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 source tree.
10 //config: bool "cmp (5.4 kb)"
13 //config: cmp is used to compare two files and returns the result
14 //config: to standard output.
16 //applet:IF_CMP(APPLET(cmp, BB_DIR_USR_BIN, BB_SUID_DROP))
18 //kbuild:lib-$(CONFIG_CMP) += cmp.o
20 //usage:#define cmp_trivial_usage
21 //usage: "[-l] [-s] FILE1 [FILE2" IF_DESKTOP(" [SKIP1 [SKIP2]]") "]"
22 //usage:#define cmp_full_usage "\n\n"
23 //usage: "Compare FILE1 with FILE2 (or stdin)\n"
24 //usage: "\n -l Write the byte numbers (decimal) and values (octal)"
25 //usage: "\n for all differing bytes"
26 //usage: "\n -s Quiet"
28 /* BB_AUDIT SUSv3 (virtually) compliant -- uses nicer GNU format for -l. */
29 /* http://www.opengroup.org/onlinepubs/007904975/utilities/cmp.html */
33 static const char fmt_eof[] ALIGN1 = "cmp: EOF on %s\n";
34 static const char fmt_differ[] ALIGN1 = "%s %s differ: char %"OFF_FMT"u, line %u\n";
35 // This fmt_l_opt uses gnu-isms. SUSv3 would be "%.0s%.0s%"OFF_FMT"u %o %o\n"
36 static const char fmt_l_opt[] ALIGN1 = "%.0s%.0s%"OFF_FMT"u %3o %3o\n";
39 #define CMP_OPT_s (1<<0)
40 #define CMP_OPT_l (1<<1)
42 int cmp_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
43 int cmp_main(int argc UNUSED_PARAM, char **argv)
45 FILE *fp1, *fp2, *outfile = stdout;
46 const char *filename1, *filename2 = "-";
47 off_t skip1 = 0, skip2 = 0, char_pos = 0;
48 int line_pos = 1; /* Hopefully won't overflow... */
54 opt = getopt32(argv, "^"
66 if (ENABLE_DESKTOP && *++argv) {
67 skip1 = XATOOFF(*argv);
69 skip2 = XATOOFF(*argv);
74 xfunc_error_retval = 2; /* missing file results in exitcode 2 */
76 logmode = 0; /* -s suppresses open error messages */
77 fp1 = xfopen_stdin(filename1);
78 fp2 = xfopen_stdin(filename2);
79 if (fp1 == fp2) { /* Paranoia check... stdin == stdin? */
80 /* Note that we don't bother reading stdin. Neither does gnu wc.
81 * But perhaps we should, so that other apps down the chain don't
82 * get the input. Consider 'echo hello | (cmp - - && cat -)'.
86 logmode = LOGMODE_STDIO;
94 while (skip1) { getc(fp1); skip1--; }
95 while (skip2) { getc(fp2); skip2--; }
101 if (c1 != c2) { /* Remember: a read error may have occurred. */
102 retval = 1; /* But assume the files are different for now. */
104 /* We know that fp1 isn't at EOF or in an error state. But to
105 * save space below, things are setup to expect an EOF in fp1
106 * if an EOF occurred. So, swap things around.
109 filename1 = filename2;
113 die_if_ferror(fp1, filename1);
114 fmt = fmt_eof; /* Well, no error, so it must really be EOF. */
116 /* There may have been output to stdout (option -l), so
117 * make sure we fflush before writing to stderr. */
120 if (!(opt & CMP_OPT_s)) {
121 if (opt & CMP_OPT_l) {
122 line_pos = c1; /* line_pos is unused in the -l case. */
124 fprintf(outfile, fmt, filename1, filename2, char_pos, line_pos, c2);
125 if (opt) { /* This must be -l since not -s. */
126 /* If we encountered an EOF,
127 * the while check will catch it. */
138 die_if_ferror(fp1, filename1);
139 die_if_ferror(fp2, filename2);
141 fflush_stdout_and_exit(retval);