gio/gmemoryoutputstream.c

   1 /* GIO - GLib Input, Output and Streaming Library
   2  *
   3  * Copyright (C) 2006-2007 Red Hat, Inc.
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General
  16  * Public License along with this library; if not, write to the
  17  * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  18  * Boston, MA 02111-1307, USA.
  19  *
  20  * Authors:
  21  *   Christian Kellner <gicmo@gnome.org>
  22  *   Krzysztof Kosiński <tweenk.pl@gmail.com>
  23  */
  24
  25 #include "config.h"
  26 #include "gmemoryoutputstream.h"
  27 #include "goutputstream.h"
  28 #include "gpollableoutputstream.h"
  29 #include "gseekable.h"
  30 #include "gsimpleasyncresult.h"
  31 #include "gioerror.h"
  32 #include "string.h"
  33 #include "glibintl.h"
  34
  35
  36 /**
  37  * SECTION:gmemoryoutputstream
  38  * @short_description: Streaming output operations on memory chunks
  39  * @include: gio/gio.h
  40  * @see_also: #GMemoryInputStream
  41  *
  42  * #GMemoryOutputStream is a class for using arbitrary
  43  * memory chunks as output for GIO streaming output operations.
  44  *
  45  * As of GLib 2.34, #GMemoryOutputStream implements
  46  * #GPollableOutputStream.
  47  */
  48
  49 #define MIN_ARRAY_SIZE  16
  50
  51 enum {
  52   PROP_0,
  53   PROP_DATA,
  54   PROP_SIZE,
  55   PROP_DATA_SIZE,
  56   PROP_REALLOC_FUNCTION,
  57   PROP_DESTROY_FUNCTION
  58 };
  59
  60 struct _GMemoryOutputStreamPrivate {
  61
  62   gpointer       data; /* Write buffer */
  63   gsize          len; /* Current length of the data buffer. Can change with resizing. */
  64   gsize          valid_len; /* The part of data that has been written to */
  65   gsize          pos; /* Current position in the stream. Distinct from valid_len,
  66                          because the stream is seekable. */
  67
  68   GReallocFunc   realloc_fn;
  69   GDestroyNotify destroy;
  70 };
  71
  72 static void     g_memory_output_stream_set_property (GObject      *object,
  73                                                      guint         prop_id,
  74                                                      const GValue *value,
  75                                                      GParamSpec   *pspec);
  76 static void     g_memory_output_stream_get_property (GObject      *object,
  77                                                      guint         prop_id,
  78                                                      GValue       *value,
  79                                                      GParamSpec   *pspec);
  80 static void     g_memory_output_stream_finalize     (GObject      *object);
  81
  82 static gssize   g_memory_output_stream_write       (GOutputStream *stream,
  83                                                     const void    *buffer,
  84                                                     gsize          count,
  85                                                     GCancellable  *cancellable,
  86                                                     GError       **error);
  87
  88 static gboolean g_memory_output_stream_close       (GOutputStream  *stream,
  89                                                     GCancellable   *cancellable,
  90                                                     GError        **error);
  91
  92 static void     g_memory_output_stream_write_async  (GOutputStream        *stream,
  93                                                      const void           *buffer,
  94                                                      gsize                 count,
  95                                                      int                   io_priority,
  96                                                      GCancellable         *cancellable,
  97                                                      GAsyncReadyCallback   callback,
  98                                                      gpointer              data);
  99 static gssize   g_memory_output_stream_write_finish (GOutputStream        *stream,
 100                                                      GAsyncResult         *result,
 101                                                      GError              **error);
 102 static void     g_memory_output_stream_close_async  (GOutputStream        *stream,
 103                                                      int                   io_priority,
 104                                                      GCancellable         *cancellable,
 105                                                      GAsyncReadyCallback   callback,
 106                                                      gpointer              data);
 107 static gboolean g_memory_output_stream_close_finish (GOutputStream        *stream,
 108                                                      GAsyncResult         *result,
 109                                                      GError              **error);
 110
 111 static void     g_memory_output_stream_seekable_iface_init (GSeekableIface  *iface);
 112 static goffset  g_memory_output_stream_tell                (GSeekable       *seekable);
 113 static gboolean g_memory_output_stream_can_seek            (GSeekable       *seekable);
