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/* vi: set sw=4 ts=4: */
/*
* cksum - calculate the CRC32 checksum of a file
*
* Copyright (C) 2006 by Rob Sullivan, with ideas from code by Walter Harms
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
#include "libbb.h"
int cksum_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int cksum_main(int argc UNUSED_PARAM, char **argv)
{
uint32_t *crc32_table = crc32_filltable(NULL, 1);
uint32_t crc;
off_t length, filesize;
int bytes_read;
int exit_code = EXIT_SUCCESS;
uint8_t *cp;
#if ENABLE_DESKTOP
getopt32(argv, ""); /* coreutils 6.9 compat */
argv += optind;
#else
argv++;
#endif
do {
int fd = open_or_warn_stdin(*argv ? *argv : bb_msg_standard_input);
if (fd < 0) {
exit_code = EXIT_FAILURE;
continue;
}
crc = 0;
length = 0;
#define read_buf bb_common_bufsiz1
while ((bytes_read = safe_read(fd, read_buf, sizeof(read_buf))) > 0) {
cp = (uint8_t *) read_buf;
length += bytes_read;
do {
crc = (crc << 8) ^ crc32_table[(crc >> 24) ^ *cp++];
} while (--bytes_read);
}
close(fd);
filesize = length;
while (length) {
crc = (crc << 8) ^ crc32_table[(uint8_t)(crc >> 24) ^ (uint8_t)length];
/* must ensure that shift is unsigned! */
if (sizeof(length) <= sizeof(unsigned))
length = (unsigned)length >> 8;
else if (sizeof(length) <= sizeof(unsigned long))
length = (unsigned long)length >> 8;
else
length = (unsigned long long)length >> 8;
}
crc = ~crc;
printf((*argv ? "%"PRIu32" %"OFF_FMT"i %s\n" : "%"PRIu32" %"OFF_FMT"i\n"),
crc, filesize, *argv);
} while (*argv && *++argv);
fflush_stdout_and_exit(exit_code);
}
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