gio/gbufferedinputstream.c

   1 /* GIO - GLib Input, Output and Streaming Library
   2  *
   3  * Copyright (C) 2006-2007 Red Hat, Inc.
   4  * Copyright (C) 2007 Jürg Billeter
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General
  17  * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  *
  19  * Author: Christian Kellner <gicmo@gnome.org>
  20  */
  21
  22 #include "config.h"
  23 #include "gbufferedinputstream.h"
  24 #include "ginputstream.h"
  25 #include "gcancellable.h"
  26 #include "gasyncresult.h"
  27 #include "gtask.h"
  28 #include "gseekable.h"
  29 #include "gioerror.h"
  30 #include <string.h>
  31 #include "glibintl.h"
  32
  33
  34 /**
  35  * SECTION:gbufferedinputstream
  36  * @short_description: Buffered Input Stream
  37  * @include: gio/gio.h
  38  * @see_also: #GFilterInputStream, #GInputStream
  39  *
  40  * Buffered input stream implements #GFilterInputStream and provides
  41  * for buffered reads.
  42  *
  43  * By default, #GBufferedInputStream's buffer size is set at 4 kilobytes.
  44  *
  45  * To create a buffered input stream, use g_buffered_input_stream_new(),
  46  * or g_buffered_input_stream_new_sized() to specify the buffer's size at
  47  * construction.
  48  *
  49  * To get the size of a buffer within a buffered input stream, use
  50  * g_buffered_input_stream_get_buffer_size(). To change the size of a
  51  * buffered input stream's buffer, use
  52  * g_buffered_input_stream_set_buffer_size(). Note that the buffer's size
  53  * cannot be reduced below the size of the data within the buffer.
  54  */
  55
  56
  57 #define DEFAULT_BUFFER_SIZE 4096
  58
  59 struct _GBufferedInputStreamPrivate {
  60   guint8 *buffer;
  61   gsize   len;
  62   gsize   pos;
  63   gsize   end;
  64   GAsyncReadyCallback outstanding_callback;
  65 };
  66
  67 enum {
  68   PROP_0,
  69   PROP_BUFSIZE
  70 };
  71
  72 static void g_buffered_input_stream_set_property  (GObject      *object,
  73                                                    guint         prop_id,
  74                                                    const GValue *value,
  75                                                    GParamSpec   *pspec);
  76
  77 static void g_buffered_input_stream_get_property  (GObject      *object,
  78                                                    guint         prop_id,
  79                                                    GValue       *value,
  80                                                    GParamSpec   *pspec);
  81 static void g_buffered_input_stream_finalize      (GObject *object);
  82
  83
  84 static gssize g_buffered_input_stream_skip             (GInputStream          *stream,
  85                                                         gsize                  count,
  86                                                         GCancellable          *cancellable,
  87                                                         GError               **error);
  88 static void   g_buffered_input_stream_skip_async       (GInputStream          *stream,
  89                                                         gsize                  count,
  90                                                         int                    io_priority,
  91                                                         GCancellable          *cancellable,
  92                                                         GAsyncReadyCallback    callback,
  93                                                         gpointer               user_data);
  94 static gssize g_buffered_input_stream_skip_finish      (GInputStream          *stream,
  95                                                         GAsyncResult          *result,
  96                                                         GError               **error);
  97 static gssize g_buffered_input_stream_read             (GInputStream          *stream,
  98                                                         void                  *buffer,
  99                                                         gsize                  count,
 100                                                         GCancellable          *cancellable,
 101                                                         GError               **error);
 102 static gssize g_buffered_input_stream_real_fill        (GBufferedInputStream  *stream,
 103                                                         gssize                 count,
 104                                                         GCancellable          *cancellable,
 105                                                         GError               **error);
 106 static void   g_buffered_input_stream_real_fill_async  (GBufferedInputStream  *stream,
 107                                                         gssize                 count,
 108                                                         int                    io_priority,
 109                                                         GCancellable          *cancellable,
 110                                                         GAsyncReadyCallback    callback,
 111                                                         gpointer               user_data);
 112 static gssize g_buffered_input_stream_real_fill_finish (GBufferedInputStream  *stream,
 113                                                         GAsyncResult          *result,
 114                                                         GError               **error);
 115
 116 static void     g_buffered_input_stream_seekable_iface_init (GSeekableIface  *iface);
 117 static goffset  g_buffered_input_stream_tell                (GSeekable       *seekable);
 118 static gboolean g_buffered_input_stream_can_seek            (GSeekable       *seekable);
 119 static gboolean g_buffered_input_stream_seek                (GSeekable       *seekable,
 120                                                              goffset          offset,
 121                                                              GSeekType        type,
 122                                                              GCancellable    *cancellable,
 123                                                              GError         **error);
 124 static gboolean g_buffered_input_stream_can_truncate        (GSeekable       *seekable);
 125 static gboolean g_buffered_input_stream_truncate            (GSeekable       *seekable,
 126                                                              goffset          offset,
 127                                                              GCancellable    *cancellable,
 128                                                              GError         **error);
 129
 130 static void compact_buffer (GBufferedInputStream *stream);
 131
 132 G_DEFINE_TYPE_WITH_CODE (GBufferedInputStream,
