source: MondoRescue/branches/3.3/mindi-busybox/coreutils/sum.c

/* vi: set sw=4 ts=4: */
/*
 * sum -- checksum and count the blocks in a file
 *     Like BSD sum or SysV sum -r, except like SysV sum if -s option is given.
 *
 * Copyright (C) 86, 89, 91, 1995-2002, 2004 Free Software Foundation, Inc.
 * Copyright (C) 2005 by Erik Andersen <andersen@codepoet.org>
 * Copyright (C) 2005 by Mike Frysinger <vapier@gentoo.org>
 *
 * Written by Kayvan Aghaiepour and David MacKenzie
 * Taken from coreutils and turned into a busybox applet by Mike Frysinger
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

//usage:#define sum_trivial_usage
//usage:       "[-rs] [FILE]..."
//usage:#define sum_full_usage "\n\n"
//usage:       "Checksum and count the blocks in a file\n"
//usage:     "\n    -r  Use BSD sum algorithm (1K blocks)"
//usage:     "\n    -s  Use System V sum algorithm (512byte blocks)"

#include "libbb.h"
#include "common_bufsiz.h"

enum { SUM_BSD, PRINT_NAME, SUM_SYSV };

/* BSD: calculate and print the rotated checksum and the size in 1K blocks
   The checksum varies depending on sizeof (int). */
/* SYSV: calculate and print the checksum and the size in 512-byte blocks */
/* Return 1 if successful.  */
static unsigned sum_file(const char *file, unsigned type)
{
    unsigned long long total_bytes = 0;
    int fd, r;
    /* The sum of all the input bytes, modulo (UINT_MAX + 1).  */
    unsigned s = 0;

#define buf bb_common_bufsiz1
    setup_common_bufsiz();

    fd = open_or_warn_stdin(file);
    if (fd == -1)
        return 0;

    while (1) {
        size_t bytes_read = safe_read(fd, buf, COMMON_BUFSIZE);

        if ((ssize_t)bytes_read <= 0) {
            r = (fd && close(fd) != 0);
            if (!bytes_read && !r)
                /* no error */
                break;
            bb_simple_perror_msg(file);
            return 0;
        }

        total_bytes += bytes_read;
        if (type >= SUM_SYSV) {
            do s += buf[--bytes_read]; while (bytes_read);
        } else {
            r = 0;
            do {
                s = (s >> 1) + ((s & 1) << 15);
                s += buf[r++];
                s &= 0xffff; /* Keep it within bounds. */
            } while (--bytes_read);
        }
    }

    if (type < PRINT_NAME)
        file = "";
    if (type >= SUM_SYSV) {
        r = (s & 0xffff) + ((s & 0xffffffff) >> 16);
        s = (r & 0xffff) + (r >> 16);
        printf("%u %llu %s\n", s, (total_bytes + 511) / 512, file);
    } else
        printf("%05u %5llu %s\n", s, (total_bytes + 1023) / 1024, file);
    return 1;
#undef buf
}

int sum_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int sum_main(int argc UNUSED_PARAM, char **argv)
{
    unsigned n;
    unsigned type = SUM_BSD;

    n = getopt32(argv, "sr");
    argv += optind;
    if (n & 1) type = SUM_SYSV;
    /* give the bsd priority over sysv func */
    if (n & 2) type = SUM_BSD;

    if (!argv[0]) {
        /* Do not print the name */
        n = sum_file("-", type);
    } else {
        /* Need to print the name if either
         * - more than one file given
         * - doing sysv */
        type += (argv[1] || type == SUM_SYSV);
        n = 1;
        do {
            n &= sum_file(*argv, type);
        } while (*++argv);
    }
    return !n;
}