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 tarball for details. 8 */ 9 10/* BB_AUDIT SUSv3 (virtually) compliant -- uses nicer GNU format for -l. */ 11/* http://www.opengroup.org/onlinepubs/007904975/utilities/cmp.html */ 12 13/* Mar 16, 2003 Manuel Novoa III (mjn3@codepoet.org) 14 * 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 21 * in the '-l' case. 22 */ 23 24#include "libbb.h" 25 26static FILE *cmp_xfopen_input(const char *filename) 27{ 28 FILE *fp; 29 30 fp = fopen_or_warn_stdin(filename); 31 if (fp) 32 return fp; 33 xfunc_die(); /* We already output an error message. */ 34} 35 36static const char fmt_eof[] ALIGN1 = "cmp: EOF on %s\n"; 37static const char fmt_differ[] ALIGN1 = "%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" 39static const char fmt_l_opt[] ALIGN1 = "%.0s%.0s%"OFF_FMT"d %3o %3o\n"; 40 41static const char opt_chars[] ALIGN1 = "sl"; 42#define CMP_OPT_s (1<<0) 43#define CMP_OPT_l (1<<1) 44 45int cmp_main(int argc, char **argv); 46int cmp_main(int argc, char **argv) 47{ 48 FILE *fp1, *fp2, *outfile = stdout; 49 const char *filename1, *filename2 = "-"; 50 USE_DESKTOP(off_t skip1 = 0, skip2 = 0;) 51 off_t char_pos = 0; 52 int line_pos = 1; /* Hopefully won't overflow... */ 53 const char *fmt; 54 int c1, c2; 55 unsigned opt; 56 int retval = 0; 57 58 xfunc_error_retval = 2; /* 1 is returned if files are different. */ 59 60 opt_complementary = "-1" 61 USE_DESKTOP(":?4") 62 SKIP_DESKTOP(":?2") 63 ":l--s:s--l"; 64 opt = getopt32(argv, opt_chars); 65 argv += optind; 66 67 filename1 = *argv; 68 fp1 = cmp_xfopen_input(filename1); 69 70 if (*++argv) { 71 filename2 = *argv; 72#if ENABLE_DESKTOP 73 if (*++argv) { 74 skip1 = XATOOFF(*argv); 75 if (*++argv) { 76 skip2 = XATOOFF(*argv); 77 } 78 } 79#endif 80 } 81 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 -)'. 87 */ 88 return 0; 89 } 90 91 if (opt & CMP_OPT_l) 92 fmt = fmt_l_opt; 93 else 94 fmt = fmt_differ; 95 96#if ENABLE_DESKTOP 97 while (skip1) { getc(fp1); skip1--; } 98 while (skip2) { getc(fp2); skip2--; } 99#endif 100 do { 101 c1 = getc(fp1); 102 c2 = getc(fp2); 103 ++char_pos; 104 if (c1 != c2) { /* Remember: a read error may have occurred. */ 105 retval = 1; /* But assume the files are different for now. */ 106 if (c2 == EOF) { 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. 110 */ 111 fp1 = fp2; 112 filename1 = filename2; 113 c1 = c2; 114 } 115 if (c1 == EOF) { 116 die_if_ferror(fp1, filename1); 117 fmt = fmt_eof; /* Well, no error, so it must really be EOF. */ 118 outfile = stderr; 119 /* There may have been output to stdout (option -l), so 120 * make sure we fflush before writing to stderr. */ 121 xfflush_stdout(); 122 } 123 if (!(opt & CMP_OPT_s)) { 124 if (opt & CMP_OPT_l) { 125 line_pos = c1; /* line_pos is unused in the -l case. */ 126 } 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. */ 131 continue; 132 } 133 } 134 break; 135 } 136 if (c1 == '\n') { 137 ++line_pos; 138 } 139 } while (c1 != EOF); 140 141 die_if_ferror(fp1, filename1); 142 die_if_ferror(fp2, filename2); 143 144 fflush_stdout_and_exit(retval); 145} 146