev_id, &dev)) < 0)
+		return r;
+	if ((fd->fd_omode & O_ACCMODE) == O_RDONLY) {
+		cprintf("[%08x] ftruncate %d -- bad mode\n",
+			thisenv->env_id, fdnum);
+		return -E_INVAL;
+	}
+	if (!dev->dev_trunc)
+		return -E_NOT_SUPP;
+	return (*dev->dev_trunc)(fd, newsize);
+}
+
+int
+fstat(int fdnum, struct Stat *stat)
+{
+	int r;
+	struct Dev *dev;
+	struct Fd *fd;
+
+	if ((r = fd_lookup(fdnum, &fd)) < 0
+	    || (r = dev_lookup(fd->fd_dev_id, &dev)) < 0)
+		return r;
+	if (!dev->dev_stat)
+		return -E_NOT_SUPP;
+	stat->st_name[0] = 0;
+	stat->st_size = 0;
+	stat->st_isdir = 0;
+	stat->st_dev = dev;
+	return (*dev->dev_stat)(fd, stat);
+}
+
+int
+stat(const char *path, struct Stat *stat)
+{
+	int fd, r;
+
+	if ((fd = open(path, O_RDONLY)) < 0)
+		return fd;
+	r = fstat(fd, stat);
+	close(fd);
+	return r;
+}
+

lib/file.c

@@ -0,0 +1,180 @@
+#include <inc/fs.h>
+#include <inc/string.h>
+#include <inc/lib.h>
+
+#define debug 0
+
+union Fsipc fsipcbuf __attribute__((aligned(PGSIZE)));
+
+// Send an inter-environment request to the file server, and wait for
+// a reply.  The request body should be in fsipcbuf, and parts of the
+// response may be written back to fsipcbuf.
+// type: request code, passed as the simple integer IPC value.
+// dstva: virtual address at which to receive reply page, 0 if none.
+// Returns result from the file server.
+static int
+fsipc(unsigned type, void *dstva)
+{
+	static envid_t fsenv;
+	if (fsenv == 0)
+		fsenv = ipc_find_env(ENV_TYPE_FS);
+
+	static_assert(sizeof(fsipcbuf) == PGSIZE);
+
+	if (debug)
+		cprintf("[%08x] fsipc %d %08x\n", thisenv->env_id, type, *(uint32_t *)&fsipcbuf);
+
+	ipc_send(fsenv, type, &fsipcbuf, PTE_P | PTE_W | PTE_U);
+	return ipc_recv(NULL, dstva, NULL);
+}
+
+static int devfile_flush(struct Fd *fd);
+static ssize_t devfile_read(struct Fd *fd, void *buf, size_t n);
+static ssize_t devfile_write(struct Fd *fd, const void *buf, size_t n);
+static int devfile_stat(struct Fd *fd, struct Stat *stat);
+static int devfile_trunc(struct Fd *fd, off_t newsize);
+
+struct Dev devfile =
+{
+	.dev_id =	'f',
+	.dev_name =	"file",
+	.dev_read =	devfile_read,
+	.dev_close =	devfile_flush,
+	.dev_stat =	devfile_stat,
+	.dev_write =	devfile_write,
+	.dev_trunc =	devfile_trunc
+};
+
+// Open a file (or directory).
+//
+// Returns:
+// 	The file descriptor index on success
+// 	-E_BAD_PATH if the path is too long (>= MAXPATHLEN)
+// 	< 0 for other errors.
+int
+open(const char *path, int mode)
+{
+	// Find an unused file descriptor page using fd_alloc.
+	// Then send a file-open request to the file server.
+	// Include 'path' and 'omode' in request,
+	// and map the returned file descriptor page
+	// at the appropriate fd address.
+	// FSREQ_OPEN returns 0 on success, < 0 on failure.
+	//
+	// (fd_alloc does not allocate a page, it just returns an
+	// unused fd address.  Do you need to allocate a page?)
+	//
+	// Return the file descriptor index.
+	// If any step after fd_alloc fails, use fd_close to free the
+	// file descriptor.
+
+	int r;
+	struct Fd *fd;
+
+	if (strlen(path) >= MAXPATHLEN)
+		return -E_BAD_PATH;
+
+	if ((r = fd_alloc(&fd)) < 0)
+		return r;
+
+	strcpy(fsipcbuf.open.req_path, path);
+	fsipcbuf.open.req_omode = mode;
+
+	if ((r = fsipc(FSREQ_OPEN, fd)) < 0) {
+		fd_close(fd, 0);
+		return r;
+	}
+
+	return fd2num(fd);
+}
+
+// Flush the file descriptor.  After this the fileid is invalid.
+//
+// This function is called by fd_close.  fd_close will take care of
+// unmapping the FD page from this environment.  Since the server uses
+// the reference counts on the FD pages to detect which files are
+// open, unmapping it is enough to free up server-side resources.
+// Other than that, we just have to make sure our changes are flushed
+// to disk.
+static int
+devfile_flush(struct Fd *fd)
+{
+	fsipcbuf.flush.req_fileid = fd->fd_file.id;
+	return fsipc(FSREQ_FLUSH, NULL);
+}
+
+// Read at most 'n' bytes from 'fd' at the current position into 'buf'.
+//
+// Returns:
+// 	The number of bytes successfully read.
+// 	< 0 on error.
+static ssize_t
+devfile_read(struct Fd *fd, void *buf, size_t n)
+{
+	// Make an FSREQ_READ request to the file system server after
+	// filling fsipcbuf.read with the request arguments.  The
+	// bytes read will be written back to fsipcbuf by the file
+	// system server.
+	int r;
+
+	fsipcbuf.read.req_fileid = fd->fd_file.id;
+	fsipcbuf.read.req_n = n;
+	if ((r = fsipc(FSREQ_READ, NULL)) < 0)
+		return r;
+	assert(r <= n);
+	assert(r <= PGSIZE);
+	memmove(buf, fsipcbuf.readRet.ret_buf, r);
+	return r;
+}
+
+
+// Write at most 'n' bytes from 'buf' to 'fd' at the current seek position.
+//
+// Returns:
+//	 The number of bytes successfully written.
+//	 < 0 on error.
+static ssize_t
+devfile_write(struct Fd *fd, const void *buf, size_t n)
+{
+	// Make an FSREQ_WRITE request to the file system server.  Be
+	// careful: fsipcbuf.write.req_buf is only so large, but
+	// remember that write is always allowed to write *fewer*
+	// bytes than requested.
+	// LAB 5: Your code here
+	panic("devfile_write not implemented");
+}
+
+static int
+devfile_stat(struct Fd *fd, struct Stat *st)
+{
+	int r;
+
+	fsipcbuf.stat.req_fileid = fd->fd_file.id;
+	if ((r = fsipc(FSREQ_STAT, NULL)) < 0)
+		return r;
+	strcpy(st->st_name, fsipcbuf.statRet.ret_name);
+	st->st_size = fsipcbuf.statRet.ret_size;
+	st->st_isdir = fsipcbuf.statRet.ret_isdir;
+	return 0;
+}
+
+// Truncate or extend an open file to 'size' bytes
+static int
+devfile_trunc(struct Fd *fd, off_t newsize)
+{
+	fsipcbuf.set_size.req_fileid = fd->fd_file.id;
+	fsipcbuf.set_size.req_size = newsize;
+	return fsipc(FSREQ_SET_SIZE, NULL);
+}
+
+
+// Synchronize disk with buffer cache
+int
+sync(void)
+{
+	// Ask the file server to update the disk
+	// by writing any dirty blocks in the buffer cache.
+
+	return fsipc(FSREQ_SYNC, NULL);
+}
+

lib/fprintf.c

@@ -0,0 +1,81 @@
+#include <inc/lib.h>
+
+// Collect up to 256 characters into a buffer
+// and perform ONE system call to print all of them,
+// in order to make the lines output to the console atomic
+// and prevent interrupts from causing context switches
+// in the middle of a console output line and such.
+struct printbuf {
+	int fd;		// file descriptor
+	int idx;	// current buffer index
+	ssize_t result;	// accumulated results from write
+	int error;	// first error that occurred
+	char buf[256];
+};
+
+
+static void
+writebuf(struct printbuf *b)
+{
+	if (b->error > 0) {
+		ssize_t result = write(b->fd, b->buf, b->idx);
+		if (result > 0)
+			b->result += result;
+		if (result != b->idx) // error, or wrote less than supplied
+			b->error = (result < 0 ? result : 0);
+	}
+}
+
+static void
+putch(int ch, void *thunk)
+{
+	struct printbuf *b = (struct printbuf *) thunk;
+	b->buf[b->idx++] = ch;
+	if (b->idx == 256) {
+		writebuf(b);
+		b->idx = 0;
+	}
+}
+
+int
+vfprintf(int fd, const char *fmt, va_list ap)
+{
+	struct printbuf b;
+
+	b.fd = fd;
+	b.idx = 0;
+	b.result = 0;
+	b.error = 1;
+	vprintfmt(putch, &b, fmt, ap);
+	if (b.idx > 0)
+		writebuf(&b);
+
+	return (b.result ? b.result : b.error);
+}
+
+int
+fprintf(int fd, const char *fmt, ...)
+{
+	va_list ap;
+	int cnt;
+
+	va_start(ap, fmt);
+	cnt = vfprintf(fd, fmt, ap);
+	va_end(ap);
+
+	return cnt;
+}
+
+int
+printf(const char *fmt, ...)
+{
+	va_list ap;
+	int cnt;
+
+	va_start(ap, fmt);
+	cnt = vfprintf(1, fmt, ap);
+	va_end(ap);
+
+	return cnt;
+}
+

