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 <gfileinputstream.h>
27 #include <gseekable.h>
28 #include "gcancellable.h"
29 #include "gasyncresult.h"
30 #include "gtask.h"
31 #include "gioerror.h"
32 #include "glibintl.h"
33
34
35 /**
36 * GFileInputStream:
37 *
38 * `GFileInputStream` provides input streams that take their
39 * content from a file.
40 *
41 * `GFileInputStream` implements [iface@Gio.Seekable], which allows the input
42 * stream to jump to arbitrary positions in the file, provided the
43 * filesystem of the file allows it. To find the position of a file
44 * input stream, use [method@Gio.Seekable.tell]. To find out if a file input
45 * stream supports seeking, use [iface@Gio.Seekable.can_seek].
46 * To position a file input stream, use [iface@Gio.Seekable.seek].
47 **/
48
49 static void g_file_input_stream_seekable_iface_init (GSeekableIface *iface);
50 static goffset g_file_input_stream_seekable_tell (GSeekable *seekable);
51 static gboolean g_file_input_stream_seekable_can_seek (GSeekable *seekable);
52 static gboolean g_file_input_stream_seekable_seek (GSeekable *seekable,
53 goffset offset,
54 GSeekType type,
55 GCancellable *cancellable,
56 GError **error);
57 static gboolean g_file_input_stream_seekable_can_truncate (GSeekable *seekable);
58 static gboolean g_file_input_stream_seekable_truncate (GSeekable *seekable,
59 goffset offset,
60 GCancellable *cancellable,
61 GError **error);
62 static void g_file_input_stream_real_query_info_async (GFileInputStream *stream,
63 const char *attributes,
64 int io_priority,
65 GCancellable *cancellable,
66 GAsyncReadyCallback callback,
67 gpointer user_data);
68 static GFileInfo *g_file_input_stream_real_query_info_finish (GFileInputStream *stream,
69 GAsyncResult *result,
70 GError **error);
71
72
73 struct _GFileInputStreamPrivate {
74 GAsyncReadyCallback outstanding_callback;
75 };
76
77 G_DEFINE_TYPE_WITH_CODE (GFileInputStream, g_file_input_stream, G_TYPE_INPUT_STREAM,
78 G_ADD_PRIVATE (GFileInputStream)
79 G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
80 g_file_input_stream_seekable_iface_init))
81
82 static void
83 g_file_input_stream_class_init (GFileInputStreamClass *klass)
84 {
85 klass->query_info_async = g_file_input_stream_real_query_info_async;
86 klass->query_info_finish = g_file_input_stream_real_query_info_finish;
87 }
88
89 static void
90 g_file_input_stream_seekable_iface_init (GSeekableIface *iface)
91 {
92 iface->tell = g_file_input_stream_seekable_tell;
93 iface->can_seek = g_file_input_stream_seekable_can_seek;
94 iface->seek = g_file_input_stream_seekable_seek;
95 iface->can_truncate = g_file_input_stream_seekable_can_truncate;
96 iface->truncate_fn = g_file_input_stream_seekable_truncate;
97 }
98
99 static void
100 g_file_input_stream_init (GFileInputStream *stream)
101 {
102 stream->priv = g_file_input_stream_get_instance_private (stream);
103 }
104
105 /**
106 * g_file_input_stream_query_info:
107 * @stream: a #GFileInputStream.
108 * @attributes: a file attribute query string.
109 * @cancellable: (nullable): optional #GCancellable object, %NULL to ignore.
110 * @error: a #GError location to store the error occurring, or %NULL to
111 * ignore.
112 *
113 * Queries a file input stream the given @attributes. This function blocks
114 * while querying the stream. For the asynchronous (non-blocking) version
115 * of this function, see g_file_input_stream_query_info_async(). While the
116 * stream is blocked, the stream will set the pending flag internally, and
117 * any other operations on the stream will fail with %G_IO_ERROR_PENDING.
118 *
119 * Returns: (transfer full): a #GFileInfo, or %NULL on error.
120 **/
121 GFileInfo *
122 g_file_input_stream_query_info (GFileInputStream *stream,
123 const char *attributes,
124 GCancellable *cancellable,
125 GError **error)
126 {
127 GFileInputStreamClass *class;
128 GInputStream *input_stream;
129 GFileInfo *info;
130
131 g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), NULL);
132
133 input_stream = G_INPUT_STREAM (stream);
134
135 if (!g_input_stream_set_pending (input_stream, error))
136 return NULL;
137
138 info = NULL;
139
140 if (cancellable)
141 g_cancellable_push_current (cancellable);
142
143 class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
144 if (class->query_info)
145 info = class->query_info (stream, attributes, cancellable, error);
146 else
147 g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
148 _("Stream doesn’t support query_info"));
149
150 if (cancellable)
151 g_cancellable_pop_current (cancellable);
152
153 g_input_stream_clear_pending (input_stream);
154
155 return info;
156 }
157
158 static void
159 async_ready_callback_wrapper (GObject *source_object,
160 GAsyncResult *res,
161 gpointer user_data)
162 {
163 GFileInputStream *stream = G_FILE_INPUT_STREAM (source_object);
164
165 g_input_stream_clear_pending (G_INPUT_STREAM (stream));
166 if (stream->priv->outstanding_callback)
167 (*stream->priv->outstanding_callback) (source_object, res, user_data);
168 g_object_unref (stream);
169 }
170
171 /**
172 * g_file_input_stream_query_info_async:
173 * @stream: a #GFileInputStream.
174 * @attributes: a file attribute query string.
175 * @io_priority: the [I/O priority][io-priority] of the request
176 * @cancellable: (nullable): optional #GCancellable object, %NULL to ignore.
177 * @callback: (scope async): a #GAsyncReadyCallback
178 * to call when the request is satisfied
179 * @user_data: 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_source_tag (task, g_file_input_stream_real_query_info_async);
414 g_task_set_task_data (task, g_strdup (attributes), g_free);
415 g_task_set_priority (task, io_priority);
416
417 g_task_run_in_thread (task, query_info_async_thread);
418 g_object_unref (task);
419 }
420
421 static GFileInfo *
422 g_file_input_stream_real_query_info_finish (GFileInputStream *stream,
423 GAsyncResult *res,
424 GError **error)
425 {
426 g_return_val_if_fail (g_task_is_valid (res, stream), NULL);
427
428 return g_task_propagate_pointer (G_TASK (res), error);
429 }