 133                          g_buffered_input_stream,
 134                          G_TYPE_FILTER_INPUT_STREAM,
 135                          G_ADD_PRIVATE (GBufferedInputStream)
 136                          G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
 137                                                 g_buffered_input_stream_seekable_iface_init))
 138
 139 static void
 140 g_buffered_input_stream_class_init (GBufferedInputStreamClass *klass)
 141 {
 142   GObjectClass *object_class;
 143   GInputStreamClass *istream_class;
 144   GBufferedInputStreamClass *bstream_class;
 145
 146   object_class = G_OBJECT_CLASS (klass);
 147   object_class->get_property = g_buffered_input_stream_get_property;
 148   object_class->set_property = g_buffered_input_stream_set_property;
 149   object_class->finalize     = g_buffered_input_stream_finalize;
 150
 151   istream_class = G_INPUT_STREAM_CLASS (klass);
 152   istream_class->skip = g_buffered_input_stream_skip;
 153   istream_class->skip_async  = g_buffered_input_stream_skip_async;
 154   istream_class->skip_finish = g_buffered_input_stream_skip_finish;
 155   istream_class->read_fn = g_buffered_input_stream_read;
 156
 157   bstream_class = G_BUFFERED_INPUT_STREAM_CLASS (klass);
 158   bstream_class->fill = g_buffered_input_stream_real_fill;
 159   bstream_class->fill_async = g_buffered_input_stream_real_fill_async;
 160   bstream_class->fill_finish = g_buffered_input_stream_real_fill_finish;
 161
 162   g_object_class_install_property (object_class,
 163                                    PROP_BUFSIZE,
 164                                    g_param_spec_uint ("buffer-size",
 165                                                       P_("Buffer Size"),
 166                                                       P_("The size of the backend buffer"),
 167                                                       1,
 168                                                       G_MAXUINT,
 169                                                       DEFAULT_BUFFER_SIZE,
 170                                                       G_PARAM_READWRITE | G_PARAM_CONSTRUCT |
 171                                                       G_PARAM_STATIC_NAME|G_PARAM_STATIC_NICK|G_PARAM_STATIC_BLURB));
 172
 173
 174 }
 175
 176 /**
 177  * g_buffered_input_stream_get_buffer_size:
 178  * @stream: a #GBufferedInputStream
 179  *
 180  * Gets the size of the input buffer.
 181  *
 182  * Returns: the current buffer size.
 183  */
 184 gsize
 185 g_buffered_input_stream_get_buffer_size (GBufferedInputStream  *stream)
 186 {
 187   g_return_val_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream), 0);
 188
 189   return stream->priv->len;
 190 }
 191
 192 /**
 193  * g_buffered_input_stream_set_buffer_size:
 194  * @stream: a #GBufferedInputStream
 195  * @size: a #gsize
 196  *
 197  * Sets the size of the internal buffer of @stream to @size, or to the
 198  * size of the contents of the buffer. The buffer can never be resized
 199  * smaller than its current contents.
 200  */
 201 void
 202 g_buffered_input_stream_set_buffer_size (GBufferedInputStream *stream,
 203                                          gsize                 size)
 204 {
 205   GBufferedInputStreamPrivate *priv;
 206   gsize in_buffer;
 207   guint8 *buffer;
 208
 209   g_return_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream));
 210
 211   priv = stream->priv;
 212
 213   if (priv->len == size)
 214     return;
 215
 216   if (priv->buffer)
 217     {
 218       in_buffer = priv->end - priv->pos;
 219
 220       /* Never resize smaller than current buffer contents */
 221       size = MAX (size, in_buffer);
 222
 223       buffer = g_malloc (size);
 224       memcpy (buffer, priv->buffer + priv->pos, in_buffer);
 225       priv->len = size;
 226       priv->pos = 0;
 227       priv->end = in_buffer;
 228       g_free (priv->buffer);
 229       priv->buffer = buffer;
 230     }
 231   else
 232     {
 233       priv->len = size;
 234       priv->pos = 0;
 235       priv->end = 0;
 236       priv->buffer = g_malloc (size);
 237     }
 238
 239   g_object_notify (G_OBJECT (stream), "buffer-size");
 240 }
 241
 242 static void
 243 g_buffered_input_stream_set_property (GObject      *object,
 244                                       guint         prop_id,
 245                                       const GValue *value,
 246                                       GParamSpec   *pspec)
 247 {
 248   GBufferedInputStream        *bstream;
 249
 250   bstream = G_BUFFERED_INPUT_STREAM (object);
 251
 252   switch (prop_id)
 253     {
 254     case PROP_BUFSIZE:
 255       g_buffered_input_stream_set_buffer_size (bstream, g_value_get_uint (value));
 256       break;
 257
 258     default:
 259       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
 260       break;
 261     }
 262 }
 263
 264 static void
 265 g_buffered_input_stream_get_property (GObject    *object,
 266                                       guint       prop_id,
 267                                       GValue     *value,
 268                                       GParamSpec *pspec)
 269 {
 270   GBufferedInputStreamPrivate *priv;
 271   GBufferedInputStream        *bstream;
 272
 273   bstream = G_BUFFERED_INPUT_STREAM (object);
 274   priv = bstream->priv;
 275
 276   switch (prop_id)
 277     {
 278     case PROP_BUFSIZE:
 279       g_value_set_uint (value, priv->len);
 280       break;
 281
 282     default:
 283       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
 284       break;
 285     }
 286 }
 287
 288 static void
 289 g_buffered_input_stream_finalize (GObject *object)
 290 {
 291   GBufferedInputStreamPrivate *priv;
 292   GBufferedInputStream        *stream;
 293
 294   stream = G_BUFFERED_INPUT_STREAM (object);
 295   priv = stream->priv;
 296
 297   g_free (priv->buffer);
 298
 299   G_OBJECT_CLASS (g_buffered_input_stream_parent_class)->finalize (object);
 300 }
 301
 302 static void
 303 g_buffered_input_stream_seekable_iface_init (GSeekableIface *iface)
 304 {
 305   iface->tell         = g_buffered_input_stream_tell;
 306   iface->can_seek     = g_buffered_input_stream_can_seek;
 307   iface->seek         = g_buffered_input_stream_seek;
 308   iface->can_truncate = g_buffered_input_stream_can_truncate;
 309   iface->truncate_fn  = g_buffered_input_stream_truncate;
 310 }
 311
 312 static void
 313 g_buffered_input_stream_init (GBufferedInputStream *stream)
 314 {
 315   stream->priv = g_buffered_input_stream_get_instance_private (stream);
 316 }
 317
 318
 319 /**
 320  * g_buffered_input_stream_new:
 321  * @base_stream: a #GInputStream
 322  *
 323  * Creates a new #GInputStream from the given @base_stream, with
 324  * a buffer set to the default size (4 kilobytes).
