Make GDataOutputStream implement GSeekable

https://bugzilla.gnome.org/show_bug.cgi?id=673034

2 files changed, 299 insertions, 3 deletions

diff --git a/gio/gdataoutputstream.c b/gio/gdataoutputstream.c
index e03003b36..5abf68f94 100644
--- a/gio/gdataoutputstream.c
+++ b/gio/gdataoutputstream.c
@@ -23,7 +23,9 @@
 #include "config.h"
 #include <string.h>
 #include "gdataoutputstream.h"
+#include "gseekable.h"
 #include "gioenumtypes.h"
+#include "gioerror.h"
 #include "glibintl.h"
 
 
@@ -58,9 +60,25 @@ static void g_data_output_stream_get_property (GObject      *object,
 					       GValue       *value,
 					       GParamSpec   *pspec);
 
-G_DEFINE_TYPE (GDataOutputStream,
-               g_data_output_stream,
-               G_TYPE_FILTER_OUTPUT_STREAM)
+static void     g_data_output_stream_seekable_iface_init (GSeekableIface  *iface);
+static goffset  g_data_output_stream_tell                (GSeekable       *seekable);
+static gboolean g_data_output_stream_can_seek            (GSeekable       *seekable);
+static gboolean g_data_output_stream_seek                (GSeekable       *seekable,
+							  goffset          offset,
+							  GSeekType        type,
+							  GCancellable    *cancellable,
+							  GError         **error);
+static gboolean g_data_output_stream_can_truncate        (GSeekable       *seekable);
+static gboolean g_data_output_stream_truncate            (GSeekable       *seekable,
+							  goffset          offset,
+							  GCancellable    *cancellable,
+							  GError         **error);
+
+G_DEFINE_TYPE_WITH_CODE (GDataOutputStream,
+			 g_data_output_stream,
+			 G_TYPE_FILTER_OUTPUT_STREAM,
+			 G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
+						g_data_output_stream_seekable_iface_init))
 
 
 static void
@@ -147,6 +165,16 @@ g_data_output_stream_init (GDataOutputStream *stream)
   stream->priv->byte_order = G_DATA_STREAM_BYTE_ORDER_BIG_ENDIAN;
 }
 
+static void
+g_data_output_stream_seekable_iface_init (GSeekableIface *iface)
+{
+  iface->tell         = g_data_output_stream_tell;
+  iface->can_seek     = g_data_output_stream_can_seek;
+  iface->seek         = g_data_output_stream_seek;
+  iface->can_truncate = g_data_output_stream_can_truncate;
+  iface->truncate_fn  = g_data_output_stream_truncate;
+}
+
 /**
  * g_data_output_stream_new:
  * @base_stream: a #GOutputStream.
@@ -500,3 +528,77 @@ g_data_output_stream_put_string (GDataOutputStream  *stream,
 				    &bytes_written,
 				    cancellable, error);
 }
+
+static goffset
+g_data_output_stream_tell (GSeekable *seekable)
+{
+  GOutputStream *base_stream;
+  GSeekable *base_stream_seekable;
+
+  base_stream = G_FILTER_OUTPUT_STREAM (seekable)->base_stream;
+  if (!G_IS_SEEKABLE (base_stream))
+    return 0;
+  base_stream_seekable = G_SEEKABLE (base_stream);
+  return g_seekable_tell (base_stream_seekable);
+}
+
+static gboolean
+g_data_output_stream_can_seek (GSeekable *seekable)
+{
+  GOutputStream *base_stream;
+  
+  base_stream = G_FILTER_OUTPUT_STREAM (seekable)->base_stream;
+  return G_IS_SEEKABLE (base_stream) && g_seekable_can_seek (G_SEEKABLE (base_stream));
+}
+
+static gboolean
+g_data_output_stream_seek (GSeekable     *seekable,
+			   goffset        offset,
+			   GSeekType      type,
+			   GCancellable  *cancellable,
+			   GError       **error)
+{
+  GOutputStream *base_stream;
+  GSeekable *base_stream_seekable;
+
+  base_stream = G_FILTER_OUTPUT_STREAM (seekable)->base_stream;
+  if (!G_IS_SEEKABLE (base_stream))
+    {
+      g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
+                           _("Seek not supported on base stream"));
+      return FALSE;
+    }
+
+  base_stream_seekable = G_SEEKABLE (base_stream);
+  return g_seekable_seek (base_stream_seekable, offset, type, cancellable, error);
+}
+
+static gboolean
+g_data_output_stream_can_truncate (GSeekable *seekable)
+{
+  GOutputStream *base_stream;
+  
+  base_stream = G_FILTER_OUTPUT_STREAM (seekable)->base_stream;
+  return G_IS_SEEKABLE (base_stream) && g_seekable_can_truncate (G_SEEKABLE (base_stream));
+}
+
+static gboolean
+g_data_output_stream_truncate (GSeekable     *seekable,
+				   goffset        offset,
+				   GCancellable  *cancellable,
+				   GError       **error)
+{
+  GOutputStream *base_stream;
+  GSeekable *base_stream_seekable;
+
+  base_stream = G_FILTER_OUTPUT_STREAM (seekable)->base_stream;
+  if (!G_IS_SEEKABLE (base_stream))
+    {
+      g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
+                           _("Truncate not supported on base stream"));
+      return FALSE;
+    }
+
+  base_stream_seekable = G_SEEKABLE (base_stream);
+  return g_seekable_truncate (base_stream_seekable, offset, cancellable, error);
+}
diff --git a/gio/tests/data-output-stream.c b/gio/tests/data-output-stream.c
index a97201e60..f2ffd2396 100644
--- a/gio/tests/data-output-stream.c
+++ b/gio/tests/data-output-stream.c
@@ -298,6 +298,198 @@ test_read_int (void)
   g_free (buffer);
 }
 