lib/pageref.c

@@ -0,0 +1,14 @@
+#include <inc/lib.h>
+
+int
+pageref(void *v)
+{
+	pte_t pte;
+
+	if (!(uvpd[PDX(v)] & PTE_P))
+		return 0;
+	pte = uvpt[PGNUM(v)];
+	if (!(pte & PTE_P))
+		return 0;
+	return pages[PGNUM(pte)].pp_ref;
+}

lib/pipe.c

@@ -0,0 +1,191 @@
+#include <inc/lib.h>
+
+#define debug 0
+
+static ssize_t devpipe_read(struct Fd *fd, void *buf, size_t n);
+static ssize_t devpipe_write(struct Fd *fd, const void *buf, size_t n);
+static int devpipe_stat(struct Fd *fd, struct Stat *stat);
+static int devpipe_close(struct Fd *fd);
+
+struct Dev devpipe =
+{
+	.dev_id =	'p',
+	.dev_name =	"pipe",
+	.dev_read =	devpipe_read,
+	.dev_write =	devpipe_write,
+	.dev_close =	devpipe_close,
+	.dev_stat =	devpipe_stat,
+};
+
+#define PIPEBUFSIZ 32		// small to provoke races
+
+struct Pipe {
+	off_t p_rpos;		// read position
+	off_t p_wpos;		// write position
+	uint8_t p_buf[PIPEBUFSIZ];	// data buffer
+};
+
+int
+pipe(int pfd[2])
+{
+	int r;
+	struct Fd *fd0, *fd1;
+	void *va;
+
+	// allocate the file descriptor table entries
+	if ((r = fd_alloc(&fd0)) < 0
+	    || (r = sys_page_alloc(0, fd0, PTE_P|PTE_W|PTE_U|PTE_SHARE)) < 0)
+		goto err;
+
+	if ((r = fd_alloc(&fd1)) < 0
+	    || (r = sys_page_alloc(0, fd1, PTE_P|PTE_W|PTE_U|PTE_SHARE)) < 0)
+		goto err1;
+
+	// allocate the pipe structure as first data page in both
+	va = fd2data(fd0);
+	if ((r = sys_page_alloc(0, va, PTE_P|PTE_W|PTE_U|PTE_SHARE)) < 0)
+		goto err2;
+	if ((r = sys_page_map(0, va, 0, fd2data(fd1), PTE_P|PTE_W|PTE_U|PTE_SHARE)) < 0)
+		goto err3;
+
+	// set up fd structures
+	fd0->fd_dev_id = devpipe.dev_id;
+	fd0->fd_omode = O_RDONLY;
+
+	fd1->fd_dev_id = devpipe.dev_id;
+	fd1->fd_omode = O_WRONLY;
+
+	if (debug)
+		cprintf("[%08x] pipecreate %08x\n", thisenv->env_id, uvpt[PGNUM(va)]);
+
+	pfd[0] = fd2num(fd0);
+	pfd[1] = fd2num(fd1);
+	return 0;
+
+    err3:
+	sys_page_unmap(0, va);
+    err2:
+	sys_page_unmap(0, fd1);
+    err1:
+	sys_page_unmap(0, fd0);
+    err:
+	return r;
+}
+
+static int
+_pipeisclosed(struct Fd *fd, struct Pipe *p)
+{
+	int n, nn, ret;
+
+	while (1) {
+		n = thisenv->env_runs;
+		ret = pageref(fd) == pageref(p);
+		nn = thisenv->env_runs;
+		if (n == nn)
+			return ret;
+		if (n != nn && ret == 1)
+			cprintf("pipe race avoided\n", n, thisenv->env_runs, ret);
+	}
+}
+
+int
+pipeisclosed(int fdnum)
+{
+	struct Fd *fd;
+	struct Pipe *p;
+	int r;
+
+	if ((r = fd_lookup(fdnum, &fd)) < 0)
+		return r;
+	p = (struct Pipe*) fd2data(fd);
+	return _pipeisclosed(fd, p);
+}
+
+static ssize_t
+devpipe_read(struct Fd *fd, void *vbuf, size_t n)
+{
+	uint8_t *buf;
+	size_t i;
+	struct Pipe *p;
+
+	p = (struct Pipe*)fd2data(fd);
+	if (debug)
+		cprintf("[%08x] devpipe_read %08x %d rpos %d wpos %d\n",
+			thisenv->env_id, uvpt[PGNUM(p)], n, p->p_rpos, p->p_wpos);
+
+	buf = vbuf;
+	for (i = 0; i < n; i++) {
+		while (p->p_rpos == p->p_wpos) {
+			// pipe is empty
+			// if we got any data, return it
+			if (i > 0)
+				return i;
+			// if all the writers are gone, note eof
+			if (_pipeisclosed(fd, p))
+				return 0;
+			// yield and see what happens
+			if (debug)
+				cprintf("devpipe_read yield\n");
+			sys_yield();
+		}
+		// there's a byte.  take it.
+		// wait to increment rpos until the byte is taken!
+		buf[i] = p->p_buf[p->p_rpos % PIPEBUFSIZ];
+		p->p_rpos++;
+	}
+	return i;
+}
+
+static ssize_t
+devpipe_write(struct Fd *fd, const void *vbuf, size_t n)
+{
+	const uint8_t *buf;
+	size_t i;
+	struct Pipe *p;
+
+	p = (struct Pipe*) fd2data(fd);
+	if (debug)
+		cprintf("[%08x] devpipe_write %08x %d rpos %d wpos %d\n",
+			thisenv->env_id, uvpt[PGNUM(p)], n, p->p_rpos, p->p_wpos);
+
+	buf = vbuf;
+	for (i = 0; i < n; i++) {
+		while (p->p_wpos >= p->p_rpos + sizeof(p->p_buf)) {
+			// pipe is full
+			// if all the readers are gone
+			// (it's only writers like us now),
+			// note eof
+			if (_pipeisclosed(fd, p))
+				return 0;
+			// yield and see what happens
+			if (debug)
+				cprintf("devpipe_write yield\n");
+			sys_yield();
+		}
+		// there's room for a byte.  store it.
+		// wait to increment wpos until the byte is stored!
+		p->p_buf[p->p_wpos % PIPEBUFSIZ] = buf[i];
+		p->p_wpos++;
+	}
+
+	return i;
+}
+
+static int
+devpipe_stat(struct Fd *fd, struct Stat *stat)
+{
+	struct Pipe *p = (struct Pipe*) fd2data(fd);
+	strcpy(stat->st_name, "<pipe>");
+	stat->st_size = p->p_wpos - p->p_rpos;
+	stat->st_isdir = 0;
+	stat->st_dev = &devpipe;
+	return 0;
+}
+
+static int
+devpipe_close(struct Fd *fd)
+{
+	(void) sys_page_unmap(0, fd);
+	return sys_page_unmap(0, fd2data(fd));
+}
+

lib/printfmt.c

@@ -28,6 +28,13 @@ static const char * const error_string[MAXERROR] =
 	[E_FAULT]	= "segmentation fault",
 	[E_IPC_NOT_RECV]= "env is not recving",
 	[E_EOF]		= "unexpected end of file",
+	[E_NO_DISK]	= "no free space on disk",
+	[E_MAX_OPEN]	= "too many files are open",
+	[E_NOT_FOUND]	= "file or block not found",
+	[E_BAD_PATH]	= "invalid path",
+	[E_FILE_EXISTS]	= "file already exists",
+	[E_NOT_EXEC]	= "file is not a valid executable",
+	[E_NOT_SUPP]	= "operation not supported",
 };
 
 /*

lib/readline.c

@@ -9,14 +9,20 @@ readline(const char *prompt)
 {
 	int i, c, echoing;
 
+#if JOS_KERNEL
 	if (prompt != NULL)
 		cprintf("%s", prompt);
+#else
+	if (prompt != NULL)
+		fprintf(1, "%s", prompt);
+#endif
 
 	i = 0;
 	echoing = iscons(0);
 	while (1) {
 		c = getchar();
 		if (c < 0) {
+			if (c != -E_EOF)
 				cprintf("read error: %e\n", c);
 			return NULL;
 		} else if ((c == '\b' || c == '\x7f') && i > 0) {

