src/md5sum.c

   1 /* Compute MD5, SHA1, SHA224, SHA256, SHA384 or SHA512 checksum of files or strings
   2    Copyright (C) 1995-2010 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>.  */
  18
  19 #include <config.h>
  20
  21 #include <getopt.h>
  22 #include <sys/types.h>
  23
  24 #include "system.h"
  25
  26 #if HASH_ALGO_MD5
  27 # include "md5.h"
  28 #endif
  29 #if HASH_ALGO_SHA1
  30 # include "sha1.h"
  31 #endif
  32 #if HASH_ALGO_SHA256 || HASH_ALGO_SHA224
  33 # include "sha256.h"
  34 #endif
  35 #if HASH_ALGO_SHA512 || HASH_ALGO_SHA384
  36 # include "sha512.h"
  37 #endif
  38 #include "error.h"
  39 #include "stdio--.h"
  40 #include "xfreopen.h"
  41
  42 /* The official name of this program (e.g., no `g' prefix).  */
  43 #if HASH_ALGO_MD5
  44 # define PROGRAM_NAME "md5sum"
  45 # define DIGEST_TYPE_STRING "MD5"
  46 # define DIGEST_STREAM md5_stream
  47 # define DIGEST_BITS 128
  48 # define DIGEST_REFERENCE "RFC 1321"
  49 # define DIGEST_ALIGN 4
  50 #elif HASH_ALGO_SHA1
  51 # define PROGRAM_NAME "sha1sum"
  52 # define DIGEST_TYPE_STRING "SHA1"
  53 # define DIGEST_STREAM sha1_stream
  54 # define DIGEST_BITS 160
  55 # define DIGEST_REFERENCE "FIPS-180-1"
  56 # define DIGEST_ALIGN 4
  57 #elif HASH_ALGO_SHA256
  58 # define PROGRAM_NAME "sha256sum"
  59 # define DIGEST_TYPE_STRING "SHA256"
  60 # define DIGEST_STREAM sha256_stream
  61 # define DIGEST_BITS 256
  62 # define DIGEST_REFERENCE "FIPS-180-2"
  63 # define DIGEST_ALIGN 4
  64 #elif HASH_ALGO_SHA224
  65 # define PROGRAM_NAME "sha224sum"
  66 # define DIGEST_TYPE_STRING "SHA224"
  67 # define DIGEST_STREAM sha224_stream
  68 # define DIGEST_BITS 224
  69 # define DIGEST_REFERENCE "RFC 3874"
  70 # define DIGEST_ALIGN 4
  71 #elif HASH_ALGO_SHA512
  72 # define PROGRAM_NAME "sha512sum"
  73 # define DIGEST_TYPE_STRING "SHA512"
  74 # define DIGEST_STREAM sha512_stream
  75 # define DIGEST_BITS 512
  76 # define DIGEST_REFERENCE "FIPS-180-2"
  77 # define DIGEST_ALIGN 8
  78 #elif HASH_ALGO_SHA384
  79 # define PROGRAM_NAME "sha384sum"
  80 # define DIGEST_TYPE_STRING "SHA384"
  81 # define DIGEST_STREAM sha384_stream
  82 # define DIGEST_BITS 384
  83 # define DIGEST_REFERENCE "FIPS-180-2"
  84 # define DIGEST_ALIGN 8
  85 #else
  86 # error "Can't decide which hash algorithm to compile."
  87 #endif
  88
  89 #define DIGEST_HEX_BYTES (DIGEST_BITS / 4)
  90 #define DIGEST_BIN_BYTES (DIGEST_BITS / 8)
  91
  92 #define AUTHORS \
  93   proper_name ("Ulrich Drepper"), \
  94   proper_name ("Scott Miller"), \
  95   proper_name ("David Madore")
  96
  97 /* The minimum length of a valid digest line.  This length does
  98    not include any newline character at the end of a line.  */
  99 #define MIN_DIGEST_LINE_LENGTH \
 100   (DIGEST_HEX_BYTES /* length of hexadecimal message digest */ \
 101    + 2 /* blank and binary indicator */ \
 102    + 1 /* minimum filename length */ )
 103
 104 /* True if any of the files read were the standard input. */
 105 static bool have_read_stdin;
 106
 107 /* The minimum length of a valid checksum line for the selected algorithm.  */
 108 static size_t min_digest_line_length;
 109
 110 /* Set to the length of a digest hex string for the selected algorithm.  */
 111 static size_t digest_hex_bytes;
 112
 113 /* With --check, don't generate any output.