+static void
+test_seek (void)
+{
+  GDataOutputStream *stream;
+  GMemoryOutputStream *base_stream;
+  GSeekable *seekable;
+  GError *error;
+  guchar *stream_data;
+  gsize len;
+  gboolean res;
+
+  len = 8;
+  
+  /*  create objects */
+  stream_data = g_malloc0 (len);
+  base_stream = G_MEMORY_OUTPUT_STREAM (g_memory_output_stream_new (stream_data, len, NULL, NULL));
+  stream = g_data_output_stream_new (G_OUTPUT_STREAM (base_stream));
+  g_data_output_stream_set_byte_order (stream, G_DATA_STREAM_BYTE_ORDER_BIG_ENDIAN);
+  seekable = G_SEEKABLE (stream);
+  g_assert (!g_seekable_can_truncate (seekable));
+  error = NULL;
+  
+  /* Write */
+  g_assert_cmpint (g_seekable_tell (seekable), ==, 0);
+  res = g_data_output_stream_put_uint16 (stream, 0x0123, NULL, &error);
+  g_assert_no_error (error);
+  g_assert (res);
+  g_data_output_stream_put_uint16 (stream, 0x4567, NULL, NULL);
+  g_assert_cmpint (g_seekable_tell (seekable), ==, 4);
+  g_assert_cmpint (stream_data[0], ==, 0x01);
+  g_assert_cmpint (stream_data[1], ==, 0x23);
+  g_assert_cmpint (stream_data[2], ==, 0x45);
+  g_assert_cmpint (stream_data[3], ==, 0x67);
+  g_assert_cmpint (g_memory_output_stream_get_data_size (base_stream), ==, 4);
+
+  /* Forward relative seek */
+  res = g_seekable_seek (seekable, 2, G_SEEK_CUR, NULL, &error);
+  g_assert_no_error (error);
+  g_assert (res);
+  g_assert_cmpint (g_seekable_tell (seekable), ==, 6);
+  g_assert_cmpint (g_memory_output_stream_get_data_size (base_stream), ==, 4);
+  res = g_data_output_stream_put_uint16 (stream, 0x89AB, NULL, &error);
+  g_assert (res);
+  g_assert_cmpint (g_seekable_tell (seekable), ==, 8);
+  g_assert_cmpint (g_memory_output_stream_get_data_size (base_stream), ==, 8);
+  g_assert_cmpint (stream_data[0], ==, 0x01);
+  g_assert_cmpint (stream_data[1], ==, 0x23);
+  g_assert_cmpint (stream_data[2], ==, 0x45);
+  g_assert_cmpint (stream_data[3], ==, 0x67);
+  g_assert_cmpint (stream_data[4], ==, 0x00);
+  g_assert_cmpint (stream_data[5], ==, 0x00);
+  g_assert_cmpint (stream_data[6], ==, 0x89);
+  g_assert_cmpint (stream_data[7], ==, 0xAB);
+
+  /* Backward relative seek */
+  res = g_seekable_seek (seekable, -3, G_SEEK_CUR, NULL, &error);
+  g_assert_no_error (error);
+  g_assert (res);
+  g_assert_cmpint (g_seekable_tell (seekable), ==, 5);
+  g_assert_cmpint (g_memory_output_stream_get_data_size (base_stream), ==, 8);
+  res = g_data_output_stream_put_uint16 (stream, 0xCDEF, NULL, &error);
+  g_assert_no_error (error);
+  g_assert (res);
+  g_assert_cmpint (g_seekable_tell (seekable), ==, 7);
+  g_assert_cmpint (g_memory_output_stream_get_data_size (base_stream), ==, 8);
+  g_assert_cmpint (stream_data[0], ==, 0x01);
+  g_assert_cmpint (stream_data[1], ==, 0x23);