lib/spawn.c

@@ -0,0 +1,307 @@
+#include <inc/lib.h>
+#include <inc/elf.h>
+
+#define UTEMP2USTACK(addr)	((void*) (addr) + (USTACKTOP - PGSIZE) - UTEMP)
+#define UTEMP2			(UTEMP + PGSIZE)
+#define UTEMP3			(UTEMP2 + PGSIZE)
+
+// Helper functions for spawn.
+static int init_stack(envid_t child, const char **argv, uintptr_t *init_esp);
+static int map_segment(envid_t child, uintptr_t va, size_t memsz,
+		       int fd, size_t filesz, off_t fileoffset, int perm);
+static int copy_shared_pages(envid_t child);
+
+// Spawn a child process from a program image loaded from the file system.
+// prog: the pathname of the program to run.
+// argv: pointer to null-terminated array of pointers to strings,
+// 	 which will be passed to the child as its command-line arguments.
+// Returns child envid on success, < 0 on failure.
+int
+spawn(const char *prog, const char **argv)
+{
+	unsigned char elf_buf[512];
+	struct Trapframe child_tf;
+	envid_t child;
+
+	int fd, i, r;
+	struct Elf *elf;
+	struct Proghdr *ph;
+	int perm;
+
+	// This code follows this procedure:
+	//
+	//   - Open the program file.
+	//
+	//   - Read the ELF header, as you have before, and sanity check its
+	//     magic number.  (Check out your load_icode!)
+	//
+	//   - Use sys_exofork() to create a new environment.
+	//
+	//   - Set child_tf to an initial struct Trapframe for the child.
+	//
+	//   - Call the init_stack() function above to set up
+	//     the initial stack page for the child environment.
+	//
+	//   - Map all of the program's segments that are of p_type
+	//     ELF_PROG_LOAD into the new environment's address space.
+	//     Use the p_flags field in the Proghdr for each segment
+	//     to determine how to map the segment:
+	//
+	//	* If the ELF flags do not include ELF_PROG_FLAG_WRITE,
+	//	  then the segment contains text and read-only data.
+	//	  Use read_map() to read the contents of this segment,
+	//	  and map the pages it returns directly into the child
+	//        so that multiple instances of the same program
+	//	  will share the same copy of the program text.
+	//        Be sure to map the program text read-only in the child.
+	//        Read_map is like read but returns a pointer to the data in
+	//        *blk rather than copying the data into another buffer.
+	//
+	//	* If the ELF segment flags DO include ELF_PROG_FLAG_WRITE,
+	//	  then the segment contains read/write data and bss.
+	//	  As with load_icode() in Lab 3, such an ELF segment
+	//	  occupies p_memsz bytes in memory, but only the FIRST
+	//	  p_filesz bytes of the segment are actually loaded
+	//	  from the executable file - you must clear the rest to zero.
+	//        For each page to be mapped for a read/write segment,
+	//        allocate a page in the parent temporarily at UTEMP,
+	//        read() the appropriate portion of the file into that page
+	//	  and/or use memset() to zero non-loaded portions.
+	//	  (You can avoid calling memset(), if you like, if
+	//	  page_alloc() returns zeroed pages already.)
+	//        Then insert the page mapping into the child.
+	//        Look at init_stack() for inspiration.
+	//        Be sure you understand why you can't use read_map() here.
+	//
+	//     Note: None of the segment addresses or lengths above
+	//     are guaranteed to be page-aligned, so you must deal with
+	//     these non-page-aligned values appropriately.
+	//     The ELF linker does, however, guarantee that no two segments
+	//     will overlap on the same page; and it guarantees that
+	//     PGOFF(ph->p_offset) == PGOFF(ph->p_va).
+	//
+	//   - Call sys_env_set_trapframe(child, &child_tf) to set up the
+	//     correct initial eip and esp values in the child.
+	//
+	//   - Start the child process running with sys_env_set_status().
+
+	if ((r = open(prog, O_RDONLY)) < 0)
+		return r;
+	fd = r;
+
+	// Read elf header
+	elf = (struct Elf*) elf_buf;
+	if (readn(fd, elf_buf, sizeof(elf_buf)) != sizeof(elf_buf)
+	    || elf->e_magic != ELF_MAGIC) {
+		close(fd);
+		cprintf("elf magic %08x want %08x\n", elf->e_magic, ELF_MAGIC);
+		return -E_NOT_EXEC;
+	}
+
+	// Create new child environment
+	if ((r = sys_exofork()) < 0)
+		return r;
+	child = r;
+
+	// Set up trap frame, including initial stack.
+	child_tf = envs[ENVX(child)].env_tf;
+	child_tf.tf_eip = elf->e_entry;
+
+	if ((r = init_stack(child, argv, &child_tf.tf_esp)) < 0)
+		return r;
+
+	// Set up program segments as defined in ELF header.
+	ph = (struct Proghdr*) (elf_buf + elf->e_phoff);
+	for (i = 0; i < elf->e_phnum; i++, ph++) {
+		if (ph->p_type != ELF_PROG_LOAD)
+			continue;
+		perm = PTE_P | PTE_U;
+		if (ph->p_flags & ELF_PROG_FLAG_WRITE)
+			perm |= PTE_W;
+		if ((r = map_segment(child, ph->p_va, ph->p_memsz,
+				     fd, ph->p_filesz, ph->p_offset, perm)) < 0)
+			goto error;
+	}
+	close(fd);
+	fd = -1;
+
+	// Copy shared library state.
+	if ((r = copy_shared_pages(child)) < 0)
+		panic("copy_shared_pages: %e", r);
+
+	child_tf.tf_eflags |= FL_IOPL_3;   // devious: see user/faultio.c
+	if ((r = sys_env_set_trapframe(child, &child_tf)) < 0)
+		panic("sys_env_set_trapframe: %e", r);
+
+	if ((r = sys_env_set_status(child, ENV_RUNNABLE)) < 0)
+		panic("sys_env_set_status: %e", r);
+
+	return child;
+
+error:
+	sys_env_destroy(child);
+	close(fd);
+	return r;
+}
+
+// Spawn, taking command-line arguments array directly on the stack.
+// NOTE: Must have a sentinal of NULL at the end of the args
+// (none of the args may be NULL).
+int
+spawnl(const char *prog, const char *arg0, ...)
+{
+	// We calculate argc by advancing the args until we hit NULL.
+	// The contract of the function guarantees that the last
+	// argument will always be NULL, and that none of the other
+	// arguments will be NULL.
+	int argc=0;
+	va_list vl;
+	va_start(vl, arg0);
+	while(va_arg(vl, void *) != NULL)
+		argc++;
+	va_end(vl);
+
+	// Now that we have the size of the args, do a second pass
+	// and store the values in a VLA, which has the format of argv
+	const char *argv[argc+2];
+	argv[0] = arg0;
+	argv[argc+1] = NULL;
+
+	va_start(vl, arg0);
+	unsigned i;
+	for(i=0;i<argc;i++)
+		argv[i+1] = va_arg(vl, const char *);
+	va_end(vl);
+	return spawn(prog, argv);
+}
+
+
+// Set up the initial stack page for the new child process with envid 'child'
+// using the arguments array pointed to by 'argv',
+// which is a null-terminated array of pointers to null-terminated strings.
+//
+// On success, returns 0 and sets *init_esp
+// to the initial stack pointer with which the child should start.
+// Returns < 0 on failure.
+static int
+init_stack(envid_t child, const char **argv, uintptr_t *init_esp)
+{
+	size_t string_size;
+	int argc, i, r;
+	char *string_store;
+	uintptr_t *argv_store;
+
+	// Count the number of arguments (argc)
+	// and the total amount of space needed for strings (string_size).
+	string_size = 0;
+	for (argc = 0; argv[argc] != 0; argc++)
+		string_size += strlen(argv[argc]) + 1;
+
+	// Determine where to place the strings and the argv array.
+	// Set up pointers into the temporary page 'UTEMP'; we'll map a page
+	// there later, then remap that page into the child environment
+	// at (USTACKTOP - PGSIZE).
+	// strings is the topmost thing on the stack.
+	string_store = (char*) UTEMP + PGSIZE - string_size;
+	// argv is below that.  There's one argument pointer per argument, plus
+	// a null pointer.
+	argv_store = (uintptr_t*) (ROUNDDOWN(string_store, 4) - 4 * (argc + 1));
+
+	// Make sure that argv, strings, and the 2 words that hold 'argc'
+	// and 'argv' themselves will all fit in a single stack page.
+	if ((void*) (argv_store - 2) < (void*) UTEMP)
+		return -E_NO_MEM;
+
+	// Allocate the single stack page at UTEMP.
+	if ((r = sys_page_alloc(0, (void*) UTEMP, PTE_P|PTE_U|PTE_W)) < 0)
+		return r;
+
+
+	//	* Initialize 'argv_store[i]' to point to argument string i,
+	//	  for all 0 <= i < argc.
+	//	  Also, copy the argument strings from 'argv' into the
+	//	  newly-allocated stack page.
+	//
+	//	* Set 'argv_store[argc]' to 0 to null-terminate the args array.
+	//
+	//	* Push two more words onto the child's stack below 'args',
+	//	  containing the argc and argv parameters to be passed
+	//	  to the child's umain() function.
+	//	  argv should be below argc on the stack.
+	//	  (Again, argv should use an address valid in the child's
+	//	  environment.)
+	//
+	//	* Set *init_esp to the initial stack pointer for the child,
+	//	  (Again, use an address valid in the child's environment.)
+	for (i = 0; i < argc; i++) {
+		argv_store[i] = UTEMP2USTACK(string_store);
+		strcpy(string_store, argv[i]);
+		string_store += strlen(argv[i]) + 1;
+	}
+	argv_store[argc] = 0;
+	assert(string_store == (char*)UTEMP + PGSIZE);
+
+	argv_store[-1] = UTEMP2USTACK(argv_store);
+	argv_store[-2] = argc;
+
+	*init_esp = UTEMP2USTACK(&argv_store[-2]);
+
+	// After completing the stack, map it into the child's address space
+	// and unmap it from ours!
+	if ((r = sys_page_map(0, UTEMP, child, (void*) (USTACKTOP - PGSIZE), PTE_P | PTE_U | PTE_W)) < 0)
+		goto error;
+	if ((r = sys_page_unmap(0, UTEMP)) < 0)
+		goto error;
+
+	return 0;
+
+error:
+	sys_page_unmap(0, UTEMP);
+	return r;
+}
+
+static int
+map_segment(envid_t child, uintptr_t va, size_t memsz,
+	int fd, size_t filesz, off_t fileoffset, int perm)
+{
+	int i, r;
+	void *blk;
+
+	//cprintf("map_segment %x+%x\n", va, memsz);
+
+	if ((i = PGOFF(va))) {
+		va -= i;
+		memsz += i;
+		filesz += i;
+		fileoffset -= i;
+	}
+
+	for (i = 0; i < memsz; i += PGSIZE) {
+		if (i >= filesz) {
+			// allocate a blank page
+			if ((r = sys_page_alloc(child, (void*) (va + i), perm)) < 0)
+				return r;
+		} else {
+			// from file
+			if ((r = sys_page_alloc(0, UTEMP, PTE_P|PTE_U|PTE_W)) < 0)
+				return r;
+			if ((r = seek(fd, fileoffset + i)) < 0)
+				return r;
+			if ((r = readn(fd, UTEMP, MIN(PGSIZE, filesz-i))) < 0)
+				return r;
+			if ((r = sys_page_map(0, UTEMP, child, (void*) (va + i), perm)) < 0)
+				panic("spawn: sys_page_map data: %e", r);
+			sys_page_unmap(0, UTEMP);
+		}
+	}
+	return 0;
+}
+
+// Copy the mappings for shared pages into the child address space.
+static int
+copy_shared_pages(envid_t child)
+{
+	// LAB 5: Your code here.
+	return 0;
+}
+

lib/syscall.c

@@ -93,6 +93,12 @@ sys_env_set_status(envid_t envid, int status)
 	return syscall(SYS_env_set_status, 1, envid, status, 0, 0, 0);
 }
 