 325  *
 326  * Returns: a #GInputStream for the given @base_stream.
 327  */
 328 GInputStream *
 329 g_buffered_input_stream_new (GInputStream *base_stream)
 330 {
 331   GInputStream *stream;
 332
 333   g_return_val_if_fail (G_IS_INPUT_STREAM (base_stream), NULL);
 334
 335   stream = g_object_new (G_TYPE_BUFFERED_INPUT_STREAM,
 336                          "base-stream", base_stream,
 337                          NULL);
 338
 339   return stream;
 340 }
 341
 342 /**
 343  * g_buffered_input_stream_new_sized:
 344  * @base_stream: a #GInputStream
 345  * @size: a #gsize
 346  *
 347  * Creates a new #GBufferedInputStream from the given @base_stream,
 348  * with a buffer set to @size.
 349  *
 350  * Returns: a #GInputStream.
 351  */
 352 GInputStream *
 353 g_buffered_input_stream_new_sized (GInputStream *base_stream,
 354                                    gsize         size)
 355 {
 356   GInputStream *stream;
 357
 358   g_return_val_if_fail (G_IS_INPUT_STREAM (base_stream), NULL);
 359
 360   stream = g_object_new (G_TYPE_BUFFERED_INPUT_STREAM,
 361                          "base-stream", base_stream,
 362                          "buffer-size", (guint)size,
 363                          NULL);
 364
 365   return stream;
 366 }
 367
 368 /**
 369  * g_buffered_input_stream_fill:
 370  * @stream: a #GBufferedInputStream
 371  * @count: the number of bytes that will be read from the stream
 372  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore
 373  * @error: location to store the error occurring, or %NULL to ignore
 374  *
 375  * Tries to read @count bytes from the stream into the buffer.
 376  * Will block during this read.
 377  *
 378  * If @count is zero, returns zero and does nothing. A value of @count
 379  * larger than %G_MAXSSIZE will cause a %G_IO_ERROR_INVALID_ARGUMENT error.
 380  *
 381  * On success, the number of bytes read into the buffer is returned.
 382  * It is not an error if this is not the same as the requested size, as it
 383  * can happen e.g. near the end of a file. Zero is returned on end of file
 384  * (or if @count is zero),  but never otherwise.
 385  *
 386  * If @count is -1 then the attempted read size is equal to the number of
 387  * bytes that are required to fill the buffer.
 388  *
 389  * If @cancellable is not %NULL, then the operation can be cancelled by
 390  * triggering the cancellable object from another thread. If the operation
 391  * was cancelled, the error %G_IO_ERROR_CANCELLED will be returned. If an
 392  * operation was partially finished when the operation was cancelled the
 393  * partial result will be returned, without an error.
 394  *
 395  * On error -1 is returned and @error is set accordingly.
 396  *
 397  * For the asynchronous, non-blocking, version of this function, see
 398  * g_buffered_input_stream_fill_async().
 399  *
 400  * Returns: the number of bytes read into @stream's buffer, up to @count,
 401  *     or -1 on error.
