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