C++ G_SEEKABLE函数代码示例

static gint64
xmms_gvfs_seek (xmms_xform_t *xform, gint64 offset,
                xmms_xform_seek_mode_t whence, xmms_error_t *error)
{
    GSeekType type;
    GError *err = NULL;
    xmms_gvfs_data_t *data = xmms_xform_private_data_get (xform);

    g_return_val_if_fail (data, -1);
    g_return_val_if_fail (!g_input_stream_is_closed (data->handle), -1);

    switch (whence) {
    case XMMS_XFORM_SEEK_CUR:
        type = G_SEEK_CUR;
        break;
    case XMMS_XFORM_SEEK_SET:
        type = G_SEEK_SET;
        break;
    case XMMS_XFORM_SEEK_END:
        type = G_SEEK_END;
        break;
    }

    if (g_seekable_seek (G_SEEKABLE (data->handle), offset, type, NULL, &err)) {
        return g_seekable_tell (G_SEEKABLE (data->handle));
    }

    xmms_error_set (error, XMMS_ERROR_GENERIC, err->message);
    return -1;
}

static gboolean
try_seek_on_read (GVfsBackend *backend,
                  GVfsJobSeekRead *job,
                  GVfsBackendHandle handle,
                  goffset    offset,
                  GSeekType  type)
{
  GInputStream    *stream;
  GError          *error = NULL;

  stream = G_INPUT_STREAM (handle);

  if (!g_seekable_seek (G_SEEKABLE (stream), offset, type,
                        G_VFS_JOB (job)->cancellable, &error))
    {
      g_vfs_job_failed_literal (G_VFS_JOB (job),
                                error->domain,
                                error->code,
                                error->message);
      g_error_free (error);
      return FALSE;
    }
  else
    {
      g_vfs_job_seek_read_set_offset (job, g_seekable_tell (G_SEEKABLE (stream)));
      g_vfs_job_succeeded (G_VFS_JOB (job));
    }

  return TRUE;
}

static void
extract_gibest_hash (GTask        *task,
                     gpointer      source_object,
                     gpointer      task_data,
                     GCancellable *cancellable)
{
  GFile *file = source_object;
  guint64 buffer[2][CHUNK_N_BYTES/8];
  GInputStream *stream = NULL;
  gssize n_bytes, file_size;
  GError *error = NULL;
  guint64 hash = 0;
  gint i;
  char *str;
  ResolveData *resolve_data = task_data;
  GrlLocalMetadataSourcePriv *priv;

  priv = GRL_LOCAL_METADATA_SOURCE_GET_PRIVATE (resolve_data->source);

  stream = G_INPUT_STREAM (g_file_read (file, cancellable, &error));
  if (stream == NULL)
    goto fail;

  /* Extract start/end chunks of the file */
  n_bytes = g_input_stream_read (stream, buffer[0], CHUNK_N_BYTES, cancellable, &error);
  if (n_bytes == -1)
    goto fail;

  if (!g_seekable_seek (G_SEEKABLE (stream), -CHUNK_N_BYTES, G_SEEK_END, cancellable, &error))
    goto fail;

  n_bytes = g_input_stream_read (stream, buffer[1], CHUNK_N_BYTES, cancellable, &error);
  if (n_bytes == -1)
    goto fail;

  for (i = 0; i < G_N_ELEMENTS (buffer[0]); i++)
    hash += buffer[0][i] + buffer[1][i];

  file_size = g_seekable_tell (G_SEEKABLE (stream));

  if (file_size < CHUNK_N_BYTES)
    goto fail;

  /* Include file size */
  hash += file_size;
  g_object_unref (stream);

  str = g_strdup_printf ("%" G_GINT64_FORMAT, hash);
  grl_data_set_string (GRL_DATA (resolve_data->rs->media), priv->hash_keyid, str);
  g_free (str);

  g_task_return_boolean (task, TRUE);
  return;

fail:
  GRL_DEBUG ("Could not get file hash: %s\n", error ? error->message : "Unknown error");
  g_task_return_error (task, error);
  g_clear_object (&stream);
}

static void
ddb_gvfs_rewind (DB_FILE *stream)
{
  vfs_gvfs_data_t *data = (vfs_gvfs_data_t *) stream;
  g_return_if_fail (data != NULL);

  if (g_seekable_can_seek (G_SEEKABLE (data->handle)))
    g_seekable_seek (G_SEEKABLE (data->handle), 0, G_SEEK_SET, NULL, NULL);
}

gint
test_message_compare (CamelMimeMessage *msg)
{
    CamelMimeMessage *msg2;
    CamelStream *stream1;
    CamelStream *stream2;
    GByteArray *byte_array1;
    GByteArray *byte_array2;

