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Diffstat (limited to 'src/cmp.c')
| -rw-r--r-- | src/cmp.c | 661 |
1 files changed, 661 insertions, 0 deletions
diff --git a/src/cmp.c b/src/cmp.c new file mode 100644 index 0000000..ba5553b --- /dev/null +++ b/src/cmp.c @@ -0,0 +1,661 @@ +/* cmp - compare two files byte by byte + + Copyright (C) 1990-1996, 1998, 2001-2002, 2004, 2006-2007, 2009-2013, + 2015-2016 Free Software Foundation, Inc. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. */ + +#include "system.h" +#include "paths.h" + +#include <stdio.h> + +#include <c-stack.h> +#include <cmpbuf.h> +#include <error.h> +#include <exitfail.h> +#include <file-type.h> +#include <getopt.h> +#include <hard-locale.h> +#include <inttostr.h> +#include <progname.h> +#include <unlocked-io.h> +#include <version-etc.h> +#include <xalloc.h> +#include <binary-io.h> +#include <xstrtol.h> + +/* The official name of this program (e.g., no 'g' prefix). */ +#define PROGRAM_NAME "cmp" + +#define AUTHORS \ + proper_name_utf8 ("Torbjorn Granlund", "Torbj\303\266rn Granlund"), \ + proper_name ("David MacKenzie") + +#if defined LC_MESSAGES && ENABLE_NLS +# define hard_locale_LC_MESSAGES hard_locale (LC_MESSAGES) +#else +# define hard_locale_LC_MESSAGES 0 +#endif + +static int cmp (void); +static off_t file_position (int); +static size_t block_compare (word const *, word const *) _GL_ATTRIBUTE_PURE; +static size_t count_newlines (char *, size_t); +static void sprintc (char *, unsigned char); + +/* Filenames of the compared files. */ +static char const *file[2]; + +/* File descriptors of the files. */ +static int file_desc[2]; + +/* Status of the files. */ +static struct stat stat_buf[2]; + +/* Read buffers for the files. */ +static word *buffer[2]; + +/* Optimal block size for the files. */ +static size_t buf_size; + +/* Initial prefix to ignore for each file. */ +static off_t ignore_initial[2]; + +/* Number of bytes to compare. */ +static uintmax_t bytes = UINTMAX_MAX; + +/* Output format. */ +static enum comparison_type + { + type_first_diff, /* Print the first difference. */ + type_all_diffs, /* Print all differences. */ + type_no_stdout, /* Do not output to stdout; only stderr. */ + type_status /* Exit status only. */ + } comparison_type; + +/* If nonzero, print values of bytes quoted like cat -t does. */ +static bool opt_print_bytes; + +/* Values for long options that do not have single-letter equivalents. */ +enum +{ + HELP_OPTION = CHAR_MAX + 1 +}; + +static struct option const long_options[] = +{ + {"print-bytes", 0, 0, 'b'}, + {"print-chars", 0, 0, 'c'}, /* obsolescent as of diffutils 2.7.3 */ + {"ignore-initial", 1, 0, 'i'}, + {"verbose", 0, 0, 'l'}, + {"bytes", 1, 0, 'n'}, + {"silent", 0, 0, 's'}, + {"quiet", 0, 0, 's'}, + {"version", 0, 0, 'v'}, + {"help", 0, 0, HELP_OPTION}, + {0, 0, 0, 0} +}; + +static void try_help (char const *, char const *) __attribute__((noreturn)); +static void +try_help (char const *reason_msgid, char const *operand) +{ + if (reason_msgid) + error (0, 0, _(reason_msgid), operand); + error (EXIT_TROUBLE, 0, + _("Try '%s --help' for more information."), program_name); + abort (); +} + +static char const valid_suffixes[] = "kKMGTPEZY0"; + +/* Update ignore_initial[F] according to the result of parsing an + *operand ARGPTR of --ignore-initial, updating *ARGPTR to point + *after the operand. If DELIMITER is nonzero, the operand may be + *followed by DELIMITER; otherwise