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1 office 1 /* GIO - GLib Input, IO 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 <gfileiostream.h>
25 #include <gseekable.h>
26 #include "gasyncresult.h"
27 #include "gtask.h"
28 #include "gcancellable.h"
29 #include "gioerror.h"
30 #include "gfileoutputstream.h"
31 #include "glibintl.h"
32  
33  
34 /**
35 * SECTION:gfileiostream
36 * @short_description: File read and write streaming operations
37 * @include: gio/gio.h
38 * @see_also: #GIOStream, #GFileInputStream, #GFileOutputStream, #GSeekable
39 *
40 * GFileIOStream provides io streams that both read and write to the same
41 * file handle.
42 *
43 * GFileIOStream implements #GSeekable, which allows the io
44 * stream to jump to arbitrary positions in the file and to truncate
45 * the file, provided the filesystem of the file supports these
46 * operations.
47 *
48 * To find the position of a file io stream, use
49 * g_seekable_tell().
50 *
51 * To find out if a file io stream supports seeking, use g_seekable_can_seek().
52 * To position a file io stream, use g_seekable_seek().
53 * To find out if a file io stream supports truncating, use
54 * g_seekable_can_truncate(). To truncate a file io
55 * stream, use g_seekable_truncate().
56 *
57 * The default implementation of all the #GFileIOStream operations
58 * and the implementation of #GSeekable just call into the same operations
59 * on the output stream.
60 * Since: 2.22
61 **/
62  
63 static void g_file_io_stream_seekable_iface_init (GSeekableIface *iface);
64 static goffset g_file_io_stream_seekable_tell (GSeekable *seekable);
65 static gboolean g_file_io_stream_seekable_can_seek (GSeekable *seekable);
66 static gboolean g_file_io_stream_seekable_seek (GSeekable *seekable,
67 goffset offset,
68 GSeekType type,
69 GCancellable *cancellable,
70 GError **error);
71 static gboolean g_file_io_stream_seekable_can_truncate (GSeekable *seekable);
72 static gboolean g_file_io_stream_seekable_truncate (GSeekable *seekable,
73 goffset offset,
74 GCancellable *cancellable,
75 GError **error);
76 static void g_file_io_stream_real_query_info_async (GFileIOStream *stream,
77 const char *attributes,
78 int io_priority,
79 GCancellable *cancellable,
80 GAsyncReadyCallback callback,
81 gpointer user_data);
82 static GFileInfo *g_file_io_stream_real_query_info_finish (GFileIOStream *stream,
83 GAsyncResult *result,
84 GError **error);
85  
86 struct _GFileIOStreamPrivate {
87 GAsyncReadyCallback outstanding_callback;
88 };
89  
90 G_DEFINE_TYPE_WITH_CODE (GFileIOStream, g_file_io_stream, G_TYPE_IO_STREAM,
91 G_ADD_PRIVATE (GFileIOStream)
92 G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
93 g_file_io_stream_seekable_iface_init))
94  
95 static void
96 g_file_io_stream_seekable_iface_init (GSeekableIface *iface)
97 {
98 iface->tell = g_file_io_stream_seekable_tell;
99 iface->can_seek = g_file_io_stream_seekable_can_seek;
100 iface->seek = g_file_io_stream_seekable_seek;
101 iface->can_truncate = g_file_io_stream_seekable_can_truncate;
102 iface->truncate_fn = g_file_io_stream_seekable_truncate;
103 }
104  
105 static void
106 g_file_io_stream_init (GFileIOStream *stream)
107 {
108 stream->priv = g_file_io_stream_get_instance_private (stream);
109 }
110  
111 /**
112 * g_file_io_stream_query_info:
113 * @stream: a #GFileIOStream.
114 * @attributes: a file attribute query string.
115 * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
116 * @error: a #GError, %NULL to ignore.
117 *
118 * Queries a file io stream for the given @attributes.
119 * This function blocks while querying the stream. For the asynchronous
120 * version of this function, see g_file_io_stream_query_info_async().
121 * While the stream is blocked, the stream will set the pending flag
122 * internally, and any other operations on the stream will fail with
123 * %G_IO_ERROR_PENDING.
