coreutils/cksum.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * cksum - calculate the CRC32 checksum of a file
   4  *
   5  * Copyright (C) 2006 by Rob Sullivan, with ideas from code by Walter Harms
   6  *
   7  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
   8  */
   9 #include "libbb.h"
  10
  11 int cksum_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  12 int cksum_main(int argc UNUSED_PARAM, char **argv)
  13 {
  14         uint32_t *crc32_table = crc32_filltable(NULL, 1);
  15         uint32_t crc;
  16         off_t length, filesize;
  17         int bytes_read;
  18         int exit_code = EXIT_SUCCESS;
  19         uint8_t *cp;
  20
  21 #if ENABLE_DESKTOP
  22         getopt32(argv, ""); /* coreutils 6.9 compat */
  23         argv += optind;
  24 #else
  25         argv++;
  26 #endif
  27
  28         do {
  29                 int fd = open_or_warn_stdin(*argv ? *argv : bb_msg_standard_input);
  30
  31                 if (fd < 0) {
  32                         exit_code = EXIT_FAILURE;
  33                         continue;
  34                 }
  35                 crc = 0;
  36                 length = 0;
  37
  38 #define read_buf bb_common_bufsiz1
  39                 while ((bytes_read = safe_read(fd, read_buf, sizeof(read_buf))) > 0) {
  40                         cp = (uint8_t *) read_buf;
  41                         length += bytes_read;
  42                         do {
  43                                 crc = (crc << 8) ^ crc32_table[(crc >> 24) ^ *cp++];
  44                         } while (--bytes_read);
  45                 }
  46                 close(fd);
  47
  48                 filesize = length;
  49
  50                 while (length) {
  51                         crc = (crc << 8) ^ crc32_table[(uint8_t)(crc >> 24) ^ (uint8_t)length];
  52                         /* must ensure that shift is unsigned! */
  53                         if (sizeof(length) <= sizeof(unsigned))
  54                                 length = (unsigned)length >> 8;
  55                         else if (sizeof(length) <= sizeof(unsigned long))
  56                                 length = (unsigned long)length >> 8;
  57                         else
  58                                 length = (unsigned long long)length >> 8;
  59                 }
  60                 crc = ~crc;
  61
  62                 printf((*argv ? "%"PRIu32" %"OFF_FMT"i %s\n" : "%"PRIu32" %"OFF_FMT"i\n"),
  63                                 crc, filesize, *argv);
  64         } while (*argv && *++argv);
  65
  66         fflush_stdout_and_exit(exit_code);
  67 }