it must be null-terminated. */ +static void +specify_ignore_initial (int f, char **argptr, char delimiter) +{ + uintmax_t val; + char const *arg = *argptr; + strtol_error e = xstrtoumax (arg, argptr, 0, &val, valid_suffixes); + if (! (e == LONGINT_OK + || (e == LONGINT_INVALID_SUFFIX_CHAR && **argptr == delimiter)) + || TYPE_MAXIMUM (off_t) < val) + try_help ("invalid --ignore-initial value '%s'", arg); + if (ignore_initial[f] < val) + ignore_initial[f] = val; +} + +/* Specify the output format. */ +static void +specify_comparison_type (enum comparison_type t) +{ + if (comparison_type && comparison_type != t) + try_help ("options -l and -s are incompatible", 0); + comparison_type = t; +} + +static void +check_stdout (void) +{ + if (ferror (stdout)) + error (EXIT_TROUBLE, 0, "%s", _("write failed")); + else if (fclose (stdout) != 0) + error (EXIT_TROUBLE, errno, "%s", _("standard output")); +} + +static char const * const option_help_msgid[] = { + N_("-b, --print-bytes print differing bytes"), + N_("-i, --ignore-initial=SKIP skip first SKIP bytes of both inputs"), + N_("-i, --ignore-initial=SKIP1:SKIP2 skip first SKIP1 bytes of FILE1 and\n" + " first SKIP2 bytes of FILE2"), + N_("-l, --verbose output byte numbers and differing byte values"), + N_("-n, --bytes=LIMIT compare at most LIMIT bytes"), + N_("-s, --quiet, --silent suppress all normal output"), + N_(" --help display this help and exit"), + N_("-v, --version output version information and exit"), + 0 +}; + +static void +usage (void) +{ + char const * const *p; + + printf (_("Usage: %s [OPTION]... FILE1 [FILE2 [SKIP1 [SKIP2]]]\n"), + program_name); + printf ("%s\n", _("Compare two files byte by byte.")); + printf ("\n%s\n\n", +_("The optional SKIP1 and SKIP2 specify the number of bytes to skip\n" + "at the beginning of each file (zero by default).")); + + fputs (_("\ +Mandatory arguments to long options are mandatory for short options too.\n\ +"), stdout); + for (p = option_help_msgid; *p; p++) + printf (" %s\n", _(*p)); + printf ("\n%s\n\n%s\n%s\n", + _("SKIP values may be followed by the following multiplicative suffixes:\n\ +kB 1000, K 1024, MB 1,000,000, M 1,048,576,\n\ +GB 1,000,000,000, G 1,073,741,824, and so on for T, P, E, Z, Y."), + _("If a FILE is '-' or missing, read standard input."), + _("Exit status is 0 if inputs are the same, 1 if different, 2 if trouble.")); + emit_bug_reporting_address (); +} + +int +main (int argc, char **argv) +{ + int c, f, exit_status; + size_t words_per_buffer; + + exit_failure = EXIT_TROUBLE; + initialize_main (&argc, &argv); + set_program_name (argv[0]); + setlocale (LC_ALL, ""); + bindtextdomain (PACKAGE, LOCALEDIR); + textdomain (PACKAGE); + c_stack_action (0); + + /* Parse command line options. */ + + while ((c = getopt_long (argc, argv, "bci:ln:sv", long_options, 0)) + != -1) + switch (c) + { + case 'b': + case 'c': /* 'c' is obsolescent as of diffutils 2.7.3 */ + opt_print_bytes = true; + break; + + case 'i': + specify_ignore_initial (0, &optarg, ':'); + if (*optarg++ == ':') + specify_ignore_initial (1, &optarg, 0); + else if (ignore_initial[1] < ignore_initial[0]) + ignore_initial[1] = ignore_initial[0]; + break; + + case 'l': + specify_comparison_type (type_all_diffs); + break; + + case 'n': + { + uintmax_t n; + if (xstrtoumax (optarg, 0, 0, &n, valid_suffixes) != LONGINT_OK) + try_help ("invalid --bytes value '%s'", optarg); + if (n < bytes) + bytes = n; + } + break; + + case 