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49 lines
1.1 KiB
C
49 lines
1.1 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Utility routines.
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*
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* Copyright (C) 2010 Denys Vlasenko
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*
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* Licensed under GPLv2, see file LICENSE in this tarball for details.
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*/
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#include "libbb.h"
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uoff_t FAST_FUNC get_volume_size_in_bytes(int fd,
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const char *override,
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unsigned override_units,
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int extend)
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{
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uoff_t result;
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if (override) {
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result = XATOOFF(override);
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if (result >= (uoff_t)(MAXINT(off_t)) / override_units)
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bb_error_msg_and_die("image size is too big");
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result *= override_units;
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/* seek past end fails on block devices but works on files */
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if (lseek(fd, result - 1, SEEK_SET) != (off_t)-1) {
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if (extend)
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xwrite(fd, "", 1); /* file grows if needed */
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}
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//else {
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// bb_error_msg("warning, block device is smaller");
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//}
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} else {
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/* more portable than BLKGETSIZE[64] */
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result = xlseek(fd, 0, SEEK_END);
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}
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xlseek(fd, 0, SEEK_SET);
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/* Prevent things like this:
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* $ dd if=/dev/zero of=foo count=1 bs=1024
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* $ mkswap foo
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* Setting up swapspace version 1, size = 18446744073709548544 bytes
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*
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* Picked 16k arbitrarily: */
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if (result < 16*1024)
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bb_error_msg_and_die("image is too small");
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return result;
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}
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