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1 office 1 /* GIO - GLib Input, Output and Streaming Library
2 *
3 * Copyright (C) 2006-2007 Red Hat, Inc.
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
14 *
15 * You should have received a copy of the GNU Lesser General
16 * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
17 *
18 * Author: Alexander Larsson <alexl@redhat.com>
19 */
20  
21 #include "config.h"
22  
23 #include <glib.h>
24 #include <gfileoutputstream.h>
25 #include <gseekable.h>
26 #include "gasyncresult.h"
27 #include "gtask.h"
28 #include "gcancellable.h"
29 #include "gioerror.h"
30 #include "glibintl.h"
31  
32  
33 /**
34 * SECTION:gfileoutputstream
35 * @short_description: File output streaming operations
36 * @include: gio/gio.h
37 * @see_also: #GOutputStream, #GDataOutputStream, #GSeekable
38 *
39 * GFileOutputStream provides output streams that write their
40 * content to a file.
41 *
42 * GFileOutputStream implements #GSeekable, which allows the output
43 * stream to jump to arbitrary positions in the file and to truncate
44 * the file, provided the filesystem of the file supports these
45 * operations.
46 *
47 * To find the position of a file output stream, use g_seekable_tell().
48 * To find out if a file output stream supports seeking, use
49 * g_seekable_can_seek().To position a file output stream, use
50 * g_seekable_seek(). To find out if a file output stream supports
51 * truncating, use g_seekable_can_truncate(). To truncate a file output
52 * stream, use g_seekable_truncate().
53 **/
54  
55 static void g_file_output_stream_seekable_iface_init (GSeekableIface *iface);
56 static goffset g_file_output_stream_seekable_tell (GSeekable *seekable);
57 static gboolean g_file_output_stream_seekable_can_seek (GSeekable *seekable);
58 static gboolean g_file_output_stream_seekable_seek (GSeekable *seekable,
59 goffset offset,
60 GSeekType type,
61 GCancellable *cancellable,
62 GError **error);
63 static gboolean g_file_output_stream_seekable_can_truncate (GSeekable *seekable);
64 static gboolean g_file_output_stream_seekable_truncate (GSeekable *seekable,
65 goffset offset,
66 GCancellable *cancellable,
67 GError **error);
68 static void g_file_output_stream_real_query_info_async (GFileOutputStream *stream,
69 const char *attributes,
70 int io_priority,
71 GCancellable *cancellable,
72 GAsyncReadyCallback callback,
73 gpointer user_data);
74 static GFileInfo *g_file_output_stream_real_query_info_finish (GFileOutputStream *stream,
75 GAsyncResult *result,
76 GError **error);
77  
78 struct _GFileOutputStreamPrivate {
79 GAsyncReadyCallback outstanding_callback;
80 };
81  
82 G_DEFINE_TYPE_WITH_CODE (GFileOutputStream, g_file_output_stream, G_TYPE_OUTPUT_STREAM,
83 G_ADD_PRIVATE (GFileOutputStream)
84 G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
85 g_file_output_stream_seekable_iface_init));
86  
87 static void
88 g_file_output_stream_class_init (GFileOutputStreamClass *klass)
89 {
90 klass->query_info_async = g_file_output_stream_real_query_info_async;
91 klass->query_info_finish = g_file_output_stream_real_query_info_finish;
92 }
93  
94 static void
95 g_file_output_stream_seekable_iface_init (GSeekableIface *iface)
96 {
97 iface->tell = g_file_output_stream_seekable_tell;
98 iface->can_seek = g_file_output_stream_seekable_can_seek;
99 iface->seek = g_file_output_stream_seekable_seek;
100 iface->can_truncate = g_file_output_stream_seekable_can_truncate;
101 iface->truncate_fn = g_file_output_stream_seekable_truncate;
102 }
103  
104 static void
105 g_file_output_stream_init (GFileOutputStream *stream)
106 {
107 stream->priv = g_file_output_stream_get_instance_private (stream);
108 }
109  
110 /**
111 * g_file_output_stream_query_info:
112 * @stream: a #GFileOutputStream.
113 * @attributes: a file attribute query string.
114 * @cancellable: optional #GCancellable object, %NULL to ignore.