+int
+sys_env_set_trapframe(envid_t envid, struct Trapframe *tf)
+{
+	return syscall(SYS_env_set_trapframe, 1, envid, (uint32_t) tf, 0, 0, 0);
+}
+
 int
 sys_env_set_pgfault_upcall(envid_t envid, void *upcall)
 {

lib/wait.c

@@ -0,0 +1,13 @@
+#include <inc/lib.h>
+
+// Waits until 'envid' exits.
+void
+wait(envid_t envid)
+{
+	const volatile struct Env *e;
+
+	assert(envid != 0);
+	e = &envs[ENVX(envid)];
+	while (e->env_id == envid && e->env_status != ENV_FREE)
+		sys_yield();
+}

user/Makefrag

@@ -10,7 +10,8 @@ $(OBJDIR)/user/%.o: user/%.c $(OBJDIR)/.vars.USER_CFLAGS
 
 $(OBJDIR)/user/%: $(OBJDIR)/user/%.o $(OBJDIR)/lib/entry.o $(USERLIBS:%=$(OBJDIR)/lib/lib%.a) user/user.ld
 	@echo + ld $@
-	$(V)$(LD) -o $@ $(ULDFLAGS) $(LDFLAGS) -nostdlib $(OBJDIR)/lib/entry.o $@.o -L$(OBJDIR)/lib $(USERLIBS:%=-l%) $(GCC_LIB)
+	$(V)$(LD) -o $@.debug $(ULDFLAGS) $(LDFLAGS) -nostdlib $(OBJDIR)/lib/entry.o $@.o -L$(OBJDIR)/lib $(USERLIBS:%=-l%) $(GCC_LIB)
-	$(V)$(OBJDUMP) -S $@ > $@.asm
+	$(V)$(OBJDUMP) -S $@.debug > $@.asm
-	$(V)$(NM) -n $@ > $@.sym
+	$(V)$(NM) -n $@.debug > $@.sym
+	$(V)$(OBJCOPY) -R .stab -R .stabstr --add-gnu-debuglink=$(basename $@.debug) $@.debug $@
 

user/cat.c

@@ -0,0 +1,36 @@
+#include <inc/lib.h>
+
+char buf[8192];
+
+void
+cat(int f, char *s)
+{
+	long n;
+	int r;
+
+	while ((n = read(f, buf, (long)sizeof(buf))) > 0)
+		if ((r = write(1, buf, n)) != n)
+			panic("write error copying %s: %e", s, r);
+	if (n < 0)
+		panic("error reading %s: %e", s, n);
+}
+
+void
+umain(int argc, char **argv)
+{
+	int f, i;
+
+	binaryname = "cat";
+	if (argc == 1)
+		cat(0, "<stdin>");
+	else
+		for (i = 1; i < argc; i++) {
+			f = open(argv[i], O_RDONLY);
+			if (f < 0)
+				printf("can't open %s: %e\n", argv[i], f);
+			else {
+				cat(f, argv[i]);
+				close(f);
+			}
+		}
+}

user/echo.c

@@ -0,0 +1,21 @@
+#include <inc/lib.h>
+
+void
+umain(int argc, char **argv)
+{
+	int i, nflag;
+
+	nflag = 0;
+	if (argc > 1 && strcmp(argv[1], "-n") == 0) {
+		nflag = 1;
+		argc--;
+		argv++;
+	}
+	for (i = 1; i < argc; i++) {
+		if (i > 1)
+			write(1, " ", 1);
+		write(1, argv[i], strlen(argv[i]));
+	}
+	if (!nflag)
+		write(1, "\n", 1);
+}

user/faultio.c

@@ -0,0 +1,22 @@
+// test user-level fault handler -- alloc pages to fix faults
+
+#include <inc/lib.h>
+#include <inc/x86.h>
+
+void
+umain(int argc, char **argv)
+{
+        int x, r;
+	int nsecs = 1;
+	int secno = 0;
+	int diskno = 1;
+
+	if (read_eflags() & FL_IOPL_3)
+		cprintf("eflags wrong\n");
+
+	// this outb to select disk 1 should result in a general protection
+	// fault, because user-level code shouldn't be able to use the io space.
+	outb(0x1F6, 0xE0 | (1<<4));
+
+        cprintf("%s: made it here --- bug\n");
+}

user/icode.c

@@ -0,0 +1,29 @@
+#include <inc/lib.h>
+
+void
+umain(int argc, char **argv)
+{
+	int fd, n, r;
+	char buf[512+1];
+
+	binaryname = "icode";
+
+	cprintf("icode startup\n");
+
+	cprintf("icode: open /motd\n");
+	if ((fd = open("/motd", O_RDONLY)) < 0)
+		panic("icode: open /motd: %e", fd);
+
+	cprintf("icode: read /motd\n");
+	while ((n = read(fd, buf, sizeof buf-1)) > 0)
+		sys_cputs(buf, n);
+
+	cprintf("icode: close /motd\n");
+	close(fd);
+
+	cprintf("icode: spawn /init\n");
+	if ((r = spawnl("/init", "init", "initarg1", "initarg2", (char*)0)) < 0)
+		panic("icode: spawn /init: %e", r);
+
+	cprintf("icode: exiting\n");
+}

user/init.c

@@ -0,0 +1,69 @@
+#include <inc/lib.h>
+
+struct {
+	char msg1[5000];
+	char msg2[1000];
+} data = {
+	"this is initialized data",
+	"so is this"
+};
+
+char bss[6000];
+
+int
+sum(const char *s, int n)
+{
+	int i, tot = 0;
+	for (i = 0; i < n; i++)
+		tot ^= i * s[i];
+	return tot;
+}
+
+void
+umain(int argc, char **argv)
+{
+	int i, r, x, want;
+	char args[256];
+
+	cprintf("init: running\n");
+
+	want = 0xf989e;
+	if ((x = sum((char*)&data, sizeof data)) != want)
+		cprintf("init: data is not initialized: got sum %08x wanted %08x\n",
+			x, want);
+	else
+		cprintf("init: data seems okay\n");
+	if ((x = sum(bss, sizeof bss)) != 0)
+		cprintf("bss is not initialized: wanted sum 0 got %08x\n", x);
+	else
+		cprintf("init: bss seems okay\n");
+
+	// output in one syscall per line to avoid output interleaving 
+	strcat(args, "init: args:");
+	for (i = 0; i < argc; i++) {
+		strcat(args, " '");
+		strcat(args, argv[i]);
+		strcat(args, "'");
+	}
+	cprintf("%s\n", args);
+
+	cprintf("init: running sh\n");
+
+	// being run directly from kernel, so no file descriptors open yet
+	close(0);
+	if ((r = opencons()) < 0)
+		panic("opencons: %e", r);
+	if (r != 0)
+		panic("first opencons used fd %d", r);
+	if ((r = dup(0, 1)) < 0)
+		panic("dup: %e", r);
+	while (1) {
+		cprintf("init: starting sh\n");
+		r = spawnl("/sh", "sh", (char*)0);
+		if (r < 0) {
+			cprintf("init: spawn sh: %e\n", r);
+			continue;
+		}
+		wait(r);
+	}
+}

user/initsh.c

@@ -0,0 +1,27 @@
+#include <inc/lib.h>
+
+void
+umain(int argc, char **argv)
+{
+	int i, r, x, want;
+
+	cprintf("initsh: running sh\n");
+
+	// being run directly from kernel, so no file descriptors open yet
+	close(0);
+	if ((r = opencons()) < 0)
+		panic("opencons: %e", r);
+	if (r != 0)
+		panic("first opencons used fd %d", r);
+	if ((r = dup(0, 1)) < 0)
+		panic("dup: %e", r);
+	while (1) {
+		cprintf("init: starting sh\n");
+		r = spawnl("/sh", "sh", (char*)0);
+		if (r < 0) {
+			cprintf("init: spawn sh: %e\n", r);
+			continue;
+		}
+		wait(r);
+	}
+}

