1 /* vi: set sw=4 ts=4: */
3 * Mini cmp implementation for busybox
5 * Copyright (C) 2000,2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
7 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
10 /* BB_AUDIT SUSv3 (virtually) compliant -- uses nicer GNU format for -l. */
11 /* http://www.opengroup.org/onlinepubs/007904975/utilities/cmp.html */
13 /* Mar 16, 2003 Manuel Novoa III (mjn3@codepoet.org)
15 * Original version majorly reworked for SUSv3 compliance, bug fixes, and
16 * size optimizations. Changes include:
17 * 1) Now correctly distinguishes between errors and actual file differences.
18 * 2) Proper handling of '-' args.
19 * 3) Actual error checking of i/o.
20 * 4) Accept SUSv3 -l option. Note that we use the slightly nicer gnu format
26 static const char fmt_eof[] ALIGN1 = "cmp: EOF on %s\n";
27 static const char fmt_differ[] ALIGN1 = "%s %s differ: char %"OFF_FMT"d, line %d\n";
28 // This fmt_l_opt uses gnu-isms. SUSv3 would be "%.0s%.0s%"OFF_FMT"d %o %o\n"
29 static const char fmt_l_opt[] ALIGN1 = "%.0s%.0s%"OFF_FMT"d %3o %3o\n";
31 static const char opt_chars[] ALIGN1 = "sl";
32 #define CMP_OPT_s (1<<0)
33 #define CMP_OPT_l (1<<1)
35 int cmp_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
36 int cmp_main(int argc ATTRIBUTE_UNUSED, char **argv)
38 FILE *fp1, *fp2, *outfile = stdout;
39 const char *filename1, *filename2 = "-";
40 USE_DESKTOP(off_t skip1 = 0, skip2 = 0;)
42 int line_pos = 1; /* Hopefully won't overflow... */
48 xfunc_error_retval = 2; /* 1 is returned if files are different. */
50 opt_complementary = "-1"
54 opt = getopt32(argv, opt_chars);
58 fp1 = xfopen_stdin(filename1);
64 skip1 = XATOOFF(*argv);
66 skip2 = XATOOFF(*argv);
72 fp2 = xfopen_stdin(filename2);
73 if (fp1 == fp2) { /* Paranoia check... stdin == stdin? */
74 /* Note that we don't bother reading stdin. Neither does gnu wc.
75 * But perhaps we should, so that other apps down the chain don't
76 * get the input. Consider 'echo hello | (cmp - - && cat -)'.
87 while (skip1) { getc(fp1); skip1--; }
88 while (skip2) { getc(fp2); skip2--; }
94 if (c1 != c2) { /* Remember: a read error may have occurred. */
95 retval = 1; /* But assume the files are different for now. */
97 /* We know that fp1 isn't at EOF or in an error state. But to
98 * save space below, things are setup to expect an EOF in fp1
99 * if an EOF occurred. So, swap things around.
102 filename1 = filename2;
106 die_if_ferror(fp1, filename1);
107 fmt = fmt_eof; /* Well, no error, so it must really be EOF. */
109 /* There may have been output to stdout (option -l), so
110 * make sure we fflush before writing to stderr. */
113 if (!(opt & CMP_OPT_s)) {
114 if (opt & CMP_OPT_l) {
115 line_pos = c1; /* line_pos is unused in the -l case. */
117 fprintf(outfile, fmt, filename1, filename2, char_pos, line_pos, c2);
118 if (opt) { /* This must be -l since not -s. */
119 /* If we encountered an EOF,
120 * the while check will catch it. */
131 die_if_ferror(fp1, filename1);
132 die_if_ferror(fp2, filename2);
134 fflush_stdout_and_exit(retval);