115 * @error: a #GError, %NULL to ignore.
116 *
117 * Queries a file output stream for the given @attributes.
118 * This function blocks while querying the stream. For the asynchronous
119 * version of this function, see g_file_output_stream_query_info_async().
120 * While the stream is blocked, the stream will set the pending flag
121 * internally, and any other operations on the stream will fail with
122 * %G_IO_ERROR_PENDING.
123 *
124 * Can fail if the stream was already closed (with @error being set to
125 * %G_IO_ERROR_CLOSED), the stream has pending operations (with @error being
126 * set to %G_IO_ERROR_PENDING), or if querying info is not supported for
127 * the stream's interface (with @error being set to %G_IO_ERROR_NOT_SUPPORTED). In
128 * all cases of failure, %NULL will be returned.
129 *
130 * If @cancellable is not %NULL, then the operation can be cancelled by
131 * triggering the cancellable object from another thread. If the operation
132 * was cancelled, the error %G_IO_ERROR_CANCELLED will be set, and %NULL will
133 * be returned.
134 *
135 * Returns: (transfer full): a #GFileInfo for the @stream, or %NULL on error.
136 **/
137 GFileInfo *
138 g_file_output_stream_query_info (GFileOutputStream *stream,
139 const char *attributes,
140 GCancellable *cancellable,
141 GError **error)
142 {
143 GFileOutputStreamClass *class;
144 GOutputStream *output_stream;
145 GFileInfo *info;
146  
147 g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
148  
149 output_stream = G_OUTPUT_STREAM (stream);
150  
151 if (!g_output_stream_set_pending (output_stream, error))
152 return NULL;
153  
154 info = NULL;
155  
156 if (cancellable)
157 g_cancellable_push_current (cancellable);
158  
159 class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
160 if (class->query_info)
161 info = class->query_info (stream, attributes, cancellable, error);
162 else
163 g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
164 _("Stream doesn't support query_info"));
165  
166 if (cancellable)
167 g_cancellable_pop_current (cancellable);
168  
169 g_output_stream_clear_pending (output_stream);
170  
171 return info;
172 }
173  
174 static void
175 async_ready_callback_wrapper (GObject *source_object,
176 GAsyncResult *res,
177 gpointer user_data)
178 {
179 GFileOutputStream *stream = G_FILE_OUTPUT_STREAM (source_object);
180  
181 g_output_stream_clear_pending (G_OUTPUT_STREAM (stream));
182 if (stream->priv->outstanding_callback)
183 (*stream->priv->outstanding_callback) (source_object, res, user_data);
184 g_object_unref (stream);
185 }
186  
187 /**
188 * g_file_output_stream_query_info_async:
189 * @stream: a #GFileOutputStream.
190 * @attributes: a file attribute query string.
191 * @io_priority: the [I/O priority][gio-GIOScheduler] of the request
192 * @cancellable: optional #GCancellable object, %NULL to ignore.
193 * @callback: callback to call when the request is satisfied
194 * @user_data: the data to pass to callback function
195 *
196 * Asynchronously queries the @stream for a #GFileInfo. When completed,
197 * @callback will be called with a #GAsyncResult which can be used to
198 * finish the operation with g_file_output_stream_query_info_finish().
199 *
200 * For the synchronous version of this function, see
201 * g_file_output_stream_query_info().
202 *
203 **/
204 void
205 g_file_output_stream_query_info_async (GFileOutputStream *stream,
206 const char *attributes,
207 int io_priority,
208 GCancellable *cancellable,
209 GAsyncReadyCallback callback,
210 gpointer user_data)
211 {
212 GFileOutputStreamClass *klass;
213 GOutputStream *output_stream;
214 GError *error = NULL;
215  
216 g_return_if_fail (G_IS_FILE_OUTPUT_STREAM (stream));
217  
218 output_stream = G_OUTPUT_STREAM (stream);
219  
220 if (!g_output_stream_set_pending (output_stream, &error))
221 {
222 g_task_report_error (stream, callback, user_data,
223 g_file_output_stream_query_info_async,
224 error);
225 return;
226 }
227  
228 klass = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
229  
230 stream->priv->outstanding_callback = callback;
231 g_object_ref (stream);
232 klass->query_info_async (stream, attributes, io_priority, cancellable,
233 async_ready_callback_wrapper, user_data);
234 }
235  
236 /**
237 * g_file_output_stream_query_info_finish:
238 * @stream: a #GFileOutputStream.
