Fix #48725: Support for flushing in zlib stream

ext/standard/tests/streams/bug48725_generic.phpt

@@ -0,0 +1,29 @@
+--TEST--
+Bug #48725 (Support for flushing in zlib stream, more generic issue)
+--FILE--
+<?php
+class DebugClosingFilter extends php_user_filter {
+	public function filter($in, $out, &$consumed, $closing) {
+		if ($closing) {
+			echo "Closing" . PHP_EOL;
+		}
+		while ($bucket = stream_bucket_make_writeable($in)) {
+			$consumed += $bucket->datalen;
+			stream_bucket_append($out, $bucket);
+		}
+		return PSFS_PASS_ON;
+	}
+}
+
+stream_filter_register('debug.closing', 'DebugClosingFilter');
+
+$stream = fopen('data://text/plain;base64,' . base64_encode('Foo bar baz'), 'r');
+stream_filter_append($stream, 'debug.closing', STREAM_FILTER_READ);
+$stream_contents = stream_get_contents($stream);
+print $stream_contents . PHP_EOL;
+?>
+===DONE===
+--EXPECT--
+Closing
+Foo bar baz
+===DONE===

ext/zlib/tests/bug48725.phpt

@@ -0,0 +1,14 @@
+--TEST--
+Bug #48725 (Support for flushing in zlib stream)
+--SKIPIF--
+<?php if (!extension_loaded("zlib")) print "skip"; ?>
+--FILE--
+<?php
+$stream = fopen('data://text/plain;base64,' . base64_encode('Foo bar baz'), 'r');
+stream_filter_append($stream, 'zlib.deflate', STREAM_FILTER_READ);
+print bin2hex(stream_get_contents($stream)) . PHP_EOL;
+?>
+===DONE===
+--EXPECT--
+73cbcf57484a2c02e22a00
+===DONE===

main/streams/streams.c

@@ -528,6 +528,7 @@ PHPAPI void _php_stream_fill_read_buffer(php_stream *stream, size_t size)
 	if (stream->readfilters.head) {
 		char *chunk_buf;
 		int err_flag = 0;
+		size_t justread = 0;
 		php_stream_bucket_brigade brig_in = { NULL, NULL }, brig_out = { NULL, NULL };
 		php_stream_bucket_brigade *brig_inp = &brig_in, *brig_outp = &brig_out, *brig_swap;
 
@@ -538,8 +539,7 @@ PHPAPI void _php_stream_fill_read_buffer(php_stream *stream, size_t size)
 		/* allocate a buffer for reading chunks */
 		chunk_buf = emalloc(stream->chunk_size);
 
-		while (!stream->eof && !err_flag && (stream->writepos - stream->readpos < (zend_off_t)size)) {
-			size_t justread = 0;
+		while ((justread != 0 || !stream->eof) && !err_flag && (stream->writepos - stream->readpos < (zend_off_t)size)) {
 			int flags;
 			php_stream_bucket *bucket;
 			php_stream_filter_status_t status = PSFS_ERR_FATAL;