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 FILE *cmp_xfopen_input(const char * const filename)
30 fp = fopen_or_warn_stdin(filename);
33 sleep_and_die(); /* We already output an error message. */
36 static const char fmt_eof[] = "cmp: EOF on %s\n";
37 static const char fmt_differ[] = "%s %s differ: char %"OFF_FMT"d, line %d\n";
38 // This fmt_l_opt uses gnu-isms. SUSv3 would be "%.0s%.0s%"OFF_FMT"d %o %o\n"
39 static const char fmt_l_opt[] = "%.0s%.0s%"OFF_FMT"d %3o %3o\n";
41 static const char opt_chars[] = "sl";
42 #define CMP_OPT_s (1<<0)
43 #define CMP_OPT_l (1<<1)
45 int cmp_main(int argc, char **argv);
46 int cmp_main(int argc, char **argv)
48 FILE *fp1, *fp2, *outfile = stdout;
49 const char *filename1, *filename2 = "-";
50 USE_DESKTOP(off_t skip1 = 0, skip2 = 0;)
52 int line_pos = 1; /* Hopefully won't overflow... */
58 xfunc_error_retval = 2; /* 1 is returned if files are different. */
60 opt_complementary = "?:-1"
64 opt = getopt32(argc, argv, opt_chars);
68 fp1 = cmp_xfopen_input(filename1);
74 skip1 = XATOOFF(*argv);
76 skip2 = XATOOFF(*argv);
82 fp2 = cmp_xfopen_input(filename2);
83 if (fp1 == fp2) { /* Paranoia check... stdin == stdin? */
84 /* Note that we don't bother reading stdin. Neither does gnu wc.
85 * But perhaps we should, so that other apps down the chain don't
86 * get the input. Consider 'echo hello | (cmp - - && cat -)'.
97 while (skip1) { getc(fp1); skip1--; }
98 while (skip2) { getc(fp2); skip2--; }
104 if (c1 != c2) { /* Remember: a read error may have occurred. */
105 retval = 1; /* But assume the files are different for now. */
107 /* We know that fp1 isn't at EOF or in an error state. But to
108 * save space below, things are setup to expect an EOF in fp1
109 * if an EOF occurred. So, swap things around.
112 filename1 = filename2;
116 die_if_ferror(fp1, filename1);
117 fmt = fmt_eof; /* Well, no error, so it must really be EOF. */
119 /* There may have been output to stdout (option -l), so
120 * make sure we fflush before writing to stderr. */
123 if (!(opt & CMP_OPT_s)) {
124 if (opt & CMP_OPT_l) {
125 line_pos = c1; /* line_pos is unused in the -l case. */
127 fprintf(outfile, fmt, filename1, filename2, char_pos, line_pos, c2);
128 if (opt) { /* This must be -l since not -s. */
129 /* If we encountered an EOF,
130 * the while check will catch it. */
141 die_if_ferror(fp1, filename1);
142 die_if_ferror(fp2, filename2);
144 fflush_stdout_and_exit(retval);