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: (nullable): 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 [I/O priority][io-priority] of the request
 458  * @cancellable: (nullable): optional #GCancellable object
 459  * @callback: (scope async): a #GAsyncReadyCallback
 460  * @user_data: (closure): a #gpointer
 461  *
 462  * Reads data into @stream's buffer asynchronously, up to @count size.
 463  * @io_priority can be used to prioritize reads. For the synchronous
 464  * version of this function, see g_buffered_input_stream_fill().
 465  *
 466  * If @count is -1 then the attempted read size is equal to the number
 467  * of bytes that are required to fill the buffer.
 468  */
 469 void
 470 g_buffered_input_stream_fill_async (GBufferedInputStream *stream,
 471                                     gssize                count,
 472                                     int                   io_priority,
 473                                     GCancellable         *cancellable,
 474                                     GAsyncReadyCallback   callback,
 475                                     gpointer              user_data)
 476 {
 477   GBufferedInputStreamClass *class;
 478   GError *error = NULL;
 479
 480   g_return_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream));
 481
 482   if (count == 0)
 483     {
 484       GTask *task;
 485
 486       task = g_task_new (stream, cancellable, callback, user_data);
 487       g_task_set_source_tag (task, g_buffered_input_stream_fill_async);
 488       g_task_return_int (task, 0);
 489       g_object_unref (task);
 490       return;
 491     }
 492
 493   if (count < -1)
 494     {
 495       g_task_report_new_error (stream, callback, user_data,
 496                                g_buffered_input_stream_fill_async,
 497                                G_IO_ERROR, G_IO_ERROR_INVALID_ARGUMENT,
 498                                _("Too large count value passed to %s"),
 499                                G_STRFUNC);
 500       return;
 501     }
 502
 503   if (!g_input_stream_set_pending (G_INPUT_STREAM (stream), &error))
 504     {
 505       g_task_report_error (stream, callback, user_data,
 506                            g_buffered_input_stream_fill_async,
 507                            error);
 508       return;
 509     }
 510
 511   class = G_BUFFERED_INPUT_STREAM_GET_CLASS (stream);
 512
 513   stream->priv->outstanding_callback = callback;
 514   g_object_ref (stream);
 515   class->fill_async (stream, count, io_priority, cancellable,
 516                      async_fill_callback_wrapper, user_data);
 517 }
 518
 519 /**
 520  * g_buffered_input_stream_fill_finish:
 521  * @stream: a #GBufferedInputStream
 522  * @result: a #GAsyncResult
 523  * @error: a #GError
 524  *
 525  * Finishes an asynchronous read.
 526  *
 527  * Returns: a #gssize of the read stream, or %-1 on an error.
 528  */
 529 gssize
 530 g_buffered_input_stream_fill_finish (GBufferedInputStream  *stream,
 531                                      GAsyncResult          *result,
 532                                      GError               **error)
 533 {
 534   GBufferedInputStreamClass *class;
 535
 536   g_return_val_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream), -1);
 537   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), -1);
 538
 539   if (g_async_result_legacy_propagate_error (result, error))
 540     return -1;
 541   else if (g_async_result_is_tagged (result, g_buffered_input_stream_fill_async))
 542     return g_task_propagate_int (G_TASK (result), error);
 543
 544   class = G_BUFFERED_INPUT_STREAM_GET_CLASS (stream);
 545   return class->fill_finish (stream, result, error);
 546 }
 547
 548 /**
 549  * g_buffered_input_stream_get_available:
 550  * @stream: #GBufferedInputStream
 551  *
 552  * Gets the size of the available data within the stream.
 553  *
 554  * Returns: size of the available stream.
 555  */
 556 gsize
 557 g_buffered_input_stream_get_available (GBufferedInputStream *stream)
 558 {
 559   g_return_val_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream), -1);
 560
 561   return stream->priv->end - stream->priv->pos;
 562 }
 563
 564 /**
 565  * g_buffered_input_stream_peek:
 566  * @stream: a #GBufferedInputStream
 567  * @buffer: (array length=count) (element-type guint8): a pointer to
 568  *   an allocated chunk of memory
 569  * @offset: a #gsize
 570  * @count: a #gsize
 571  *
 572  * Peeks in the buffer, copying data of size @count into @buffer,
 573  * offset @offset bytes.
 574  *
 575  * Returns: a #gsize of the number of bytes peeked, or -1 on error.
