aboutsummaryrefslogtreecommitdiffstats
path: root/camel/camel-seekable-substream.c
blob: 6d59d8994cd8f426bcef339a1434560751db4761 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/* camel-stream-fs.c : file system based stream */

/* inspired by gnome-stream-fs.c in bonobo by Miguel de Icaza */
/* 
 *
 * Author : 
 *  Bertrand Guiheneuf <bertrand@helixcode.com>
 *
 * Copyright 1999, 2000 HelixCode (http://www.helixcode.com) .
 *
 * This program is free software; you can redistribute it and/or 
 * modify it under the terms of the GNU General Public License as 
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 * USA
 */
#include <config.h>
#include "camel-seekable-substream.h"
#include "camel-log.h"

static CamelSeekableStreamClass *parent_class=NULL;


/* Returns the class for a CamelSeekableSubStream */
#define CSS_CLASS(so) CAMEL_SEEKABLE_SUBSTREAM_CLASS (GTK_OBJECT(so)->klass)




static  gint           _read                  (CamelStream *stream, 
                               gchar *buffer, gint n);
static  gint           _write                 (CamelStream *stream, 
                               const gchar *buffer, 
                               gint n);
static  void           _flush                 (CamelStream *stream);
static  gint           _available             (CamelStream *stream);
static  gboolean       _eos               (CamelStream *stream);
static  void           _close                 (CamelStream *stream);
static  gint           _seek                  (CamelSeekableStream *stream, 
                               gint offset, 
                               CamelStreamSeekPolicy policy);

static  void           _finalize              (GtkObject *object);
static  void           _destroy               (GtkObject *object);

static  void           _init_with_seekable_stream_and_bounds     (CamelSeekableSubstream *seekable_substream, 
                                  CamelSeekableStream *parent_stream,
                                  guint32 inf_bound, 
                                  gint64  sup_bound);




static void
camel_seekable_substream_class_init (CamelSeekableSubstreamClass *camel_seekable_substream_class)
{
    CamelSeekableStreamClass *camel_seekable_stream_class = CAMEL_SEEKABLE_STREAM_CLASS (camel_seekable_substream_class);
    CamelStreamClass *camel_stream_class = CAMEL_STREAM_CLASS (camel_seekable_substream_class);
    GtkObjectClass *gtk_object_class = GTK_OBJECT_CLASS (camel_seekable_substream_class);

    parent_class = gtk_type_class (camel_seekable_stream_get_type ());
    
    /* virtual method definition */
    camel_seekable_substream_class->init_with_seekable_stream_and_bounds = _init_with_seekable_stream_and_bounds;
    
    /* virtual method overload */
    camel_stream_class->read = _read;
    camel_stream_class->write = _write;
    camel_stream_class->flush = _flush;
    camel_stream_class->available = _available;
    camel_stream_class->eos = _eos;
    camel_stream_class->close = _close;

    camel_seekable_stream_class->seek = _seek;

    gtk_object_class->finalize = _finalize;
    gtk_object_class->destroy = _destroy;

}

static void
camel_seekable_substream_init (gpointer   object,  gpointer   klass)
{
    /* does nothing */
}




GtkType
camel_seekable_substream_get_type (void)
{
    static GtkType camel_seekable_substream_type = 0;
    
    if (!camel_seekable_substream_type) {
        GtkTypeInfo camel_seekable_substream_info = 
        {
            "CamelSeekableSubstream",
            sizeof (CamelSeekableSubstream),
            sizeof (CamelSeekableSubstreamClass),
            (GtkClassInitFunc) camel_seekable_substream_class_init,
            (GtkObjectInitFunc) camel_seekable_substream_init,
                /* reserved_1 */ NULL,
                /* reserved_2 */ NULL,
            (GtkClassInitFunc) NULL,
        };
        
        camel_seekable_substream_type = gtk_type_unique (camel_seekable_stream_get_type (), &camel_seekable_substream_info);
    }
    
    return camel_seekable_substream_type;
}






static void           
_destroy (GtkObject *object)
{
    
    CAMEL_LOG_FULL_DEBUG ("Entering CamelSeekableSubstream::destroy\n");
    
    /* does nothing for the moment */
    GTK_OBJECT_CLASS (parent_class)->destroy (object);
    
