[cairo-output-stream] Introduce _cairo_output_stream_create_in_error()

Use a utility function to wrap an incoming error status into a new
error stream. As a side-effect, all error streams must be destroyed as
in the general case the caller can not distinguish between a static
error object and one allocated to hold an unusual error status.

1 files changed, 24 insertions, 2 deletions

diff --git a/src/cairo-output-stream.c b/src/cairo-output-stream.c
index 6451b0fe6..2cb9e03bc 100644
--- a/src/cairo-output-stream.c
+++ b/src/cairo-output-stream.c
@@ -134,6 +134,29 @@ _cairo_output_stream_create (cairo_write_func_t		write_func,
     return &stream->base;
 }
 
+cairo_output_stream_t *
+_cairo_output_stream_create_in_error (cairo_status_t status)
+{
+    cairo_output_stream_t *stream;
+
+    /* check for the common ones */
+    if (status == CAIRO_STATUS_NO_MEMORY)
+	return (cairo_output_stream_t *) &_cairo_output_stream_nil;
+    if (status == CAIRO_STATUS_WRITE_ERROR)
+	return (cairo_output_stream_t *) &_cairo_output_stream_nil_write_error;
+
+    stream = malloc (sizeof (cairo_output_stream_t));
+    if (stream == NULL) {
+	_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
+	return (cairo_output_stream_t *) &_cairo_output_stream_nil;
+    }
+
+    _cairo_output_stream_init (stream, NULL, NULL);
+    stream->status = status;
+
+    return stream;
+}
+
 cairo_status_t
 _cairo_output_stream_close (cairo_output_stream_t *stream)
 {
@@ -165,8 +188,7 @@ _cairo_output_stream_destroy (cairo_output_stream_t *stream)
 {
     cairo_status_t status;
 
-    if (stream == NULL)
-	return _cairo_error (CAIRO_STATUS_NULL_POINTER);
+    assert (stream != NULL);
 
     if (stream == &_cairo_output_stream_nil ||
 	stream == &_cairo_output_stream_nil_write_error)