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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 <gfileinputstream.h>
25 #include <gseekable.h>
26 #include "gcancellable.h"
27 #include "gasyncresult.h"
28 #include "gtask.h"
29 #include "gioerror.h"
30 #include "glibintl.h"
31  
32  
33 /**
34 * SECTION:gfileinputstream
35 * @short_description: File input streaming operations
36 * @include: gio/gio.h
37 * @see_also: #GInputStream, #GDataInputStream, #GSeekable
38 *
39 * GFileInputStream provides input streams that take their
40 * content from a file.
41 *
42 * GFileInputStream implements #GSeekable, which allows the input
43 * stream to jump to arbitrary positions in the file, provided the
44 * filesystem of the file allows it. To find the position of a file
45 * input stream, use g_seekable_tell(). To find out if a file input
46 * stream supports seeking, use g_seekable_can_seek().
47 * To position a file input stream, use g_seekable_seek().
48 **/
49  
50 static void g_file_input_stream_seekable_iface_init (GSeekableIface *iface);
51 static goffset g_file_input_stream_seekable_tell (GSeekable *seekable);
52 static gboolean g_file_input_stream_seekable_can_seek (GSeekable *seekable);
53 static gboolean g_file_input_stream_seekable_seek (GSeekable *seekable,
54 goffset offset,
55 GSeekType type,
56 GCancellable *cancellable,
57 GError **error);
58 static gboolean g_file_input_stream_seekable_can_truncate (GSeekable *seekable);
59 static gboolean g_file_input_stream_seekable_truncate (GSeekable *seekable,
60 goffset offset,
61 GCancellable *cancellable,
62 GError **error);
63 static void g_file_input_stream_real_query_info_async (GFileInputStream *stream,
64 const char *attributes,
65 int io_priority,
66 GCancellable *cancellable,
67 GAsyncReadyCallback callback,
68 gpointer user_data);
69 static GFileInfo *g_file_input_stream_real_query_info_finish (GFileInputStream *stream,
70 GAsyncResult *result,
71 GError **error);
72  
73  
74 struct _GFileInputStreamPrivate {
75 GAsyncReadyCallback outstanding_callback;
76 };
77  
78 G_DEFINE_TYPE_WITH_CODE (GFileInputStream, g_file_input_stream, G_TYPE_INPUT_STREAM,
79 G_ADD_PRIVATE (GFileInputStream)
80 G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
81 g_file_input_stream_seekable_iface_init))
82  
83 static void
84 g_file_input_stream_class_init (GFileInputStreamClass *klass)
85 {
86 klass->query_info_async = g_file_input_stream_real_query_info_async;
87 klass->query_info_finish = g_file_input_stream_real_query_info_finish;
88 }
89  
90 static void
91 g_file_input_stream_seekable_iface_init (GSeekableIface *iface)
92 {
93 iface->tell = g_file_input_stream_seekable_tell;
94 iface->can_seek = g_file_input_stream_seekable_can_seek;
95 iface->seek = g_file_input_stream_seekable_seek;
96 iface->can_truncate = g_file_input_stream_seekable_can_truncate;
97 iface->truncate_fn = g_file_input_stream_seekable_truncate;
98 }
99  
100 static void
101 g_file_input_stream_init (GFileInputStream *stream)
102 {
103 stream->priv = g_file_input_stream_get_instance_private (stream);
104 }
105  
106 /**
107 * g_file_input_stream_query_info:
108 * @stream: a #GFileInputStream.
109 * @attributes: a file attribute query string.
110 * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
111 * @error: a #GError location to store the error occurring, or %NULL to
112 * ignore.
113 *
114 * Queries a file input stream the given @attributes. This function blocks
115 * while querying the stream. For the asynchronous (non-blocking) version
116 * of this function, see g_file_input_stream_query_info_async(). While the
117 * stream is blocked, the stream will set the pending flag internally, and
118 * any other operations on the stream will fail with %G_IO_ERROR_PENDING.
119 *
120 * Returns: (transfer full): a #GFileInfo, or %NULL on error.
