Fix #75273: php_zlib_inflate_filter() may not update bytes_consumed

Whenever we return with `PSFS_PASS_ON`, we need to update
`bytes_consumed` to not mislead the caller.  Instead of fixing the
respective `if` clauses, we eschew the early bail-outs to simplify the
code a bit.

NEWS

@@ -19,6 +19,10 @@ PHP                                                                        NEWS
   . Fixed bug #74764 (Bindto IPv6 works with file_get_contents but fails with 
     stream_socket_client). (Ville Hukkamäki)
 
+- Zlib:
+  . Fixed bug #75273 (php_zlib_inflate_filter() may not update bytes_consumed).
+    (Martin Burke, cmb)
+
 13 Sep 2018, PHP 7.1.22
 
 - Core:

ext/zlib/tests/bug75273.phpt

@@ -0,0 +1,58 @@
+--TEST--
+Bug #75273 (php_zlib_inflate_filter() may not update bytes_consumed)
+--SKIPIF--
+<?php
+if (!extension_loaded('zlib')) die('skip zlib extension not available');
+?>
+--FILE--
+<?php
+function non_repeating_str($len = 8192) {
+	$ret = '';
+	mt_srand(1);
+	$iterations = (int) ($len / 256) + 1;
+	for ($i = 0; $i < $iterations; $i++) {
+		$haves = array();
+		$cnt = 0;
+		while ($cnt < 256) {
+			$j = mt_rand(0, 255);
+			if (!isset($haves[$j])) {
+				$haves[$j] = $j;
+				$cnt++;
+				$ret .= chr($j);
+			}
+		}
+	}
+	return substr($ret, 0, $len);
+}
+
+$base_len = 32768 - 23 /*overhead*/;
+
+$stream = fopen('php://memory', 'rb+');
+
+for ($i = 1; $i <= 8; $i++) {
+	$in_data = non_repeating_str($base_len + $i);
+
+	$deflate_filter = stream_filter_append($stream, 'zlib.deflate',  STREAM_FILTER_WRITE, ['window' => 16 + 15]);
+	rewind($stream);
+	fwrite($stream, $in_data);
+	stream_filter_remove($deflate_filter);
+
+	rewind($stream);
+	$out_data = stream_get_contents($stream);
+	$out_data_len = strlen($out_data);
+
+	$inflate_filter = stream_filter_prepend($stream, 'zlib.inflate',  STREAM_FILTER_WRITE, ['window' => 16 + 15]);
+	rewind($stream);
+	$fwrite_len = fwrite($stream, $out_data);
+	stream_filter_remove($inflate_filter);
+
+	if ($out_data_len !== $fwrite_len) {
+		echo "bug i=$i out_data_len=$out_data_len fwrite_len=$fwrite_len\n";
+	}
+}
+
+fclose($stream);
+?>
+===DONE===
+--EXPECT--
+===DONE===

ext/zlib/zlib_filter.c

@@ -78,12 +78,7 @@ static php_stream_filter_status_t php_zlib_inflate_filter(
 
 		bucket = php_stream_bucket_make_writeable(buckets_in->head);
 
-		while (bin < (unsigned int) bucket->buflen) {
-
-			if (data->finished) {
-				consumed += bucket->buflen;
-				break;
-			}
+		while (bin < (unsigned int) bucket->buflen && !data->finished) {
 
 			desired = bucket->buflen - bin;
 			if (desired > data->inbuf_len) {
@@ -96,6 +91,7 @@ static php_stream_filter_status_t php_zlib_inflate_filter(
 			if (status == Z_STREAM_END) {
 				inflateEnd(&(data->strm));
 				data->finished = '\1';
+				exit_status = PSFS_PASS_ON;
 			} else if (status != Z_OK) {
 				/* Something bad happened */
 				php_stream_bucket_delref(bucket);
@@ -118,10 +114,6 @@ static php_stream_filter_status_t php_zlib_inflate_filter(
 				data->strm.avail_out = data->outbuf_len;
 				data->strm.next_out = data->outbuf;
 				exit_status = PSFS_PASS_ON;
-			} else if (status == Z_STREAM_END && data->strm.avail_out >= data->outbuf_len) {
-				/* no more data to decompress, and nothing was spat out */
-				php_stream_bucket_delref(bucket);
-				return PSFS_PASS_ON;
 			}
 
 		}