stream: implement initial changes to control filter seeking

Author: bukka

main/streams/filter.c

@@ -259,6 +259,23 @@ PHPAPI php_stream_filter *php_stream_filter_create(const char *filtername, zval
 	return filter;
 }
 
+PHPAPI php_stream_filter *_php_stream_filter_alloc_ex(const php_stream_filter_ops *fops,
+		const php_stream_filter_extra_ops *feops, void *abstract, uint8_t persistent, uint16_t flags STREAMS_DC)
+{
+	php_stream_filter *filter;
+
+	filter = (php_stream_filter*) pemalloc_rel_orig(sizeof(php_stream_filter), persistent);
+	memset(filter, 0, sizeof(php_stream_filter));
+
+	filter->fops = fops;
+	filter->feops = feops;
+	filter->seekable = flags & PHP_STREAM_FILTER_SEEKABLE_MASK;
+	Z_PTR(filter->abstract) = abstract;
+	filter->is_persistent = persistent;
+
+	return filter;
+}
+
 PHPAPI php_stream_filter *_php_stream_filter_alloc(const php_stream_filter_ops *fops, void *abstract, uint8_t persistent STREAMS_DC)
 {
 	php_stream_filter *filter;

main/streams/php_stream_filter_api.h

@@ -34,6 +34,11 @@
 #define PHP_STREAM_FILTER_WRITE	0x0002
 #define PHP_STREAM_FILTER_ALL	(PHP_STREAM_FILTER_READ | PHP_STREAM_FILTER_WRITE)
 
+#define PHP_STREAM_FILTER_SEEKABLE_NEVER  0
+#define PHP_STREAM_FILTER_SEEKABLE_START  1
+#define PHP_STREAM_FILTER_SEEKABLE_ALWAYS 2
+#define PHP_STREAM_FILTER_SEEKABLE_MASK   3
+
 typedef struct _php_stream_bucket			php_stream_bucket;
 typedef struct _php_stream_bucket_brigade	php_stream_bucket_brigade;
 
@@ -94,6 +99,26 @@ typedef struct _php_stream_filter_ops {
 
 } php_stream_filter_ops;
 
+typedef struct _php_stream_filter_extra_ops {
+	/* it should indicate whether seeking is supported and possibly modify internal state */
+	zend_result (*seek)(
+			php_stream *stream,
+			php_stream_filter *thisfilter,
+			zend_off_t offset,
+			int whence
+	);
+
+	/* this is a generic interface for possible further extensions */
+	zend_result (*set_option)(
+			php_stream *stream,
+			php_stream_filter *thisfilter,
+			int option,
+			void *value,
+			size_t size
+	);
+
+} php_stream_filter_extra_ops;
+
 typedef struct _php_stream_filter_chain {
 	php_stream_filter *head, *tail;
 
@@ -103,10 +128,12 @@ typedef struct _php_stream_filter_chain {
 
 struct _php_stream_filter {
 	const php_stream_filter_ops *fops;
+	const php_stream_filter_extra_ops *feops;
 	zval abstract; /* for use by filter implementation */
 	php_stream_filter *next;
 	php_stream_filter *prev;
-	int is_persistent;
+	bool is_persistent;
+	uint8_t seekable;
 
 	/* link into stream and chain */
 	php_stream_filter_chain *chain;
@@ -128,8 +155,12 @@ PHPAPI zend_result _php_stream_filter_flush(php_stream_filter *filter, bool fini
 PHPAPI php_stream_filter *php_stream_filter_remove(php_stream_filter *filter, bool call_dtor);
 PHPAPI void php_stream_filter_free(php_stream_filter *filter);
 PHPAPI php_stream_filter *_php_stream_filter_alloc(const php_stream_filter_ops *fops, void *abstract, uint8_t persistent STREAMS_DC);
+PHPAPI php_stream_filter *_php_stream_filter_alloc_ex(const php_stream_filter_ops *fops,
+		const php_stream_filter_extra_ops *feops, void *abstract, uint8_t persistent, uint16_t flags STREAMS_DC);
 END_EXTERN_C()
 #define php_stream_filter_alloc(fops, thisptr, persistent) _php_stream_filter_alloc((fops), (thisptr), (persistent) STREAMS_CC)
+#define php_stream_filter_alloc_ex(fops, feops, thisptr, persistent) \
+	_php_stream_filter_alloc_ex((fops), (feops), (thisptr), (persistent) STREAMS_CC)
 #define php_stream_filter_alloc_rel(fops, thisptr, persistent) _php_stream_filter_alloc((fops), (thisptr), (persistent) STREAMS_REL_CC)
 #define php_stream_filter_prepend(chain, filter) _php_stream_filter_prepend((chain), (filter))
 #define php_stream_filter_append(chain, filter) _php_stream_filter_append((chain), (filter))

main/streams/streams.c

@@ -1360,6 +1360,40 @@ PHPAPI zend_off_t _php_stream_tell(const php_stream *stream)
 	return stream->position;
 }
 
