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//config:config CKSUM
  10//config:       bool "cksum"
  11//config:       default y
  12//config:       help
  13//config:         cksum is used to calculate the CRC32 checksum of a file.
  14
  15//applet:IF_CKSUM(APPLET_NOEXEC(cksum, cksum, BB_DIR_USR_BIN, BB_SUID_DROP, cksum))
  16
  17//kbuild:lib-$(CONFIG_CKSUM) += cksum.o
  18
  19//usage:#define cksum_trivial_usage
  20//usage:       "FILES..."
  21//usage:#define cksum_full_usage "\n\n"
  22//usage:       "Calculate the CRC32 checksums of FILES"
  23
  24#include "libbb.h"
  25#include "common_bufsiz.h"
  26
  27/* This is a NOEXEC applet. Be very careful! */
  28
  29int cksum_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  30int cksum_main(int argc UNUSED_PARAM, char **argv)
  31{
  32        uint32_t *crc32_table = crc32_filltable(NULL, 1);
  33        uint32_t crc;
  34        off_t length, filesize;
  35        int bytes_read;
  36        int exit_code = EXIT_SUCCESS;
  37
  38#if ENABLE_DESKTOP
  39        getopt32(argv, ""); /* coreutils 6.9 compat */
  40        argv += optind;
  41#else
  42        argv++;
  43#endif
  44
  45        setup_common_bufsiz();
  46        do {
  47                int fd = open_or_warn_stdin(*argv ? *argv : bb_msg_standard_input);
  48
  49                if (fd < 0) {
  50                        exit_code = EXIT_FAILURE;
  51                        continue;
  52                }
  53                crc = 0;
  54                length = 0;
  55
  56#define read_buf bb_common_bufsiz1
  57                while ((bytes_read = safe_read(fd, read_buf, COMMON_BUFSIZE)) > 0) {
  58                        length += bytes_read;
  59                        crc = crc32_block_endian1(crc, read_buf, bytes_read, crc32_table);
  60                }
  61                close(fd);
  62
  63                filesize = length;
  64
  65                while (length) {
  66                        crc = (crc << 8) ^ crc32_table[(uint8_t)(crc >> 24) ^ (uint8_t)length];
  67                        /* must ensure that shift is unsigned! */
  68                        if (sizeof(length) <= sizeof(unsigned))
  69                                length = (unsigned)length >> 8;
  70                        else if (sizeof(length) <= sizeof(unsigned long))
  71                                length = (unsigned long)length >> 8;
  72                        else
  73                                length = (unsigned long long)length >> 8;
  74                }
  75                crc = ~crc;
  76
  77                printf((*argv ? "%"PRIu32" %"OFF_FMT"i %s\n" : "%"PRIu32" %"OFF_FMT"i\n"),
  78                                crc, filesize, *argv);
  79        } while (*argv && *++argv);
  80
  81        fflush_stdout_and_exit(exit_code);
  82}
  83