's': + specify_comparison_type (type_status); + break; + + case 'v': + version_etc (stdout, PROGRAM_NAME, PACKAGE_NAME, Version, + AUTHORS, (char *) NULL); + check_stdout (); + return EXIT_SUCCESS; + + case HELP_OPTION: + usage (); + check_stdout (); + return EXIT_SUCCESS; + + default: + try_help (0, 0); + } + + if (optind == argc) + try_help ("missing operand after '%s'", argv[argc - 1]); + + file[0] = argv[optind++]; + file[1] = optind < argc ? argv[optind++] : "-"; + + for (f = 0; f < 2 && optind < argc; f++) + { + char *arg = argv[optind++]; + specify_ignore_initial (f, &arg, 0); + } + + if (optind < argc) + try_help ("extra operand '%s'", argv[optind]); + + for (f = 0; f < 2; f++) + { + /* If file[1] is "-", treat it first; this avoids a misdiagnostic if + stdin is closed and opening file[0] yields file descriptor 0. */ + int f1 = f ^ (STREQ (file[1], "-")); + + /* Two files with the same name and offset are identical. + But wait until we open the file once, for proper diagnostics. */ + if (f && ignore_initial[0] == ignore_initial[1] + && file_name_cmp (file[0], file[1]) == 0) + return EXIT_SUCCESS; + + if (STREQ (file[f1], "-")) + { + file_desc[f1] = STDIN_FILENO; + if (O_BINARY && ! isatty (STDIN_FILENO)) + set_binary_mode (STDIN_FILENO, O_BINARY); + } + else + file_desc[f1] = open (file[f1], O_RDONLY | O_BINARY, 0); + + if (file_desc[f1] < 0 || fstat (file_desc[f1], stat_buf + f1) != 0) + { + if (file_desc[f1] < 0 && comparison_type == type_status) + exit (EXIT_TROUBLE); + else + error (EXIT_TROUBLE, errno, "%s", file[f1]); + } + } + + /* If the files are links to the same inode and have the same file position, + they are identical. */ + + if (0 < same_file (&stat_buf[0], &stat_buf[1]) + && same_file_attributes (&stat_buf[0], &stat_buf[1]) + && file_position (0) == file_position (1)) + return EXIT_SUCCESS; + + /* If output is redirected to the null device, we can avoid some of + the work. */ + + if (comparison_type != type_status) + { + struct stat outstat, nullstat; + + if (fstat (STDOUT_FILENO, &outstat) == 0 + && stat (NULL_DEVICE, &nullstat) == 0 + && 0 < same_file (&outstat, &nullstat)) + comparison_type = type_no_stdout; + } + + /* If only a return code is needed, + and if both input descriptors are associated with plain files, + conclude that the files differ if they have different sizes + and if more bytes will be compared than are in the smaller file. */ + + if (comparison_type == type_status + && S_ISREG (stat_buf[0].st_mode) + && S_ISREG (stat_buf[1].st_mode)) + { + off_t s0 = stat_buf[0].st_size - file_position (0); + off_t s1 = stat_buf[1].st_size - file_position (1); + if (s0 < 0) + s0 = 0; + if (s1 < 0) + s1 = 0; + if (s0 != s1 && MIN (s0, s1) < bytes) + exit (EXIT_FAILURE); + } + + /* Get the optimal block size of the files. */ + + buf_size = buffer_lcm (STAT_BLOCKSIZE (stat_buf[0]), + STAT_BLOCKSIZE (stat_buf[1]), + PTRDIFF_MAX - sizeof (word)); + + /* Allocate word-aligned buffers, with space for sentinels at the end. */ + + words_per_buffer = (buf_size + 2 * sizeof (word) - 1) / sizeof (word); + buffer[0] = xmalloc (2 * sizeof (word) * words_per_buffer); + buffer[1] = buffer[0] + words_per_buffer; + + exit_status = cmp (); + + for (f = 0; f < 2; f++) + if (close (file_desc[f]) != 0) + error (EXIT_TROUBLE, errno, "%s", file[f]); + if (exit_status != EXIT_SUCCESS && comparison_type < type_no_stdout) + check_stdout (); + exit (exit_status); + return exit_status; +} + +/* Compare