From: salsi at icosaedro dot it
Operating system: Slackware 14.1
PHP version: Irrelevant
Package: Filter related
Bug Type: Bug
Bug description:fread() does not detects decoding errors from filter bzip2.decompress
Description:
------------
When the bzip2.decompress filter is applied to a stream, the fread()
function does not detect decoding errors on a corrupted file and keeps
instead returning the empty string or garbage. The following script
illustrates 3 distinct cases.
Checking what really happens inside the php_bz2_decompress_filter()
function, in 2 of the 3 cases this function correctly detects an error
in the corrupted file and returns PSFS_ERR_FATAL, but in the script the
fread() function always succeeds.
In one case the php_bz2_decompress_filter() function does not detect
anything, but fread() succeeds and returns the empty string.
In my opinion, if a decoding error is detected it is just like reading
from a damaged file and fread() should return FALSE and triggering
E_WARNING (which this script would map to ErrorException).
I've tested on PHP 7.0-dev, but I don't think the PHP version does
really matters here.
Unsure if this bug is in some way related to #17651.
Test script:
---------------
<?php
// Bug report: bzip2.decompress fails to detect corrupted data.
// Set a safe environment:
error_reporting(-1);
ini_set("track_errors", "1");
/**
* Maps errors to ErrorException.
* @access private
* @param int $errno
* @param string $message
* @return boolean
* @throws ErrorException
*/
function my_error_handler($errno, $message /*, $filename, $lineno,
$context */)
{
throw new ErrorException($message);
}
set_error_handler("my_error_handler");
/**
* Testing reading corrupted BZIP2 file using bzip2.decompress filter.
* @throws ErrorException
*/
function main()
{
$plain = "The quick brown fox jumps over the lazy dog.";
$fn = "test.bz2";
$compressed = (string) bzcompress($plain);
echo "Compressed len = ", strlen($compressed), "\n";
// Set a random byte in the middle of the compressed data
// --> php_bz2_decompress_filter() detects fatal error
// --> fread() displays empty string then garbage, no errors detected:
$compressed[strlen($compressed) - 15] = 'X';
// Truncate the compressed data
// --> php_bz2_decompress_filter() does not detect errors,
// --> fread() displays the empty string:
// $compressed = substr($compressed, 0, strlen($compressed) - 20);
// Corrupted final CRC
// --> php_bz2_decompress_filter() detects fatal error
// --> fread() displays an empty string, then the correct plain text,
no error detected:
// $compressed[strlen($compressed)-2] = 'X';
file_put_contents($fn, $compressed);
$r = fopen($fn, "r");
stream_filter_append($r, 'bzip2.decompress', STREAM_FILTER_READ);
while( ! feof($r) ){
$s = fread($r, 100);
echo "read: "; var_dump($s);
}
fclose($r);
unlink($fn);
}
main();
?>
Expected result:
----------------
Compressed len = 81
Fatal error: Uncaught ErrorException: fread() I/O error in
/home/salsi/BZIP2-bug-report.php:24
(or possibly a more descriptive error message, although it might be
difficult to do due to the limitations of the filter interface)
Actual result:
--------------
Compressed len = 81
read: string(0) ""
read: string(43) "bthes ohe rpujumr.bthes ohe rpujumr.bthes o"
--
Edit bug report at https://bugs.php.net/bug.php?id=71263&edit=1
--
Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=71263&r=trysnapshot54
Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=71263&r=trysnapshot55
Try a snapshot (trunk): https://bugs.php.net/fix.php?id=71263&r=trysnapshottrunk
Fixed in SVN: https://bugs.php.net/fix.php?id=71263&r=fixed
Fixed in release: https://bugs.php.net/fix.php?id=71263&r=alreadyfixed
Need backtrace: https://bugs.php.net/fix.php?id=71263&r=needtrace
Need Reproduce Script: https://bugs.php.net/fix.php?id=71263&r=needscript
Try newer version: https://bugs.php.net/fix.php?id=71263&r=oldversion
Not developer issue: https://bugs.php.net/fix.php?id=71263&r=support
Expected behavior: https://bugs.php.net/fix.php?id=71263&r=notwrong
Not enough info: https://bugs.php.net/fix.php?id=71263&r=notenoughinfo
Submitted twice: https://bugs.php.net/fix.php?id=71263&r=submittedtwice
register_globals: https://bugs.php.net/fix.php?id=71263&r=globals
PHP 4 support discontinued: https://bugs.php.net/fix.php?id=71263&r=php4
Daylight Savings: https://bugs.php.net/fix.php?id=71263&r=dst
IIS Stability: https://bugs.php.net/fix.php?id=71263&r=isapi
Install GNU Sed: https://bugs.php.net/fix.php?id=71263&r=gnused
Floating point limitations: https://bugs.php.net/fix.php?id=71263&r=float
No Zend Extensions: https://bugs.php.net/fix.php?id=71263&r=nozend
MySQL Configuration Error: https://bugs.php.net/fix.php?id=71263&r=mysqlcfg