 402  */
 403 gssize
 404 g_buffered_input_stream_fill (GBufferedInputStream  *stream,
 405                               gssize                 count,
 406                               GCancellable          *cancellable,
 407                               GError               **error)
 408 {
 409   GBufferedInputStreamClass *class;
 410   GInputStream *input_stream;
 411   gssize res;
 412
 413   g_return_val_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream), -1);
 414
 415   input_stream = G_INPUT_STREAM (stream);
 416
 417   if (count < -1)
 418     {
 419       g_set_error (error, G_IO_ERROR, G_IO_ERROR_INVALID_ARGUMENT,
 420                    _("Too large count value passed to %s"), G_STRFUNC);
 421       return -1;
 422     }
 423
 424   if (!g_input_stream_set_pending (input_stream, error))
 425     return -1;
 426
 427   if (cancellable)
 428     g_cancellable_push_current (cancellable);
 429
 430   class = G_BUFFERED_INPUT_STREAM_GET_CLASS (stream);
 431   res = class->fill (stream, count, cancellable, error);
 432
 433   if (cancellable)
 434     g_cancellable_pop_current (cancellable);
 435
 436   g_input_stream_clear_pending (input_stream);
 437
 438   return res;
 439 }
 440
 441 static void
 442 async_fill_callback_wrapper (GObject      *source_object,
 443                              GAsyncResult *res,
 444                              gpointer      user_data)
 445 {
 446   GBufferedInputStream *stream = G_BUFFERED_INPUT_STREAM (source_object);
 447
 448   g_input_stream_clear_pending (G_INPUT_STREAM (stream));
 449   (*stream->priv->outstanding_callback) (source_object, res, user_data);
 450   g_object_unref (stream);
 451 }
 452
 453 /**
 454  * g_buffered_input_stream_fill_async:
 455  * @stream: a #GBufferedInputStream
 456  * @count: the number of bytes that will be read from the stream
 457  * @io_priority: the <link linkend="io-priority">I/O priority</link>
 458  *     of the request
 459  * @cancellable: (allow-none): optional #GCancellable object
 460  * @callback: (scope async): a #GAsyncReadyCallback
 461  * @user_data: (closure): a #gpointer
 462  *
 463  * Reads data into @stream's buffer asynchronously, up to @count size.
 464  * @io_priority can be used to prioritize reads. For the synchronous
 465  * version of this function, see g_buffered_input_stream_fill().
 466  *
 467  * If @count is -1 then the attempted read size is equal to the number
 468  * of bytes that are required to fill the buffer.
 469  */
 470 void
 471 g_buffered_input_stream_fill_async (GBufferedInputStream *stream,
 472                                     gssize                count,
 473                                     int                   io_priority,
 474                                     GCancellable         *cancellable,
 475                                     GAsyncReadyCallback   callback,
 476                                     gpointer              user_data)
 477 {
 478   GBufferedInputStreamClass *class;
 479   GError *error = NULL;
 480
 481   g_return_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream));
 482
 483   if (count == 0)
 484     {
 485       GTask *task;
 486
 487       task = g_task_new (stream, cancellable, callback, user_data);
 488       g_task_set_source_tag (task, g_buffered_input_stream_fill_async);
 489       g_task_return_int (task, 0);
 490       g_object_unref (task);
 491       return;
 492     }
 493
 494   if (count < -1)
 495     {
 496       g_task_report_new_error (stream, callback, user_data,
 497                                g_buffered_input_stream_fill_async,
 498                                G_IO_ERROR, G_IO_ERROR_INVALID_ARGUMENT,
 499                                _("Too large count value passed to %s"),
 500                                G_STRFUNC);
 501       return;
 502     }
 503
 504   if (!g_input_stream_set_pending (G_INPUT_STREAM (stream), &error))
 505     {
 506       g_task_report_error (stream, callback, user_data,
 507                            g_buffered_input_stream_fill_async,
 508                            error);
 509       return;
 510     }
 511
 512   class = G_BUFFERED_INPUT_STREAM_GET_CLASS (stream);
 513
 514   stream->priv->outstanding_callback = callback;
 515   g_object_ref (stream);
 516   class->fill_async (stream, count, io_priority, cancellable,
 517                      async_fill_callback_wrapper, user_data);
 518 }
 519
 520 /**
 521  * g_buffered_input_stream_fill_finish:
 522  * @stream: a #GBufferedInputStream
 523  * @result: a #GAsyncResult
 524  * @error: a #GError
 525  *
 526  * Finishes an asynchronous read.
 527  *
 528  * Returns: a #gssize of the read stream, or %-1 on an error.
 529  */
 530 gssize
 531 g_buffered_input_stream_fill_finish (GBufferedInputStream  *stream,
 532                                      GAsyncResult          *result,
 533                                      GError               **error)
 534 {
 535   GBufferedInputStreamClass *class;
 536
 537   g_return_val_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream), -1);
 538   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), -1);
 539
 540   if (g_async_result_legacy_propagate_error (result, error))
 541     return -1;
 542   else if (g_async_result_is_tagged (result, g_buffered_input_stream_fill_async))
 543     return g_task_propagate_int (G_TASK (result), error);
 544
 545   class = G_BUFFERED_INPUT_STREAM_GET_CLASS (stream);
 546   return class->fill_finish (stream, result, error);
 547 }
 548
 549 /**
 550  * g_buffered_input_stream_get_available:
 551  * @stream: #GBufferedInputStream
 552  *
 553  * Gets the size of the available data within the stream.
 554  *
 555  * Returns: size of the available stream.
 556  */
 557 gsize
 558 g_buffered_input_stream_get_available (GBufferedInputStream *stream)
 559 {
 560   g_return_val_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream), -1);
 561
 562   return stream->priv->end - stream->priv->pos;
 563 }
 564
 565 /**
 566  * g_buffered_input_stream_peek:
 567  * @stream: a #GBufferedInputStream
 568  * @buffer: (array length=count) (element-type guint8): a pointer to
 569  *   an allocated chunk of memory
 570  * @offset: a #gsize
 571  * @count: a #gsize
 572  *
 573  * Peeks in the buffer, copying data of size @count into @buffer,
 574  * offset @offset bytes.
 575  *
 576  * Returns: a #gsize of the number of bytes peeked, or -1 on error.
