LXR busybox/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
  11int cksum_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  12int 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        uint8_t *cp;
  19
  20#if ENABLE_DESKTOP
  21        getopt32(argv, ""); /* coreutils 6.9 compat */
  22        argv += optind;
  23#else
  24        argv++;
  25#endif
  26
  27        do {
  28                int fd = open_or_warn_stdin(*argv ? *argv : bb_msg_standard_input);
  29
  30                if (fd < 0)
  31                        continue;
  32                crc = 0;
  33                length = 0;
  34
  35#define read_buf bb_common_bufsiz1
  36                while ((bytes_read = safe_read(fd, read_buf, sizeof(read_buf))) > 0) {
  37                        cp = (uint8_t *) read_buf;
  38                        length += bytes_read;
  39                        do {
  40                                crc = (crc << 8) ^ crc32_table[(crc >> 24) ^ *cp++];
  41                        } while (--bytes_read);
  42                }
  43                close(fd);
  44
  45                filesize = length;
  46
  47                while (length) {
  48                        crc = (crc << 8) ^ crc32_table[(uint8_t)(crc >> 24) ^ (uint8_t)length];
  49                        /* must ensure that shift is unsigned! */
  50                        if (sizeof(length) <= sizeof(unsigned))
  51                                length = (unsigned)length >> 8;
  52                        else if (sizeof(length) <= sizeof(unsigned long))
  53                                length = (unsigned long)length >> 8;
  54                        else
  55                                length = (unsigned long long)length >> 8;
  56                }
  57                crc = ~crc;
  58
  59                printf((*argv ? "%"PRIu32" %"OFF_FMT"i %s\n" : "%"PRIu32" %"OFF_FMT"i\n"),
  60                                crc, filesize, *argv);
  61        } while (*argv && *++argv);
  62
  63        fflush_stdout_and_exit(EXIT_SUCCESS);
  64}
  65