    CAMEL_LOG_FULL_DEBUG ("Leaving CamelSeekableSubstream::destroy\n");
}


static void           
_finalize (GtkObject *object)
{
    CamelSeekableStream *seekable_stream;
    CAMEL_LOG_FULL_DEBUG ("Entering CamelSeekableSubstream::finalize\n");
    
    seekable_stream = CAMEL_SEEKABLE_STREAM (object);

    if (seekable_stream->parent_stream)
        gtk_object_unref (seekable_stream->parent_stream);

    GTK_OBJECT_CLASS (parent_class)->finalize (object);
    CAMEL_LOG_FULL_DEBUG ("Leaving CamelSeekableSubstream::finalize\n");
}



static void 
_set_bounds (CamelSeekableSubstream *seekable_substream, guint32 inf_bound, gint64 sup_bound)
{
    CAMEL_LOG_FULL_DEBUG ("CamelSeekableSubstream::_set_bounds entering\n");

    g_assert (seekable_substream);
    g_assert (seekable_substream->parent_stream);
    
    /* store the bounds */
    seekable_substream->inf_bound = inf_bound;
    seekable_substream->sup_bound = sup_bound;


    seekable_substream->cur_pos = 0;
    
    CAMEL_LOG_FULL_DEBUG ("In CamelSeekableSubstream::_set_bounds, "
                  "setting inf bound to %lu, "
                  "sup bound to %lld, current position to %lu from %lu\n", 
                  seekable_substream->inf_bound, seekable_substream->sup_bound,
                  seekable_substream->cur_pos, inf_bound);
    
    CAMEL_LOG_FULL_DEBUG ("CamelSeekableSubstream::_set_bounds Leaving\n");
}



static void        
_init_with_seekable_stream_and_bounds    (CamelSeekableSubstream *seekable_substream, 
                      CamelSeekableStream    *parent_stream,
                      guint32                 inf_bound, 
                      gint64                  sup_bound)
{
    /* sanity checks */
    g_assert (seekable_substream);
    g_assert (!seekable_substream->parent_stream);
    g_assert (parent_stream);
    
    /* store the parent stream */
    seekable_substream->parent_stream = parent_stream;
    gtk_object_ref (parent_stream);

    /* set the bound of the substream */
    _set_bounds (seekable_substream, inf_bound, sup_bound);
}



CamelSeekableSubstream *
camel_seekable_substream_new_with_seekable_stream_and_bounds (CamelSeekableStream    *parent_stream,
                                  guint32                 inf_bound, 
                                  gint64                  sup_bound)
{
    CamelSeekableSubstream *seekable_substream;

    /* create the seekable substream */
    seekable_substream = gtk_type_new (camel_seekable_substream_get_type ());

    /* initialize it */
    CSS_CLASS (seekable_substream)->init_with_seekable_stream_and_bounds (seekable_substream,
                                          parent_stream,
                                          inf_bound,
                                          sup_bound);
    return seekable_substream;
}





/**
 * _read: read bytes from a stream
 * @stream: stream
 * @buffer: buffer where bytes are stored
 * @n: max number of bytes to read
 * 
 * 
 * 
 * Return value: number of bytes actually read.
 **/
static gint
_read (CamelStream *stream, gchar *buffer, gint n)
{
    CamelSeekableStream *seekable_stream = CAMEL_SEEKABLE_STREAM (stream);
    CamelSeekableSubstream *seekable_substream = CAMEL_SEEKABLE_SUBSTREAM (stream);
    gint v;
    gint nb_to_read;
    guint32 parent_stream_current_position;
    guint32 position_in_parent;
    
    g_assert (stream);
    g_assert (seekable_substream->parent_stream);



    /* 
       we are doing something quite infefficient : 
       
       each time we want to read a block, we store
       the parent stream position so that we can 
       change it, and restore it before returning 

       This may change. I don't know yet. 
       It may be useless to reseek every time
       and is incompatible with buffering. 
    */

    parent_stream_current_position = 
        camel_seekable_stream_get_current_position (seekable_substream->parent_stream);

    /* compute the position in the parent stream */
    position_in_parent =  
        seekable_stream->cur_pos + seekable_substream->inf_bound;
        
    /* go to our position in the parent stream */
    if (parent_stream_current_position != position_in_parent)
        camel_seekable_stream_seek (seekable_substream->parent_stream, 
                        position_in_parent,
                        CAMEL_STREAM_SET);



    /* compute how much byte should be read */
    if (seekable_substream->sup_bound != -1)
        nb_to_read = 
            MIN (seekable_substream->sup_bound - position_in_parent, n);
    else
        nb_to_read = n;

