Add chunked encoding test with multiple buckets

Filters work on bucket brigades consisting of multiple buckets of data.
For the dechunk filter this means that php_dechunk is called on every
bucket. This test splits the data into two buckets. This tests that
continuing parsing on another bucket works, and handling of the end of
the bucket on any point.

Author: Sjoerd Langkemper

ext/standard/tests/filters/chunked_004.phpt

@@ -0,0 +1,94 @@
+--TEST--
+Chunked encoding (multiple buckets)
+--SKIPIF--
+<?php
+$filters = stream_get_filters();
+if(! in_array( "dechunk", $filters )) die( "skip Chunked filter not available." );
+?>
+--INI--
+allow_url_fopen=1
+--FILE--
+<?php
+
+// Filter that splits each bucket in the input into two, with $chunkSize bytes in the first bucket.
+final class Splitter extends php_user_filter {
+    public static int $chunkSize;
+    function filter($in, $out, &$consumed, $closing): int {
+        while ($bucket = stream_bucket_make_writeable($in)) {
+            $head = substr($bucket->data, 0, self::$chunkSize);
+            $head_bucket = stream_bucket_new($this->stream, $head);
+            stream_bucket_append($out, $head_bucket);
+
+            $tail = substr($bucket->data, self::$chunkSize);
+            $tail_bucket = stream_bucket_new($this->stream, $tail);
+            stream_bucket_append($out, $tail_bucket);
+
+            $consumed += strlen($bucket->data);
+            return PSFS_PASS_ON;
+        }
+        return PSFS_FEED_ME;
+    }
+}
+stream_filter_register("Splitter", "Splitter");
+
+$testdata = "2;key=value\r\nte\r\n2\r\nst\r\n0\r\nTrailer: section\r\n\r\n";
+
+// Split test data on every possible position
+for ($i = 1; $i < strlen($testdata); $i++) {
+    Splitter::$chunkSize = $i;
+
+    $fp = fopen("data:text/plain,$testdata", "r");
+    stream_filter_append($fp, "Splitter", STREAM_FILTER_READ);
+    stream_filter_append($fp, "dechunk", STREAM_FILTER_READ);
+
+    var_dump(stream_get_contents($fp));
+    fclose($fp);
+}
+?>
+--EXPECT--
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"
+string(4) "test"