    byte_array1 = g_byte_array_new ();
    stream1 = camel_stream_mem_new_with_byte_array (byte_array1);
    check_msg (camel_data_wrapper_write_to_stream_sync (
                   CAMEL_DATA_WRAPPER (msg), stream1, NULL, NULL) != -1,
               "write_to_stream 1 failed", NULL);
    g_seekable_seek (G_SEEKABLE (stream1), 0, G_SEEK_SET, NULL, NULL);

    msg2 = camel_mime_message_new ();
    check_msg (camel_data_wrapper_construct_from_stream_sync (
                   CAMEL_DATA_WRAPPER (msg2), stream1, NULL, NULL) != -1,
               "construct_from_stream 1 failed");
    g_seekable_seek (G_SEEKABLE (stream1), 0, G_SEEK_SET, NULL, NULL);

    byte_array2 = g_byte_array_new ();
    stream2 = camel_stream_mem_new_with_byte_array (byte_array2);
    check_msg (camel_data_wrapper_write_to_stream_sync (
                   CAMEL_DATA_WRAPPER (msg2), stream2, NULL, NULL) != -1,
               "write_to_stream 2 failed");
    g_seekable_seek (G_SEEKABLE (stream2), 0, G_SEEK_SET, NULL, NULL);

    if (byte_array1->len != byte_array2->len) {
        CamelDataWrapper *content;

        printf ("stream1 stream:\n%.*s\n", byte_array1->len, byte_array1->data);
        printf ("stream2 stream:\n%.*s\n\n", byte_array2->len, byte_array2->data);

        printf ("msg1:\n");
        test_message_dump_structure (msg);
        printf ("msg2:\n");
        test_message_dump_structure (msg2);

        content = camel_medium_get_content ((CamelMedium *) msg);
    }

    check_unref (msg2, 1);

    check_msg (
        byte_array1->len == byte_array2->len,
        "byte_array1->len = %d, byte_array2->len = %d",
        byte_array1->len, byte_array2->len);

    check_msg (memcmp (byte_array1->data, byte_array2->data, byte_array1->len) == 0, "msg/stream compare");

    g_object_unref (stream1);
    g_object_unref (stream2);

    return 0;
}

/* Called from gpgme to seek a file */
static off_t
vfs_data_seek (void *handle, off_t offset, int whence)
{
    VfsAsyncHandle* ah = (VfsAsyncHandle*)handle;
    GSeekable *seekable = NULL;
    GSeekType wh;
    
    /* If the file isn't open yet, then do that now */
    if (!ah->ostream && !ah->istream && ah->state == VFS_ASYNC_READY)
        vfs_data_open_helper (ah);
        
    /* Just in case we have an operation, like open */
    if (!vfs_data_wait_results(ah, TRUE))
        return (off_t)-1;
           
    g_assert (ah->state == VFS_ASYNC_READY);
    
    if (ah->writer && G_IS_SEEKABLE (ah->ostream))
        seekable = G_SEEKABLE (ah->ostream);
    else
        seekable = G_SEEKABLE (ah->istream);
    
    if (!seekable || !g_seekable_can_seek (seekable)) {
        errno = ENOTSUP;
        return -1;
    }
    
    switch(whence)
    {
    case SEEK_SET:
        wh = G_SEEK_SET;
        break;
    case SEEK_CUR:
        wh = G_SEEK_CUR;
        break;
    case SEEK_END:
        wh = G_SEEK_END;
        break;
    default:
        g_assert_not_reached();
        break;
    }
    
    /* All seek operations are not async */
    g_clear_error (&ah->error);
    g_seekable_seek (seekable, (goffset)offset, wh, ah->cancellable, &ah->error);
    
    /* Start async operation */
    ah->state = VFS_ASYNC_READY;
    if (!vfs_data_wait_results (ah, TRUE))
        return -1;
    