 114 static gboolean g_memory_output_stream_seek                (GSeekable       *seekable,
 115                                                            goffset          offset,
 116                                                            GSeekType        type,
 117                                                            GCancellable    *cancellable,
 118                                                            GError         **error);
 119 static gboolean g_memory_output_stream_can_truncate        (GSeekable       *seekable);
 120 static gboolean g_memory_output_stream_truncate            (GSeekable       *seekable,
 121                                                            goffset          offset,
 122                                                            GCancellable    *cancellable,
 123                                                            GError         **error);
 124
 125 static gboolean g_memory_output_stream_is_writable       (GPollableOutputStream *stream);
 126 static GSource *g_memory_output_stream_create_source     (GPollableOutputStream *stream,
 127                                                           GCancellable          *cancellable);
 128
 129 static void g_memory_output_stream_pollable_iface_init (GPollableOutputStreamInterface *iface);
 130
 131 G_DEFINE_TYPE_WITH_CODE (GMemoryOutputStream, g_memory_output_stream, G_TYPE_OUTPUT_STREAM,
 132                          G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
 133                                                 g_memory_output_stream_seekable_iface_init);
 134                          G_IMPLEMENT_INTERFACE (G_TYPE_POLLABLE_OUTPUT_STREAM,
 135                                                 g_memory_output_stream_pollable_iface_init))
 136
 137
 138 static void
 139 g_memory_output_stream_class_init (GMemoryOutputStreamClass *klass)
 140 {
 141   GOutputStreamClass *ostream_class;
 142   GObjectClass *gobject_class;
 143
 144   g_type_class_add_private (klass, sizeof (GMemoryOutputStreamPrivate));
 145
 146   gobject_class = G_OBJECT_CLASS (klass);
 147   gobject_class->set_property = g_memory_output_stream_set_property;
 148   gobject_class->get_property = g_memory_output_stream_get_property;
 149   gobject_class->finalize     = g_memory_output_stream_finalize;
 150
 151   ostream_class = G_OUTPUT_STREAM_CLASS (klass);
 152
 153   ostream_class->write_fn = g_memory_output_stream_write;
 154   ostream_class->close_fn = g_memory_output_stream_close;
 155   ostream_class->write_async  = g_memory_output_stream_write_async;
 156   ostream_class->write_finish = g_memory_output_stream_write_finish;
 157   ostream_class->close_async  = g_memory_output_stream_close_async;
 158   ostream_class->close_finish = g_memory_output_stream_close_finish;
 159
 160   /**
 161    * GMemoryOutputStream:data:
 162    *
 163    * Pointer to buffer where data will be written.
 164    *
 165    * Since: 2.24
 166    **/
 167   g_object_class_install_property (gobject_class,
 168                                    PROP_DATA,
 169                                    g_param_spec_pointer ("data",
 170                                                          P_("Data Buffer"),
 171                                                          P_("Pointer to buffer where data will be written."),
 172                                                          G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY |
 173                                                          G_PARAM_STATIC_STRINGS));
 174
 175   /**
 176    * GMemoryOutputStream:size:
 177    *
 178    * Current size of the data buffer.
 179    *
 180    * Since: 2.24
 181    **/
 182   g_object_class_install_property (gobject_class,
 183                                    PROP_SIZE,
 184                                    g_param_spec_ulong ("size",
 185                                                        P_("Data Buffer Size"),
 186                                                        P_("Current size of the data buffer."),
 187                                                        0, G_MAXULONG, 0,
 188                                                        G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY |
 189                                                        G_PARAM_STATIC_STRINGS));
 190
 191   /**
 192    * GMemoryOutputStream:data-size:
 193    *
 194    * Size of data written to the buffer.
 195    *
 196    * Since: 2.24
 197    **/
 198   g_object_class_install_property (gobject_class,
 199                                    PROP_DATA_SIZE,
 200                                    g_param_spec_ulong ("data-size",
 201                                                        P_("Data Size"),
 202                                                        P_("Size of data written to the buffer."),
 203                                                        0, G_MAXULONG, 0,
 204                                                        G_PARAM_READABLE |
 205                                                        G_PARAM_STATIC_STRINGS));
 206
 207   /**
 208    * GMemoryOutputStream:realloc-function: (skip)
 209    *
 210    * Function with realloc semantics called to enlarge the buffer.
