1 /* vi: set sw=4 ts=4: */
2 /*
3 * Mini cmp implementation for busybox
4 *
5 * Copyright (C) 2000,2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
6 *
7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
8 */
9 //config:config CMP
10 //config: bool "cmp (4.9 kb)"
11 //config: default y
12 //config: help
13 //config: cmp is used to compare two files and returns the result
14 //config: to standard output.
15
16 //applet:IF_CMP(APPLET(cmp, BB_DIR_USR_BIN, BB_SUID_DROP))
17
18 //kbuild:lib-$(CONFIG_CMP) += cmp.o
19
20 //usage:#define cmp_trivial_usage
21 //usage: "[-ls] [-n NUM] 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"
27 //usage: "\n -n NUM Compare at most NUM bytes"
28
29 /* BB_AUDIT SUSv3 (virtually) compliant -- uses nicer GNU format for -l. */
30 /* http://www.opengroup.org/onlinepubs/007904975/utilities/cmp.html */
31
32 #include "libbb.h"
33
34 static const char fmt_eof[] ALIGN1 = "cmp: EOF on %s\n";
35 static const char fmt_differ[] ALIGN1 = "%s %s differ: char %"OFF_FMT"u, line %u\n";
36 // This fmt_l_opt uses gnu-isms. SUSv3 would be "%.0s%.0s%"OFF_FMT"u %o %o\n"
37 static const char fmt_l_opt[] ALIGN1 = "%.0s%.0s%"OFF_FMT"u %3o %3o\n";
38
39 #define OPT_STR "sln:+"
40 #define CMP_OPT_s (1<<0)
41 #define CMP_OPT_l (1<<1)
42 #define CMP_OPT_n (1<<2)
43
44 int cmp_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
cmp_main(int argc UNUSED_PARAM,char ** argv)45 int cmp_main(int argc UNUSED_PARAM, char **argv)
46 {
47 FILE *fp1, *fp2, *outfile = stdout;
48 const char *filename1, *filename2 = "-";
49 off_t skip1 = 0, skip2 = 0, char_pos = 0;
50 int line_pos = 1; /* Hopefully won't overflow... */
51 const char *fmt;
52 int c1, c2;
53 unsigned opt;
54 int retval = 0;
55 int max_count = -1;
56
57 opt = getopt32(argv, "^"
58 OPT_STR
59 "\0" "-1"
60 IF_DESKTOP(":?4")
61 IF_NOT_DESKTOP(":?2")
62 ":l--s:s--l",
63 &max_count
64 );
65 argv += optind;
66
67 filename1 = *argv;
68 if (*++argv) {
69 filename2 = *argv;
70 if (ENABLE_DESKTOP && *++argv) {
71 skip1 = XATOOFF(*argv);
72 if (*++argv) {
73 skip2 = XATOOFF(*argv);
74 }
75 }
76 }
77
78 xfunc_error_retval = 2; /* missing file results in exitcode 2 */
79 if (opt & CMP_OPT_s)
80 logmode = 0; /* -s suppresses open error messages */
81 fp1 = xfopen_stdin(filename1);
82 fp2 = xfopen_stdin(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 -)'.
87 */
88 return 0;
89 }
90 logmode = LOGMODE_STDIO;
91
92 if (opt & CMP_OPT_l)
93 fmt = fmt_l_opt;
94 else
95 fmt = fmt_differ;
96
97 if (ENABLE_DESKTOP) {
98 while (skip1) { getc(fp1); skip1--; }
99 while (skip2) { getc(fp2); skip2--; }
100 }
101 do {
102 if (max_count >= 0 && --max_count < 0)
103 break;
104 c1 = getc(fp1);
105 c2 = getc(fp2);
106 ++char_pos;
107 if (c1 != c2) { /* Remember: a read error may have occurred. */
108 retval = 1; /* But assume the files are different for now. */
109 if (c2 == EOF) {
110 /* We know that fp1 isn't at EOF or in an error state. But to
111 * save space below, things are setup to expect an EOF in fp1
112 * if an EOF occurred. So, swap things around.
113 */
114 fp1 = fp2;
115 filename1 = filename2;
116 c1 = c2;
117 }
118 if (c1 == EOF) {
119 die_if_ferror(fp1, filename1);
120 fmt = fmt_eof; /* Well, no error, so it must really be EOF. */
121 outfile = stderr;
122 /* There may have been output to stdout (option -l), so
123 * make sure we fflush before writing to stderr. */
124 fflush_all();
125 }
126 if (!(opt & CMP_OPT_s)) {
127 if (opt & CMP_OPT_l) {
128 line_pos = c1; /* line_pos is unused in the -l case. */
129 }
130 fprintf(outfile, fmt, filename1, filename2, char_pos, line_pos, c2);
131 if (opt) { /* This must be -l since not -s. */
132 /* If we encountered an EOF,
133 * the while check will catch it. */
134 continue;
135 }
136 }
137 break;
138 }
139 if (c1 == '\n') {
140 ++line_pos;
141 }
142 } while (c1 != EOF);
143
144 die_if_ferror(fp1, filename1);
145 die_if_ferror(fp2, filename2);
146
147 fflush_stdout_and_exit(retval);
148 }
149