 576  */
 577 gsize
 578 g_buffered_input_stream_peek (GBufferedInputStream *stream,
 579                               void                 *buffer,
 580                               gsize                 offset,
 581                               gsize                 count)
 582 {
 583   gsize available;
 584   gsize end;
 585
 586   g_return_val_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream), -1);
 587   g_return_val_if_fail (buffer != NULL, -1);
 588
 589   available = g_buffered_input_stream_get_available (stream);
 590
 591   if (offset > available)
 592     return 0;
 593
 594   end = MIN (offset + count, available);
 595   count = end - offset;
 596
 597   memcpy (buffer, stream->priv->buffer + stream->priv->pos + offset, count);
 598   return count;
 599 }
 600
 601 /**
 602  * g_buffered_input_stream_peek_buffer:
 603  * @stream: a #GBufferedInputStream
 604  * @count: (out): a #gsize to get the number of bytes available in the buffer
 605  *
 606  * Returns the buffer with the currently available bytes. The returned
 607  * buffer must not be modified and will become invalid when reading from
 608  * the stream or filling the buffer.
 609  *
 610  * Returns: (array length=count) (element-type guint8) (transfer none):
 611  *          read-only buffer
 612  */
 613 const void*
 614 g_buffered_input_stream_peek_buffer (GBufferedInputStream *stream,
 615                                      gsize                *count)
 616 {
 617   GBufferedInputStreamPrivate *priv;
 618
 619   g_return_val_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream), NULL);
 620
 621   priv = stream->priv;
 622
 623   if (count)
 624     *count = priv->end - priv->pos;
 625
 626   return priv->buffer + priv->pos;
 627 }
 628
 629 static void
 630 compact_buffer (GBufferedInputStream *stream)
 631 {
 632   GBufferedInputStreamPrivate *priv;
 633   gsize current_size;
 634
 635   priv = stream->priv;
 636
 637   current_size = priv->end - priv->pos;
 638
 639   memmove (priv->buffer, priv->buffer + priv->pos, current_size);
 640
 641   priv->pos = 0;
 642   priv->end = current_size;
 643 }
 644
 645 static gssize
 646 g_buffered_input_stream_real_fill (GBufferedInputStream  *stream,
 647                                    gssize                 count,
 648                                    GCancellable          *cancellable,
 649                                    GError               **error)
 650 {
 651   GBufferedInputStreamPrivate *priv;
 652   GInputStream *base_stream;
 653   gssize nread;
 654   gsize in_buffer;
 655
 656   priv = stream->priv;
 657
 658   if (count == -1)
 659     count = priv->len;
 660
 661   in_buffer = priv->end - priv->pos;
 662
 663   /* Never fill more than can fit in the buffer */
 664   count = MIN (count, priv->len - in_buffer);
 665
 666   /* If requested length does not fit at end, compact */
 667   if (priv->len - priv->end < count)
 668     compact_buffer (stream);
 669
 670   base_stream = G_FILTER_INPUT_STREAM (stream)->base_stream;
 671   nread = g_input_stream_read (base_stream,
 672                                priv->buffer + priv->end,
 673                                count,
 674                                cancellable,
 675                                error);
 676
 677   if (nread > 0)
 678     priv->end += nread;
 679
 680   return nread;
 681 }
 682
 683 static gssize
 684 g_buffered_input_stream_skip (GInputStream  *stream,
 685                               gsize          count,
 686                               GCancellable  *cancellable,
 687                               GError       **error)
 688 {
 689   GBufferedInputStream        *bstream;
 690   GBufferedInputStreamPrivate *priv;
 691   GBufferedInputStreamClass *class;
 692   GInputStream *base_stream;
 693   gsize available, bytes_skipped;
 694   gssize nread;
 695
 696   bstream = G_BUFFERED_INPUT_STREAM (stream);
 697   priv = bstream->priv;
 698
 699   available = priv->end - priv->pos;
 700
 701   if (count <= available)
 702     {
 703       priv->pos += count;