user/ls.c

@@ -0,0 +1,91 @@
+#include <inc/lib.h>
+
+int flag[256];
+
+void lsdir(const char*, const char*);
+void ls1(const char*, bool, off_t, const char*);
+
+void
+ls(const char *path, const char *prefix)
+{
+	int r;
+	struct Stat st;
+
+	if ((r = stat(path, &st)) < 0)
+		panic("stat %s: %e", path, r);
+	if (st.st_isdir && !flag['d'])
+		lsdir(path, prefix);
+	else
+		ls1(0, st.st_isdir, st.st_size, path);
+}
+
+void
+lsdir(const char *path, const char *prefix)
+{
+	int fd, n;
+	struct File f;
+
+	if ((fd = open(path, O_RDONLY)) < 0)
+		panic("open %s: %e", path, fd);
+	while ((n = readn(fd, &f, sizeof f)) == sizeof f)
+		if (f.f_name[0])
+			ls1(prefix, f.f_type==FTYPE_DIR, f.f_size, f.f_name);
+	if (n > 0)
+		panic("short read in directory %s", path);
+	if (n < 0)
+		panic("error reading directory %s: %e", path, n);
+}
+
+void
+ls1(const char *prefix, bool isdir, off_t size, const char *name)
+{
+	const char *sep;
+
+	if(flag['l'])
+		printf("%11d %c ", size, isdir ? 'd' : '-');
+	if(prefix) {
+		if (prefix[0] && prefix[strlen(prefix)-1] != '/')
+			sep = "/";
+		else
+			sep = "";
+		printf("%s%s", prefix, sep);
+	}
+	printf("%s", name);
+	if(flag['F'] && isdir)
+		printf("/");
+	printf("\n");
+}
+
+void
+usage(void)
+{
+	printf("usage: ls [-dFl] [file...]\n");
+	exit();
+}
+
+void
+umain(int argc, char **argv)
+{
+	int i;
+	struct Argstate args;
+
+	argstart(&argc, argv, &args);
+	while ((i = argnext(&args)) >= 0)
+		switch (i) {
+		case 'd':
+		case 'F':
+		case 'l':
+			flag[i]++;
+			break;
+		default:
+			usage();
+		}
+
+	if (argc == 1)
+		ls("/", "");
+	else {
+		for (i = 1; i < argc; i++)
+			ls(argv[i], argv[i]);
+	}
+}
+

user/lsfd.c

@@ -0,0 +1,35 @@
+#include <inc/lib.h>
+
+void
+usage(void)
+{
+	cprintf("usage: lsfd [-1]\n");
+	exit();
+}
+
+void
+umain(int argc, char **argv)
+{
+	int i, usefprint = 0;
+	struct Stat st;
+	struct Argstate args;
+
+	argstart(&argc, argv, &args);
+	while ((i = argnext(&args)) >= 0)
+		if (i == '1')
+			usefprint = 1;
+		else
+			usage();
+
+	for (i = 0; i < 32; i++)
+		if (fstat(i, &st) >= 0) {
+			if (usefprint)
+				fprintf(1, "fd %d: name %s isdir %d size %d dev %s\n",
+					i, st.st_name, st.st_isdir,
+					st.st_size, st.st_dev->dev_name);
+			else
+				cprintf("fd %d: name %s isdir %d size %d dev %s\n",
+					i, st.st_name, st.st_isdir,
+					st.st_size, st.st_dev->dev_name);
+		}
+}

user/num.c

@@ -0,0 +1,47 @@
+#include <inc/lib.h>
+
+int bol = 1;
+int line = 0;
+
+void
+num(int f, const char *s)
+{
+	long n;
+	int r;
+	char c;
+
+	while ((n = read(f, &c, 1)) > 0) {
+		if (bol) {
+			printf("%5d ", ++line);
+			bol = 0;
+		}
+		if ((r = write(1, &c, 1)) != 1)
+			panic("write error copying %s: %e", s, r);
+		if (c == '\n')
+			bol = 1;
+	}
+	if (n < 0)
+		panic("error reading %s: %e", s, n);
+}
+
+void
+umain(int argc, char **argv)
+{
+	int f, i;
+
+	binaryname = "num";
+	if (argc == 1)
+		num(0, "<stdin>");
+	else
+		for (i = 1; i < argc; i++) {
+			f = open(argv[i], O_RDONLY);
+			if (f < 0)
+				panic("can't open %s: %e", argv[i], f);
+			else {
+				num(f, argv[i]);
+				close(f);
+			}
+		}
+	exit();
+}
+

user/primespipe.c

@@ -0,0 +1,76 @@
+// Concurrent version of prime sieve of Eratosthenes.
+// Invented by Doug McIlroy, inventor of Unix pipes.
+// See http://swtch.com/~rsc/thread/.
+// The picture halfway down the page and the text surrounding it
+// explain what's going on here.
+//
+// Since NENV is 1024, we can print 1022 primes before running out.
+// The remaining two environments are the integer generator at the bottom
+// of main and user/idle.
+
+#include <inc/lib.h>
+
+unsigned
+primeproc(int fd)
+{
+	int i, id, p, pfd[2], wfd, r;
+
+	// fetch a prime from our left neighbor
+top:
+	if ((r = readn(fd, &p, 4)) != 4)
+		panic("primeproc could not read initial prime: %d, %e", r, r >= 0 ? 0 : r);
+
+	cprintf("%d\n", p);
+
+	// fork a right neighbor to continue the chain
+	if ((i=pipe(pfd)) < 0)
+		panic("pipe: %e", i);
+	if ((id = fork()) < 0)
+		panic("fork: %e", id);
+	if (id == 0) {
+		close(fd);
+		close(pfd[1]);
+		fd = pfd[0];
+		goto top;
+	}
+
+	close(pfd[0]);
+	wfd = pfd[1];
+
+	// filter out multiples of our prime
+	for (;;) {
+		if ((r=readn(fd, &i, 4)) != 4)
+			panic("primeproc %d readn %d %d %e", p, fd, r, r >= 0 ? 0 : r);
+		if (i%p)
+			if ((r=write(wfd, &i, 4)) != 4)
+				panic("primeproc %d write: %d %e", p, r, r >= 0 ? 0 : r);
+	}
+}
+
+void
+umain(int argc, char **argv)
+{
+	int i, id, p[2], r;
+
+	binaryname = "primespipe";
+
+	if ((i=pipe(p)) < 0)
+		panic("pipe: %e", i);
+
+	// fork the first prime process in the chain
+	if ((id=fork()) < 0)
+		panic("fork: %e", id);
+
+	if (id == 0) {
+		close(p[1]);
+		primeproc(p[0]);
+	}
+
+	close(p[0]);
+
+	// feed all the integers through
+	for (i=2;; i++)
+		if ((r=write(p[1], &i, 4)) != 4)
+			panic("generator write: %d, %e", r, r >= 0 ? 0 : r);
+}
+