 211    *
 212    * Since: 2.24
 213    **/
 214   g_object_class_install_property (gobject_class,
 215                                    PROP_REALLOC_FUNCTION,
 216                                    g_param_spec_pointer ("realloc-function",
 217                                                          P_("Memory Reallocation Function"),
 218                                                          P_("Function with realloc semantics called to enlarge the buffer."),
 219                                                          G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY |
 220                                                          G_PARAM_STATIC_STRINGS));
 221
 222   /**
 223    * GMemoryOutputStream:destroy-function: (skip)
 224    *
 225    * Function called with the buffer as argument when the stream is destroyed.
 226    *
 227    * Since: 2.24
 228    **/
 229   g_object_class_install_property (gobject_class,
 230                                    PROP_DESTROY_FUNCTION,
 231                                    g_param_spec_pointer ("destroy-function",
 232                                                          P_("Destroy Notification Function"),
 233                                                          P_("Function called with the buffer as argument when the stream is destroyed."),
 234                                                          G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY |
 235                                                          G_PARAM_STATIC_STRINGS));
 236 }
 237
 238 static void
 239 g_memory_output_stream_pollable_iface_init (GPollableOutputStreamInterface *iface)
 240 {
 241   iface->is_writable = g_memory_output_stream_is_writable;
 242   iface->create_source = g_memory_output_stream_create_source;
 243 }
 244
 245 static void
 246 g_memory_output_stream_set_property (GObject      *object,
 247                                      guint         prop_id,
 248                                      const GValue *value,
 249                                      GParamSpec   *pspec)
 250 {
 251   GMemoryOutputStream        *stream;
 252   GMemoryOutputStreamPrivate *priv;
 253
 254   stream = G_MEMORY_OUTPUT_STREAM (object);
 255   priv = stream->priv;
 256
 257   switch (prop_id)
 258     {
 259     case PROP_DATA:
 260       priv->data = g_value_get_pointer (value);
 261       break;
 262     case PROP_SIZE:
 263       priv->len = g_value_get_ulong (value);
 264       break;
 265     case PROP_REALLOC_FUNCTION:
 266       priv->realloc_fn = g_value_get_pointer (value);
 267       break;
 268     case PROP_DESTROY_FUNCTION:
 269       priv->destroy = g_value_get_pointer (value);
 270       break;
 271     default:
 272       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
 273       break;
 274     }
 275 }
 276
 277 static void
 278 g_memory_output_stream_get_property (GObject      *object,
 279                                      guint         prop_id,
 280                                      GValue       *value,
 281                                      GParamSpec   *pspec)
 282 {
 283   GMemoryOutputStream        *stream;
 284   GMemoryOutputStreamPrivate *priv;
 285
 286   stream = G_MEMORY_OUTPUT_STREAM (object);
 287   priv = stream->priv;
 288
 289   switch (prop_id)
 290     {
 291     case PROP_DATA:
 292       g_value_set_pointer (value, priv->data);
 293       break;
 294     case PROP_SIZE:
 295       g_value_set_ulong (value, priv->len);
 296       break;
 297     case PROP_DATA_SIZE:
 298       g_value_set_ulong (value, priv->valid_len);
 299       break;
 300     case PROP_REALLOC_FUNCTION:
 301       g_value_set_pointer (value, priv->realloc_fn);
 302       break;
 303     case PROP_DESTROY_FUNCTION:
 304       g_value_set_pointer (value, priv->destroy);
 305       break;
 306     default:
 307       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
 308       break;
 309     }
 310 }
 311
 312 static void
 313 g_memory_output_stream_finalize (GObject *object)
 314 {
 315   GMemoryOutputStream        *stream;
 316   GMemoryOutputStreamPrivate *priv;
 317
 318   stream = G_MEMORY_OUTPUT_STREAM (object);
 319   priv = stream->priv;
 320
 321   if (priv->destroy)
 322     priv->destroy (priv->data);
 323
 324   G_OBJECT_CLASS (g_memory_output_stream_parent_class)->finalize (object);
 325 }
 326
 327 static void
 328 g_memory_output_stream_seekable_iface_init (GSeekableIface *iface)
 329 {
 330   iface->tell         = g_memory_output_stream_tell;
 331   iface->can_seek     = g_memory_output_stream_can_seek;
 332   iface->seek         = g_memory_output_stream_seek;
 333   iface->can_truncate = g_memory_output_stream_can_truncate;
 334   iface->truncate_fn  = g_memory_output_stream_truncate;
 335 }
 336
 337
 338 static void
 339 g_memory_output_stream_init (GMemoryOutputStream *stream)
 340 {
 341   stream->priv = G_TYPE_INSTANCE_GET_PRIVATE (stream,
 342                                               G_TYPE_MEMORY_OUTPUT_STREAM,
 343                                               GMemoryOutputStreamPrivate);
 344   stream->priv->pos = 0;
 345   stream->priv->valid_len = 0;
 346 }
 347
 348 /**
 349  * g_memory_output_stream_new: (skip)
 350  * @data: (allow-none): pointer to a chunk of memory to use, or %NULL
 351  * @size: the size of @data
 352  * @realloc_function: (allow-none): a function with realloc() semantics (like g_realloc())
 353  *     to be called when @data needs to be grown, or %NULL
 354  * @destroy_function: (allow-none): a function to be called on @data when the stream is
 355  *     finalized, or %NULL
 356  *
 357  * Creates a new #GMemoryOutputStream.
