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        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}
  68