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 source tree.
   8 */
   9
  10//usage:#define cksum_trivial_usage
  11//usage:       "FILES..."
  12//usage:#define cksum_full_usage "\n\n"
  13//usage:       "Calculate the CRC32 checksums of FILES"
  14
  15#include "libbb.h"
  16
  17/* This is a NOEXEC applet. Be very careful! */
  18
  19int cksum_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  20int cksum_main(int argc UNUSED_PARAM, char **argv)
  21{
  22        uint32_t *crc32_table = crc32_filltable(NULL, 1);
  23        uint32_t crc;
  24        off_t length, filesize;
  25        int bytes_read;
  26        int exit_code = EXIT_SUCCESS;
  27
  28#if ENABLE_DESKTOP
  29        getopt32(argv, ""); /* coreutils 6.9 compat */
  30        argv += optind;
  31#else
  32        argv++;
  33#endif
  34
  35        do {
  36                int fd = open_or_warn_stdin(*argv ? *argv : bb_msg_standard_input);
  37
  38                if (fd < 0) {
  39                        exit_code = EXIT_FAILURE;
  40                        continue;
  41                }
  42                crc = 0;
  43                length = 0;
  44
  45#define read_buf bb_common_bufsiz1
  46                while ((bytes_read = safe_read(fd, read_buf, sizeof(read_buf))) > 0) {
  47                        length += bytes_read;
  48                        crc = crc32_block_endian1(crc, read_buf, bytes_read, crc32_table);
  49                }
  50                close(fd);
  51
  52                filesize = length;
  53
  54                while (length) {
  55                        crc = (crc << 8) ^ crc32_table[(uint8_t)(crc >> 24) ^ (uint8_t)length];
  56                        /* must ensure that shift is unsigned! */
  57                        if (sizeof(length) <= sizeof(unsigned))
  58                                length = (unsigned)length >> 8;
  59                        else if (sizeof(length) <= sizeof(unsigned long))
  60                                length = (unsigned long)length >> 8;
  61                        else
  62                                length = (unsigned long long)length >> 8;
  63                }
  64                crc = ~crc;
  65
  66                printf((*argv ? "%"PRIu32" %"OFF_FMT"i %s\n" : "%"PRIu32" %"OFF_FMT"i\n"),
  67                                crc, filesize, *argv);
  68        } while (*argv && *++argv);
  69
  70        fflush_stdout_and_exit(exit_code);
  71}
  72