124 *
125 * Can fail if the stream was already closed (with @error being set to
126 * %G_IO_ERROR_CLOSED), the stream has pending operations (with @error being
127 * set to %G_IO_ERROR_PENDING), or if querying info is not supported for
128 * the stream's interface (with @error being set to %G_IO_ERROR_NOT_SUPPORTED). I
129 * all cases of failure, %NULL will be returned.
130 *
131 * If @cancellable is not %NULL, then the operation can be cancelled by
132 * triggering the cancellable object from another thread. If the operation
133 * was cancelled, the error %G_IO_ERROR_CANCELLED will be set, and %NULL will
134 * be returned.
135 *
136 * Returns: (transfer full): a #GFileInfo for the @stream, or %NULL on error.
137 *
138 * Since: 2.22
139 **/
140 GFileInfo *
141 g_file_io_stream_query_info (GFileIOStream *stream,
142 const char *attributes,
143 GCancellable *cancellable,
144 GError **error)
145 {
146 GFileIOStreamClass *class;
147 GIOStream *io_stream;
148 GFileInfo *info;
149  
150 g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), NULL);
151  
152 io_stream = G_IO_STREAM (stream);
153  
154 if (!g_io_stream_set_pending (io_stream, error))
155 return NULL;
156  
157 info = NULL;
158  
159 if (cancellable)
160 g_cancellable_push_current (cancellable);
161  
162 class = G_FILE_IO_STREAM_GET_CLASS (stream);
163 if (class->query_info)
164 info = class->query_info (stream, attributes, cancellable, error);
165 else
166 g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
167 _("Stream doesn't support query_info"));
168  
169 if (cancellable)
170 g_cancellable_pop_current (cancellable);
171  
172 g_io_stream_clear_pending (io_stream);
173  
174 return info;
175 }
176  
177 static void
178 async_ready_callback_wrapper (GObject *source_object,
179 GAsyncResult *res,
180 gpointer user_data)
181 {
182 GFileIOStream *stream = G_FILE_IO_STREAM (source_object);
183  
184 g_io_stream_clear_pending (G_IO_STREAM (stream));
185 if (stream->priv->outstanding_callback)
186 (*stream->priv->outstanding_callback) (source_object, res, user_data);
187 g_object_unref (stream);
188 }
189  
190 /**
191 * g_file_io_stream_query_info_async:
192 * @stream: a #GFileIOStream.
193 * @attributes: a file attribute query string.
194 * @io_priority: the [I/O priority][gio-GIOScheduler] of the request
195 * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
196 * @callback: (scope async): callback to call when the request is satisfied
197 * @user_data: (closure): the data to pass to callback function
198 *
199 * Asynchronously queries the @stream for a #GFileInfo. When completed,
200 * @callback will be called with a #GAsyncResult which can be used to
201 * finish the operation with g_file_io_stream_query_info_finish().
202 *
203 * For the synchronous version of this function, see
204 * g_file_io_stream_query_info().
205 *
206 * Since: 2.22
207 **/
208 void
209 g_file_io_stream_query_info_async (GFileIOStream *stream,
210 const char *attributes,
211 int io_priority,
212 GCancellable *cancellable,
213 GAsyncReadyCallback callback,
214 gpointer user_data)
215 {
216 GFileIOStreamClass *klass;
217 GIOStream *io_stream;
218 GError *error = NULL;
219  
220 g_return_if_fail (G_IS_FILE_IO_STREAM (stream));
221  
222 io_stream = G_IO_STREAM (stream);
223  
224 if (!g_io_stream_set_pending (io_stream, &error))
225 {
226 g_task_report_error (stream, callback, user_data,
227 g_file_io_stream_query_info_async,
228 error);
229 return;
230 }
231  
232 klass = G_FILE_IO_STREAM_GET_CLASS (stream);
233  
234 stream->priv->outstanding_callback = callback;
235 g_object_ref (stream);
236 klass->query_info_async (stream, attributes, io_priority, cancellable,
237 async_ready_callback_wrapper, user_data);
238 }
239  
240 /**
241 * g_file_io_stream_query_info_finish:
242 * @stream: a #GFileIOStream.