 358  *
 359  * If @data is non-%NULL, the stream  will use that for its internal storage.
 360  * If @realloc_fn is non-%NULL, it will be used for resizing the internal
 361  * storage when necessary. To construct a fixed-size output stream,
 362  * pass %NULL as @realloc_fn.
 363  *
 364  * |[
 365  * /&ast; a stream that can grow &ast;/
 366  * stream = g_memory_output_stream_new (NULL, 0, realloc, free);
 367  *
 368  * /&ast; another stream that can grow &ast;/
 369  * stream2 = g_memory_output_stream_new (NULL, 0, g_realloc, g_free);
 370  *
 371  * /&ast; a fixed-size stream &ast;/
 372  * data = malloc (200);
 373  * stream3 = g_memory_output_stream_new (data, 200, NULL, free);
 374  * ]|
 375  *
 376  * Return value: A newly created #GMemoryOutputStream object.
 377  **/
 378 GOutputStream *
 379 g_memory_output_stream_new (gpointer       data,
 380                             gsize          size,
 381                             GReallocFunc   realloc_function,
 382                             GDestroyNotify destroy_function)
 383 {
 384   GOutputStream *stream;
 385
 386   stream = g_object_new (G_TYPE_MEMORY_OUTPUT_STREAM,
 387                          "data", data,
 388                          "size", size,
 389                          "realloc-function", realloc_function,
 390                          "destroy-function", destroy_function,
 391                          NULL);
 392
 393   return stream;
 394 }
 395
 396 /**
 397  * g_memory_output_stream_get_data:
 398  * @ostream: a #GMemoryOutputStream
 399  *
 400  * Gets any loaded data from the @ostream.
 401  *
 402  * Note that the returned pointer may become invalid on the next
 403  * write or truncate operation on the stream.
 404  *
 405  * Returns: (transfer none): pointer to the stream's data
 406  **/
 407 gpointer
 408 g_memory_output_stream_get_data (GMemoryOutputStream *ostream)
 409 {
 410   g_return_val_if_fail (G_IS_MEMORY_OUTPUT_STREAM (ostream), NULL);
 411
 412   return ostream->priv->data;
 413 }
 414
 415 /**
 416  * g_memory_output_stream_get_size:
 417  * @ostream: a #GMemoryOutputStream
 418  *
 419  * Gets the size of the currently allocated data area (available from
 420  * g_memory_output_stream_get_data()). If the stream isn't
 421  * growable (no realloc was passed to g_memory_output_stream_new()) then
 422  * this is the maximum size of the stream and further writes
 423  * will return %G_IO_ERROR_NO_SPACE.
 424  *
 425  * Note that for growable streams the returned size may become invalid on
 426  * the next write or truncate operation on the stream.
 427  *
 428  * If you want the number of bytes currently written to the stream, use
 429  * g_memory_output_stream_get_data_size().
 430  *
 431  * Returns: the number of bytes allocated for the data buffer
 432  */
 433 gsize
 434 g_memory_output_stream_get_size (GMemoryOutputStream *ostream)
 435 {
 436   g_return_val_if_fail (G_IS_MEMORY_OUTPUT_STREAM (ostream), 0);
 437
 438   return ostream->priv->len;
 439 }
 440
 441 /**
 442  * g_memory_output_stream_get_data_size:
 443  * @ostream: a #GMemoryOutputStream
 444  *
 445  * Returns the number of bytes from the start up
 446  * to including the last byte written in the stream
 447  * that has not been truncated away.