239 * @result: a #GAsyncResult.
240 * @error: a #GError, %NULL to ignore.
241 *
242 * Finalizes the asynchronous query started
243 * by g_file_output_stream_query_info_async().
244 *
245 * Returns: (transfer full): A #GFileInfo for the finished query.
246 **/
247 GFileInfo *
248 g_file_output_stream_query_info_finish (GFileOutputStream *stream,
249 GAsyncResult *result,
250 GError **error)
251 {
252 GFileOutputStreamClass *class;
253  
254 g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
255 g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
256  
257 if (g_async_result_legacy_propagate_error (result, error))
258 return NULL;
259 else if (g_async_result_is_tagged (result, g_file_output_stream_query_info_async))
260 return g_task_propagate_pointer (G_TASK (result), error);
261  
262 class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
263 return class->query_info_finish (stream, result, error);
264 }
265  
266 /**
267 * g_file_output_stream_get_etag:
268 * @stream: a #GFileOutputStream.
269 *
270 * Gets the entity tag for the file when it has been written.
271 * This must be called after the stream has been written
272 * and closed, as the etag can change while writing.
273 *
274 * Returns: the entity tag for the stream.
275 **/
276 char *
277 g_file_output_stream_get_etag (GFileOutputStream *stream)
278 {
279 GFileOutputStreamClass *class;
280 GOutputStream *output_stream;
281 char *etag;
282  
283 g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
284  
285 output_stream = G_OUTPUT_STREAM (stream);
286  
287 if (!g_output_stream_is_closed (output_stream))
288 {
289 g_warning ("stream is not closed yet, can't get etag");
290 return NULL;
291 }
292  
293 etag = NULL;
294  
295 class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
296 if (class->get_etag)
297 etag = class->get_etag (stream);
298  
299 return etag;
300 }
301  
302 static goffset
303 g_file_output_stream_tell (GFileOutputStream *stream)
304 {
305 GFileOutputStreamClass *class;
306 goffset offset;
307  
308 g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), 0);
309  
310 class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
311  
312 offset = 0;
313 if (class->tell)
314 offset = class->tell (stream);
315  
316 return offset;
317 }
318  
319 static goffset
320 g_file_output_stream_seekable_tell (GSeekable *seekable)
321 {
322 return g_file_output_stream_tell (G_FILE_OUTPUT_STREAM (seekable));
323 }
324  
325 static gboolean
326 g_file_output_stream_can_seek (GFileOutputStream *stream)
327 {
328 GFileOutputStreamClass *class;
329 gboolean can_seek;
330  
331 g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
332  
333 class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
334  
335 can_seek = FALSE;
336 if (class->seek)
337 {
338 can_seek = TRUE;
339 if (class->can_seek)
340 can_seek = class->can_seek (stream);
341 }
342  
343 return can_seek;
344 }
345  
346 static gboolean
347 g_file_output_stream_seekable_can_seek (GSeekable *seekable)
348 {
349 return g_file_output_stream_can_seek (G_FILE_OUTPUT_STREAM (seekable));
350 }
351  
352 static gboolean
353 g_file_output_stream_seek (GFileOutputStream *stream,
354 goffset offset,
355 GSeekType type,
356 GCancellable *cancellable,
357 GError **error)
358 {
359 GFileOutputStreamClass *class;
360 GOutputStream *output_stream;
361 gboolean res;
362  
363 g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
364  
365 output_stream = G_OUTPUT_STREAM (stream);
366 class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
367  
368 if (!class->seek)
369 {
370 g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
371 _("Seek not supported on stream"));
372 return FALSE;
373 }
374  
375 if (!g_output_stream_set_pending (output_stream, error))
376 return FALSE;
377  
378 if (cancellable)
379 g_cancellable_push_current (cancellable);
380  
381 res = class->seek (stream, offset, type, cancellable, error);
382  
383 if (cancellable)
384 g_cancellable_pop_current (cancellable);
385  
386 g_output_stream_clear_pending (output_stream);