 577  */
 578 gsize
 579 g_buffered_input_stream_peek (GBufferedInputStream *stream,
 580                               void                 *buffer,
 581                               gsize                 offset,
 582                               gsize                 count)
 583 {
 584   gsize available;
 585   gsize end;
 586
 587   g_return_val_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream), -1);
 588   g_return_val_if_fail (buffer != NULL, -1);
 589
 590   available = g_buffered_input_stream_get_available (stream);
 591
 592   if (offset > available)
 593     return 0;
 594
 595   end = MIN (offset + count, available);
 596   count = end - offset;
 597
 598   memcpy (buffer, stream->priv->buffer + stream->priv->pos + offset, count);
 599   return count;
 600 }
 601
 602 /**
 603  * g_buffered_input_stream_peek_buffer:
 604  * @stream: a #GBufferedInputStream
 605  * @count: (out): a #gsize to get the number of bytes available in the buffer
 606  *
 607  * Returns the buffer with the currently available bytes. The returned
 608  * buffer must not be modified and will become invalid when reading from
 609  * the stream or filling the buffer.
 610  *
 611  * Returns: (array length=count) (element-type guint8) (transfer none):
 612  *          read-only buffer
 613  */
 614 const void*
 615 g_buffered_input_stream_peek_buffer (GBufferedInputStream *stream,
 616                                      gsize                *count)
 617 {
 618   GBufferedInputStreamPrivate *priv;
 619
 620   g_return_val_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream), NULL);
 621
 622   priv = stream->priv;
 623
 624   if (count)
 625     *count = priv->end - priv->pos;
 626
 627   return priv->buffer + priv->pos;
 628 }
 629
 630 static void
 631 compact_buffer (GBufferedInputStream *stream)
 632 {
 633   GBufferedInputStreamPrivate *priv;
 634   gsize current_size;
 635
 636   priv = stream->priv;
 637
 638   current_size = priv->end - priv->pos;
 639
 640   memmove (priv->buffer, priv->buffer + priv->pos, current_size);
 641
 642   priv->pos = 0;
 643   priv->end = current_size;
 644 }
 645
 646 static gssize
 647 g_buffered_input_stream_real_fill (GBufferedInputStream  *stream,
 648                                    gssize                 count,
 649                                    GCancellable          *cancellable,
 650                                    GError               **error)
 651 {
 652   GBufferedInputStreamPrivate *priv;
 653   GInputStream *base_stream;
 654   gssize nread;
 655   gsize in_buffer;
 656
 657   priv = stream->priv;
 658
 659   if (count == -1)
 660     count = priv->len;
 661
 662   in_buffer = priv->end - priv->pos;
 663
 664   /* Never fill more than can fit in the buffer */
 665   count = MIN (count, priv->len - in_buffer);
 666
 667   /* If requested length does not fit at end, compact */
 668   if (priv->len - priv->end < count)
 669     compact_buffer (stream);
 670
 671   base_stream = G_FILTER_INPUT_STREAM (stream)->base_stream;
 672   nread = g_input_stream_read (base_stream,
 673                                priv->buffer + priv->end,
 674                                count,
 675                                cancellable,
 676                                error);
 677
 678   if (nread > 0)
 679     priv->end += nread;
 680
 681   return nread;
 682 }
 683
 684 static gssize
 685 g_buffered_input_stream_skip (GInputStream  *stream,
 686                               gsize          count,
 687                               GCancellable  *cancellable,
 688                               GError       **error)
 689 {
 690   GBufferedInputStream        *bstream;
 691   GBufferedInputStreamPrivate *priv;
 692   GBufferedInputStreamClass *class;
 693   GInputStream *base_stream;
 694   gsize available, bytes_skipped;
 695   gssize nread;
 696
 697   bstream = G_BUFFERED_INPUT_STREAM (stream);
 698   priv = bstream->priv;
 699
 700   available = priv->end - priv->pos;
 701
 702   if (count <= available)
 703     {
 704       priv->pos += count;
 705       return count;
 706     }
 707
 708   /* Full request not available, skip all currently available and
 709    * request refill for more
 710    */
 711
 712   priv->pos = 0;
 713   priv->end = 0;
 714   bytes_skipped = available;
 715   count -= available;
 716
 717   if (bytes_skipped > 0)
 718     error = NULL; /* Ignore further errors if we already read some data */
 719
 720   if (count > priv->len)
 721     {
 722       /* Large request, shortcut buffer */
 723
 724       base_stream = G_FILTER_INPUT_STREAM (stream)->base_stream;
 725
 726       nread = g_input_stream_skip (base_stream,
 727                                    count,
 728                                    cancellable,
 729                                    error);
 730
 731       if (nread < 0 && bytes_skipped == 0)
 732         return -1;
 733
 734       if (nread > 0)
 735         bytes_skipped += nread;
 736
 737       return bytes_skipped;
 738     }
 739
 740   class = G_BUFFERED_INPUT_STREAM_GET_CLASS (stream);
 741   nread = class->fill (bstream, priv->len, cancellable, error);
 742
 743   if (nread < 0)
 744     {
 745       if (bytes_skipped == 0)
 746         return -1;
 747       else
 748         return bytes_skipped;
 749     }
 750
 751   available = priv->end - priv->pos;
 752   count = MIN (count, available);
 753
 754   bytes_skipped += count;
 755   priv->pos += count;
 756
 757   return bytes_skipped;
 758 }
 759
 760 static gssize
 761 g_buffered_input_stream_read (GInputStream *stream,
 762                               void         *buffer,
 763                               gsize         count,
 764                               GCancellable *cancellable,