user/sh.c

@@ -0,0 +1,322 @@
+#include <inc/lib.h>
+
+#define BUFSIZ 1024		/* Find the buffer overrun bug! */
+int debug = 0;
+
+
+// gettoken(s, 0) prepares gettoken for subsequent calls and returns 0.
+// gettoken(0, token) parses a shell token from the previously set string,
+// null-terminates that token, stores the token pointer in '*token',
+// and returns a token ID (0, '<', '>', '|', or 'w').
+// Subsequent calls to 'gettoken(0, token)' will return subsequent
+// tokens from the string.
+int gettoken(char *s, char **token);
+
+
+// Parse a shell command from string 's' and execute it.
+// Do not return until the shell command is finished.
+// runcmd() is called in a forked child,
+// so it's OK to manipulate file descriptor state.
+#define MAXARGS 16
+void
+runcmd(char* s)
+{
+	char *argv[MAXARGS], *t, argv0buf[BUFSIZ];
+	int argc, c, i, r, p[2], fd, pipe_child;
+
+	pipe_child = 0;
+	gettoken(s, 0);
+
+again:
+	argc = 0;
+	while (1) {
+		switch ((c = gettoken(0, &t))) {
+
+		case 'w':	// Add an argument
+			if (argc == MAXARGS) {
+				cprintf("too many arguments\n");
+				exit();
+			}
+			argv[argc++] = t;
+			break;
+
+		case '<':	// Input redirection
+			// Grab the filename from the argument list
+			if (gettoken(0, &t) != 'w') {
+				cprintf("syntax error: < not followed by word\n");
+				exit();
+			}
+			// Open 't' for reading as file descriptor 0
+			// (which environments use as standard input).
+			// We can't open a file onto a particular descriptor,
+			// so open the file as 'fd',
+			// then check whether 'fd' is 0.
+			// If not, dup 'fd' onto file descriptor 0,
+			// then close the original 'fd'.
+
+			// LAB 5: Your code here.
+			panic("< redirection not implemented");
+			break;
+
+		case '>':	// Output redirection
+			// Grab the filename from the argument list
+			if (gettoken(0, &t) != 'w') {
+				cprintf("syntax error: > not followed by word\n");
+				exit();
+			}
+			if ((fd = open(t, O_WRONLY|O_CREAT|O_TRUNC)) < 0) {
+				cprintf("open %s for write: %e", t, fd);
+				exit();
+			}
+			if (fd != 1) {
+				dup(fd, 1);
+				close(fd);
+			}
+			break;
+
+		case '|':	// Pipe
+			if ((r = pipe(p)) < 0) {
+				cprintf("pipe: %e", r);
+				exit();
+			}
+			if (debug)
+				cprintf("PIPE: %d %d\n", p[0], p[1]);
+			if ((r = fork()) < 0) {
+				cprintf("fork: %e", r);
+				exit();
+			}
+			if (r == 0) {
+				if (p[0] != 0) {
+					dup(p[0], 0);
+					close(p[0]);
+				}
+				close(p[1]);
+				goto again;
+			} else {
+				pipe_child = r;
+				if (p[1] != 1) {
+					dup(p[1], 1);
+					close(p[1]);
+				}
+				close(p[0]);
+				goto runit;
+			}
+			panic("| not implemented");
+			break;
+
+		case 0:		// String is complete
+			// Run the current command!
+			goto runit;
+
+		default:
+			panic("bad return %d from gettoken", c);
+			break;
+
+		}
+	}
+
+runit:
+	// Return immediately if command line was empty.
+	if(argc == 0) {
+		if (debug)
+			cprintf("EMPTY COMMAND\n");
+		return;
+	}
+
+	// Clean up command line.
+	// Read all commands from the filesystem: add an initial '/' to
+	// the command name.
+	// This essentially acts like 'PATH=/'.
+	if (argv[0][0] != '/') {
+		argv0buf[0] = '/';
+		strcpy(argv0buf + 1, argv[0]);
+		argv[0] = argv0buf;
+	}
+	argv[argc] = 0;
+
+	// Print the command.
+	if (debug) {
+		cprintf("[%08x] SPAWN:", thisenv->env_id);
+		for (i = 0; argv[i]; i++)
+			cprintf(" %s", argv[i]);
+		cprintf("\n");
+	}
+
+	// Spawn the command!
+	if ((r = spawn(argv[0], (const char**) argv)) < 0)
+		cprintf("spawn %s: %e\n", argv[0], r);
+
+	// In the parent, close all file descriptors and wait for the
+	// spawned command to exit.
+	close_all();
+	if (r >= 0) {
+		if (debug)
+			cprintf("[%08x] WAIT %s %08x\n", thisenv->env_id, argv[0], r);
+		wait(r);
+		if (debug)
+			cprintf("[%08x] wait finished\n", thisenv->env_id);
+	}
+
+	// If we were the left-hand part of a pipe,
+	// wait for the right-hand part to finish.
+	if (pipe_child) {
+		if (debug)
+			cprintf("[%08x] WAIT pipe_child %08x\n", thisenv->env_id, pipe_child);
+		wait(pipe_child);
+		if (debug)
+			cprintf("[%08x] wait finished\n", thisenv->env_id);
+	}
+
+	// Done!
+	exit();
+}
+
+
+// Get the next token from string s.
+// Set *p1 to the beginning of the token and *p2 just past the token.
+// Returns
+//	0 for end-of-string;
+//	< for <;
+//	> for >;
+//	| for |;
+//	w for a word.
+//
+// Eventually (once we parse the space where the \0 will go),
+// words get nul-terminated.
+#define WHITESPACE " \t\r\n"
+#define SYMBOLS "<|>&;()"
+
+int
+_gettoken(char *s, char **p1, char **p2)
+{
+	int t;
+
+	if (s == 0) {
+		if (debug > 1)
+			cprintf("GETTOKEN NULL\n");
+		return 0;
+	}
+
+	if (debug > 1)
+		cprintf("GETTOKEN: %s\n", s);
+
+	*p1 = 0;
+	*p2 = 0;
+
+	while (strchr(WHITESPACE, *s))
+		*s++ = 0;
+	if (*s == 0) {
+		if (debug > 1)
+			cprintf("EOL\n");
+		return 0;
+	}
+	if (strchr(SYMBOLS, *s)) {
+		t = *s;
+		*p1 = s;
+		*s++ = 0;
+		*p2 = s;
+		if (debug > 1)
+			cprintf("TOK %c\n", t);
+		return t;
+	}
+	*p1 = s;
+	while (*s && !strchr(WHITESPACE SYMBOLS, *s))
+		s++;
+	*p2 = s;
+	if (debug > 1) {
+		t = **p2;
+		**p2 = 0;
+		cprintf("WORD: %s\n", *p1);
+		**p2 = t;
+	}
+	return 'w';
+}
+
+int
+gettoken(char *s, char **p1)
+{
+	static int c, nc;
+	static char* np1, *np2;
+
+	if (s) {
+		nc = _gettoken(s, &np1, &np2);
+		return 0;
+	}
+	c = nc;
+	*p1 = np1;
+	nc = _gettoken(np2, &np1, &np2);
+	return c;
+}
+
+
+void
+usage(void)
+{
+	cprintf("usage: sh [-dix] [command-file]\n");
+	exit();
+}
+
+void
+umain(int argc, char **argv)
+{
+	int r, interactive, echocmds;
+	struct Argstate args;
+
+	interactive = '?';
+	echocmds = 0;
+	argstart(&argc, argv, &args);
+	while ((r = argnext(&args)) >= 0)
+		switch (r) {
+		case 'd':
+			debug++;
+			break;
+		case 'i':
+			interactive = 1;
+			break;
+		case 'x':
+			echocmds = 1;
+			break;
+		default:
+			usage();
+		}
+
+	if (argc > 2)
+		usage();
+	if (argc == 2) {
+		close(0);
+		if ((r = open(argv[1], O_RDONLY)) < 0)
+			panic("open %s: %e", argv[1], r);
+		assert(r == 0);
+	}
+	if (interactive == '?')
+		interactive = iscons(0);
+
+	while (1) {
+		char *buf;
+
+		buf = readline(interactive ? "$ " : NULL);
+		if (buf == NULL) {
+			if (debug)
+				cprintf("EXITING\n");
+			exit();	// end of file
+		}
+		if (debug)
+			cprintf("LINE: %s\n", buf);
+		if (buf[0] == '#')
+			continue;
+		if (echocmds)
+			printf("# %s\n", buf);
+		if (debug)
+			cprintf("BEFORE FORK\n");
+		if ((r = fork()) < 0)
+			panic("fork: %e", r);
+		if (debug)
+			cprintf("FORK: %d\n", r);
+		if (r == 0) {
+			runcmd(buf);
+			exit();
+		} else
+			wait(r);
+	}
+}
+

user/spawnfaultio.c

@@ -0,0 +1,10 @@
+#include <inc/lib.h>
+
+void
+umain(int argc, char **argv)
+{
+	int r;
+	cprintf("i am parent environment %08x\n", thisenv->env_id);
+	if ((r = spawnl("faultio", "faultio", 0)) < 0)
+		panic("spawn(faultio) failed: %e", r);
+}

user/spawnhello.c

@@ -0,0 +1,10 @@
+#include <inc/lib.h>
+
+void
+umain(int argc, char **argv)
+{
+	int r;
+	cprintf("i am parent environment %08x\n", thisenv->env_id);
+	if ((r = spawnl("hello", "hello", 0)) < 0)
+		panic("spawn(hello) failed: %e", r);
+}

user/spawninit.c

@@ -0,0 +1,10 @@
+#include <inc/lib.h>
+
+void
+umain(int argc, char **argv)
+{
+	int r;
+	cprintf("i am parent environment %08x\n", thisenv->env_id);
+	if ((r = spawnl("init", "init", "one", "two", 0)) < 0)
+		panic("spawnl(init) failed: %e", r);
+}

user/testfdsharing.c

@@ -0,0 +1,38 @@
+#include <inc/x86.h>
+#include <inc/lib.h>
+
+char buf[512], buf2[512];
+
+void
+umain(int argc, char **argv)
+{
+	int fd, r, n, n2;
+
+	if ((fd = open("motd", O_RDONLY)) < 0)
+		panic("open motd: %e", fd);
+	seek(fd, 0);
+	if ((n = readn(fd, buf, sizeof buf)) <= 0)
+		panic("readn: %e", n);
+
+	if ((r = fork()) < 0)
+		panic("fork: %e", r);
+	if (r == 0) {
+		seek(fd, 0);
+		cprintf("going to read in child (might page fault if your sharing is buggy)\n");
+		if ((n2 = readn(fd, buf2, sizeof buf2)) != n)
+			panic("read in parent got %d, read in child got %d", n, n2);
+		if (memcmp(buf, buf2, n) != 0)
+			panic("read in parent got different bytes from read in child");
+		cprintf("read in child succeeded\n");
+		seek(fd, 0);
+		close(fd);
+		exit();
+	}
+	wait(r);
+	if ((n2 = readn(fd, buf2, sizeof buf2)) != n)
+		panic("read in parent got %d, then got %d", n, n2);
+	cprintf("read in parent succeeded\n");
+	close(fd);
+
+	breakpoint();
+}