 114    The exit code indicates success or failure.  */
 115 static bool status_only = false;
 116
 117 /* With --check, print a message to standard error warning about each
 118    improperly formatted checksum line.  */
 119 static bool warn = false;
 120
 121 /* With --check, suppress the "OK" printed for each verified file.  */
 122 static bool quiet = false;
 123
 124 /* For long options that have no equivalent short option, use a
 125    non-character as a pseudo short option, starting with CHAR_MAX + 1.  */
 126 enum
 127 {
 128   STATUS_OPTION = CHAR_MAX + 1,
 129   QUIET_OPTION
 130 };
 131
 132 static struct option const long_options[] =
 133 {
 134   { "binary", no_argument, NULL, 'b' },
 135   { "check", no_argument, NULL, 'c' },
 136   { "quiet", no_argument, NULL, QUIET_OPTION },
 137   { "status", no_argument, NULL, STATUS_OPTION },
 138   { "text", no_argument, NULL, 't' },
 139   { "warn", no_argument, NULL, 'w' },
 140   { GETOPT_HELP_OPTION_DECL },
 141   { GETOPT_VERSION_OPTION_DECL },
 142   { NULL, 0, NULL, 0 }
 143 };
 144
 145 void
 146 usage (int status)
 147 {
 148   if (status != EXIT_SUCCESS)
 149     fprintf (stderr, _("Try `%s --help' for more information.\n"),
 150              program_name);
 151   else
 152     {
 153       printf (_("\
 154 Usage: %s [OPTION]... [FILE]...\n\
 155 Print or check %s (%d-bit) checksums.\n\
 156 With no FILE, or when FILE is -, read standard input.\n\
 157 \n\
 158 "),
 159               program_name,
 160               DIGEST_TYPE_STRING,
 161               DIGEST_BITS);
 162       if (O_BINARY)
 163         fputs (_("\
 164   -b, --binary            read in binary mode (default unless reading tty stdin)\n\
 165 "), stdout);
 166       else
 167         fputs (_("\
 168   -b, --binary            read in binary mode\n\
 169 "), stdout);
 170       printf (_("\
 171   -c, --check             read %s sums from the FILEs and check them\n"),
 172               DIGEST_TYPE_STRING);
 173       if (O_BINARY)
 174         fputs (_("\
 175   -t, --text              read in text mode (default if reading tty stdin)\n\
 176 "), stdout);
 177       else
 178         fputs (_("\
 179   -t, --text              read in text mode (default)\n\
 180 "), stdout);
 181       fputs (_("\
 182 \n\
 183 The following three options are useful only when verifying checksums:\n\
 184       --quiet             don't print OK for each successfully verified file\n\
 185       --status            don't output anything, status code shows success\n\
 186   -w, --warn              warn about improperly formatted checksum lines\n\
 187 \n\
 188 "), stdout);
 189       fputs (HELP_OPTION_DESCRIPTION, stdout);
 190       fputs (VERSION_OPTION_DESCRIPTION, stdout);
 191       printf (_("\
 192 \n\
 193 The sums are computed as described in %s.  When checking, the input\n\
 194 should be a former output of this program.  The default mode is to print\n\
 195 a line with checksum, a character indicating type (`*' for binary, ` ' for\n\
 196 text), and name for each FILE.\n"),
 197               DIGEST_REFERENCE);
 198       emit_ancillary_info ();
 199     }
 200
 201   exit (status);
 202 }
 203
 204 #define ISWHITE(c) ((c) == ' ' || (c) == '\t')
 205
 206 /* Split the checksum string S (of length S_LEN) from a BSD 'md5' or
 207    'sha1' command into two parts: a hexadecimal digest, and the file
 208    name.  S is modified.  Return true if successful.  */
 209
 210 static bool
 211 bsd_split_3 (char *s, size_t s_len, unsigned char **hex_digest, char **file_name)
 212 {
 213   size_t i;
 214
 215   if (s_len == 0)
 216     return false;
 217
 218   *file_name = s;
 219
 220   /* Find end of filename. The BSD 'md5' and 'sha1' commands do not escape
 221      filenames, so search backwards for the last ')'. */
 222   i = s_len - 1;
 223   while (i && s[i] != ')')
 224     i--;
 225
 226   if (s[i] != ')')
 227     return false;
 228
 229   s[i++] = '\0';
 230
 231   while (ISWHITE (s[i]))
 232     i++;
 233
 234   if (s[i] != '=')
 235     return false;
 236
 237   i++;
 238
 239   while (ISWHITE (s[i]))
 240     i++;
 241
 242   *hex_digest = (unsigned char *) &s[i];
 243   return true;
 244 }
 245
 246 /* Split the string S (of length S_LEN) into three parts:
 247    a hexadecimal digest, binary flag, and the file name.