243 * @result: a #GAsyncResult.
244 * @error: a #GError, %NULL to ignore.
245 *
246 * Finalizes the asynchronous query started
247 * by g_file_io_stream_query_info_async().
248 *
249 * Returns: (transfer full): A #GFileInfo for the finished query.
250 *
251 * Since: 2.22
252 **/
253 GFileInfo *
254 g_file_io_stream_query_info_finish (GFileIOStream *stream,
255 GAsyncResult *result,
256 GError **error)
257 {
258 GFileIOStreamClass *class;
259  
260 g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), NULL);
261 g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
262  
263 if (g_async_result_legacy_propagate_error (result, error))
264 return NULL;
265 else if (g_async_result_is_tagged (result, g_file_io_stream_query_info_async))
266 return g_task_propagate_pointer (G_TASK (result), error);
267  
268 class = G_FILE_IO_STREAM_GET_CLASS (stream);
269 return class->query_info_finish (stream, result, error);
270 }
271  
272 /**
273 * g_file_io_stream_get_etag:
274 * @stream: a #GFileIOStream.
275 *
276 * Gets the entity tag for the file when it has been written.
277 * This must be called after the stream has been written
278 * and closed, as the etag can change while writing.
279 *
280 * Returns: the entity tag for the stream.
281 *
282 * Since: 2.22
283 **/
284 char *
285 g_file_io_stream_get_etag (GFileIOStream *stream)
286 {
287 GFileIOStreamClass *class;
288 GIOStream *io_stream;
289 char *etag;
290  
291 g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), NULL);
292  
293 io_stream = G_IO_STREAM (stream);
294  
295 if (!g_io_stream_is_closed (io_stream))
296 {
297 g_warning ("stream is not closed yet, can't get etag");
298 return NULL;
299 }
300  
301 etag = NULL;
302  
303 class = G_FILE_IO_STREAM_GET_CLASS (stream);
304 if (class->get_etag)
305 etag = class->get_etag (stream);
306  
307 return etag;
308 }
309  
310 static goffset
311 g_file_io_stream_tell (GFileIOStream *stream)
312 {
313 GFileIOStreamClass *class;
314 goffset offset;
315  
316 g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), 0);
317  
318 class = G_FILE_IO_STREAM_GET_CLASS (stream);
319  
320 offset = 0;
321 if (class->tell)
322 offset = class->tell (stream);
323  
324 return offset;
325 }
326  
327 static goffset
328 g_file_io_stream_seekable_tell (GSeekable *seekable)
329 {
330 return g_file_io_stream_tell (G_FILE_IO_STREAM (seekable));
331 }
332  
333 static gboolean
334 g_file_io_stream_can_seek (GFileIOStream *stream)
335 {
336 GFileIOStreamClass *class;
337 gboolean can_seek;
338  
339 g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
340  
341 class = G_FILE_IO_STREAM_GET_CLASS (stream);
342  
343 can_seek = FALSE;
344 if (class->seek)
345 {
346 can_seek = TRUE;
347 if (class->can_seek)
348 can_seek = class->can_seek (stream);
349 }
350  
351 return can_seek;
352 }
353  
354 static gboolean
355 g_file_io_stream_seekable_can_seek (GSeekable *seekable)
356 {
357 return g_file_io_stream_can_seek (G_FILE_IO_STREAM (seekable));
358 }
359  
360 static gboolean
361 g_file_io_stream_seek (GFileIOStream *stream,
362 goffset offset,
363 GSeekType type,
364 GCancellable *cancellable,
365 GError **error)
366 {
367 GFileIOStreamClass *class;
368 GIOStream *io_stream;
369 gboolean res;
370  
371 g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
372  
373 io_stream = G_IO_STREAM (stream);
374 class = G_FILE_IO_STREAM_GET_CLASS (stream);
375  
376 if (!class->seek)
377 {
378 g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
379 _("Seek not supported on stream"));
380 return FALSE;
381 }
382  
383 if (!g_io_stream_set_pending (io_stream, error))
384 return FALSE;
385  
386 if (cancellable)
387 g_cancellable_push_current (cancellable);