 704       return count;
 705     }
 706
 707   /* Full request not available, skip all currently available and
 708    * request refill for more
 709    */
 710
 711   priv->pos = 0;
 712   priv->end = 0;
 713   bytes_skipped = available;
 714   count -= available;
 715
 716   if (bytes_skipped > 0)
 717     error = NULL; /* Ignore further errors if we already read some data */
 718
 719   if (count > priv->len)
 720     {
 721       /* Large request, shortcut buffer */
 722
 723       base_stream = G_FILTER_INPUT_STREAM (stream)->base_stream;
 724
 725       nread = g_input_stream_skip (base_stream,
 726                                    count,
 727                                    cancellable,
 728                                    error);
 729
 730       if (nread < 0 && bytes_skipped == 0)
 731         return -1;
 732
 733       if (nread > 0)
 734         bytes_skipped += nread;
 735
 736       return bytes_skipped;
 737     }
 738
 739   class = G_BUFFERED_INPUT_STREAM_GET_CLASS (stream);
 740   nread = class->fill (bstream, priv->len, cancellable, error);
 741
 742   if (nread < 0)
 743     {
 744       if (bytes_skipped == 0)
 745         return -1;
 746       else
 747         return bytes_skipped;
 748     }
 749
 750   available = priv->end - priv->pos;
 751   count = MIN (count, available);
 752
 753   bytes_skipped += count;
 754   priv->pos += count;
 755
 756   return bytes_skipped;
 757 }
 758
 759 static gssize
 760 g_buffered_input_stream_read (GInputStream *stream,
 761                               void         *buffer,
 762                               gsize         count,
 763                               GCancellable *cancellable,
 764                               GError      **error)
 765 {
 766   GBufferedInputStream        *bstream;
 767   GBufferedInputStreamPrivate *priv;
 768   GBufferedInputStreamClass *class;
 769   GInputStream *base_stream;
 770   gsize available, bytes_read;
 771   gssize nread;
 772
 773   bstream = G_BUFFERED_INPUT_STREAM (stream);
 774   priv = bstream->priv;
 775
 776   available = priv->end - priv->pos;
 777
 778   if (count <= available)
 779     {
 780       memcpy (buffer, priv->buffer + priv->pos, count);
 781       priv->pos += count;
 782       return count;
 783     }
 784
 785   /* Full request not available, read all currently available and
 786    * request refill for more
 787    */
 788
 789   memcpy (buffer, priv->buffer + priv->pos, available);
 790   priv->pos = 0;
 791   priv->end = 0;
 792   bytes_read = available;
 793   count -= available;
 794
 795   if (bytes_read > 0)
 796     error = NULL; /* Ignore further errors if we already read some data */
 797
 798   if (count > priv->len)
 799     {
 800       /* Large request, shortcut buffer */
 801
 802       base_stream = G_FILTER_INPUT_STREAM (stream)->base_stream;
 803
 804       nread = g_input_stream_read (base_stream,
 805                                    (char *)buffer + bytes_read,
 806                                    count,
 807                                    cancellable,
 808                                    error);
 809
 810       if (nread < 0 && bytes_read == 0)
 811         return -1;
 812
 813       if (nread > 0)
 814         bytes_read += nread;
 815
 816       return bytes_read;
 817     }
 818
 819   class = G_BUFFERED_INPUT_STREAM_GET_CLASS (stream);
 820   nread = class->fill (bstream, priv->len, cancellable, error);
 821   if (nread < 0)
 822     {
 823       if (bytes_read == 0)
 824         return -1;
 825       else
 826         return bytes_read;
 827     }
 828
 829   available = priv->end - priv->pos;
 830   count = MIN (count, available);
 831
 832   memcpy ((char *)buffer + bytes_read, (char *)priv->buffer + priv->pos, count);
 833   bytes_read += count;
 834   priv->pos += count;
 835
 836   return bytes_read;
 837 }
 838
 839 static goffset
 840 g_buffered_input_stream_tell (GSeekable *seekable)
 841 {
 842   GBufferedInputStream        *bstream;
 843   GBufferedInputStreamPrivate *priv;
 844   GInputStream *base_stream;