121 **/
122 GFileInfo *
123 g_file_input_stream_query_info (GFileInputStream *stream,
124 const char *attributes,
125 GCancellable *cancellable,
126 GError **error)
127 {
128 GFileInputStreamClass *class;
129 GInputStream *input_stream;
130 GFileInfo *info;
131  
132 g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), NULL);
133  
134 input_stream = G_INPUT_STREAM (stream);
135  
136 if (!g_input_stream_set_pending (input_stream, error))
137 return NULL;
138  
139 info = NULL;
140  
141 if (cancellable)
142 g_cancellable_push_current (cancellable);
143  
144 class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
145 if (class->query_info)
146 info = class->query_info (stream, attributes, cancellable, error);
147 else
148 g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
149 _("Stream doesn't support query_info"));
150  
151 if (cancellable)
152 g_cancellable_pop_current (cancellable);
153  
154 g_input_stream_clear_pending (input_stream);
155  
156 return info;
157 }
158  
159 static void
160 async_ready_callback_wrapper (GObject *source_object,
161 GAsyncResult *res,
162 gpointer user_data)
163 {
164 GFileInputStream *stream = G_FILE_INPUT_STREAM (source_object);
165  
166 g_input_stream_clear_pending (G_INPUT_STREAM (stream));
167 if (stream->priv->outstanding_callback)
168 (*stream->priv->outstanding_callback) (source_object, res, user_data);
169 g_object_unref (stream);
170 }
171  
172 /**
173 * g_file_input_stream_query_info_async:
174 * @stream: a #GFileInputStream.
175 * @attributes: a file attribute query string.
176 * @io_priority: the [I/O priority][io-priority] of the request
177 * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
178 * @callback: (scope async): callback to call when the request is satisfied
179 * @user_data: (closure): the data to pass to callback function
180 *
181 * Queries the stream information asynchronously.
182 * When the operation is finished @callback will be called.
183 * You can then call g_file_input_stream_query_info_finish()
184 * to get the result of the operation.
185 *
186 * For the synchronous version of this function,
187 * see g_file_input_stream_query_info().
188 *
189 * If @cancellable is not %NULL, then the operation can be cancelled by
190 * triggering the cancellable object from another thread. If the operation
191 * was cancelled, the error %G_IO_ERROR_CANCELLED will be set
192 *
193 **/
194 void
195 g_file_input_stream_query_info_async (GFileInputStream *stream,
196 const char *attributes,
197 int io_priority,
198 GCancellable *cancellable,
199 GAsyncReadyCallback callback,
200 gpointer user_data)
201 {
202 GFileInputStreamClass *klass;
203 GInputStream *input_stream;
204 GError *error = NULL;
205  
206 g_return_if_fail (G_IS_FILE_INPUT_STREAM (stream));
207  
208 input_stream = G_INPUT_STREAM (stream);
209  
210 if (!g_input_stream_set_pending (input_stream, &error))
211 {
212 g_task_report_error (stream, callback, user_data,
213 g_file_input_stream_query_info_async,
214 error);
215 return;
216 }
217  
218 klass = G_FILE_INPUT_STREAM_GET_CLASS (stream);
219  
220 stream->priv->outstanding_callback = callback;
221 g_object_ref (stream);
222 klass->query_info_async (stream, attributes, io_priority, cancellable,
223 async_ready_callback_wrapper, user_data);
224 }
225  
226 /**
227 * g_file_input_stream_query_info_finish:
228 * @stream: a #GFileInputStream.
229 * @result: a #GAsyncResult.
230 * @error: a #GError location to store the error occurring,
231 * or %NULL to ignore.
232 *
233 * Finishes an asynchronous info query operation.
234 *
235 * Returns: (transfer full): #GFileInfo.