+  g_assert_cmpint (stream_data[2], ==, 0x45);
+  g_assert_cmpint (stream_data[3], ==, 0x67);
+  g_assert_cmpint (stream_data[4], ==, 0x00);
+  g_assert_cmpint (stream_data[5], ==, 0xCD);
+  g_assert_cmpint (stream_data[6], ==, 0xEF);
+  g_assert_cmpint (stream_data[7], ==, 0xAB);
+
+  /* From start */
+  res = g_seekable_seek (seekable, 4, G_SEEK_SET, NULL, &error);
+  g_assert_no_error (error);
+  g_assert (res);
+  g_assert_cmpint (g_seekable_tell (seekable), ==, 4);
+  g_assert_cmpint (g_memory_output_stream_get_data_size (base_stream), ==, 8);
+  res = g_data_output_stream_put_uint16 (stream, 0xFEDC, NULL, &error);
+  g_assert_no_error (error);
+  g_assert (res);
+  g_assert_cmpint (g_seekable_tell (seekable), ==, 6);
+  g_assert_cmpint (g_memory_output_stream_get_data_size (base_stream), ==, 8);
+  g_assert_cmpint (stream_data[0], ==, 0x01);
+  g_assert_cmpint (stream_data[1], ==, 0x23);
+  g_assert_cmpint (stream_data[2], ==, 0x45);
+  g_assert_cmpint (stream_data[3], ==, 0x67);
+  g_assert_cmpint (stream_data[4], ==, 0xFE);
+  g_assert_cmpint (stream_data[5], ==, 0xDC);
+  g_assert_cmpint (stream_data[6], ==, 0xEF);
+  g_assert_cmpint (stream_data[7], ==, 0xAB);
+
+  /* From end */
+  res = g_seekable_seek (seekable, -4, G_SEEK_END, NULL, &error);
+  g_assert_no_error (error);
+  g_assert (res);
+  g_assert_cmpint (g_seekable_tell (seekable), ==, 4);
+  g_assert_cmpint (g_memory_output_stream_get_data_size (base_stream), ==, 8);
+  res = g_data_output_stream_put_uint16 (stream, 0xBA87, NULL, &error);
+  g_assert_no_error (error);
+  g_assert (res);
+  g_assert_cmpint (g_seekable_tell (seekable), ==, 6);
+  g_assert_cmpint (g_memory_output_stream_get_data_size (base_stream), ==, 8);
+  g_assert_cmpint (stream_data[0], ==, 0x01);
+  g_assert_cmpint (stream_data[1], ==, 0x23);
+  g_assert_cmpint (stream_data[2], ==, 0x45);
+  g_assert_cmpint (stream_data[3], ==, 0x67);
+  g_assert_cmpint (stream_data[4], ==, 0xBA);
+  g_assert_cmpint (stream_data[5], ==, 0x87);
+  g_assert_cmpint (stream_data[6], ==, 0xEF);
+  g_assert_cmpint (stream_data[7], ==, 0xAB);
+
+  g_object_unref (stream);
+  g_object_unref (base_stream);
+  g_free (stream_data);
+}
+
+static void
+test_truncate (void)
+{
+  GDataOutputStream *stream;
+  GMemoryOutputStream *base_stream;
+  GSeekable *seekable;
+  GError *error;
+  guchar *stream_data;
+  gsize len;
+  gboolean res;
+
+  len = 8;
+
+  /* Create objects */
+  stream_data = g_malloc0 (len);
+  base_stream = G_MEMORY_OUTPUT_STREAM (g_memory_output_stream_new (stream_data, len, g_realloc, g_free));
+  stream = g_data_output_stream_new (G_OUTPUT_STREAM (base_stream));
+  g_data_output_stream_set_byte_order (stream, G_DATA_STREAM_BYTE_ORDER_BIG_ENDIAN);
+  seekable = G_SEEKABLE (stream);
