69 lines
1.5 KiB
C
69 lines
1.5 KiB
C
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/* cat.c
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Compares two files. */
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#include <stdio.h>
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#include <syscall.h>
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int
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main (int argc, char *argv[])
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{
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int fd[2];
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if (argc != 3)
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{
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printf ("usage: cmp A B\n");
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return EXIT_FAILURE;
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}
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/* Open files. */
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fd[0] = open (argv[1]);
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if (fd[0] < 0)
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{
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printf ("%s: open failed\n", argv[1]);
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return EXIT_FAILURE;
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}
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fd[1] = open (argv[2]);
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if (fd[1] < 0)
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{
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printf ("%s: open failed\n", argv[1]);
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return EXIT_FAILURE;
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}
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/* Compare data. */
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for (;;)
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{
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int pos;
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char buffer[2][1024];
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int bytes_read[2];
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int min_read;
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int i;
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pos = tell (fd[0]);
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bytes_read[0] = read (fd[0], buffer[0], sizeof buffer[0]);
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bytes_read[1] = read (fd[1], buffer[1], sizeof buffer[1]);
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min_read = bytes_read[0] < bytes_read[1] ? bytes_read[0] : bytes_read[1];
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if (min_read == 0)
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break;
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for (i = 0; i < min_read; i++)
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if (buffer[0][i] != buffer[1][i])
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{
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printf ("Byte %d is %02hhx ('%c') in %s but %02hhx ('%c') in %s\n",
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pos + i,
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buffer[0][i], buffer[0][i], argv[1],
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buffer[1][i], buffer[1][i], argv[2]);
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return EXIT_FAILURE;
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}
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if (min_read < bytes_read[1])
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printf ("%s is shorter than %s\n", argv[1], argv[2]);
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else if (min_read < bytes_read[0])
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printf ("%s is shorter than %s\n", argv[2], argv[1]);
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}
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printf ("%s and %s are identical\n", argv[1], argv[2]);
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return EXIT_SUCCESS;
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}
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