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/* vi: set sw=4 ts=4: */
/*
* Mini cmp implementation for busybox
*
* Copyright (C) 2000,2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
/* BB_AUDIT SUSv3 (virtually) compliant -- uses nicer GNU format for -l. */
/* http://www.opengroup.org/onlinepubs/007904975/utilities/cmp.html */
/* Mar 16, 2003 Manuel Novoa III (mjn3@codepoet.org)
*
* Original version majorly reworked for SUSv3 compliance, bug fixes, and
* size optimizations. Changes include:
* 1) Now correctly distinguishes between errors and actual file differences.
* 2) Proper handling of '-' args.
* 3) Actual error checking of i/o.
* 4) Accept SUSv3 -l option. Note that we use the slightly nicer gnu format
* in the '-l' case.
*/
#include "busybox.h"
static FILE *cmp_xfopen_input(const char *filename)
{
FILE *fp;
if ((fp = bb_wfopen_input(filename)) != NULL) {
return fp;
}
exit(bb_default_error_retval); /* We already output an error message. */
}
static const char fmt_eof[] = "cmp: EOF on %s\n";
static const char fmt_differ[] = "%s %s differ: char %d, line %d\n";
// This fmt_l_opt uses gnu-isms. SUSv3 would be "%.0s%.0s%d %o %o\n"
static const char fmt_l_opt[] = "%.0s%.0s%d %3o %3o\n";
static const char opt_chars[] = "sl";
enum {
OPT_s = 1,
OPT_l = 2
};
int cmp_main(int argc, char **argv)
{
FILE *fp1, *fp2, *outfile = stdout;
const char *filename1, *filename2;
const char *fmt;
int c1, c2, char_pos, line_pos;
int opt_flags;
int exit_val = 0;
bb_default_error_retval = 2; /* 1 is returned if files are different. */
opt_flags = bb_getopt_ulflags(argc, argv, opt_chars);
if ((opt_flags == 3) || (((unsigned int)(--argc - optind)) > 1)) {
bb_show_usage();
}
fp1 = cmp_xfopen_input(filename1 = *(argv += optind));
filename2 = "-";
if (*++argv) {
filename2 = *argv;
}
fp2 = cmp_xfopen_input(filename2);
if (fp1 == fp2) { /* Paranioa check... stdin == stdin? */
/* Note that we don't bother reading stdin. Neither does gnu wc.
* But perhaps we should, so that other apps down the chain don't
* get the input. Consider 'echo hello | (cmp - - && cat -)'.
*/
return 0;
}
fmt = fmt_differ;
if (opt_flags == OPT_l) {
fmt = fmt_l_opt;
}
char_pos = 0;
line_pos = 1;
do {
c1 = getc(fp1);
c2 = getc(fp2);
++char_pos;
if (c1 != c2) { /* Remember -- a read error may have occurred. */
exit_val = 1; /* But assume the files are different for now. */
if (c2 == EOF) {
/* We know that fp1 isn't at EOF or in an error state. But to
* save space below, things are setup to expect an EOF in fp1
* if an EOF occurred. So, swap things around.
*/
fp1 = fp2;
filename1 = filename2;
c1 = c2;
}
if (c1 == EOF) {
xferror(fp1, filename1);
fmt = fmt_eof; /* Well, no error, so it must really be EOF. */
outfile = stderr;
/* There may have been output to stdout (option -l), so
* make sure we fflush before writing to stderr. */
xfflush_stdout();
}
if (opt_flags != OPT_s) {
if (opt_flags == OPT_l) {
line_pos = c1; /* line_pos is unused in the -l case. */
}
bb_fprintf(outfile, fmt, filename1, filename2, char_pos, line_pos, c2);
if (opt_flags) { /* This must be -l since not -s. */
/* If we encountered and EOF, the while check will catch it. */
continue;
}
}
break;
}
if (c1 == '\n') {
++line_pos;
}
} while (c1 != EOF);
xferror(fp1, filename1);
xferror(fp2, filename2);
bb_fflush_stdout_and_exit(exit_val);
}
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