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 exit(xfunc_error_retval); /* 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 %d, line %d\n";
38 // This fmt_l_opt uses gnu-isms. SUSv3 would be "%.0s%.0s%d %o %o\n"
39 static const char fmt_l_opt[] = "%.0s%.0s%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)
47 FILE *fp1, *fp2, *outfile = stdout;
48 const char *filename1, *filename2 = "-";
50 int c1, c2, char_pos = 0, line_pos = 1;
54 xfunc_error_retval = 2; /* 1 is returned if files are different. */
56 opt = getopt32(argc, argv, opt_chars);
58 if (((opt & (CMP_OPT_s|CMP_OPT_l)) == (CMP_OPT_s|CMP_OPT_l))
59 || (((unsigned int)(--argc - optind)) > 1))
62 fp1 = cmp_xfopen_input(filename1 = *(argv += optind));
67 fp2 = cmp_xfopen_input(filename2);
69 if (fp1 == fp2) { /* Paranioa check... stdin == stdin? */
70 /* Note that we don't bother reading stdin. Neither does gnu wc.
71 * But perhaps we should, so that other apps down the chain don't
72 * get the input. Consider 'echo hello | (cmp - - && cat -)'.
86 if (c1 != c2) { /* Remember: a read error may have occurred. */
87 retval = 1; /* But assume the files are different for now. */
89 /* We know that fp1 isn't at EOF or in an error state. But to
90 * save space below, things are setup to expect an EOF in fp1
91 * if an EOF occurred. So, swap things around.
94 filename1 = filename2;
98 die_if_ferror(fp1, filename1);
99 fmt = fmt_eof; /* Well, no error, so it must really be EOF. */
101 /* There may have been output to stdout (option -l), so
102 * make sure we fflush before writing to stderr. */
105 if (!(opt & CMP_OPT_s)) {
106 if (opt & CMP_OPT_l) {
107 line_pos = c1; /* line_pos is unused in the -l case. */
109 fprintf(outfile, fmt, filename1, filename2, char_pos, line_pos, c2);
110 if (opt) { /* This must be -l since not -s. */
111 /* If we encountered an EOF,
112 * the while check will catch it. */
123 die_if_ferror(fp1, filename1);
124 die_if_ferror(fp2, filename2);
126 fflush_stdout_and_exit(retval);