- [DOC] Reverted rev #304382 and rev #304380, as I figured out a way to

  fix the erratic behavior without breaking backwards compatibility. Namely,
  $offset retains SEEK_SET behavior but actually SEEK_CUR is passed to
  _php_stream_seek, if possible, by moving the offset stream->position bytes.
- Addresses bug #53006.

Author: cataphract

ext/standard/streamsfuncs.c

@@ -415,7 +415,7 @@ PHP_FUNCTION(stream_get_contents)
 {
 	php_stream *stream;
 	zval *zsrc;
-	long maxlen = PHP_STREAM_COPY_ALL, pos = 0;
+	long maxlen = PHP_STREAM_COPY_ALL, pos = -1L;
 	int len, newlen;
 	char *contents = NULL;
 
@@ -425,12 +425,19 @@ PHP_FUNCTION(stream_get_contents)
 
 	php_stream_from_zval(stream, &zsrc);
 
-	if ((pos > 0L) && php_stream_seek(stream, pos, SEEK_CUR) < 0) {
-		php_error_docref(NULL TSRMLS_CC, E_WARNING, "Failed to seek %ld bytes from current position in the stream", pos);
-		RETURN_FALSE;
-	} else if (pos < 0L) {
-		php_error_docref(NULL TSRMLS_CC, E_WARNING, "Number of bytes to seek must be non-negative, given %ld", pos);
-		RETURN_FALSE;
+	if (pos >= 0) {
+		int seek_res = 0;
+		if (pos > stream->position) {
+			/* use SEEK_CUR to allow emulation in streams that don't support seeking */
+			seek_res = php_stream_seek(stream, pos - stream->position, SEEK_CUR);
+		} else if (pos < stream->position)  {
+			seek_res = php_stream_seek(stream, pos, SEEK_SET);
+		}
+
+		if (seek_res != 0) {
+			php_error_docref(NULL TSRMLS_CC, E_WARNING, "Failed to seek to position %ld in the stream", pos);
+			RETURN_FALSE;
+		}
 	}
 
 	len = php_stream_copy_to_mem(stream, &contents, maxlen, 0);

ext/standard/tests/streams/bug46426.phpt

@@ -7,31 +7,27 @@ $tmp = tmpfile();
 
 fwrite($tmp, b"12345");
 
-fseek($tmp, 0);
-echo stream_get_contents($tmp, 2, 1); //23
+echo stream_get_contents($tmp, 2, 1);
 echo "\n";
-echo stream_get_contents($tmp, -1); //45
+echo stream_get_contents($tmp, -1);
 echo "\n";
-fseek($tmp, -1, SEEK_CUR);
-echo stream_get_contents($tmp, -1, 0); //5
+echo stream_get_contents($tmp, -1, 0);
 echo "\n";
-fseek($tmp, 0);
-echo stream_get_contents($tmp, -1, 2); //345
+echo stream_get_contents($tmp, -1, 2);
 echo "\n";
-fseek($tmp, 0);
-echo stream_get_contents($tmp, 0, 0); //""
+echo stream_get_contents($tmp, 0, 0);
 echo "\n";
-echo stream_get_contents($tmp, 1, 0); //1
+echo stream_get_contents($tmp, 1, 0);
 echo "\n";
-echo stream_get_contents($tmp, -1); //2345
+echo stream_get_contents($tmp, -1);
 
 @unlink($tmp);
 
 ?>
 --EXPECT--
 23
 45
-5
+12345
 345
 
 1

ext/standard/tests/streams/stream_get_contents_001.phpt

@@ -9,17 +9,14 @@ fwrite($tmp, b"12345");
 
 echo stream_get_contents($tmp, 2, 5), "--\n";
 echo stream_get_contents($tmp, 2), "--\n";
-fseek($tmp, 0);
 echo stream_get_contents($tmp, 2, 3), "--\n";
 echo stream_get_contents($tmp, 2, -1), "--\n";
 
 @unlink($tmp);
 
 ?>
---EXPECTF--
+--EXPECT--
 --
 --
 45--
-
-Warning: stream_get_contents(): Number of bytes to seek must be non-negative, given -1 in %s on line %d
 --