 248    S is modified.  Return true if successful.  */
 249
 250 static bool
 251 split_3 (char *s, size_t s_len,
 252          unsigned char **hex_digest, int *binary, char **file_name)
 253 {
 254   bool escaped_filename = false;
 255   size_t algo_name_len;
 256
 257   size_t i = 0;
 258   while (ISWHITE (s[i]))
 259     ++i;
 260
 261   /* Check for BSD-style checksum line. */
 262   algo_name_len = strlen (DIGEST_TYPE_STRING);
 263   if (strncmp (s + i, DIGEST_TYPE_STRING, algo_name_len) == 0)
 264     {
 265       if (s[i + algo_name_len] == ' ')
 266         ++i;
 267       if (s[i + algo_name_len] == '(')
 268         {
 269           *binary = 0;
 270           return bsd_split_3 (s +      i + algo_name_len + 1,
 271                               s_len - (i + algo_name_len + 1),
 272                               hex_digest, file_name);
 273         }
 274     }
 275
 276   /* Ignore this line if it is too short.
 277      Each line must have at least `min_digest_line_length - 1' (or one more, if
 278      the first is a backslash) more characters to contain correct message digest
 279      information.  */
 280   if (s_len - i < min_digest_line_length + (s[i] == '\\'))
 281     return false;
 282
 283   if (s[i] == '\\')
 284     {
 285       ++i;
 286       escaped_filename = true;
 287     }
 288   *hex_digest = (unsigned char *) &s[i];
 289
 290   /* The first field has to be the n-character hexadecimal
 291      representation of the message digest.  If it is not followed
 292      immediately by a white space it's an error.  */
 293   i += digest_hex_bytes;
 294   if (!ISWHITE (s[i]))
 295     return false;
 296
 297   s[i++] = '\0';
 298
 299   if (s[i] != ' ' && s[i] != '*')
 300     return false;
 301   *binary = (s[i++] == '*');
 302
 303   /* All characters between the type indicator and end of line are
 304      significant -- that includes leading and trailing white space.  */
 305   *file_name = &s[i];
 306
 307   if (escaped_filename)
 308     {
 309       /* Translate each `\n' string in the file name to a NEWLINE,
 310          and each `\\' string to a backslash.  */
 311
 312       char *dst = &s[i];
 313
 314       while (i < s_len)
 315         {
 316           switch (s[i])
 317             {
 318             case '\\':
 319               if (i == s_len - 1)
 320                 {
 321                   /* A valid line does not end with a backslash.  */
 322                   return false;
 323                 }
 324               ++i;
 325               switch (s[i++])
 326                 {
 327                 case 'n':
 328                   *dst++ = '\n';
 329                   break;
 330                 case '\\':
 331                   *dst++ = '\\';
 332                   break;
 333                 default:
 334                   /* Only `\' or `n' may follow a backslash.  */
 335                   return false;
 336                 }
 337               break;
 338
 339             case '\0':
 340               /* The file name may not contain a NUL.  */
 341               return false;
 342               break;
 343
 344             default:
 345               *dst++ = s[i++];
 346               break;
 347             }
 348         }
 349       *dst = '\0';
 350     }
 351   return true;
 352 }
 353
 354 /* Return true if S is a NUL-terminated string of DIGEST_HEX_BYTES hex digits.
 355    Otherwise, return false.  */
 356 static bool
 357 hex_digits (unsigned char const *s)
 358 {
 359   unsigned int i;
 360   for (i = 0; i < digest_hex_bytes; i++)
 361     {
 362       if (!isxdigit (*s))
 363         return false;
 364       ++s;
 365     }
 366   return *s == '\0';
 367 }
 368
 369 /* An interface to the function, DIGEST_STREAM.