the two files already open on 'file_desc[0]' and 'file_desc[1]', + using 'buffer[0]' and 'buffer[1]'. + Return EXIT_SUCCESS if identical, EXIT_FAILURE if different, + >1 if error. */ + +static int +cmp (void) +{ + off_t line_number = 1; /* Line number (1...) of difference. */ + off_t byte_number = 1; /* Byte number (1...) of difference. */ + uintmax_t remaining = bytes; /* Remaining number of bytes to compare. */ + size_t read0, read1; /* Number of bytes read from each file. */ + size_t first_diff; /* Offset (0...) in buffers of 1st diff. */ + size_t smaller; /* The lesser of 'read0' and 'read1'. */ + word *buffer0 = buffer[0]; + word *buffer1 = buffer[1]; + char *buf0 = (char *) buffer0; + char *buf1 = (char *) buffer1; + int differing = 0; + int f; + int offset_width IF_LINT (= 0); + + if (comparison_type == type_all_diffs) + { + off_t byte_number_max = MIN (bytes, TYPE_MAXIMUM (off_t)); + + for (f = 0; f < 2; f++) + if (S_ISREG (stat_buf[f].st_mode)) + { + off_t file_bytes = stat_buf[f].st_size - file_position (f); + if (file_bytes < byte_number_max) + byte_number_max = file_bytes; + } + + for (offset_width = 1; (byte_number_max /= 10) != 0; offset_width++) + continue; + } + + for (f = 0; f < 2; f++) + { + off_t ig = ignore_initial[f]; + if (ig && file_position (f) == -1) + { + /* lseek failed; read and discard the ignored initial prefix. */ + do + { + size_t bytes_to_read = MIN (ig, buf_size); + size_t r = block_read (file_desc[f], buf0, bytes_to_read); + if (r != bytes_to_read) + { + if (r == SIZE_MAX) + error (EXIT_TROUBLE, errno, "%s", file[f]); + break; + } + ig -= r; + } + while (ig); + } + } + + do + { + size_t bytes_to_read = buf_size; + + if (remaining != UINTMAX_MAX) + { + if (remaining < bytes_to_read) + bytes_to_read = remaining; + remaining -= bytes_to_read; + } + + read0 = block_read (file_desc[0], buf0, bytes_to_read); + if (read0 == SIZE_MAX) + error (EXIT_TROUBLE, errno, "%s", file[0]); + read1 = block_read (file_desc[1], buf1, bytes_to_read); + if (read1 == SIZE_MAX) + error (EXIT_TROUBLE, errno, "%s", file[1]); + + smaller = MIN (read0, read1); + + /* Optimize the common case where the buffers are the same. */ + if (memcmp (buf0, buf1, smaller) == 0) + first_diff = smaller; + else + { + /* Insert sentinels for the block compare. */ + buf0[read0] = ~buf1[read0]; + buf1[read1] = ~buf0[read1]; + + first_diff = block_compare (buffer0, buffer1); + } + + byte_number += first_diff; + if (comparison_type == type_first_diff) + line_number += count_newlines (buf0, first_diff); + + if (first_diff < smaller) + { + switch (comparison_type) + { + case type_first_diff: + { + char byte_buf[INT_BUFSIZE_BOUND (off_t)]; + char line_buf[INT_BUFSIZE_BOUND (off_t)]; + char const *byte_num = offtostr (byte_number, byte_buf); + char const *line_num = offtostr (line_number, line_buf); + if (!opt_print_bytes) + { + /* See POSIX 1003.1-2001 for this format. This + message is used only in the POSIX locale, so it + need not be translated. */ + static char const char_message[] = + "%s %s differ: char %s, line %s\n"; + + /* The POSIX rationale recommends using the word + "byte" outside the POSIX locale. Some gettext + implementations translate even in the POSIX + locale if certain other environment variables + are set, so use "byte" if a translation is + available, or if outside the POSIX locale. */ + static char const byte_msgid[] = + N_("%s %s differ: byte %s, line %s\n"); + char const *byte_message = _(byte_msgid); + bool use_byte_message = (byte_message != byte_msgid + || hard_locale_LC_MESSAGES); + + printf (use_byte_message ? byte_message : char_message, + file[0], file[1], byte_num, line_num); + } + else + { + unsigned char c0 = buf0[first_diff]; + unsigned char c1 = buf1[first_diff]; + char s0[5]; + char s1[5]; + sprintc (s0, c0); + sprintc (s1, c1); + printf (_("%s %s differ: byte %s, line %s is %3o %s %3o %s\n"), + file[0], file[1], byte_num, line_num, + c0, s0, c1, s1); + } + } + /* Fall through. */ + case type_status: + return EXIT_FAILURE; + + case type_all_diffs: + do + { + unsigned char c0 = buf0[first_diff]; + unsigned char c1 = buf1[first_diff]; + if (c0 != c1) + { + char byte_buf[INT_BUFSIZE_BOUND (off_t)]; + char const *byte_num = offtostr (byte_number, byte_buf); + if (!opt_print_bytes) + { + /* See POSIX 1003.1-2001 for this format. */ + printf ("%*s %3o %3o\n", + offset_width, byte_num, c0, c1); + } + else + { + char s0[5]; + char s1[5]; + sprintc (s0, c0); + sprintc (s1, c1); + printf ("%*s %3o %-4s %3o %s\n", + offset_width, byte_num, c0, s0, c1, s1); + } + } + byte_number++; + first_diff++; + } + while (first_diff < smaller); + differing = -1; + break; + + case type_no_stdout: + differing = 1; + break; + } + } + + if (read0 != read1) + { + if (differing <= 0 && comparison_type != type_status) + { + /* See POSIX 1003.1-2001 for this format. */ + fprintf (stderr, _("cmp: EOF on %s\n"), file[read1 < read0]); + } + + return EXIT_FAILURE; + } + } + while (differing <= 0 && read0 == buf_size); + + return differing == 0 ? EXIT_SUCCESS : EXIT_FAILURE; +} + +/* Compare two blocks of memory P0 and P1 until they differ. + If the blocks are not guaranteed to be different, put sentinels at the ends + of the blocks before calling this function. + + Return the offset of the first byte that differs. */ + +static size_t +block_compare (word const *p0, word const *p1) +{ + word const *l0, *l1; + char const *c0, *c1; + + /* Find the rough position of the first difference by reading words, + not bytes. */ + + for (l0 = p0, l1 = p1; *l0 == *l1; l0++, l1++) + continue; + + /* Find the exact differing position (endianness independent). */ + + for (c0 = (char const *) l0, c1 = (char const *) l1; + *c0 == *c1; + c0++, c1++) + continue; + + return c0 - (char const *) p0; +} + +/* Return the number of newlines in BUF, of size BUFSIZE, + where BUF[NBYTES] is available for use as a sentinel. */ + +static size_t +count_newlines (char *buf, size_t bufsize) +{ + size_t count = 0; + char *p; + char *lim = buf + bufsize; + *lim = '\n'; + for (p = buf; (p = rawmemchr (p, '\n')) != lim; p++) + count++; + return count; +} + +/* Put into BUF the unsigned char C, making unprintable bytes + visible by quoting like cat -t does. */ + +static void +sprintc (char *buf, unsigned char c) +{ + if (! isprint (c)) + { + if (c >= 128) + { + *buf++ = 'M'; + *buf++ = '-'; + c -= 128; + } + if (c < 32) + { + *buf++ = '^'; + c += 64; + } + else if (c == 127) + { + *buf++ = '^'; + c = '?'; + } + } + + *buf++ = c; + *buf = 0; +} + +/* Position file F to ignore_initial[F] bytes from its initial position, + and yield its new position. Don't try more than once. */ + +static off_t +file_position (int f) +{ + static bool positioned[2]; + static off_t position[2]; + + if (! positioned[f]) + { + positioned[f] = true; + position[f] = lseek (file_desc[f], ignore_initial[f], SEEK_CUR); + } + return position[f]; +} |