1 /* vi: set sw=4 ts=4: */
3 * cksum - calculate the CRC32 checksum of a file
5 * Copyright (C) 2006 by Rob Sullivan, with ideas from code by Walter Harms
7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
10 //usage:#define cksum_trivial_usage
12 //usage:#define cksum_full_usage "\n\n"
13 //usage: "Calculate the CRC32 checksums of FILES"
16 #include "common_bufsiz.h"
18 /* This is a NOEXEC applet. Be very careful! */
20 int cksum_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
21 int cksum_main(int argc UNUSED_PARAM, char **argv)
23 uint32_t *crc32_table = crc32_filltable(NULL, 1);
25 off_t length, filesize;
27 int exit_code = EXIT_SUCCESS;
30 getopt32(argv, ""); /* coreutils 6.9 compat */
36 setup_common_bufsiz();
38 int fd = open_or_warn_stdin(*argv ? *argv : bb_msg_standard_input);
41 exit_code = EXIT_FAILURE;
47 #define read_buf bb_common_bufsiz1
48 while ((bytes_read = safe_read(fd, read_buf, COMMON_BUFSIZE)) > 0) {
50 crc = crc32_block_endian1(crc, read_buf, bytes_read, crc32_table);
57 crc = (crc << 8) ^ crc32_table[(uint8_t)(crc >> 24) ^ (uint8_t)length];
58 /* must ensure that shift is unsigned! */
59 if (sizeof(length) <= sizeof(unsigned))
60 length = (unsigned)length >> 8;
61 else if (sizeof(length) <= sizeof(unsigned long))
62 length = (unsigned long)length >> 8;
64 length = (unsigned long long)length >> 8;
68 printf((*argv ? "%"PRIu32" %"OFF_FMT"i %s\n" : "%"PRIu32" %"OFF_FMT"i\n"),
69 crc, filesize, *argv);
70 } while (*argv && *++argv);
72 fflush_stdout_and_exit(exit_code);