236 **/
237 GFileInfo *
238 g_file_input_stream_query_info_finish (GFileInputStream *stream,
239 GAsyncResult *result,
240 GError **error)
241 {
242 GFileInputStreamClass *class;
243  
244 g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), NULL);
245 g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
246  
247 if (g_async_result_legacy_propagate_error (result, error))
248 return NULL;
249 else if (g_async_result_is_tagged (result, g_file_input_stream_query_info_async))
250 return g_task_propagate_pointer (G_TASK (result), error);
251  
252 class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
253 return class->query_info_finish (stream, result, error);
254 }
255  
256 static goffset
257 g_file_input_stream_tell (GFileInputStream *stream)
258 {
259 GFileInputStreamClass *class;
260 goffset offset;
261  
262 g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), 0);
263  
264 class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
265  
266 offset = 0;
267 if (class->tell)
268 offset = class->tell (stream);
269  
270 return offset;
271 }
272  
273 static goffset
274 g_file_input_stream_seekable_tell (GSeekable *seekable)
275 {
276 return g_file_input_stream_tell (G_FILE_INPUT_STREAM (seekable));
277 }
278  
279 static gboolean
280 g_file_input_stream_can_seek (GFileInputStream *stream)
281 {
282 GFileInputStreamClass *class;
283 gboolean can_seek;
284  
285 g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), FALSE);
286  
287 class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
288  
289 can_seek = FALSE;
290 if (class->seek)
291 {
292 can_seek = TRUE;
293 if (class->can_seek)
294 can_seek = class->can_seek (stream);
295 }
296  
297 return can_seek;
298 }
299  
300 static gboolean
301 g_file_input_stream_seekable_can_seek (GSeekable *seekable)
302 {
303 return g_file_input_stream_can_seek (G_FILE_INPUT_STREAM (seekable));
304 }
305  
306 static gboolean
307 g_file_input_stream_seek (GFileInputStream *stream,
308 goffset offset,
309 GSeekType type,
310 GCancellable *cancellable,
311 GError **error)
312 {
313 GFileInputStreamClass *class;
314 GInputStream *input_stream;
315 gboolean res;
316  
317 g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), FALSE);
318  
319 input_stream = G_INPUT_STREAM (stream);
320 class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
321  
322 if (!class->seek)
323 {
324 g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
325 _("Seek not supported on stream"));
326 return FALSE;
327 }
328  
329 if (!g_input_stream_set_pending (input_stream, error))
330 return FALSE;
331  
332 if (cancellable)
333 g_cancellable_push_current (cancellable);
334  
335 res = class->seek (stream, offset, type, cancellable, error);
336  
337 if (cancellable)
338 g_cancellable_pop_current (cancellable);
339  
340 g_input_stream_clear_pending (input_stream);
341  
342 return res;
343 }
344  
345 static gboolean
346 g_file_input_stream_seekable_seek (GSeekable *seekable,
347 goffset offset,
348 GSeekType type,
349 GCancellable *cancellable,
350 GError **error)
351 {
352 return g_file_input_stream_seek (G_FILE_INPUT_STREAM (seekable),
353 offset, type, cancellable, error);
354 }
355  
356 static gboolean
357 g_file_input_stream_seekable_can_truncate (GSeekable *seekable)
358 {
359 return FALSE;
360 }
361  
362 static gboolean
363 g_file_input_stream_seekable_truncate (GSeekable *seekable,
364 goffset offset,
365 GCancellable *cancellable,
366 GError **error)
367 {
368 g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
369 _("Truncate not allowed on input stream"));
370 return FALSE;
371 }
372  
373 /********************************************
374 * Default implementation of async ops *
375 ********************************************/
376  
377 static void
378 query_info_async_thread (GTask *task,
379 gpointer source_object,
380 gpointer task_data,
381 GCancellable *cancellable)
382 {
383 GFileInputStream *stream = source_object;
384 const char *attributes = task_data;
385 GFileInputStreamClass *class;
386 GError *error = NULL;
387 GFileInfo *info = NULL;
388  
389 class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
390 if (class->query_info)
391 info = class->query_info (stream, attributes, cancellable, &error);
392 else
393 g_set_error_literal (&error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
394 _("Stream doesn't support query_info"));
395  
396 if (info == NULL)
397 g_task_return_error (task, error);
398 else
399 g_task_return_pointer (task, info, g_object_unref);
400 }
401  
402 static void
403 g_file_input_stream_real_query_info_async (GFileInputStream *stream,
404 const char *attributes,
405 int io_priority,
406 GCancellable *cancellable,
407 GAsyncReadyCallback callback,
408 gpointer user_data)
409 {
410 GTask *task;
411  
412 task = g_task_new (stream, cancellable, callback, user_data);
413 g_task_set_task_data (task, g_strdup (attributes), g_free);
414 g_task_set_priority (task, io_priority);
415  
416 g_task_run_in_thread (task, query_info_async_thread);
417 g_object_unref (task);
418 }
419  
420 static GFileInfo *
421 g_file_input_stream_real_query_info_finish (GFileInputStream *stream,
422 GAsyncResult *res,
423 GError **error)
424 {
425 g_return_val_if_fail (g_task_is_valid (res, stream), NULL);
426  
427 return g_task_propagate_pointer (G_TASK (res), error);
428 }