 448  *
 449  * Returns: the number of bytes written to the stream
 450  *
 451  * Since: 2.18
 452  */
 453 gsize
 454 g_memory_output_stream_get_data_size (GMemoryOutputStream *ostream)
 455 {
 456   g_return_val_if_fail (G_IS_MEMORY_OUTPUT_STREAM (ostream), 0);
 457
 458   return ostream->priv->valid_len;
 459 }
 460
 461 /**
 462  * g_memory_output_stream_steal_data:
 463  * @ostream: a #GMemoryOutputStream
 464  *
 465  * Gets any loaded data from the @ostream. Ownership of the data
 466  * is transferred to the caller; when no longer needed it must be
 467  * freed using the free function set in @ostream's
 468  * #GMemoryOutputStream:destroy-function property.
 469  *
 470  * @ostream must be closed before calling this function.
 471  *
 472  * Returns: (transfer full): the stream's data
 473  *
 474  * Since: 2.26
 475  **/
 476 gpointer
 477 g_memory_output_stream_steal_data (GMemoryOutputStream *ostream)
 478 {
 479   gpointer data;
 480
 481   g_return_val_if_fail (G_IS_MEMORY_OUTPUT_STREAM (ostream), NULL);
 482   g_return_val_if_fail (g_output_stream_is_closed (G_OUTPUT_STREAM (ostream)), NULL);
 483
 484   data = ostream->priv->data;
 485   ostream->priv->data = NULL;
 486
 487   return data;
 488 }
 489
 490 static gboolean
 491 array_resize (GMemoryOutputStream  *ostream,
 492               gsize                 size,
 493               gboolean              allow_partial,
 494               GError              **error)
 495 {
 496   GMemoryOutputStreamPrivate *priv;
 497   gpointer data;
 498   gsize len;
 499
 500   priv = ostream->priv;
 501
 502   if (priv->len == size)
 503     return TRUE;
 504
 505   if (!priv->realloc_fn)
 506     {
 507       if (allow_partial &&
 508           priv->pos < priv->len)
 509         return TRUE; /* Short write */
 510
 511       g_set_error_literal (error,
 512                            G_IO_ERROR,
 513                            G_IO_ERROR_NO_SPACE,
 514                            _("Memory output stream not resizable"));
 515       return FALSE;
 516     }
 517
 518   len = priv->len;
 519   data = priv->realloc_fn (priv->data, size);
 520
 521   if (size > 0 && !data)
 522     {
 523       if (allow_partial &&
 524           priv->pos < priv->len)
 525         return TRUE; /* Short write */
 526
 527       g_set_error_literal (error,
 528                            G_IO_ERROR,
 529                            G_IO_ERROR_NO_SPACE,
 530                            _("Failed to resize memory output stream"));
 531       return FALSE;
 532     }
 533
 534   if (size > len)
 535     memset ((guint8 *)data + len, 0, size - len);
 536
 537   priv->data = data;
 538   priv->len = size;
 539
 540   if (priv->len < priv->valid_len)
 541     priv->valid_len = priv->len;
 542
 543   return TRUE;
 544 }
 545
 546 static gint
 547 g_nearest_pow (gint num)
 548 {
 549   gint n = 1;
 550
 551   while (n < num)
 552     n <<= 1;
 553
 554   return n;
 555 }
 556
 557 static gssize
 558 g_memory_output_stream_write (GOutputStream  *stream,
 559                               const void     *buffer,
 560                               gsize           count,
 561                               GCancellable   *cancellable,
 562                               GError        **error)
 563 {
 564   GMemoryOutputStream        *ostream;
 565   GMemoryOutputStreamPrivate *priv;
 566   guint8   *dest;
 567   gsize new_size;
 568
 569   ostream = G_MEMORY_OUTPUT_STREAM (stream);
 570   priv = ostream->priv;
 571
 572   if (count == 0)
 573     return 0;
 574
 575   /* Check for address space overflow, but only if the buffer is resizable.
 576      Otherwise we just do a short write and don't worry. */
 577   if (priv->realloc_fn && priv->pos + count < priv->pos)
 578     goto overflow;
 579
 580   if (priv->pos + count > priv->len)
 581     {
 582       /* At least enought to fit the write, rounded up
 583              for greater than linear growth.
