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 ATTRIBUTE_UNUSED, char **argv)
14 uint32_t *crc32_table = crc32_filltable(NULL, 1);
16 long length, filesize;
21 getopt32(argv, ""); /* coreutils 6.9 compat */
28 int fd = open_or_warn_stdin(*argv ? *argv : bb_msg_standard_input);
35 #define read_buf bb_common_bufsiz1
36 while ((bytes_read = safe_read(fd, read_buf, sizeof(read_buf))) > 0) {
40 crc = (crc << 8) ^ crc32_table[(crc >> 24) ^ *cp++];
41 } while (--bytes_read);
47 for (; length; length >>= 8)
48 crc = (crc << 8) ^ crc32_table[((crc >> 24) ^ length) & 0xff];
51 printf((*argv ? "%" PRIu32 " %li %s\n" : "%" PRIu32 " %li\n"),
52 crc, filesize, *argv);
53 } while (*argv && *++argv);
55 fflush_stdout_and_exit(EXIT_SUCCESS);