387  
388 return res;
389 }
390  
391 static gboolean
392 g_file_output_stream_seekable_seek (GSeekable *seekable,
393 goffset offset,
394 GSeekType type,
395 GCancellable *cancellable,
396 GError **error)
397 {
398 return g_file_output_stream_seek (G_FILE_OUTPUT_STREAM (seekable),
399 offset, type, cancellable, error);
400 }
401  
402 static gboolean
403 g_file_output_stream_can_truncate (GFileOutputStream *stream)
404 {
405 GFileOutputStreamClass *class;
406 gboolean can_truncate;
407  
408 g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
409  
410 class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
411  
412 can_truncate = FALSE;
413 if (class->truncate_fn)
414 {
415 can_truncate = TRUE;
416 if (class->can_truncate)
417 can_truncate = class->can_truncate (stream);
418 }
419  
420 return can_truncate;
421 }
422  
423 static gboolean
424 g_file_output_stream_seekable_can_truncate (GSeekable *seekable)
425 {
426 return g_file_output_stream_can_truncate (G_FILE_OUTPUT_STREAM (seekable));
427 }
428  
429 static gboolean
430 g_file_output_stream_truncate (GFileOutputStream *stream,
431 goffset size,
432 GCancellable *cancellable,
433 GError **error)
434 {
435 GFileOutputStreamClass *class;
436 GOutputStream *output_stream;
437 gboolean res;
438  
439 g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
440  
441 output_stream = G_OUTPUT_STREAM (stream);
442 class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
443  
444 if (!class->truncate_fn)
445 {
446 g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
447 _("Truncate not supported on stream"));
448 return FALSE;
449 }
450  
451 if (!g_output_stream_set_pending (output_stream, error))
452 return FALSE;
453  
454 if (cancellable)
455 g_cancellable_push_current (cancellable);
456  
457 res = class->truncate_fn (stream, size, cancellable, error);
458  
459 if (cancellable)
460 g_cancellable_pop_current (cancellable);
461  
462 g_output_stream_clear_pending (output_stream);
463  
464 return res;
465 }
466  
467 static gboolean
468 g_file_output_stream_seekable_truncate (GSeekable *seekable,
469 goffset size,
470 GCancellable *cancellable,
471 GError **error)
472 {
473 return g_file_output_stream_truncate (G_FILE_OUTPUT_STREAM (seekable),
474 size, cancellable, error);
475 }
476 /********************************************
477 * Default implementation of async ops *
478 ********************************************/
479  
480 static void
481 query_info_async_thread (GTask *task,
482 gpointer source_object,
483 gpointer task_data,
484 GCancellable *cancellable)
485 {
486 GFileOutputStream *stream = source_object;
487 const char *attributes = task_data;
488 GFileOutputStreamClass *class;
489 GError *error = NULL;
490 GFileInfo *info = NULL;
491  
492 class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
493 if (class->query_info)
494 info = class->query_info (stream, attributes, cancellable, &error);
495 else
496 g_set_error_literal (&error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
497 _("Stream doesn't support query_info"));
498  
499 if (info == NULL)
500 g_task_return_error (task, error);
501 else
502 g_task_return_pointer (task, info, g_object_unref);
503 }
504  
505 static void
506 g_file_output_stream_real_query_info_async (GFileOutputStream *stream,
507 const char *attributes,
508 int io_priority,
509 GCancellable *cancellable,
510 GAsyncReadyCallback callback,
511 gpointer user_data)
512 {
513 GTask *task;
514  
515 task = g_task_new (stream, cancellable, callback, user_data);
516 g_task_set_task_data (task, g_strdup (attributes), g_free);
517 g_task_set_priority (task, io_priority);
518  
519 g_task_run_in_thread (task, query_info_async_thread);
520 g_object_unref (task);
521 }
522  
523 static GFileInfo *
524 g_file_output_stream_real_query_info_finish (GFileOutputStream *stream,
525 GAsyncResult *res,
526 GError **error)
527 {
528 g_return_val_if_fail (g_task_is_valid (res, stream), NULL);
529  
530 return g_task_propagate_pointer (G_TASK (res), error);
531 }