1 /* GIO - GLib Input, Output and Streaming Library
2 *
3 * Copyright (C) 2006-2007 Red Hat, Inc.
4 *
5 * SPDX-License-Identifier: LGPL-2.1-or-later
6 *
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General
18 * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
19 *
20 * Author: Alexander Larsson <alexl@redhat.com>
21 */
22
23 #include "config.h"
24
25 #include <glib.h>
26 #include <gfileoutputstream.h>
27 #include <gseekable.h>
28 #include "gasyncresult.h"
29 #include "gtask.h"
30 #include "gcancellable.h"
31 #include "gioerror.h"
32 #include "glibintl.h"
33
34
35 /**
36 * GFileOutputStream:
37 *
38 * `GFileOutputStream` provides output streams that write their
39 * content to a file.
40 *
41 * `GFileOutputStream` implements [iface@Gio.Seekable], which allows the output
42 * stream to jump to arbitrary positions in the file and to truncate
43 * the file, provided the filesystem of the file supports these
44 * operations.
45 *
46 * To find the position of a file output stream, use [method@Gio.Seekable.tell].
47 * To find out if a file output stream supports seeking, use
48 * [method@Gio.Seekable.can_seek].To position a file output stream, use
49 * [method@Gio.Seekable.seek]. To find out if a file output stream supports
50 * truncating, use [method@Gio.Seekable.can_truncate]. To truncate a file output
51 * stream, use [method@Gio.Seekable.truncate].
52 **/
53
54 static void g_file_output_stream_seekable_iface_init (GSeekableIface *iface);
55 static goffset g_file_output_stream_seekable_tell (GSeekable *seekable);
56 static gboolean g_file_output_stream_seekable_can_seek (GSeekable *seekable);
57 static gboolean g_file_output_stream_seekable_seek (GSeekable *seekable,
58 goffset offset,
59 GSeekType type,
60 GCancellable *cancellable,
61 GError **error);
62 static gboolean g_file_output_stream_seekable_can_truncate (GSeekable *seekable);
63 static gboolean g_file_output_stream_seekable_truncate (GSeekable *seekable,
64 goffset offset,
65 GCancellable *cancellable,
66 GError **error);
67 static void g_file_output_stream_real_query_info_async (GFileOutputStream *stream,
68 const char *attributes,
69 int io_priority,
70 GCancellable *cancellable,
71 GAsyncReadyCallback callback,
72 gpointer user_data);
73 static GFileInfo *g_file_output_stream_real_query_info_finish (GFileOutputStream *stream,
74 GAsyncResult *result,
75 GError **error);
76
77 struct _GFileOutputStreamPrivate {
78 GAsyncReadyCallback outstanding_callback;
79 };
80
81 G_DEFINE_TYPE_WITH_CODE (GFileOutputStream, g_file_output_stream, G_TYPE_OUTPUT_STREAM,
82 G_ADD_PRIVATE (GFileOutputStream)
83 G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
84 g_file_output_stream_seekable_iface_init));
85
86 static void
87 g_file_output_stream_class_init (GFileOutputStreamClass *klass)
88 {
89 klass->query_info_async = g_file_output_stream_real_query_info_async;
90 klass->query_info_finish = g_file_output_stream_real_query_info_finish;
91 }
92
93 static void
94 g_file_output_stream_seekable_iface_init (GSeekableIface *iface)
95 {
96 iface->tell = g_file_output_stream_seekable_tell;
97 iface->can_seek = g_file_output_stream_seekable_can_seek;
98 iface->seek = g_file_output_stream_seekable_seek;
99 iface->can_truncate = g_file_output_stream_seekable_can_truncate;
100 iface->truncate_fn = g_file_output_stream_seekable_truncate;
101 }
102
103 static void
104 g_file_output_stream_init (GFileOutputStream *stream)
105 {
106 stream->priv = g_file_output_stream_get_instance_private (stream);
107 }
108
109 /**
110 * g_file_output_stream_query_info:
111 * @stream: a #GFileOutputStream.
112 * @attributes: a file attribute query string.
113 * @cancellable: optional #GCancellable object, %NULL to ignore.
114 * @error: a #GError, %NULL to ignore.
115 *
116 * Queries a file output stream for the given @attributes.
117 * This function blocks while querying the stream. For the asynchronous
118 * version of this function, see g_file_output_stream_query_info_async().
119 * While the stream is blocked, the stream will set the pending flag
120 * internally, and any other operations on the stream will fail with
121 * %G_IO_ERROR_PENDING.
122 *
123 * Can fail if the stream was already closed (with @error being set to
124 * %G_IO_ERROR_CLOSED), the stream has pending operations (with @error being
125 * set to %G_IO_ERROR_PENDING), or if querying info is not supported for
126 * the stream's interface (with @error being set to %G_IO_ERROR_NOT_SUPPORTED). In
127 * all cases of failure, %NULL will be returned.
128 *
129 * If @cancellable is not %NULL, then the operation can be cancelled by
130 * triggering the cancellable object from another thread. If the operation
131 * was cancelled, the error %G_IO_ERROR_CANCELLED will be set, and %NULL will
132 * be returned.
133 *
134 * Returns: (transfer full): a #GFileInfo for the @stream, or %NULL on error.
135 **/
136 GFileInfo *
137 g_file_output_stream_query_info (GFileOutputStream *stream,
138 const char *attributes,
139 GCancellable *cancellable,
140 GError **error)
141 {
142 GFileOutputStreamClass *class;
143 GOutputStream *output_stream;
144 GFileInfo *info;
145
146 g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
147
148 output_stream = G_OUTPUT_STREAM (stream);
149
150 if (!g_output_stream_set_pending (output_stream, error))
151 return NULL;
152
153 info = NULL;
154
155 if (cancellable)
156 g_cancellable_push_current (cancellable);
157
158 class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
159 if (class->query_info)
160 info = class->query_info (stream, attributes, cancellable, error);
161 else
162 g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
163 _("Stream doesn’t support query_info"));
164
165 if (cancellable)
166 g_cancellable_pop_current (cancellable);
167
168 g_output_stream_clear_pending (output_stream);
169
170 return info;
171 }
172
173 static void
174 async_ready_callback_wrapper (GObject *source_object,
175 GAsyncResult *res,
176 gpointer user_data)
177 {
178 GFileOutputStream *stream = G_FILE_OUTPUT_STREAM (source_object);
179
180 g_output_stream_clear_pending (G_OUTPUT_STREAM (stream));
181 if (stream->priv->outstanding_callback)
182 (*stream->priv->outstanding_callback) (source_object, res, user_data);
183 g_object_unref (stream);
184 }
185
186 /**
187 * g_file_output_stream_query_info_async:
188 * @stream: a #GFileOutputStream.
189 * @attributes: a file attribute query string.
190 * @io_priority: the [I/O priority](iface.AsyncResult.html#io-priority) of the
191 * 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: (nullable) (transfer full): 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_source_tag (task, g_file_output_stream_real_query_info_async);
517 g_task_set_task_data (task, g_strdup (attributes), g_free);
518 g_task_set_priority (task, io_priority);
519
520 g_task_run_in_thread (task, query_info_async_thread);
521 g_object_unref (task);
522 }
523
524 static GFileInfo *
525 g_file_output_stream_real_query_info_finish (GFileOutputStream *stream,
526 GAsyncResult *res,
527 GError **error)
528 {
529 g_return_val_if_fail (g_task_is_valid (res, stream), NULL);
530
531 return g_task_propagate_pointer (G_TASK (res), error);
532 }