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 tarball for details. */
11 int cksum_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
12 int cksum_main(int argc UNUSED_PARAM, char **argv)
14 uint32_t *crc32_table = crc32_filltable(NULL, 1);
16 off_t length, filesize;
18 int exit_code = EXIT_SUCCESS;
22 getopt32(argv, ""); /* coreutils 6.9 compat */
29 int fd = open_or_warn_stdin(*argv ? *argv : bb_msg_standard_input);
32 exit_code = EXIT_FAILURE;
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;
43 crc = (crc << 8) ^ crc32_table[(crc >> 24) ^ *cp++];
44 } while (--bytes_read);
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;
58 length = (unsigned long long)length >> 8;
62 printf((*argv ? "%"PRIu32" %"OFF_FMT"i %s\n" : "%"PRIu32" %"OFF_FMT"i\n"),
63 crc, filesize, *argv);
64 } while (*argv && *++argv);
66 fflush_stdout_and_exit(exit_code);