 765                               GError      **error)
 766 {
 767   GBufferedInputStream        *bstream;
 768   GBufferedInputStreamPrivate *priv;
 769   GBufferedInputStreamClass *class;
 770   GInputStream *base_stream;
 771   gsize available, bytes_read;
 772   gssize nread;
 773
 774   bstream = G_BUFFERED_INPUT_STREAM (stream);
 775   priv = bstream->priv;
 776
 777   available = priv->end - priv->pos;
 778
 779   if (count <= available)
 780     {
 781       memcpy (buffer, priv->buffer + priv->pos, count);
 782       priv->pos += count;
 783       return count;
 784     }
 785
 786   /* Full request not available, read all currently available and
 787    * request refill for more
 788    */
 789
 790   memcpy (buffer, priv->buffer + priv->pos, available);
 791   priv->pos = 0;
 792   priv->end = 0;
 793   bytes_read = available;
 794   count -= available;
 795
 796   if (bytes_read > 0)
 797     error = NULL; /* Ignore further errors if we already read some data */
 798
 799   if (count > priv->len)
 800     {
 801       /* Large request, shortcut buffer */
 802
 803       base_stream = G_FILTER_INPUT_STREAM (stream)->base_stream;
 804
 805       nread = g_input_stream_read (base_stream,
 806                                    (char *)buffer + bytes_read,
 807                                    count,
 808                                    cancellable,
 809                                    error);
 810
 811       if (nread < 0 && bytes_read == 0)
 812         return -1;
 813
 814       if (nread > 0)
 815         bytes_read += nread;
 816
 817       return bytes_read;
 818     }
 819
 820   class = G_BUFFERED_INPUT_STREAM_GET_CLASS (stream);
 821   nread = class->fill (bstream, priv->len, cancellable, error);
 822   if (nread < 0)
 823     {
 824       if (bytes_read == 0)
 825         return -1;
 826       else
 827         return bytes_read;
 828     }
 829
 830   available = priv->end - priv->pos;
 831   count = MIN (count, available);
 832
 833   memcpy ((char *)buffer + bytes_read, (char *)priv->buffer + priv->pos, count);
 834   bytes_read += count;
 835   priv->pos += count;
 836
 837   return bytes_read;
 838 }
 839
 840 static goffset
 841 g_buffered_input_stream_tell (GSeekable *seekable)
 842 {
 843   GBufferedInputStream        *bstream;
 844   GBufferedInputStreamPrivate *priv;
 845   GInputStream *base_stream;
 846   GSeekable    *base_stream_seekable;
 847   gsize available;
 848   goffset base_offset;
 849
 850   bstream = G_BUFFERED_INPUT_STREAM (seekable);
 851   priv = bstream->priv;
 852
 853   base_stream = G_FILTER_INPUT_STREAM (seekable)->base_stream;
 854   if (!G_IS_SEEKABLE (base_stream))
 855     return 0;
 856   base_stream_seekable = G_SEEKABLE (base_stream);
 857
 858   available = priv->end - priv->pos;
 859   base_offset = g_seekable_tell (base_stream_seekable);
 860
 861   return base_offset - available;
 862 }
 863
 864 static gboolean
 865 g_buffered_input_stream_can_seek (GSeekable *seekable)
 866 {
 867   GInputStream *base_stream;
 868
 869   base_stream = G_FILTER_INPUT_STREAM (seekable)->base_stream;
 870   return G_IS_SEEKABLE (base_stream) && g_seekable_can_seek (G_SEEKABLE (base_stream));
 871 }
 872
 873 static gboolean
 874 g_buffered_input_stream_seek (GSeekable     *seekable,
 875                               goffset        offset,
 876                               GSeekType      type,
 877                               GCancellable  *cancellable,
 878                               GError       **error)
 879 {
 880   GBufferedInputStream        *bstream;
 881   GBufferedInputStreamPrivate *priv;
 882   GInputStream *base_stream;
 883   GSeekable *base_stream_seekable;
 884
 885   bstream = G_BUFFERED_INPUT_STREAM (seekable);
 886   priv = bstream->priv;
 887
 888   base_stream = G_FILTER_INPUT_STREAM (seekable)->base_stream;
 889   if (!G_IS_SEEKABLE (base_stream))
 890     {
 891       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 892                            _("Seek not supported on base stream"));
 893       return FALSE;
 894     }
 895
 896   base_stream_seekable = G_SEEKABLE (base_stream);
 897
 898   if (type == G_SEEK_CUR)
 899     {
 900       if (offset <= priv->end - priv->pos && offset >= -priv->pos)
 901         {
 902           priv->pos += offset;
 903           return TRUE;
 904         }
 905       else
 906         {
 907           offset -= priv->end - priv->pos;
 908         }
 909     }
 910
 911   if (g_seekable_seek (base_stream_seekable, offset, type, cancellable, error))
 912     {
 913       priv->pos = 0;
 914       priv->end = 0;
 915       return TRUE;
 916     }
 917   else
 918     {
 919       return FALSE;
 920     }
 921 }
 922
 923 static gboolean
 924 g_buffered_input_stream_can_truncate (GSeekable *seekable)
 925 {
 926   return FALSE;
 927 }
 928
 929 static gboolean
 930 g_buffered_input_stream_truncate (GSeekable     *seekable,
 931                                   goffset        offset,
 932                                   GCancellable  *cancellable,
 933                                   GError       **error)
 934 {
 935   g_set_error_literal (error,
 936                        G_IO_ERROR,
 937                        G_IO_ERROR_NOT_SUPPORTED,
 938                        _("Cannot truncate GBufferedInputStream"));
 939   return FALSE;
 940 }
 941
 942 /**
 943  * g_buffered_input_stream_read_byte:
 944  * @stream: a #GBufferedInputStream
 945  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore
 946  * @error: location to store the error occurring, or %NULL to ignore
 947  *
 948  * Tries to read a single byte from the stream or the buffer. Will block
 949  * during this read.