+  error = NULL;
+  g_assert (g_seekable_can_truncate (seekable));
+  
+  /* Write */
+  g_assert_cmpint (g_memory_output_stream_get_size (base_stream), ==, len);
+  g_assert_cmpint (g_memory_output_stream_get_data_size (base_stream), ==, 0);
+  res = g_data_output_stream_put_uint16 (stream, 0x0123, NULL, &error);
+  g_assert_no_error (error);
+  g_assert (res);
+  res = g_data_output_stream_put_uint16 (stream, 0x4567, NULL, NULL);
+  g_assert_no_error (error);
+  g_assert (res);
+  g_assert_cmpint (g_memory_output_stream_get_size (base_stream), ==, len);
+  g_assert_cmpint (g_memory_output_stream_get_data_size (base_stream), ==, 4);
+  g_assert_cmpint (stream_data[0], ==, 0x01);
+  g_assert_cmpint (stream_data[1], ==, 0x23);
+  g_assert_cmpint (stream_data[2], ==, 0x45);
+  g_assert_cmpint (stream_data[3], ==, 0x67);
+
+  /* Truncate at position */
+  res = g_seekable_truncate (seekable, 4, NULL, &error);
+  g_assert_no_error (error);
+  g_assert (res);
+  g_assert_cmpint (g_memory_output_stream_get_size (base_stream), ==, 4);
+  g_assert_cmpint (g_memory_output_stream_get_data_size (base_stream), ==, 4);
+  g_assert_cmpint (stream_data[0], ==, 0x01);
+  g_assert_cmpint (stream_data[1], ==, 0x23);
+  g_assert_cmpint (stream_data[2], ==, 0x45);
+  g_assert_cmpint (stream_data[3], ==, 0x67);
+
+  /* Truncate beyond position */
+  res = g_seekable_truncate (seekable, 6, NULL, &error);
+  g_assert_no_error (error);
+  g_assert (res);
+  g_assert_cmpint (g_memory_output_stream_get_size (base_stream), ==, 6);
+  g_assert_cmpint (g_memory_output_stream_get_data_size (base_stream), ==, 4);
+  g_assert_cmpint (stream_data[0], ==, 0x01);
+  g_assert_cmpint (stream_data[1], ==, 0x23);
+  g_assert_cmpint (stream_data[2], ==, 0x45);
+  g_assert_cmpint (stream_data[3], ==, 0x67);
+
+  /* Truncate before position */
+  res = g_seekable_truncate (seekable, 2, NULL, &error);
+  g_assert_no_error (error);
+  g_assert (res);
+  g_assert_cmpint (g_memory_output_stream_get_size (base_stream), ==, 2);
+  g_assert_cmpint (g_memory_output_stream_get_data_size (base_stream), ==, 2);
+  g_assert_cmpint (stream_data[0], ==, 0x01);
+  g_assert_cmpint (stream_data[1], ==, 0x23);
+
+  g_object_unref (stream);
+  g_object_unref (base_stream);
+}
+
 int
 main (int   argc,
       char *argv[])
@@ -310,6 +502,8 @@ main (int   argc,
   g_test_add_func ("/data-output-stream/write-lines-CR", test_read_lines_CR);
   g_test_add_func ("/data-output-stream/write-lines-CR-LF", test_read_lines_CR_LF);
   g_test_add_func ("/data-output-stream/write-int", test_read_int);
+  g_test_add_func ("/data-output-stream/seek", test_seek);
+  g_test_add_func ("/data-output-stream/truncate", test_truncate);
 
   return g_test_run();
 }