388  
389 res = class->seek (stream, offset, type, cancellable, error);
390  
391 if (cancellable)
392 g_cancellable_pop_current (cancellable);
393  
394 g_io_stream_clear_pending (io_stream);
395  
396 return res;
397 }
398  
399 static gboolean
400 g_file_io_stream_seekable_seek (GSeekable *seekable,
401 goffset offset,
402 GSeekType type,
403 GCancellable *cancellable,
404 GError **error)
405 {
406 return g_file_io_stream_seek (G_FILE_IO_STREAM (seekable),
407 offset, type, cancellable, error);
408 }
409  
410 static gboolean
411 g_file_io_stream_can_truncate (GFileIOStream *stream)
412 {
413 GFileIOStreamClass *class;
414 gboolean can_truncate;
415  
416 g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
417  
418 class = G_FILE_IO_STREAM_GET_CLASS (stream);
419  
420 can_truncate = FALSE;
421 if (class->truncate_fn)
422 {
423 can_truncate = TRUE;
424 if (class->can_truncate)
425 can_truncate = class->can_truncate (stream);
426 }
427  
428 return can_truncate;
429 }
430  
431 static gboolean
432 g_file_io_stream_seekable_can_truncate (GSeekable *seekable)
433 {
434 return g_file_io_stream_can_truncate (G_FILE_IO_STREAM (seekable));
435 }
436  
437 static gboolean
438 g_file_io_stream_truncate (GFileIOStream *stream,
439 goffset size,
440 GCancellable *cancellable,
441 GError **error)
442 {
443 GFileIOStreamClass *class;
444 GIOStream *io_stream;
445 gboolean res;
446  
447 g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
448  
449 io_stream = G_IO_STREAM (stream);
450 class = G_FILE_IO_STREAM_GET_CLASS (stream);
451  
452 if (!class->truncate_fn)
453 {
454 g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
455 _("Truncate not supported on stream"));
456 return FALSE;
457 }
458  
459 if (!g_io_stream_set_pending (io_stream, error))
460 return FALSE;
461  
462 if (cancellable)
463 g_cancellable_push_current (cancellable);
464  
465 res = class->truncate_fn (stream, size, cancellable, error);
466  
467 if (cancellable)
468 g_cancellable_pop_current (cancellable);
469  
470 g_io_stream_clear_pending (io_stream);
471  
472 return res;
473 }
474  
475 static gboolean
476 g_file_io_stream_seekable_truncate (GSeekable *seekable,
477 goffset size,
478 GCancellable *cancellable,
479 GError **error)
480 {
481 return g_file_io_stream_truncate (G_FILE_IO_STREAM (seekable),
482 size, cancellable, error);
483 }
484 /*****************************************************
485 * Default implementations based on output stream *
486 *****************************************************/
487  
488 static goffset
489 g_file_io_stream_real_tell (GFileIOStream *stream)
490 {
491 GOutputStream *out;
492 GSeekable *seekable;
493  
494 out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
495 seekable = G_SEEKABLE (out);
496  
497 return g_seekable_tell (seekable);
498 }
499  
500 static gboolean
501 g_file_io_stream_real_can_seek (GFileIOStream *stream)
502 {
503 GOutputStream *out;
504 GSeekable *seekable;
505  
506 out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
507 seekable = G_SEEKABLE (out);
508  
509 return g_seekable_can_seek (seekable);
510 }
511  
512 static gboolean
513 g_file_io_stream_real_seek (GFileIOStream *stream,
514 goffset offset,
515 GSeekType type,
516 GCancellable *cancellable,
517 GError **error)
518 {
519 GOutputStream *out;
520 GSeekable *seekable;
521  
522 out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
523 seekable = G_SEEKABLE (out);
524  
525 return g_seekable_seek (seekable, offset, type, cancellable, error);
526 }
527  
528 static gboolean
529 g_file_io_stream_real_can_truncate (GFileIOStream *stream)
530 {
531 GOutputStream *out;
532 GSeekable *seekable;
533  