 370    Operate on FILENAME (it may be "-").
 371
 372    *BINARY indicates whether the file is binary.  BINARY < 0 means it
 373    depends on whether binary mode makes any difference and the file is
 374    a terminal; in that case, clear *BINARY if the file was treated as
 375    text because it was a terminal.
 376
 377    Put the checksum in *BIN_RESULT, which must be properly aligned.
 378    Return true if successful.  */
 379
 380 static bool
 381 digest_file (const char *filename, int *binary, unsigned char *bin_result)
 382 {
 383   FILE *fp;
 384   int err;
 385   bool is_stdin = STREQ (filename, "-");
 386
 387   if (is_stdin)
 388     {
 389       have_read_stdin = true;
 390       fp = stdin;
 391       if (O_BINARY && *binary)
 392         {
 393           if (*binary < 0)
 394             *binary = ! isatty (STDIN_FILENO);
 395           if (*binary)
 396             xfreopen (NULL, "rb", stdin);
 397         }
 398     }
 399   else
 400     {
 401       fp = fopen (filename, (O_BINARY && *binary ? "rb" : "r"));
 402       if (fp == NULL)
 403         {
 404           error (0, errno, "%s", filename);
 405           return false;
 406         }
 407     }
 408
 409   err = DIGEST_STREAM (fp, bin_result);
 410   if (err)
 411     {
 412       error (0, errno, "%s", filename);
 413       if (fp != stdin)
 414         fclose (fp);
 415       return false;
 416     }
 417
 418   if (!is_stdin && fclose (fp) != 0)
 419     {
 420       error (0, errno, "%s", filename);
 421       return false;
 422     }
 423
 424   return true;
 425 }
 426
 427 static bool
 428 digest_check (const char *checkfile_name)
 429 {
 430   FILE *checkfile_stream;
 431   uintmax_t n_properly_formatted_lines = 0;
 432   uintmax_t n_mismatched_checksums = 0;
 433   uintmax_t n_open_or_read_failures = 0;
 434   unsigned char bin_buffer_unaligned[DIGEST_BIN_BYTES + DIGEST_ALIGN];
 435   /* Make sure bin_buffer is properly aligned. */
 436   unsigned char *bin_buffer = ptr_align (bin_buffer_unaligned, DIGEST_ALIGN);
 437   uintmax_t line_number;
 438   char *line;
 439   size_t line_chars_allocated;
 440   bool is_stdin = STREQ (checkfile_name, "-");
 441
 442   if (is_stdin)
 443     {
 444       have_read_stdin = true;
 445       checkfile_name = _("standard input");
 446       checkfile_stream = stdin;
 447     }
 448   else
 449     {
 450       checkfile_stream = fopen (checkfile_name, "r");
 451       if (checkfile_stream == NULL)
 452         {
 453           error (0, errno, "%s", checkfile_name);
 454           return false;
 455         }
 456     }
 457
 458   line_number = 0;
 459   line = NULL;
 460   line_chars_allocated = 0;
 461   do
 462     {
 463       char *filename IF_LINT (= NULL);
 464       int binary;
 465       unsigned char *hex_digest IF_LINT (= NULL);
 466       ssize_t line_length;
 467
 468       ++line_number;
 469       if (line_number == 0)
 470         error (EXIT_FAILURE, 0, _("%s: too many checksum lines"),
 471                checkfile_name);
 472
 473       line_length = getline (&line, &line_chars_allocated, checkfile_stream);
 474       if (line_length <= 0)
 475         break;
 476
 477       /* Ignore comment lines, which begin with a '#' character.  */
 478       if (line[0] == '#')
 479         continue;
 480
 481       /* Remove any trailing newline.  */
 482       if (line[line_length - 1] == '\n')
 483         line[--line_length] = '\0';
 484
 485       if (! (split_3 (line, line_length, &hex_digest, &binary, &filename)
 486              && ! (is_stdin && STREQ (filename, "-"))
 487              && hex_digits (hex_digest)))
 488         {
 489           if (warn)
 490             {
 491               error (0, 0,
 492                      _("%s: %" PRIuMAX
 493                        ": improperly formatted %s checksum line"),
 494                      checkfile_name, line_number,
 495                      DIGEST_TYPE_STRING);
 496             }
 497         }
 498       else
 499         {
 500           static const char bin2hex[] = { '0', '1', '2', '3',
 501                                           '4', '5', '6', '7',
 502                                           '8', '9', 'a', 'b',
