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Fix stream filter flush corrupting a partially-read buffer #22424

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Fix stream filter flush corrupting a partially-read buffer #22424

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33 changes: 33 additions & 0 deletions ext/standard/tests/streams/stream_filter_flush_partial_read.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,33 @@
--TEST--
Flushing a read filter on a partially-read stream must not duplicate buffered bytes
--FILE--
<?php
class FlushEmitFilter extends php_user_filter
{
public function filter($in, $out, &$consumed, $closing): int
{
while ($bucket = stream_bucket_make_writeable($in)) {
$consumed += $bucket->datalen;
stream_bucket_append($out, $bucket);
}
if ($closing) {
stream_bucket_append($out, stream_bucket_new($this->stream, "<FLUSH>"));
}
return PSFS_PASS_ON;
}
}

stream_filter_register("flushemit", "FlushEmitFilter");

$fp = fopen("php://memory", "r+");
fwrite($fp, "ABCDEFGHIJKLMNOP");
rewind($fp);

$filter = stream_filter_append($fp, "flushemit", STREAM_FILTER_READ);
var_dump(fread($fp, 5));
stream_filter_remove($filter);
var_dump(fread($fp, 100));
?>
--EXPECT--
string(5) "ABCDE"
string(18) "FGHIJKLMNOP<FLUSH>"
4 changes: 2 additions & 2 deletions main/streams/filter.c
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Original file line number Diff line number Diff line change
Expand Up @@ -459,9 +459,9 @@ PHPAPI int _php_stream_filter_flush(php_stream_filter *filter, int finish)
/* Dump any newly flushed data to the read buffer */
if (stream->readpos > 0) {
/* Back the buffer up */
memcpy(stream->readbuf, stream->readbuf + stream->readpos, stream->writepos - stream->readpos);
stream->readpos = 0;
memmove(stream->readbuf, stream->readbuf + stream->readpos, stream->writepos - stream->readpos);
stream->writepos -= stream->readpos;
stream->readpos = 0;
}
if (flushed_size > (stream->readbuflen - stream->writepos)) {
/* Grow the buffer */
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