 950  *
 951  * On success, the byte read from the stream is returned. On end of stream
 952  * -1 is returned but it's not an exceptional error and @error is not set.
 953  *
 954  * If @cancellable is not %NULL, then the operation can be cancelled by
 955  * triggering the cancellable object from another thread. If the operation
 956  * was cancelled, the error %G_IO_ERROR_CANCELLED will be returned. If an
 957  * operation was partially finished when the operation was cancelled the
 958  * partial result will be returned, without an error.
 959  *
 960  * On error -1 is returned and @error is set accordingly.
 961  *
 962  * Returns: the byte read from the @stream, or -1 on end of stream or error.
 963  */
 964 int
 965 g_buffered_input_stream_read_byte (GBufferedInputStream  *stream,
 966                                    GCancellable          *cancellable,
 967                                    GError               **error)
 968 {
 969   GBufferedInputStreamPrivate *priv;
 970   GBufferedInputStreamClass *class;
 971   GInputStream *input_stream;
 972   gsize available;
 973   gssize nread;
 974
 975   g_return_val_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream), -1);
 976
 977   priv = stream->priv;
 978   input_stream = G_INPUT_STREAM (stream);
 979
 980   if (g_input_stream_is_closed (input_stream))
 981     {
 982       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_CLOSED,
 983                            _("Stream is already closed"));
 984       return -1;
 985     }
 986
 987   if (!g_input_stream_set_pending (input_stream, error))
 988     return -1;
 989
 990   available = priv->end - priv->pos;
 991
 992   if (available != 0)
 993     {
 994       g_input_stream_clear_pending (input_stream);
 995       return priv->buffer[priv->pos++];
 996     }
 997
 998   /* Byte not available, request refill for more */
 999
1000   if (cancellable)
1001     g_cancellable_push_current (cancellable);
1002
1003   priv->pos = 0;
1004   priv->end = 0;
1005
1006   class = G_BUFFERED_INPUT_STREAM_GET_CLASS (stream);
1007   nread = class->fill (stream, priv->len, cancellable, error);
1008
1009   if (cancellable)
1010     g_cancellable_pop_current (cancellable);
1011
1012   g_input_stream_clear_pending (input_stream);
1013
1014   if (nread <= 0)
1015     return -1; /* error or end of stream */
1016
1017   return priv->buffer[priv->pos++];
1018 }
1019
1020 /* ************************** */
1021 /* Async stuff implementation */
1022 /* ************************** */
1023
1024 static void
1025 fill_async_callback (GObject      *source_object,
1026                      GAsyncResult *result,
1027                      gpointer      user_data)
1028 {
1029   GError *error;
1030   gssize res;
1031   GTask *task = user_data;
1032
1033   error = NULL;
1034   res = g_input_stream_read_finish (G_INPUT_STREAM (source_object),
1035                                     result, &error);
1036   if (res == -1)
1037     g_task_return_error (task, error);
1038   else
1039     {
1040       GBufferedInputStream *stream;
1041       GBufferedInputStreamPrivate *priv;
1042
1043       stream = g_task_get_source_object (task);
1044       priv = G_BUFFERED_INPUT_STREAM (stream)->priv;
1045
1046       g_assert_cmpint (priv->end + res, <=, priv->len);
1047       priv->end += res;
1048
1049       g_task_return_int (task, res);
1050     }
1051
1052   g_object_unref (task);
1053 }
1054
1055 static void
1056 g_buffered_input_stream_real_fill_async (GBufferedInputStream *stream,
1057                                          gssize                count,
1058                                          int                   io_priority,
1059                                          GCancellable         *cancellable,
1060                                          GAsyncReadyCallback   callback,
1061                                          gpointer              user_data)
1062 {
1063   GBufferedInputStreamPrivate *priv;
1064   GInputStream *base_stream;
1065   GTask *task;
1066   gsize in_buffer;
1067
1068   priv = stream->priv;
1069
1070   if (count == -1)
1071     count = priv->len;
1072
1073   in_buffer = priv->end - priv->pos;
1074
1075   /* Never fill more than can fit in the buffer */
1076   count = MIN (count, priv->len - in_buffer);
1077
1078   /* If requested length does not fit at end, compact */
1079   if (priv->len - priv->end < count)
1080     compact_buffer (stream);
1081
1082   task = g_task_new (stream, cancellable, callback, user_data);
1083
1084   base_stream = G_FILTER_INPUT_STREAM (stream)->base_stream;
1085   g_input_stream_read_async (base_stream,
1086                              priv->buffer + priv->end,
1087                              count,
1088                              io_priority,
1089                              cancellable,
1090                              fill_async_callback,
1091                              task);
1092 }
1093
1094 static gssize
1095 g_buffered_input_stream_real_fill_finish (GBufferedInputStream *stream,
1096                                           GAsyncResult         *result,
1097                                           GError              **error)
1098 {