 845   GSeekable    *base_stream_seekable;
 846   gsize available;
 847   goffset base_offset;
 848
 849   bstream = G_BUFFERED_INPUT_STREAM (seekable);
 850   priv = bstream->priv;
 851
 852   base_stream = G_FILTER_INPUT_STREAM (seekable)->base_stream;
 853   if (!G_IS_SEEKABLE (base_stream))
 854     return 0;
 855   base_stream_seekable = G_SEEKABLE (base_stream);
 856
 857   available = priv->end - priv->pos;
 858   base_offset = g_seekable_tell (base_stream_seekable);
 859
 860   return base_offset - available;
 861 }
 862
 863 static gboolean
 864 g_buffered_input_stream_can_seek (GSeekable *seekable)
 865 {
 866   GInputStream *base_stream;
 867
 868   base_stream = G_FILTER_INPUT_STREAM (seekable)->base_stream;
 869   return G_IS_SEEKABLE (base_stream) && g_seekable_can_seek (G_SEEKABLE (base_stream));
 870 }
 871
 872 static gboolean
 873 g_buffered_input_stream_seek (GSeekable     *seekable,
 874                               goffset        offset,
 875                               GSeekType      type,
 876                               GCancellable  *cancellable,
 877                               GError       **error)
 878 {
 879   GBufferedInputStream        *bstream;
 880   GBufferedInputStreamPrivate *priv;
 881   GInputStream *base_stream;
 882   GSeekable *base_stream_seekable;
 883
 884   bstream = G_BUFFERED_INPUT_STREAM (seekable);
 885   priv = bstream->priv;
 886
 887   base_stream = G_FILTER_INPUT_STREAM (seekable)->base_stream;
 888   if (!G_IS_SEEKABLE (base_stream))
 889     {
 890       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 891                            _("Seek not supported on base stream"));
 892       return FALSE;
 893     }
 894
 895   base_stream_seekable = G_SEEKABLE (base_stream);
 896
 897   if (type == G_SEEK_CUR)
 898     {
 899       if (offset <= priv->end - priv->pos && offset >= -priv->pos)
 900         {
 901           priv->pos += offset;
 902           return TRUE;
 903         }
 904       else
 905         {
 906           offset -= priv->end - priv->pos;
 907         }
 908     }
 909
 910   if (g_seekable_seek (base_stream_seekable, offset, type, cancellable, error))
 911     {
 912       priv->pos = 0;
 913       priv->end = 0;
 914       return TRUE;
 915     }
 916   else
 917     {
 918       return FALSE;
 919     }
 920 }
 921
 922 static gboolean
 923 g_buffered_input_stream_can_truncate (GSeekable *seekable)
 924 {
 925   return FALSE;
 926 }
 927
 928 static gboolean
 929 g_buffered_input_stream_truncate (GSeekable     *seekable,
 930                                   goffset        offset,
 931                                   GCancellable  *cancellable,
 932                                   GError       **error)
 933 {
 934   g_set_error_literal (error,
 935                        G_IO_ERROR,
 936                        G_IO_ERROR_NOT_SUPPORTED,
 937                        _("Cannot truncate GBufferedInputStream"));
 938   return FALSE;
 939 }
 940
 941 /**
 942  * g_buffered_input_stream_read_byte:
 943  * @stream: a #GBufferedInputStream
 944  * @cancellable: (nullable): optional #GCancellable object, %NULL to ignore
 945  * @error: location to store the error occurring, or %NULL to ignore
 946  *
 947  * Tries to read a single byte from the stream or the buffer. Will block
 948  * during this read.
 949  *
 950  * On success, the byte read from the stream is returned. On end of stream
 951  * -1 is returned but it's not an exceptional error and @error is not set.
 952  *
 953  * If @cancellable is not %NULL, then the operation can be cancelled by
 954  * triggering the cancellable object from another thread. If the operation
 955  * was cancelled, the error %G_IO_ERROR_CANCELLED will be returned. If an
 956  * operation was partially finished when the operation was cancelled the
 957  * partial result will be returned, without an error.
 958  *
 959  * On error -1 is returned and @error is set accordingly.
 960  *
 961  * Returns: the byte read from the @stream, or -1 on end of stream or error.