 503                                           'c', 'd', 'e', 'f' };
 504           bool ok;
 505
 506           ++n_properly_formatted_lines;
 507
 508           ok = digest_file (filename, &binary, bin_buffer);
 509
 510           if (!ok)
 511             {
 512               ++n_open_or_read_failures;
 513               if (!status_only)
 514                 {
 515                   printf (_("%s: FAILED open or read\n"), filename);
 516                 }
 517             }
 518           else
 519             {
 520               size_t digest_bin_bytes = digest_hex_bytes / 2;
 521               size_t cnt;
 522               /* Compare generated binary number with text representation
 523                  in check file.  Ignore case of hex digits.  */
 524               for (cnt = 0; cnt < digest_bin_bytes; ++cnt)
 525                 {
 526                   if (tolower (hex_digest[2 * cnt])
 527                       != bin2hex[bin_buffer[cnt] >> 4]
 528                       || (tolower (hex_digest[2 * cnt + 1])
 529                           != (bin2hex[bin_buffer[cnt] & 0xf])))
 530                     break;
 531                 }
 532               if (cnt != digest_bin_bytes)
 533                 ++n_mismatched_checksums;
 534
 535               if (!status_only)
 536                 {
 537                   if (cnt != digest_bin_bytes)
 538                     printf ("%s: %s\n", filename, _("FAILED"));
 539                   else if (!quiet)
 540                     printf ("%s: %s\n", filename, _("OK"));
 541                 }
 542             }
 543         }
 544     }
 545   while (!feof (checkfile_stream) && !ferror (checkfile_stream));
 546
 547   free (line);
 548
 549   if (ferror (checkfile_stream))
 550     {
 551       error (0, 0, _("%s: read error"), checkfile_name);
 552       return false;
 553     }
 554
 555   if (!is_stdin && fclose (checkfile_stream) != 0)
 556     {
 557       error (0, errno, "%s", checkfile_name);
 558       return false;
 559     }
 560
 561   if (n_properly_formatted_lines == 0)
 562     {
 563       /* Warn if no tests are found.  */
 564       error (0, 0, _("%s: no properly formatted %s checksum lines found"),
 565              checkfile_name, DIGEST_TYPE_STRING);
 566     }
 567   else
 568     {
 569       if (!status_only)
 570         {
 571           if (n_open_or_read_failures != 0)
 572             error (0, 0,
 573                    ngettext ("WARNING: %" PRIuMAX " of %" PRIuMAX
 574                              " listed file could not be read",
 575                              "WARNING: %" PRIuMAX " of %" PRIuMAX
 576                              " listed files could not be read",
 577                              select_plural (n_properly_formatted_lines)),
 578                    n_open_or_read_failures, n_properly_formatted_lines);
 579
 580           if (n_mismatched_checksums != 0)
 581             {
 582               uintmax_t n_computed_checksums =
 583                 (n_properly_formatted_lines - n_open_or_read_failures);
 584               error (0, 0,
 585                      ngettext ("WARNING: %" PRIuMAX " of %" PRIuMAX
 586                                " computed checksum did NOT match",
 587                                "WARNING: %" PRIuMAX " of %" PRIuMAX
 588                                " computed checksums did NOT match",
 589                                select_plural (n_computed_checksums)),
 590                      n_mismatched_checksums, n_computed_checksums);
 591             }
 592         }
 593     }
 594
 595   return (n_properly_formatted_lines != 0
 596           && n_mismatched_checksums == 0
 597           && n_open_or_read_failures == 0);
 598 }
 599
 600 int
 601 main (int argc, char **argv)
 602 {
 603   unsigned char bin_buffer_unaligned[DIGEST_BIN_BYTES + DIGEST_ALIGN];
 604   /* Make sure bin_buffer is properly aligned. */
 605   unsigned char *bin_buffer = ptr_align (bin_buffer_unaligned, DIGEST_ALIGN);
 606   bool do_check = false;
 607   int opt;
 608   bool ok = true;
 609   int binary = -1;
 610
 611   /* Setting values of global variables.  */
 612   initialize_main (&argc, &argv);
 613   set_program_name (argv[0]);