1099   g_return_val_if_fail (g_task_is_valid (result, stream), -1);
1100
1101   return g_task_propagate_int (G_TASK (result), error);
1102 }
1103
1104 typedef struct
1105 {
1106   gssize bytes_skipped;
1107   gssize count;
1108 } SkipAsyncData;
1109
1110 static void
1111 free_skip_async_data (gpointer _data)
1112 {
1113   SkipAsyncData *data = _data;
1114   g_slice_free (SkipAsyncData, data);
1115 }
1116
1117 static void
1118 large_skip_callback (GObject      *source_object,
1119                      GAsyncResult *result,
1120                      gpointer      user_data)
1121 {
1122   GTask *task = G_TASK (user_data);
1123   SkipAsyncData *data;
1124   GError *error;
1125   gssize nread;
1126
1127   data = g_task_get_task_data (task);
1128
1129   error = NULL;
1130   nread = g_input_stream_skip_finish (G_INPUT_STREAM (source_object),
1131                                       result, &error);
1132
1133   /* Only report the error if we've not already read some data */
1134   if (nread < 0 && data->bytes_skipped == 0)
1135     g_task_return_error (task, error);
1136   else
1137     {
1138       if (error)
1139         g_error_free (error);
1140
1141       if (nread > 0)
1142         data->bytes_skipped += nread;
1143
1144       g_task_return_int (task, data->bytes_skipped);
1145     }
1146
1147   g_object_unref (task);
1148 }
1149
1150 static void
1151 skip_fill_buffer_callback (GObject      *source_object,
1152                            GAsyncResult *result,
1153                            gpointer      user_data)
1154 {
1155   GTask *task = G_TASK (user_data);
1156   GBufferedInputStream *bstream;
1157   GBufferedInputStreamPrivate *priv;
1158   SkipAsyncData *data;
1159   GError *error;
1160   gssize nread;
1161   gsize available;
1162
1163   bstream = G_BUFFERED_INPUT_STREAM (source_object);
1164   priv = bstream->priv;
1165
1166   data = g_task_get_task_data (task);
1167
1168   error = NULL;
1169   nread = g_buffered_input_stream_fill_finish (bstream,
1170                                                result, &error);
1171
1172   if (nread < 0 && data->bytes_skipped == 0)
1173     g_task_return_error (task, error);
1174   else
1175     {
1176       if (error)
1177         g_error_free (error);
1178
1179       if (nread > 0)
1180         {
1181           available = priv->end - priv->pos;
1182           data->count = MIN (data->count, available);
1183
1184           data->bytes_skipped += data->count;
1185           priv->pos += data->count;
1186         }
1187
1188       g_task_return_int (task, data->bytes_skipped);
1189     }
1190
1191   g_object_unref (task);
1192 }
1193
1194 static void
1195 g_buffered_input_stream_skip_async (GInputStream        *stream,
1196                                     gsize                count,
1197                                     int                  io_priority,
1198                                     GCancellable        *cancellable,
1199                                     GAsyncReadyCallback  callback,
1200                                     gpointer             user_data)
1201 {
1202   GBufferedInputStream *bstream;
1203   GBufferedInputStreamPrivate *priv;
1204   GBufferedInputStreamClass *class;
1205   GInputStream *base_stream;
1206   gsize available;
1207   GTask *task;
1208   SkipAsyncData *data;
1209
1210   bstream = G_BUFFERED_INPUT_STREAM (stream);
1211   priv = bstream->priv;
1212
1213   data = g_slice_new (SkipAsyncData);
1214   data->bytes_skipped = 0;
1215   task = g_task_new (stream, cancellable, callback, user_data);
1216   g_task_set_task_data (task, data, free_skip_async_data);
1217
1218   available = priv->end - priv->pos;
1219
1220   if (count <= available)
1221     {
1222       priv->pos += count;
1223
1224       g_task_return_int (task, count);
1225       g_object_unref (task);
1226       return;
1227     }
1228
1229   /* Full request not available, skip all currently available
1230    * and request refill for more
1231    */
1232
1233   priv->pos = 0;
1234   priv->end = 0;
1235
1236   count -= available;
1237
1238   data->bytes_skipped = available;
1239   data->count = count;
1240
1241   if (count > priv->len)
1242     {
1243       /* Large request, shortcut buffer */
1244
1245       base_stream = G_FILTER_INPUT_STREAM (stream)->base_stream;
1246
1247       g_input_stream_skip_async (base_stream,
1248                                  count,
1249                                  io_priority, cancellable,
1250                                  large_skip_callback,
1251                                  task);
1252     }
1253   else
1254     {
1255       class = G_BUFFERED_INPUT_STREAM_GET_CLASS (stream);
1256       class->fill_async (bstream, priv->len, io_priority, cancellable,
1257                          skip_fill_buffer_callback, task);
1258     }
1259 }
1260
1261 static gssize
1262 g_buffered_input_stream_skip_finish (GInputStream   *stream,
1263                                      GAsyncResult   *result,
1264                                      GError        **error)
1265 {
1266   g_return_val_if_fail (g_task_is_valid (result, stream), -1);
1267
1268   return g_task_propagate_int (G_TASK (result), error);
1269 }