source: src/router/busybox/coreutils/cksum.c @ 8864

/* 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 tarball for details. */

#include "libbb.h"

int cksum_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int cksum_main(int argc, char **argv)
{
        uint32_t *crc32_table = crc32_filltable(NULL, 1);

        FILE *fp;
        uint32_t crc;
        long length, filesize;
        int bytes_read;
        char *cp;

        int inp_stdin = (argc == optind) ? 1 : 0;

        do {
                fp = fopen_or_warn_stdin((inp_stdin) ? bb_msg_standard_input : *++argv);

                crc = 0;
                length = 0;

#define read_buf bb_common_bufsiz1
                while ((bytes_read = fread(read_buf, 1, BUFSIZ, fp)) > 0) {
                        cp = read_buf;
                        length += bytes_read;
                        while (bytes_read--)
                                crc = (crc << 8) ^ crc32_table[((crc >> 24) ^ (*cp++)) & 0xffL];
                }

                filesize = length;

                for (; length; length >>= 8)
                        crc = (crc << 8) ^ crc32_table[((crc >> 24) ^ length) & 0xffL];
                crc ^= 0xffffffffL;

                if (inp_stdin) {
                        printf("%" PRIu32 " %li\n", crc, filesize);
                        break;
                }

                printf("%" PRIu32 " %li %s\n", crc, filesize, *argv);
                fclose(fp);
        } while (*(argv + 1));

        fflush_stdout_and_exit(EXIT_SUCCESS);
}