user/testfile.c

@@ -0,0 +1,128 @@
+#include <inc/lib.h>
+
+const char *msg = "This is the NEW message of the day!\n\n";
+
+#define FVA ((struct Fd*)0xCCCCC000)
+
+static int
+xopen(const char *path, int mode)
+{
+	extern union Fsipc fsipcbuf;
+	envid_t fsenv;
+	
+	strcpy(fsipcbuf.open.req_path, path);
+	fsipcbuf.open.req_omode = mode;
+
+	fsenv = ipc_find_env(ENV_TYPE_FS);
+	ipc_send(fsenv, FSREQ_OPEN, &fsipcbuf, PTE_P | PTE_W | PTE_U);
+	return ipc_recv(NULL, FVA, NULL);
+}
+
+void
+umain(int argc, char **argv)
+{
+	int r, f, i;
+	struct Fd *fd;
+	struct Fd fdcopy;
+	struct Stat st;
+	char buf[512];
+
+	// We open files manually first, to avoid the FD layer
+	if ((r = xopen("/not-found", O_RDONLY)) < 0 && r != -E_NOT_FOUND)
+		panic("serve_open /not-found: %e", r);
+	else if (r >= 0)
+		panic("serve_open /not-found succeeded!");
+
+	if ((r = xopen("/newmotd", O_RDONLY)) < 0)
+		panic("serve_open /newmotd: %e", r);
+	if (FVA->fd_dev_id != 'f' || FVA->fd_offset != 0 || FVA->fd_omode != O_RDONLY)
+		panic("serve_open did not fill struct Fd correctly\n");
+	cprintf("serve_open is good\n");
+
+	if ((r = devfile.dev_stat(FVA, &st)) < 0)
+		panic("file_stat: %e", r);
+	if (strlen(msg) != st.st_size)
+		panic("file_stat returned size %d wanted %d\n", st.st_size, strlen(msg));
+	cprintf("file_stat is good\n");
+
+	memset(buf, 0, sizeof buf);
+	if ((r = devfile.dev_read(FVA, buf, sizeof buf)) < 0)
+		panic("file_read: %e", r);
+	if (strcmp(buf, msg) != 0)
+		panic("file_read returned wrong data");
+	cprintf("file_read is good\n");
+
+	if ((r = devfile.dev_close(FVA)) < 0)
+		panic("file_close: %e", r);
+	cprintf("file_close is good\n");
+
+	// We're about to unmap the FD, but still need a way to get
+	// the stale filenum to serve_read, so we make a local copy.
+	// The file server won't think it's stale until we unmap the
+	// FD page.
+	fdcopy = *FVA;
+	sys_page_unmap(0, FVA);
+
+	if ((r = devfile.dev_read(&fdcopy, buf, sizeof buf)) != -E_INVAL)
+		panic("serve_read does not handle stale fileids correctly: %e", r);
+	cprintf("stale fileid is good\n");
+
+	// Try writing
+	if ((r = xopen("/new-file", O_RDWR|O_CREAT)) < 0)
+		panic("serve_open /new-file: %e", r);
+
+	if ((r = devfile.dev_write(FVA, msg, strlen(msg))) != strlen(msg))
+		panic("file_write: %e", r);
+	cprintf("file_write is good\n");
+
+	FVA->fd_offset = 0;
+	memset(buf, 0, sizeof buf);
+	if ((r = devfile.dev_read(FVA, buf, sizeof buf)) < 0)
+		panic("file_read after file_write: %e", r);
+	if (r != strlen(msg))
+		panic("file_read after file_write returned wrong length: %d", r);
+	if (strcmp(buf, msg) != 0)
+		panic("file_read after file_write returned wrong data");
+	cprintf("file_read after file_write is good\n");
+
+	// Now we'll try out open
+	if ((r = open("/not-found", O_RDONLY)) < 0 && r != -E_NOT_FOUND)
+		panic("open /not-found: %e", r);
+	else if (r >= 0)
+		panic("open /not-found succeeded!");
+
+	if ((r = open("/newmotd", O_RDONLY)) < 0)
+		panic("open /newmotd: %e", r);
+	fd = (struct Fd*) (0xD0000000 + r*PGSIZE);
+	if (fd->fd_dev_id != 'f' || fd->fd_offset != 0 || fd->fd_omode != O_RDONLY)
+		panic("open did not fill struct Fd correctly\n");
+	cprintf("open is good\n");
+
+	// Try files with indirect blocks
+	if ((f = open("/big", O_WRONLY|O_CREAT)) < 0)
+		panic("creat /big: %e", f);
+	memset(buf, 0, sizeof(buf));
+	for (i = 0; i < (NDIRECT*3)*BLKSIZE; i += sizeof(buf)) {
+		*(int*)buf = i;
+		if ((r = write(f, buf, sizeof(buf))) < 0)
+			panic("write /big@%d: %e", i, r);
+	}
+	close(f);
+
+	if ((f = open("/big", O_RDONLY)) < 0)
+		panic("open /big: %e", f);
+	for (i = 0; i < (NDIRECT*3)*BLKSIZE; i += sizeof(buf)) {
+		*(int*)buf = i;
+		if ((r = readn(f, buf, sizeof(buf))) < 0)
+			panic("read /big@%d: %e", i, r);
+		if (r != sizeof(buf))
+			panic("read /big from %d returned %d < %d bytes",
+			      i, r, sizeof(buf));
+		if (*(int*)buf != i)
+			panic("read /big from %d returned bad data %d",
+			      i, *(int*)buf);
+	}
+	close(f);
+	cprintf("large file is good\n");
+}
+

user/testkbd.c

@@ -0,0 +1,30 @@
+
+#include <inc/lib.h>
+
+void
+umain(int argc, char **argv)
+{
+	int i, r;
+
+	// Spin for a bit to let the console quiet
+	for (i = 0; i < 10; ++i)
+		sys_yield();
+
+	close(0);
+	if ((r = opencons()) < 0)
+		panic("opencons: %e", r);
+	if (r != 0)
+		panic("first opencons used fd %d", r);
+	if ((r = dup(0, 1)) < 0)
+		panic("dup: %e", r);
+
+	for(;;){
+		char *buf;
+
+		buf = readline("Type a line: ");
+		if (buf != NULL)
+			fprintf(1, "%s\n", buf);
+		else
+			fprintf(1, "(end of file received)\n");
+	}
+}

user/testmalloc.c

@@ -0,0 +1,24 @@
+#include <inc/lib.h>
+
+void
+umain(int argc, char **argv)
+{
+	char *buf;
+	int n;
+	void *v;
+
+	while (1) {
+		buf = readline("> ");
+		if (buf == 0)
+			exit();
+		if (memcmp(buf, "free ", 5) == 0) {
+			v = (void*) strtol(buf + 5, 0, 0);
+			free(v);
+		} else if (memcmp(buf, "malloc ", 7) == 0) {
+			n = strtol(buf + 7, 0, 0);
+			v = malloc(n);
+			printf("\t0x%x\n", (uintptr_t) v);
+		} else
+			printf("?unknown command\n");
+	}
+}

user/testpipe.c

@@ -0,0 +1,64 @@
+#include <inc/lib.h>
+
+char *msg = "Now is the time for all good men to come to the aid of their party.";
+
+void
+umain(int argc, char **argv)
+{
+	char buf[100];
+	int i, pid, p[2];
+
+	binaryname = "pipereadeof";
+
+	if ((i = pipe(p)) < 0)
+		panic("pipe: %e", i);
+
+	if ((pid = fork()) < 0)
+		panic("fork: %e", i);
+
+	if (pid == 0) {
+		cprintf("[%08x] pipereadeof close %d\n", thisenv->env_id, p[1]);
+		close(p[1]);
+		cprintf("[%08x] pipereadeof readn %d\n", thisenv->env_id, p[0]);
+		i = readn(p[0], buf, sizeof buf-1);
+		if (i < 0)
+			panic("read: %e", i);
+		buf[i] = 0;
+		if (strcmp(buf, msg) == 0)
+			cprintf("\npipe read closed properly\n");
+		else
+			cprintf("\ngot %d bytes: %s\n", i, buf);
+		exit();
+	} else {
+		cprintf("[%08x] pipereadeof close %d\n", thisenv->env_id, p[0]);
+		close(p[0]);
+		cprintf("[%08x] pipereadeof write %d\n", thisenv->env_id, p[1]);
+		if ((i = write(p[1], msg, strlen(msg))) != strlen(msg))
+			panic("write: %e", i);
+		close(p[1]);
+	}
+	wait(pid);
+
+	binaryname = "pipewriteeof";
+	if ((i = pipe(p)) < 0)
+		panic("pipe: %e", i);
+
+	if ((pid = fork()) < 0)
+		panic("fork: %e", i);
+
+	if (pid == 0) {
+		close(p[0]);
+		while (1) {
+			cprintf(".");
+			if (write(p[1], "x", 1) != 1)
+				break;
+		}
+		cprintf("\npipe write closed properly\n");
+		exit();
+	}
+	close(p[0]);
+	close(p[1]);
+	wait(pid);
+
+	cprintf("pipe tests passed\n");
+}

user/testpiperace.c

@@ -0,0 +1,66 @@
+#include <inc/lib.h>
+
+void
+umain(int argc, char **argv)
+{
+	int p[2], r, pid, i, max;
+	void *va;
+	struct Fd *fd;
+	const volatile struct Env *kid;
+
+	cprintf("testing for dup race...\n");
+	if ((r = pipe(p)) < 0)
+		panic("pipe: %e", r);
+	max = 200;
+	if ((r = fork()) < 0)
+		panic("fork: %e", r);
+	if (r == 0) {
+		close(p[1]);
+		//
+		// Now the ref count for p[0] will toggle between 2 and 3
+		// as the parent dups and closes it (there's a close implicit in dup).
+		//
+		// The ref count for p[1] is 1.
+		// Thus the ref count for the underlying pipe structure
+		// will toggle between 3 and 4.
+		//
+		// If a clock interrupt catches close between unmapping
+		// the pipe structure and unmapping the fd, we'll have
+		// a ref count for p[0] of 3, a ref count for p[1] of 1,
+		// and a ref count for the pipe structure of 3, which is
+		// a no-no.
+		//
+		// If a clock interrupt catches dup between mapping the
+		// fd and mapping the pipe structure, we'll have the same
+		// ref counts, still a no-no.
+		//
+		for (i=0; i<max; i++) {
+			if(pipeisclosed(p[0])){
+				cprintf("RACE: pipe appears closed\n");
+				exit();
+			}
+			sys_yield();
+		}
+		// do something to be not runnable besides exiting
+		ipc_recv(0,0,0);
+	}
+	pid = r;
+	cprintf("pid is %d\n", pid);
+	va = 0;
+	kid = &envs[ENVX(pid)];
+	cprintf("kid is %d\n", kid-envs);
+	dup(p[0], 10);
+	while (kid->env_status == ENV_RUNNABLE)
+		dup(p[0], 10);
+
+	cprintf("child done with loop\n");
+	if (pipeisclosed(p[0]))
+		panic("somehow the other end of p[0] got closed!");
+	if ((r = fd_lookup(p[0], &fd)) < 0)
+		panic("cannot look up p[0]: %e", r);
+	va = fd2data(fd);
+	if (pageref(va) != 3+1)
+		cprintf("\nchild detected race\n");
+	else
+		cprintf("\nrace didn't happen\n", max);
+}

