source: MondoRescue/branches/3.0/mindi-busybox/libbb/get_volsize.c@ 3085

/* vi: set sw=4 ts=4: */
/*
 * Utility routines.
 *
 * Copyright (C) 2010 Denys Vlasenko
 *
 * Licensed under GPLv2, see file LICENSE in this source tree.
 */
#include "libbb.h"

uoff_t FAST_FUNC get_volume_size_in_bytes(int fd,
        const char *override,
        unsigned override_units,
        int extend)
{
    uoff_t result;

    if (override) {
        result = XATOOFF(override);
        if (result >= (uoff_t)(MAXINT(off_t)) / override_units)
            bb_error_msg_and_die("image size is too big");
        result *= override_units;
        /* seek past end fails on block devices but works on files */
        if (lseek(fd, result - 1, SEEK_SET) != (off_t)-1) {
            if (extend)
                xwrite(fd, "", 1); /* file grows if needed */
        }
        //else {
        //  bb_error_msg("warning, block device is smaller");
        //}
    } else {
        /* more portable than BLKGETSIZE[64] */
        result = xlseek(fd, 0, SEEK_END);
    }

    xlseek(fd, 0, SEEK_SET);

    /* Prevent things like this:
     * $ dd if=/dev/zero of=foo count=1 bs=1024
     * $ mkswap foo
     * Setting up swapspace version 1, size = 18446744073709548544 bytes
     *
     * Picked 16k arbitrarily: */
    if (result < 16*1024)
        bb_error_msg_and_die("image is too small");

    return result;
}