CDNWiki - View Source: copysparse.php

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Originally built to copy a block device (a mac mini in firewire mass storage mode) to an image file, excluding all-null blocks (sparse file) to save space.

Also contains examples of thousands-separator number formatting (i.e. 10,000,000) and human-readable magnitude number formatting (i.e. 10.0GB) functions.

<verbatim>
#!/usr/bin/env php
<?php

declare(ticks=1);
bcscale(3);

// Read a file and process it in chunks.
$infile = "/dev/sde";
$outfile = "/media/recover/MacMini-whole-sparse.img";
$blksz = 4096;
$blkct = 19537686;
$blkct_b = bcmul($blkct, $blksz, 0);

function ksep($number) {
	$number = (string) $number;
	$max = strlen($number);
	$recip = $max;
	for ($i = 0; $i < $max; ++$i) {
		--$recip;
		if ($i && !($i % 3))
			$out = "," . $out;
		$out = $number{$recip} . $out;
	}
	return $out;
}

function prettyGigs($bytes) {
	$powers = " kMGTPEZY";
	$power = 0;
	$mod = 1;
	while (bcdiv($bytes, $mod) > 1024) {
		$mod = bcmul($mod, 1024);
		++$power;
	}
	$num = bcdiv($bytes, $mod);
	switch (((int) $num != $num)? strpos($num, "."): 0) {
		case "0":
			$fmt = "%0.0f%s";
			break;
		case "1":
			$fmt = "%0.3f%s";
			break;
		case "2":
			$fmt = "%0.2f%s";
			break;
		case "3":
		default:
			$fmt = "%0.1f%s";
			break;
	}
	if ($power)
		$power = $powers{$power}."B";
	else	$power = "B";
	return sprintf($fmt, $num, $power);
}

function stats() {
	pcntl_alarm(1);
	$blksz = $GLOBALS['blksz'];
	$blkct = $GLOBALS['blkct'];
	$blkct_b = $GLOBALS['blkct_b'];
	$data = $GLOBALS['data'];
	$data_b = bcmul($data, $blksz, 0);
	$sparse = $GLOBALS['sparse'];
	$sparse_b = bcmul($sparse, $blksz, 0);
	$count = bcadd($GLOBALS['data'], $GLOBALS['sparse'], 0);
	$count_b = bcmul($count, $blksz, 0);
	$pct = bcmul(bcdiv($count, $GLOBALS['blkct'], 10), 100.0);
	$speed = bcmul(bcsub($count, $GLOBALS['old_count']), $blksz);

	printf("\rD: %ss (%s) S: %ss (%s) +: %ss (%s) T: %ss (%s) %%: %0.4f %s/sec    ",
		ksep($data), prettyGigs($data_b), ksep($sparse), prettyGigs($sparse_b), ksep($count), prettyGigs($count_b),
		ksep($blkct), prettyGigs($blkct_b), $pct, prettyGigs($speed));

/*	printf("\rBlk: %s Spa: %s Sum: %s Tot: %s Pct: %0.4f    ",
		thousands($GLOBALS['data']), thousands($GLOBALS['sparse']),
		thousands($count), thousands($GLOBALS['blkct']), $pct);
*/	$GLOBALS['old_count'] = $count;
}

pcntl_signal(SIGALRM, "stats", true);
pcntl_alarm(1);
echo "\n\nPrecaching...";

/* No longer required
// Precalculate crc
$bufr = str_repeat("\0", 4096);
$zero = crc32($bufr);
*/

$input = fopen($infile, "rb");
$output = fopen($outfile, "wb");

if (!is_resource($input))
	die(sprintf("%s failed!\n", $infile));
if (!is_resource($output))
	die(sprintf("%s failed!\n", $outfile));

$data = 0;
$sparse = 0;

while (!feof($input)) {
	$bufr = fread($input, $blksz);
	$chars = count_chars($bufr, 3);
	if ($chars === "\0") {
		// Nul block. Skip it.
		fseek($output, ftell($output) + $blksz);
		$sparse++;
		continue;
	}
/* Counting chars takes roughly half the time as computing the crc32.
	if (crc32($bufr) == $zero) {
		// Matching block? compare by bytes
		$chars = count_chars($bufr, 3);
		if ($chars === "\0") {
			// Null block. Skip it.
			fseek($output, ftell($output) + $blksz);
			continue;
		}
	}
*/	fwrite($output, $bufr, $blksz);
	$data++;
}

fclose($input);
fclose($output);

echo "\n\n";

?>
</verbatim>