user/testpiperace2.c

@@ -0,0 +1,69 @@
+
+#include <inc/lib.h>
+
+void
+umain(int argc, char **argv)
+{
+	int p[2], r, i;
+	struct Fd *fd;
+	const volatile struct Env *kid;
+
+	cprintf("testing for pipeisclosed race...\n");
+	if ((r = pipe(p)) < 0)
+		panic("pipe: %e", r);
+	if ((r = fork()) < 0)
+		panic("fork: %e", r);
+	if (r == 0) {
+		// child just dups and closes repeatedly,
+		// yielding so the parent can see
+		// the fd state between the two.
+		close(p[1]);
+		for (i = 0; i < 200; i++) {
+			if (i % 10 == 0)
+				cprintf("%d.", i);
+			// dup, then close.  yield so that other guy will
+			// see us while we're between them.
+			dup(p[0], 10);
+			sys_yield();
+			close(10);
+			sys_yield();
+		}
+		exit();
+	}
+
+	// We hold both p[0] and p[1] open, so pipeisclosed should
+	// never return false.
+	//
+	// Now the ref count for p[0] will toggle between 2 and 3
+	// as the child dups and closes it.
+	// The ref count for p[1] is 1.
+	// Thus the ref count for the underlying pipe structure
+	// will toggle between 3 and 4.
+	//
+	// If pipeisclosed checks pageref(p[0]) and gets 3, and
+	// then the child closes, and then pipeisclosed checks
+	// pageref(pipe structure) and gets 3, then it will return true
+	// when it shouldn't.
+	//
+	// If pipeisclosed checks pageref(pipe structure) and gets 3,
+	// and then the child dups, and then pipeisclosed checks
+	// pageref(p[0]) and gets 3, then it will return true when
+	// it shouldn't.
+	//
+	// So either way, pipeisclosed is going give a wrong answer.
+	//
+	kid = &envs[ENVX(r)];
+	while (kid->env_status == ENV_RUNNABLE)
+		if (pipeisclosed(p[0]) != 0) {
+			cprintf("\nRACE: pipe appears closed\n");
+			sys_env_destroy(r);
+			exit();
+		}
+	cprintf("child done with loop\n");
+	if (pipeisclosed(p[0]))
+		panic("somehow the other end of p[0] got closed!");
+	if ((r = fd_lookup(p[0], &fd)) < 0)
+		panic("cannot look up p[0]: %e", r);
+	(void) fd2data(fd);
+	cprintf("race didn't happen\n");
+}

user/testptelibrary.c

@@ -0,0 +1,42 @@
+#include <inc/lib.h>
+
+#define VA ((char *) 0xA0000000)
+const char *msg = "hello, world\n";
+const char *msg2 = "goodbye, world\n";
+
+void childofspawn(void);
+
+void
+umain(int argc, char **argv)
+{
+	int r;
+
+	if (argc != 0)
+		childofspawn();
+
+	if ((r = sys_page_alloc(0, VA, PTE_P|PTE_W|PTE_U|PTE_SHARE)) < 0)
+		panic("sys_page_alloc: %e", r);
+
+	// check fork
+	if ((r = fork()) < 0)
+		panic("fork: %e", r);
+	if (r == 0) {
+		strcpy(VA, msg);
+		exit();
+	}
+	wait(r);
+	cprintf("fork handles PTE_SHARE %s\n", strcmp(VA, msg) == 0 ? "right" : "wrong");
+
+	// check spawn
+	if ((r = spawnl("/testptelibrary", "testptelibrary", "arg", 0)) < 0)
+		panic("spawn: %e", r);
+	wait(r);
+	cprintf("spawn handles PTE_SHARE %s\n", strcmp(VA, msg2) == 0 ? "right" : "wrong");
+}
+
+void
+childofspawn(void)
+{
+	strcpy(VA, msg2);
+	exit();
+}

user/testpteshare.c

@@ -0,0 +1,45 @@
+#include <inc/x86.h>
+#include <inc/lib.h>
+
+#define VA	((char *) 0xA0000000)
+const char *msg = "hello, world\n";
+const char *msg2 = "goodbye, world\n";
+
+void childofspawn(void);
+
+void
+umain(int argc, char **argv)
+{
+	int r;
+
+	if (argc != 0)
+		childofspawn();
+
+	if ((r = sys_page_alloc(0, VA, PTE_P|PTE_W|PTE_U|PTE_SHARE)) < 0)
+		panic("sys_page_alloc: %e", r);
+
+	// check fork
+	if ((r = fork()) < 0)
+		panic("fork: %e", r);
+	if (r == 0) {
+		strcpy(VA, msg);
+		exit();
+	}
+	wait(r);
+	cprintf("fork handles PTE_SHARE %s\n", strcmp(VA, msg) == 0 ? "right" : "wrong");
+
+	// check spawn
+	if ((r = spawnl("/testpteshare", "testpteshare", "arg", 0)) < 0)
+		panic("spawn: %e", r);
+	wait(r);
+	cprintf("spawn handles PTE_SHARE %s\n", strcmp(VA, msg2) == 0 ? "right" : "wrong");
+
+	breakpoint();
+}
+
+void
+childofspawn(void)
+{
+	strcpy(VA, msg2);
+	exit();
+}

user/testshell.c

@@ -0,0 +1,85 @@
+#include <inc/x86.h>
+#include <inc/lib.h>
+
+void wrong(int, int, int);
+
+void
+umain(int argc, char **argv)
+{
+	char c1, c2;
+	int r, rfd, wfd, kfd, n1, n2, off, nloff;
+	int pfds[2];
+
+	close(0);
+	close(1);
+	opencons();
+	opencons();
+
+	if ((rfd = open("testshell.sh", O_RDONLY)) < 0)
+		panic("open testshell.sh: %e", rfd);
+	if ((wfd = pipe(pfds)) < 0)
+		panic("pipe: %e", wfd);
+	wfd = pfds[1];
+
+	cprintf("running sh -x < testshell.sh | cat\n");
+	if ((r = fork()) < 0)
+		panic("fork: %e", r);
+	if (r == 0) {
+		dup(rfd, 0);
+		dup(wfd, 1);
+		close(rfd);
+		close(wfd);
+		if ((r = spawnl("/sh", "sh", "-x", 0)) < 0)
+			panic("spawn: %e", r);
+		close(0);
+		close(1);
+		wait(r);
+		exit();
+	}
+	close(rfd);
+	close(wfd);
+
+	rfd = pfds[0];
+	if ((kfd = open("testshell.key", O_RDONLY)) < 0)
+		panic("open testshell.key for reading: %e", kfd);
+
+	nloff = 0;
+	for (off=0;; off++) {
+		n1 = read(rfd, &c1, 1);
+		n2 = read(kfd, &c2, 1);
+		if (n1 < 0)
+			panic("reading testshell.out: %e", n1);
+		if (n2 < 0)
+			panic("reading testshell.key: %e", n2);
+		if (n1 == 0 && n2 == 0)
+			break;
+		if (n1 != 1 || n2 != 1 || c1 != c2)
+			wrong(rfd, kfd, nloff);
+		if (c1 == '\n')
+			nloff = off+1;
+	}
+	cprintf("shell ran correctly\n");
+
+	breakpoint();
+}
+
+void
+wrong(int rfd, int kfd, int off)
+{
+	char buf[100];
+	int n;
+
+	seek(rfd, off);
+	seek(kfd, off);
+
+	cprintf("shell produced incorrect output.\n");
+	cprintf("expected:\n===\n");
+	while ((n = read(kfd, buf, sizeof buf-1)) > 0)
+		sys_cputs(buf, n);
+	cprintf("===\ngot:\n===\n");
+	while ((n = read(rfd, buf, sizeof buf-1)) > 0)
+		sys_cputs(buf, n);
+	cprintf("===\n");
+	exit();
+}
+

user/writemotd.c

@@ -0,0 +1,40 @@
+#include <inc/lib.h>
+
+void
+umain(int argc, char **argv)
+{
+	int rfd, wfd;
+	char buf[512];
+	int n, r;
+
+	if ((rfd = open("/newmotd", O_RDONLY)) < 0)
+		panic("open /newmotd: %e", rfd);
+	if ((wfd = open("/motd", O_RDWR)) < 0)
+		panic("open /motd: %e", wfd);
+	cprintf("file descriptors %d %d\n", rfd, wfd);
+	if (rfd == wfd)
+		panic("open /newmotd and /motd give same file descriptor");
+
+	cprintf("OLD MOTD\n===\n");
+	while ((n = read(wfd, buf, sizeof buf-1)) > 0)
+		sys_cputs(buf, n);
+	cprintf("===\n");
+	seek(wfd, 0);
+
+	if ((r = ftruncate(wfd, 0)) < 0)
+		panic("truncate /motd: %e", r);
+
+	cprintf("NEW MOTD\n===\n");
+	while ((n = read(rfd, buf, sizeof buf-1)) > 0) {
+		sys_cputs(buf, n);
+		if ((r = write(wfd, buf, n)) != n)
+			panic("write /motd: %e", r);
+	}
+	cprintf("===\n");
+
+	if (n < 0)
+		panic("read /newmotd: %e", n);
+
+	close(rfd);
+	close(wfd);
+}