    
    /* Read the data */
    if (nb_to_read >0 )
        v = camel_stream_read ( CAMEL_STREAM (seekable_substream->parent_stream), 
                    buffer, 
                    nb_to_read);
    else 
        v = 0;

    /* if the return value is negative, an error occured, 
       we must do something  FIXME : handle exception */ 
    if (v<0)
        CAMEL_LOG_FULL_DEBUG ("CamelSeekableSubstream::read v=%d\n", v);
    else 
        seekable_stream->cur_pos += v;



    /* return the number of bytes read */
    return v;
}


/**
 * _write: write bytes to a stream
 * @stream: the stream
 * @buffer: byte buffer
 * @n: number of bytes to write
 * 
 * 
 * 
 * Return value: the number of bytes actually written
 *  in the stream.
 **/
static gint
_write (CamelStream *stream, const gchar *buffer, gint n)
{
    /* NOT VALID ON SEEKABLE SUBSTREAM */
    g_warning ("CamelSeekableSubstream:: seekable substream don't have a write method\n");
    CAMEL_LOG_WARNING ( "CamelSeekableSubstream:: seekable substream don't have a write method\n");
    return -1;
}



/**
 * _flush: flush pending changes 
 * @stream: the stream
 * 
 * 
 **/
static void
_flush (CamelStream *stream)
{
    /* NOT VALID ON SEEKABLE SUBSTREAM */
    g_warning ("CamelSeekableSubstream:: seekable substream don't have a flush method\n");
    CAMEL_LOG_WARNING ( "CamelSeekableSubstream:: seekable substream don't have a flush method\n");
}



/**
 * _available: return the number of bytes available for reading
 * @stream: the stream
 * 
 * Return the number of bytes available without blocking.
 * 
 * Return value: the number of bytes available
 **/
static gint 
_available (CamelStream *stream)
{
    g_warning ("not implemented\n");
    return -1;
}


/**
 * _eos: test if there are bytes left to read
 * @stream: the stream
 * 
 * 
 * 
 * Return value: true if all stream has been read
 **/
static gboolean
_eos (CamelStream *stream)
{
    CamelSeekableSubstream *seekable_substream = CAMEL_SEEKABLE_SUBSTREAM (stream);
    CamelSeekableStream *seekable_stream = CAMEL_SEEKABLE_STREAM (stream);
    guint32 substream_len;
    gboolean eos;
    
    g_assert (stream);
    
    if (seekable_substream->sup_bound != -1) {
        substream_len = seekable_substream->sup_bound - seekable_substream->inf_bound;      
        eos = ( seekable_stream->cur_pos >= substream_len);
    } else {
        eos = camel_stream_eos (CAMEL_STREAM (seekable_substream->parent_stream));
    }
    
    return eos;
}


/**
 * _close: close a stream
 * @stream: the stream
 * 
 * 
 **/
static void
_close (CamelStream *stream)
{
    CamelSeekableSubstream *seekable_substream = CAMEL_SEEKABLE_SUBSTREAM (stream);

    g_assert (stream);
    seekable_substream->open = FALSE;
}


static gint
_seek (CamelSeekableStream *stream, gint offset, CamelStreamSeekPolicy policy)
{
    CamelSeekableSubstream *seekable_substream = CAMEL_SEEKABLE_SUBSTREAM (stream);
    CamelSeekableStream *seekable_stream = CAMEL_SEEKABLE_STREAM (stream);
    gint64 real_offset = 0; 
    guint32 substream_len;
    guint32 parent_pos;
    gboolean seek_done = FALSE;

    substream_len = seekable_substream->sup_bound - seekable_substream->inf_bound;
    
    switch  (policy) {

    case CAMEL_STREAM_SET:
        real_offset = offset;
        
        break;

    case CAMEL_STREAM_CUR:
        real_offset = seekable_stream->cur_pos + offset;
        
        break;

    case CAMEL_STREAM_END:
        if (seekable_substream->sup_bound != -1)
            real_offset = substream_len - offset;
        else {
            parent_pos = camel_seekable_stream_seek (seekable_substream->parent_stream, 
                                 offset, 
                                 CAMEL_STREAM_END);
            seekable_stream->cur_pos = parent_pos - seekable_substream->inf_bound;
            seek_done = TRUE;
        }

        break;

    default:
        return -1;
    }
    if (!seek_done) {
        if (real_offset > 0) {
            seekable_stream->cur_pos = MIN (real_offset, substream_len);
        } else 
            seekable_stream->cur_pos = 0;
    }
    

    return seekable_stream->cur_pos;
}