+static bool php_stream_are_filters_seekable(php_stream_filter *filter, bool is_start_seeking)
+{
+	while (filter) {
+		if (filter->seekable == PHP_STREAM_FILTER_SEEKABLE_NEVER ||
+				(!is_start_seeking && filter->seekable == PHP_STREAM_FILTER_SEEKABLE_START)) {
+			php_error_docref(NULL, E_WARNING, "Stream filter %s is not seekable", filter->fops->label);
+			return false;
+		}
+		filter = filter->next;
+	}
+	return true;
+}
+
+static zend_result php_stream_filters_seek(php_stream *stream, php_stream_filter *filter, bool is_start_seeking)
+{
+	while (filter) {
+		if ((filter->seekable == PHP_STREAM_FILTER_SEEKABLE_START && is_start_seeking &&
+				filter->feops->seek(stream, filter, 0, SEEK_SET))) {
+			php_error_docref(NULL, E_WARNING, "Stream filter seeking for %s failed", filter->fops->label);
+			return FAILURE;
+		}
+		filter = filter->next;
+	}
+	return SUCCESS;
+}
+
+static zend_result php_stream_filters_seek_all(php_stream *stream, bool is_start_seeking)
+{
+	return php_stream_filters_seek(stream, stream->writefilters.head, is_start_seeking) == SUCCESS &&
+			php_stream_filters_seek(stream, stream->readfilters.head, is_start_seeking) == SUCCESS;
+}
+
+
+
 PHPAPI int _php_stream_seek(php_stream *stream, zend_off_t offset, int whence)
 {
 	if (stream->fclose_stdiocast == PHP_STREAM_FCLOSE_FOPENCOOKIE) {
@@ -1372,6 +1406,18 @@ PHPAPI int _php_stream_seek(php_stream *stream, zend_off_t offset, int whence)
 		}
 	}
 
+	bool is_start_seeking = whence == SEEK_SET && offset == 0;
+
+	if (stream->writefilters.head) {
+		_php_stream_flush(stream, 0);
+		if (!php_stream_are_filters_seekable(stream->writefilters.head, is_start_seeking)) {
+			return -1;
+		}
+	}
+	if (stream->readfilters.head && !php_stream_are_filters_seekable(stream->readfilters.head, is_start_seeking)) {
+		return -1;
+	}
+
 	/* handle the case where we are in the buffer */
 	if ((stream->flags & PHP_STREAM_FLAG_NO_BUFFER) == 0) {
 		switch(whence) {
@@ -1381,6 +1427,7 @@ PHPAPI int _php_stream_seek(php_stream *stream, zend_off_t offset, int whence)
 					stream->position += offset;
 					stream->eof = 0;
 					stream->fatal_error = 0;
+					php_stream_filters_seek_all(stream, is_start_seeking);
 					return 0;
 				}
 				break;
@@ -1391,6 +1438,7 @@ PHPAPI int _php_stream_seek(php_stream *stream, zend_off_t offset, int whence)
 					stream->position = offset;
 					stream->eof = 0;
 					stream->fatal_error = 0;
+					php_stream_filters_seek_all(stream, is_start_seeking);
 					return 0;
 				}
 				break;
@@ -1400,11 +1448,6 @@ PHPAPI int _php_stream_seek(php_stream *stream, zend_off_t offset, int whence)
 
 	if (stream->ops->seek && (stream->flags & PHP_STREAM_FLAG_NO_SEEK) == 0) {
 		int ret;
-
-		if (stream->writefilters.head) {
-			_php_stream_flush(stream, 0);
-		}
-
 		switch(whence) {
 			case SEEK_CUR:
 				ZEND_ASSERT(stream->position >= 0);
@@ -1431,6 +1474,8 @@ PHPAPI int _php_stream_seek(php_stream *stream, zend_off_t offset, int whence)
 			/* invalidate the buffer contents */
 			stream->readpos = stream->writepos = 0;
 
+			php_stream_filters_seek_all(stream, is_start_seeking);
+
 			return ret;
 		}
 		/* else the stream has decided that it can't support seeking after all;