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