 614   setlocale (LC_ALL, "");
 615   bindtextdomain (PACKAGE, LOCALEDIR);
 616   textdomain (PACKAGE);
 617
 618   atexit (close_stdout);
 619
 620   /* Line buffer stdout to ensure lines are written atomically and immediately
 621      so that processes running in parallel do not intersperse their output.  */
 622   setvbuf (stdout, NULL, _IOLBF, 0);
 623
 624   while ((opt = getopt_long (argc, argv, "bctw", long_options, NULL)) != -1)
 625     switch (opt)
 626       {
 627       case 'b':
 628         binary = 1;
 629         break;
 630       case 'c':
 631         do_check = true;
 632         break;
 633       case STATUS_OPTION:
 634         status_only = true;
 635         warn = false;
 636         quiet = false;
 637         break;
 638       case 't':
 639         binary = 0;
 640         break;
 641       case 'w':
 642         status_only = false;
 643         warn = true;
 644         quiet = false;
 645         break;
 646       case QUIET_OPTION:
 647         status_only = false;
 648         warn = false;
 649         quiet = true;
 650         break;
 651       case_GETOPT_HELP_CHAR;
 652       case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 653       default:
 654         usage (EXIT_FAILURE);
 655       }
 656
 657   min_digest_line_length = MIN_DIGEST_LINE_LENGTH;
 658   digest_hex_bytes = DIGEST_HEX_BYTES;
 659
 660   if (0 <= binary && do_check)
 661     {
 662       error (0, 0, _("the --binary and --text options are meaningless when "
 663                      "verifying checksums"));
 664       usage (EXIT_FAILURE);
 665     }
 666
 667   if (status_only && !do_check)
 668     {
 669       error (0, 0,
 670        _("the --status option is meaningful only when verifying checksums"));
 671       usage (EXIT_FAILURE);
 672     }
 673
 674   if (warn && !do_check)
 675     {
 676       error (0, 0,
 677        _("the --warn option is meaningful only when verifying checksums"));
 678       usage (EXIT_FAILURE);
 679     }
 680
 681   if (quiet && !do_check)
 682     {
 683       error (0, 0,
 684        _("the --quiet option is meaningful only when verifying checksums"));
 685       usage (EXIT_FAILURE);
 686     }
 687
 688   if (!O_BINARY && binary < 0)
 689     binary = 0;
 690
 691   if (optind == argc)
 692     argv[argc++] = bad_cast ("-");
 693
 694   for (; optind < argc; ++optind)
 695     {
 696       char *file = argv[optind];
 697
 698       if (do_check)
 699         ok &= digest_check (file);
 700       else
 701         {
 702           int file_is_binary = binary;
 703
 704           if (! digest_file (file, &file_is_binary, bin_buffer))
 705             ok = false;
 706           else
 707             {
 708               size_t i;
 709
 710               /* Output a leading backslash if the file name contains
 711                  a newline or backslash.  */
 712               if (strchr (file, '\n') || strchr (file, '\\'))
 713                 putchar ('\\');
 714
 715               for (i = 0; i < (digest_hex_bytes / 2); ++i)
 716                 printf ("%02x", bin_buffer[i]);
 717
 718               putchar (' ');
 719               if (file_is_binary)
 720                 putchar ('*');
 721               else
 722                 putchar (' ');
 723
 724               /* Translate each NEWLINE byte to the string, "\\n",
 725                  and each backslash to "\\\\".  */
 726               for (i = 0; i < strlen (file); ++i)
 727                 {
 728                   switch (file[i])
 729                     {
 730                     case '\n':
 731                       fputs ("\\n", stdout);
 732                       break;
 733
 734                     case '\\':
 735                       fputs ("\\\\", stdout);
 736                       break;
 737
 738                     default:
 739                       putchar (file[i]);
 740                       break;
 741                     }
 742                 }
 743               putchar ('\n');
 744             }
 745         }
 746     }
 747
 748   if (have_read_stdin && fclose (stdin) == EOF)
 749     error (EXIT_FAILURE, errno, _("standard input"));
 750
 751   exit (ok ? EXIT_SUCCESS : EXIT_FAILURE);
 752 }