 584          TODO: This wastes a lot of memory at large stream sizes.
 585                Figure out a more rational allocation strategy. */
 586       new_size = g_nearest_pow (priv->pos + count);
 587       /* Check for overflow again. We have only checked if
 588          pos + count > G_MAXSIZE, but it only catches the case of writing
 589          more than 4GiB total on a 32-bit system. There's still the problem
 590          of g_nearest_pow overflowing above 0x7fffffff, so we're
 591          effectively limited to 2GiB. */
 592       if (new_size < priv->len)
 593         goto overflow;
 594
 595       new_size = MAX (new_size, MIN_ARRAY_SIZE);
 596       if (!array_resize (ostream, new_size, TRUE, error))
 597         return -1;
 598     }
 599
 600   /* Make sure we handle short writes if the array_resize
 601      only added part of the required memory */
 602   count = MIN (count, priv->len - priv->pos);
 603
 604   dest = (guint8 *)priv->data + priv->pos;
 605   memcpy (dest, buffer, count);
 606   priv->pos += count;
 607
 608   if (priv->pos > priv->valid_len)
 609     priv->valid_len = priv->pos;
 610
 611   return count;
 612
 613  overflow:
 614   /* Overflow: buffer size would need to be bigger than G_MAXSIZE. */
 615   g_set_error_literal (error,
 616                        G_IO_ERROR,
 617                        G_IO_ERROR_NO_SPACE,
 618                        _("Amount of memory required to process the write is "
 619                          "larger than available address space"));
 620   return -1;
 621 }
 622
 623 static gboolean
 624 g_memory_output_stream_close (GOutputStream  *stream,
 625                               GCancellable   *cancellable,
 626                               GError        **error)
 627 {
 628   return TRUE;
 629 }
 630
 631 static void
 632 g_memory_output_stream_write_async (GOutputStream       *stream,
 633                                     const void          *buffer,
 634                                     gsize                count,
 635                                     int                  io_priority,
 636                                     GCancellable        *cancellable,
 637                                     GAsyncReadyCallback  callback,
 638                                     gpointer             data)
 639 {
 640   GSimpleAsyncResult *simple;
 641   GError *error = NULL;
 642   gssize nwritten;
 643
 644   nwritten = G_OUTPUT_STREAM_GET_CLASS (stream)->write_fn (stream,
 645                                                            buffer,
 646                                                            count,
 647                                                            cancellable,
 648                                                            &error);
 649
 650   simple = g_simple_async_result_new (G_OBJECT (stream),
 651                                       callback,
 652                                       data,
 653                                       g_memory_output_stream_write_async);
 654
 655   if (error)
 656     g_simple_async_result_take_error (simple, error);
 657   else
 658     g_simple_async_result_set_op_res_gssize (simple, nwritten);
 659   g_simple_async_result_complete_in_idle (simple);
 660   g_object_unref (simple);
 661 }
 662
 663 static gssize
 664 g_memory_output_stream_write_finish (GOutputStream  *stream,
 665                                      GAsyncResult   *result,
 666                                      GError        **error)
 667 {
 668   GSimpleAsyncResult *simple;
 669   gssize nwritten;
 670
 671   simple = G_SIMPLE_ASYNC_RESULT (result);
 672
 673   g_warn_if_fail (g_simple_async_result_get_source_tag (simple) ==
 674                   g_memory_output_stream_write_async);
 675
 676   nwritten = g_simple_async_result_get_op_res_gssize (simple);
 677
 678   return nwritten;
 679 }
 680
 681 static void
 682 g_memory_output_stream_close_async (GOutputStream       *stream,
 683                                     int                  io_priority,
 684                                     GCancellable        *cancellable,
 685                                     GAsyncReadyCallback  callback,
 686                                     gpointer             data)
 687 {
 688   GSimpleAsyncResult *simple;
 689
 690   simple = g_simple_async_result_new (G_OBJECT (stream),
 691                                       callback,