 962  */
 963 int
 964 g_buffered_input_stream_read_byte (GBufferedInputStream  *stream,
 965                                    GCancellable          *cancellable,
 966                                    GError               **error)
 967 {
 968   GBufferedInputStreamPrivate *priv;
 969   GBufferedInputStreamClass *class;
 970   GInputStream *input_stream;
 971   gsize available;
 972   gssize nread;
 973
 974   g_return_val_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream), -1);
 975
 976   priv = stream->priv;
 977   input_stream = G_INPUT_STREAM (stream);
 978
 979   if (g_input_stream_is_closed (input_stream))
 980     {
 981       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_CLOSED,
 982                            _("Stream is already closed"));
 983       return -1;
 984     }
 985
 986   if (!g_input_stream_set_pending (input_stream, error))
 987     return -1;
 988
 989   available = priv->end - priv->pos;
 990
 991   if (available != 0)
 992     {
 993       g_input_stream_clear_pending (input_stream);
 994       return priv->buffer[priv->pos++];
 995     }
 996
 997   /* Byte not available, request refill for more */
 998
 999   if (cancellable)
1000     g_cancellable_push_current (cancellable);
1001
1002   priv->pos = 0;
1003   priv->end = 0;
1004
1005   class = G_BUFFERED_INPUT_STREAM_GET_CLASS (stream);
1006   nread = class->fill (stream, priv->len, cancellable, error);
1007
1008   if (cancellable)
1009     g_cancellable_pop_current (cancellable);
1010
1011   g_input_stream_clear_pending (input_stream);
1012
1013   if (nread <= 0)
1014     return -1; /* error or end of stream */
1015
1016   return priv->buffer[priv->pos++];
1017 }
1018
1019 /* ************************** */
1020 /* Async stuff implementation */
1021 /* ************************** */
1022
1023 static void
1024 fill_async_callback (GObject      *source_object,
1025                      GAsyncResult *result,
1026                      gpointer      user_data)
1027 {
1028   GError *error;
1029   gssize res;
1030   GTask *task = user_data;
1031
1032   error = NULL;
1033   res = g_input_stream_read_finish (G_INPUT_STREAM (source_object),
1034                                     result, &error);
1035   if (res == -1)
1036     g_task_return_error (task, error);
1037   else
1038     {
1039       GBufferedInputStream *stream;
1040       GBufferedInputStreamPrivate *priv;
1041
1042       stream = g_task_get_source_object (task);
1043       priv = G_BUFFERED_INPUT_STREAM (stream)->priv;
1044
1045       g_assert_cmpint (priv->end + res, <=, priv->len);
1046       priv->end += res;
1047
1048       g_task_return_int (task, res);
1049     }
1050
1051   g_object_unref (task);
1052 }
1053
1054 static void
1055 g_buffered_input_stream_real_fill_async (GBufferedInputStream *stream,
1056                                          gssize                count,
1057                                          int                   io_priority,
1058                                          GCancellable         *cancellable,
1059                                          GAsyncReadyCallback   callback,
1060                                          gpointer              user_data)
1061 {
1062   GBufferedInputStreamPrivate *priv;
1063   GInputStream *base_stream;
1064   GTask *task;
1065   gsize in_buffer;
1066
1067   priv = stream->priv;
1068
1069   if (count == -1)
1070     count = priv->len;
1071
1072   in_buffer = priv->end - priv->pos;
1073
1074   /* Never fill more than can fit in the buffer */
1075   count = MIN (count, priv->len - in_buffer);
1076
1077   /* If requested length does not fit at end, compact */
1078   if (priv->len - priv->end < count)
1079     compact_buffer (stream);
1080
1081   task = g_task_new (stream, cancellable, callback, user_data);
1082   g_task_set_source_tag (task, g_buffered_input_stream_real_fill_async);
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_source_tag (task, g_buffered_input_stream_skip_async);
1217   g_task_set_task_data (task, data, free_skip_async_data);
1218
1219   available = priv->end - priv->pos;
1220
1221   if (count <= available)
1222     {
1223       priv->pos += count;
1224
1225       g_task_return_int (task, count);
1226       g_object_unref (task);
1227       return;
1228     }
1229
1230   /* Full request not available, skip all currently available
1231    * and request refill for more
1232    */
1233
1234   priv->pos = 0;
1235   priv->end = 0;
1236
1237   count -= available;
1238
1239   data->bytes_skipped = available;
1240   data->count = count;
1241
1242   if (count > priv->len)
1243     {
1244       /* Large request, shortcut buffer */
1245
1246       base_stream = G_FILTER_INPUT_STREAM (stream)->base_stream;
1247
1248       g_input_stream_skip_async (base_stream,
1249                                  count,
1250                                  io_priority, cancellable,
1251                                  large_skip_callback,
1252                                  task);
1253     }
1254   else
1255     {
1256       class = G_BUFFERED_INPUT_STREAM_GET_CLASS (stream);
1257       class->fill_async (bstream, priv->len, io_priority, cancellable,
1258                          skip_fill_buffer_callback, task);
1259     }
1260 }
1261
1262 static gssize
1263 g_buffered_input_stream_skip_finish (GInputStream   *stream,
1264                                      GAsyncResult   *result,
1265                                      GError        **error)
1266 {
1267   g_return_val_if_fail (g_task_is_valid (result, stream), -1);
1268
1269   return g_task_propagate_int (G_TASK (result), error);
1270 }