534 out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
535 seekable = G_SEEKABLE (out);
536  
537 return g_seekable_can_truncate (seekable);
538 }
539  
540 static gboolean
541 g_file_io_stream_real_truncate_fn (GFileIOStream *stream,
542 goffset size,
543 GCancellable *cancellable,
544 GError **error)
545 {
546 GOutputStream *out;
547 GSeekable *seekable;
548  
549 out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
550 seekable = G_SEEKABLE (out);
551  
552 return g_seekable_truncate (seekable, size, cancellable, error);
553 }
554  
555 static char *
556 g_file_io_stream_real_get_etag (GFileIOStream *stream)
557 {
558 GOutputStream *out;
559 GFileOutputStream *file_out;
560  
561 out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
562 file_out = G_FILE_OUTPUT_STREAM (out);
563  
564 return g_file_output_stream_get_etag (file_out);
565 }
566  
567 static GFileInfo *
568 g_file_io_stream_real_query_info (GFileIOStream *stream,
569 const char *attributes,
570 GCancellable *cancellable,
571 GError **error)
572 {
573 GOutputStream *out;
574 GFileOutputStream *file_out;
575  
576 out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
577 file_out = G_FILE_OUTPUT_STREAM (out);
578  
579 return g_file_output_stream_query_info (file_out,
580 attributes, cancellable, error);
581 }
582  
583 typedef struct {
584 GObject *object;
585 GAsyncReadyCallback callback;
586 gpointer user_data;
587 } AsyncOpWrapper;
588  
589 static AsyncOpWrapper *
590 async_op_wrapper_new (gpointer object,
591 GAsyncReadyCallback callback,
592 gpointer user_data)
593 {
594 AsyncOpWrapper *data;
595  
596 data = g_new0 (AsyncOpWrapper, 1);
597 data->object = g_object_ref (object);
598 data->callback = callback;
599 data->user_data = user_data;
600  
601 return data;
602 }
603  
604 static void
605 async_op_wrapper_callback (GObject *source_object,
606 GAsyncResult *res,
607 gpointer user_data)
608 {
609 AsyncOpWrapper *data = user_data;
610 data->callback (data->object, res, data->user_data);
611 g_object_unref (data->object);
612 g_free (data);
613 }
614  
615 static void
616 g_file_io_stream_real_query_info_async (GFileIOStream *stream,
617 const char *attributes,
618 int io_priority,
619 GCancellable *cancellable,
620 GAsyncReadyCallback callback,
621 gpointer user_data)
622 {
623 GOutputStream *out;
624 GFileOutputStream *file_out;
625 AsyncOpWrapper *data;
626  
627 out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
628 file_out = G_FILE_OUTPUT_STREAM (out);
629  
630 data = async_op_wrapper_new (stream, callback, user_data);
631 g_file_output_stream_query_info_async (file_out,
632 attributes, io_priority,
633 cancellable, async_op_wrapper_callback, data);
634 }
635  
636 static GFileInfo *
637 g_file_io_stream_real_query_info_finish (GFileIOStream *stream,
638 GAsyncResult *res,
639 GError **error)
640 {
641 GOutputStream *out;
642 GFileOutputStream *file_out;
643  
644 out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
645 file_out = G_FILE_OUTPUT_STREAM (out);
646  
647 return g_file_output_stream_query_info_finish (file_out, res, error);
648 }
649  
650 static void
651 g_file_io_stream_class_init (GFileIOStreamClass *klass)
652 {
653 klass->tell = g_file_io_stream_real_tell;
654 klass->can_seek = g_file_io_stream_real_can_seek;
655 klass->seek = g_file_io_stream_real_seek;
656 klass->can_truncate = g_file_io_stream_real_can_truncate;
657 klass->truncate_fn = g_file_io_stream_real_truncate_fn;
658 klass->query_info = g_file_io_stream_real_query_info;
659 klass->query_info_async = g_file_io_stream_real_query_info_async;
660 klass->query_info_finish = g_file_io_stream_real_query_info_finish;
661 klass->get_etag = g_file_io_stream_real_get_etag;
662 }