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 //config: bool "cksum"
13 //config: cksum is used to calculate the CRC32 checksum of a file.
15 //applet:IF_CKSUM(APPLET_NOEXEC(cksum, cksum, BB_DIR_USR_BIN, BB_SUID_DROP, cksum))
17 //kbuild:lib-$(CONFIG_CKSUM) += cksum.o
19 //usage:#define cksum_trivial_usage
21 //usage:#define cksum_full_usage "\n\n"
22 //usage: "Calculate the CRC32 checksums of FILEs"
25 #include "common_bufsiz.h"
27 /* This is a NOEXEC applet. Be very careful! */
29 int cksum_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
30 int cksum_main(int argc UNUSED_PARAM, char **argv)
32 uint32_t *crc32_table = crc32_filltable(NULL, 1);
34 off_t length, filesize;
36 int exit_code = EXIT_SUCCESS;
39 getopt32(argv, ""); /* coreutils 6.9 compat */
45 setup_common_bufsiz();
47 int fd = open_or_warn_stdin(*argv ? *argv : bb_msg_standard_input);
50 exit_code = EXIT_FAILURE;
56 #define read_buf bb_common_bufsiz1
57 while ((bytes_read = safe_read(fd, read_buf, COMMON_BUFSIZE)) > 0) {
59 crc = crc32_block_endian1(crc, read_buf, bytes_read, crc32_table);
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;
73 length = (unsigned long long)length >> 8;
77 printf((*argv ? "%"PRIu32" %"OFF_FMT"i %s\n" : "%"PRIu32" %"OFF_FMT"i\n"),
78 crc, filesize, *argv);
79 } while (*argv && *++argv);
81 fflush_stdout_and_exit(exit_code);