    /* Return results */
    ah->state = VFS_ASYNC_READY;
    return offset;
}

static toff_t
seek_in_stream(thandle_t handle,
               toff_t offset,
               int whence)
{
  Priv *p = (Priv*) handle;
  GError *error = NULL;
  gboolean sought = FALSE;
  goffset position = -1;

  g_assert(p->stream);

  if (p->can_seek)
    {
      sought = g_seekable_seek(G_SEEKABLE(p->stream),
                               (goffset) offset, lseek_to_seek_type(whence),
                               NULL, &error);
      if (sought)
        position = g_seekable_tell(G_SEEKABLE(p->stream));
      else
        {
          g_warning("%s", error->message);
          g_error_free(error);
        }
    }
  else
    {
      switch (whence)
        {
        default:
        case SEEK_SET:
          if (offset <= p->allocated)
            position = p->position = offset;
          break;

        case SEEK_CUR:
          if (p->position + offset <= p->allocated)
            position = p->position += offset;
          break;

        case G_SEEK_END:
          position = p->position = p->allocated + offset;
          break;
        }
    }

  return (toff_t) position;
}

/**
 * seahorse_util_read_to_memory:
 * @input: Data to read. The #GInputStream is read till the end.
 * @len: Length of the data read (out)
 *
 * Reads data from the input stream and returns them as #guchar
 *
 * Returns: The string read from data. The returned string should be freed
 * with #g_free when no longer needed.
 **/
guchar*
seahorse_util_read_to_memory (GInputStream *input, guint *len)
{
	gsize size = 128;
	gchar *buffer, *text;
	gsize nread = 0;
	GString *string;
	GSeekable *seek;

	if (G_IS_SEEKABLE (input)) {
		seek = G_SEEKABLE (input);
		g_seekable_seek (seek, 0, SEEK_SET, NULL, NULL);
	}

	string = g_string_new ("");
	buffer = g_new (gchar, size);
    
	while (g_input_stream_read_all (input, buffer, size, &nread, NULL, NULL)) {
		string = g_string_append_len (string, buffer, nread);
		if (nread != size)
			break;
	}

	if (len)
		*len = string->len;
    
	text = g_string_free (string, FALSE);
	g_free (buffer);
	
	return (guchar*)text;
}

static void
cache_replace_ready_cb (GObject *source,
                        GAsyncResult *res,
                        gpointer user_data)
{
  GFileOutputStream *cache_stream;
  GError *error = NULL;
  NemoPreviewCoverArtFetcher *self = user_data;

  cache_stream = g_file_replace_finish (G_FILE (source),
                                        res, &error);

  if (error != NULL) {
    g_warning ("Can't save the cover art image in the cache: %s\n", error->message);
    g_error_free (error);

    return;
  }

  g_seekable_seek (G_SEEKABLE (self->priv->input_stream), 0, G_SEEK_SET,
                   NULL, NULL);

  g_output_stream_splice_async (G_OUTPUT_STREAM (cache_stream), 
                                self->priv->input_stream,
                                G_OUTPUT_STREAM_SPLICE_CLOSE_SOURCE |
                                G_OUTPUT_STREAM_SPLICE_CLOSE_TARGET,
                                G_PRIORITY_DEFAULT,
                                NULL,
                                cache_splice_ready_cb, self);

  g_object_unref (cache_stream);
}

static gboolean
gegl_tile_backend_file_write_header (GeglTileBackendFile *self)
{
  gboolean success;

  gegl_tile_backend_file_ensure_exist (self);

#if HAVE_GIO
  success = g_seekable_seek (G_SEEKABLE (self->o), 0, G_SEEK_SET,
                             NULL, NULL);
#else
  success = (lseek (self->o, 0, SEEK_SET) != -1);
#endif
  if (success == FALSE)
    {
      g_warning ("unable to seek in buffer");
      return FALSE;
    }
#if HAVE_GIO
  g_output_stream_write (self->o, &(self->header), 256, NULL, NULL);
#else
  write (self->o, &(self->header), 256);
#endif
  GEGL_NOTE (GEGL_DEBUG_TILE_BACKEND, "Wrote header, next=%i", (gint)self->header.next);
  return TRUE;
}

static gboolean
gimp_curves_tool_settings_import (GimpImageMapTool  *image_map_tool,
                                  GInputStream      *input,
                                  GError           **error)
{
  GimpCurvesTool *tool = GIMP_CURVES_TOOL (image_map_tool);
  gchar           header[64];
  gsize           bytes_read;

  if (! g_input_stream_read_all (input, header, sizeof (header),
                                 &bytes_read, NULL, error) ||
      bytes_read != sizeof (header))
    {
      g_prefix_error (error, _("Could not read header: "));
      return FALSE;
    }

  g_seekable_seek (G_SEEKABLE (input), 0, G_SEEK_SET, NULL, NULL);

  if (g_str_has_prefix (header, "# GIMP Curves File\n"))
    return gimp_curves_config_load_cruft (tool->config, input, error);

  return GIMP_IMAGE_MAP_TOOL_CLASS (parent_class)->settings_import (image_map_tool,
                                                                    input,
                                                                    error);
}

