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74 lines
1.8 KiB
C
74 lines
1.8 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* cksum - calculate the CRC32 checksum of a file
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*
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* Copyright (C) 2006 by Rob Sullivan, with ideas from code by Walter Harms
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*
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*/
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//usage:#define cksum_trivial_usage
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//usage: "FILES..."
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//usage:#define cksum_full_usage "\n\n"
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//usage: "Calculate the CRC32 checksums of FILES"
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#include "libbb.h"
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#include "common_bufsiz.h"
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/* This is a NOEXEC applet. Be very careful! */
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int cksum_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int cksum_main(int argc UNUSED_PARAM, char **argv)
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{
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uint32_t *crc32_table = crc32_filltable(NULL, 1);
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uint32_t crc;
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off_t length, filesize;
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int bytes_read;
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int exit_code = EXIT_SUCCESS;
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#if ENABLE_DESKTOP
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getopt32(argv, ""); /* coreutils 6.9 compat */
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argv += optind;
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#else
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argv++;
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#endif
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setup_common_bufsiz();
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do {
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int fd = open_or_warn_stdin(*argv ? *argv : bb_msg_standard_input);
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if (fd < 0) {
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exit_code = EXIT_FAILURE;
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continue;
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}
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crc = 0;
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length = 0;
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#define read_buf bb_common_bufsiz1
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while ((bytes_read = safe_read(fd, read_buf, COMMON_BUFSIZE)) > 0) {
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length += bytes_read;
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crc = crc32_block_endian1(crc, read_buf, bytes_read, crc32_table);
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}
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close(fd);
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filesize = length;
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while (length) {
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crc = (crc << 8) ^ crc32_table[(uint8_t)(crc >> 24) ^ (uint8_t)length];
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/* must ensure that shift is unsigned! */
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if (sizeof(length) <= sizeof(unsigned))
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length = (unsigned)length >> 8;
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else if (sizeof(length) <= sizeof(unsigned long))
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length = (unsigned long)length >> 8;
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else
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length = (unsigned long long)length >> 8;
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}
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crc = ~crc;
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printf((*argv ? "%"PRIu32" %"OFF_FMT"i %s\n" : "%"PRIu32" %"OFF_FMT"i\n"),
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crc, filesize, *argv);
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} while (*argv && *++argv);
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fflush_stdout_and_exit(exit_code);
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}
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