 692                                       data,
 693                                       g_memory_output_stream_close_async);
 694
 695
 696   /* will always return TRUE */
 697   g_memory_output_stream_close (stream, cancellable, NULL);
 698
 699   g_simple_async_result_complete_in_idle (simple);
 700   g_object_unref (simple);
 701 }
 702
 703 static gboolean
 704 g_memory_output_stream_close_finish (GOutputStream  *stream,
 705                                      GAsyncResult   *result,
 706                                      GError        **error)
 707 {
 708   GSimpleAsyncResult *simple;
 709
 710   simple = G_SIMPLE_ASYNC_RESULT (result);
 711
 712   g_warn_if_fail (g_simple_async_result_get_source_tag (simple) ==
 713                   g_memory_output_stream_close_async);
 714
 715   return TRUE;
 716 }
 717
 718 static goffset
 719 g_memory_output_stream_tell (GSeekable *seekable)
 720 {
 721   GMemoryOutputStream *stream;
 722   GMemoryOutputStreamPrivate *priv;
 723
 724   stream = G_MEMORY_OUTPUT_STREAM (seekable);
 725   priv = stream->priv;
 726
 727   return priv->pos;
 728 }
 729
 730 static gboolean
 731 g_memory_output_stream_can_seek (GSeekable *seekable)
 732 {
 733   return TRUE;
 734 }
 735
 736 static gboolean
 737 g_memory_output_stream_seek (GSeekable    *seekable,
 738                             goffset        offset,
 739                             GSeekType      type,
 740                             GCancellable  *cancellable,
 741                             GError       **error)
 742 {
 743   GMemoryOutputStream        *stream;
 744   GMemoryOutputStreamPrivate *priv;
 745   goffset absolute;
 746
 747   stream = G_MEMORY_OUTPUT_STREAM (seekable);
 748   priv = stream->priv;
 749
 750   switch (type)
 751     {
 752     case G_SEEK_CUR:
 753       absolute = priv->pos + offset;
 754       break;
 755
 756     case G_SEEK_SET:
 757       absolute = offset;
 758       break;
 759
 760     case G_SEEK_END:
 761       absolute = priv->len + offset;
 762       break;
 763
 764     default:
 765       g_set_error_literal (error,
 766                            G_IO_ERROR,
 767                            G_IO_ERROR_INVALID_ARGUMENT,
 768                            _("Invalid GSeekType supplied"));
 769
 770       return FALSE;
 771     }
 772
 773   if (absolute < 0)
 774     {
 775       g_set_error_literal (error,
 776                            G_IO_ERROR,
 777                            G_IO_ERROR_INVALID_ARGUMENT,
 778                            _("Requested seek before the beginning of the stream"));
 779       return FALSE;
 780     }
 781
 782   if (absolute > priv->len)
 783     {
 784       g_set_error_literal (error,
 785                            G_IO_ERROR,
 786                            G_IO_ERROR_INVALID_ARGUMENT,
 787                            _("Requested seek beyond the end of the stream"));
 788       return FALSE;
 789     }
 790
 791   priv->pos = absolute;
 792
 793   return TRUE;
 794 }
 795
 796 static gboolean
 797 g_memory_output_stream_can_truncate (GSeekable *seekable)
 798 {
 799   GMemoryOutputStream *ostream;
 800   GMemoryOutputStreamPrivate *priv;
 801
 802   ostream = G_MEMORY_OUTPUT_STREAM (seekable);
 803   priv = ostream->priv;
 804
 805   return priv->realloc_fn != NULL;
 806 }
 807
 808 static gboolean
 809 g_memory_output_stream_truncate (GSeekable     *seekable,
 810                                  goffset        offset,
 811                                  GCancellable  *cancellable,
 812                                  GError       **error)
 813 {
 814   GMemoryOutputStream *ostream = G_MEMORY_OUTPUT_STREAM (seekable);
 815
 816   if (!array_resize (ostream, offset, FALSE, error))
 817     return FALSE;
 818
 819   return TRUE;
 820 }
 821
 822 static gboolean
 823 g_memory_output_stream_is_writable (GPollableOutputStream *stream)
 824 {
 825   return TRUE;
 826 }
 827
 828 static GSource *
 829 g_memory_output_stream_create_source (GPollableOutputStream *stream,
 830                                       GCancellable          *cancellable)
 831 {
 832   GSource *base_source, *pollable_source;
 833
 834   base_source = g_timeout_source_new (0);
 835   pollable_source = g_pollable_source_new_full (stream, base_source,
 836                                                 cancellable);
 837   g_source_unref (base_source);
 838
 839   return pollable_source;
 840 }