/*
 * et_ogg_tell_func:
 * @datasource: the Ogg parser state
 *
 * Tell the current position of the stream from the beginning of the Ogg file.
 *
 * Returns: the current position in the Ogg file
 */
static long
et_ogg_tell_func (void *datasource)
{
    EtOggState *state = (EtOggState *)datasource;

    return g_seekable_tell (G_SEEKABLE (state->istream));
}

static gboolean
gst_gio_base_sink_event (GstBaseSink * base_sink, GstEvent * event)
{
  GstGioBaseSink *sink = GST_GIO_BASE_SINK (base_sink);
  GstFlowReturn ret = GST_FLOW_OK;

  if (sink->stream == NULL)
    return TRUE;

  switch (GST_EVENT_TYPE (event)) {
    case GST_EVENT_SEGMENT:
      if (G_IS_OUTPUT_STREAM (sink->stream)) {
        const GstSegment *segment;

        gst_event_parse_segment (event, &segment);

        if (segment->format != GST_FORMAT_BYTES) {
          GST_WARNING_OBJECT (sink, "ignored SEGMENT event in %s format",
              gst_format_get_name (segment->format));
          break;
        }

        if (GST_GIO_STREAM_IS_SEEKABLE (sink->stream)) {
          ret = gst_gio_seek (sink, G_SEEKABLE (sink->stream), segment->start,
              sink->cancel);
          if (ret == GST_FLOW_OK)
            sink->position = segment->start;
        } else {
          ret = GST_FLOW_NOT_SUPPORTED;
        }
      }
      break;

    case GST_EVENT_EOS:
    case GST_EVENT_FLUSH_START:
      if (G_IS_OUTPUT_STREAM (sink->stream)) {
        gboolean success;
        GError *err = NULL;

        success = g_output_stream_flush (sink->stream, sink->cancel, &err);

        if (!success && !gst_gio_error (sink, "g_output_stream_flush", &err,
                &ret)) {
          GST_ELEMENT_ERROR (sink, RESOURCE, WRITE, (NULL),
              ("flush failed: %s", err->message));
          g_clear_error (&err);
        }
      }
      break;

    default:
      break;
  }
  if (ret == GST_FLOW_OK)
    return GST_BASE_SINK_CLASS (parent_class)->event (base_sink, event);
  else {
    gst_event_unref (event);
    return FALSE;
  }
}

static void on_file_read_ready (GObject * object, GAsyncResult * res, gpointer data)
{
	GError *error = NULL;
	GDownloadable *download = G_DOWNLOADABLE (data);
	GioDownload   *gio_download = GIO_DOWNLOAD (data);
	g_assert (download != NULL);
	
	gio_download->priv->input = g_file_read_finish (G_FILE(object), res, &error); 
	handle_critical_error (error);
	
	if (gio_download->priv->input == NULL) {
		// TODO: Error details
		g_downloadable_set_status (download, G_DOWNLOADABLE_NETWORK_ERROR);
	} else {
		if (g_seekable_can_seek(G_SEEKABLE(gio_download->priv->input))
			&& g_file_query_exists (download->priv->local_file, NULL)) {
			//g_message ("appeding file ...\n");
			g_file_append_to_async (download->priv->local_file, 0,G_PRIORITY_DEFAULT,
									NULL, on_file_append_to_ready, download); 
		} else {
			//g_message ("replacing file ...\n");
			g_file_replace_async (download->priv->local_file, NULL, FALSE, 0, G_PRIORITY_DEFAULT,
								  NULL, on_file_replace_ready,  download);
		}
		g_downloadable_set_status (download, G_DOWNLOADABLE_DOWNLOADING);
	}
}

static gboolean
gst_gio_base_src_start (GstBaseSrc * base_src)
{
  GstGioBaseSrc *src = GST_GIO_BASE_SRC (base_src);
  GstGioBaseSrcClass *gbsrc_class = GST_GIO_BASE_SRC_GET_CLASS (src);

  src->position = 0;

  /* FIXME: This will likely block */
  src->stream = gbsrc_class->get_stream (src);
  if (G_UNLIKELY (!G_IS_INPUT_STREAM (src->stream))) {
    GST_ELEMENT_ERROR (src, RESOURCE, OPEN_READ, (NULL),
        ("No input stream provided by subclass"));
    return FALSE;
  } else if (G_UNLIKELY (g_input_stream_is_closed (src->stream))) {
    GST_ELEMENT_ERROR (src, LIBRARY, FAILED, (NULL),
        ("Input stream is already closed"));
    return FALSE;
  }

  if (G_IS_SEEKABLE (src->stream))
    src->position = g_seekable_tell (G_SEEKABLE (src->stream));

  GST_DEBUG_OBJECT (src, "started source");

  return TRUE;
}