gio/gconverterinputstream.c

   1 /* GIO - GLib Input, Output and Streaming Library
   2  *
   3  * Copyright (C) 2009 Red Hat, Inc.
   4  *
   5  * SPDX-License-Identifier: LGPL-2.1-or-later
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General
  18  * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
  19  *
  20  * Author: Alexander Larsson <alexl@redhat.com>
  21  */
  22
  23 #include "config.h"
  24
  25 #include <string.h>
  26
  27 #include "gconverterinputstream.h"
  28 #include "gpollableinputstream.h"
  29 #include "gcancellable.h"
  30 #include "gioenumtypes.h"
  31 #include "gioerror.h"
  32 #include "glibintl.h"
  33
  34
  35 /**
  36  * SECTION:gconverterinputstream
  37  * @short_description: Converter Input Stream
  38  * @include: gio/gio.h
  39  * @see_also: #GInputStream, #GConverter
  40  *
  41  * Converter input stream implements #GInputStream and allows
  42  * conversion of data of various types during reading.
  43  *
  44  * As of GLib 2.34, #GConverterInputStream implements
  45  * #GPollableInputStream.
  46  **/
  47
  48 #define INITIAL_BUFFER_SIZE 4096
  49
  50 typedef struct {
  51   char *data;
  52   gsize start;
  53   gsize end;
  54   gsize size;
  55 } Buffer;
  56
  57 struct _GConverterInputStreamPrivate {
  58   gboolean at_input_end;
  59   gboolean finished;
  60   gboolean need_input;
  61   GConverter *converter;
  62   Buffer input_buffer;
  63   Buffer converted_buffer;
  64 };
  65
  66 enum {
  67   PROP_0,
  68   PROP_CONVERTER
  69 };
  70
  71 static void   g_converter_input_stream_set_property (GObject       *object,
  72                                                      guint          prop_id,
  73                                                      const GValue  *value,
  74                                                      GParamSpec    *pspec);
  75 static void   g_converter_input_stream_get_property (GObject       *object,
  76                                                      guint          prop_id,
  77                                                      GValue        *value,
  78                                                      GParamSpec    *pspec);
  79 static void   g_converter_input_stream_finalize     (GObject       *object);
  80 static gssize g_converter_input_stream_read         (GInputStream  *stream,
  81                                                      void          *buffer,
  82                                                      gsize          count,
  83                                                      GCancellable  *cancellable,
  84                                                      GError       **error);
  85
  86 static gboolean g_converter_input_stream_can_poll         (GPollableInputStream *stream);
  87 static gboolean g_converter_input_stream_is_readable      (GPollableInputStream *stream);
  88 static gssize   g_converter_input_stream_read_nonblocking (GPollableInputStream  *stream,
  89                                                            void                  *buffer,
  90                                                            gsize                  size,
  91                                                            GError               **error);
  92
  93 static GSource *g_converter_input_stream_create_source    (GPollableInputStream *stream,
  94                                                            GCancellable          *cancellable);
  95
  96 static void g_converter_input_stream_pollable_iface_init  (GPollableInputStreamInterface *iface);
  97
  98 G_DEFINE_TYPE_WITH_CODE (GConverterInputStream,
  99                          g_converter_input_stream,
 100                          G_TYPE_FILTER_INPUT_STREAM,
 101                          G_ADD_PRIVATE (GConverterInputStream)
 102                          G_IMPLEMENT_INTERFACE (G_TYPE_POLLABLE_INPUT_STREAM,
 103                                                 g_converter_input_stream_pollable_iface_init))
 104
 105 static void
 106 g_converter_input_stream_class_init (GConverterInputStreamClass *klass)
 107 {
 108   GObjectClass *object_class;
 109   GInputStreamClass *istream_class;
 110
 111   object_class = G_OBJECT_CLASS (klass);
 112   object_class->get_property = g_converter_input_stream_get_property;
 113   object_class->set_property = g_converter_input_stream_set_property;
 114   object_class->finalize     = g_converter_input_stream_finalize;
 115
 116   istream_class = G_INPUT_STREAM_CLASS (klass);
 117   istream_class->read_fn = g_converter_input_stream_read;
 118
 119   g_object_class_install_property (object_class,
 120                                    PROP_CONVERTER,
 121                                    g_param_spec_object ("converter",
 122                                                         P_("Converter"),
 123                                                         P_("The converter object"),
 124                                                         G_TYPE_CONVERTER,
 125                                                         G_PARAM_READWRITE|
 126                                                         G_PARAM_CONSTRUCT_ONLY|
 127                                                         G_PARAM_STATIC_STRINGS));
 128
 129 }
 130
 131 static void
 132 g_converter_input_stream_pollable_iface_init (GPollableInputStreamInterface *iface)
 133 {
 134   iface->can_poll = g_converter_input_stream_can_poll;
 135   iface->is_readable = g_converter_input_stream_is_readable;
 136   iface->read_nonblocking = g_converter_input_stream_read_nonblocking;
 137   iface->create_source = g_converter_input_stream_create_source;
 138 }
 139
 140 static void
 141 g_converter_input_stream_finalize (GObject *object)
 142 {
 143   GConverterInputStreamPrivate *priv;
 144   GConverterInputStream        *stream;
 145
 146   stream = G_CONVERTER_INPUT_STREAM (object);
 147   priv = stream->priv;
 148
 149   g_free (priv->input_buffer.data);
 150   g_free (priv->converted_buffer.data);
 151   if (priv->converter)
 152     g_object_unref (priv->converter);
 153
 154   G_OBJECT_CLASS (g_converter_input_stream_parent_class)->finalize (object);
 155 }
 156
 157 static void
 158 g_converter_input_stream_set_property (GObject      *object,
 159                                        guint         prop_id,
 160                                        const GValue *value,
 161                                        GParamSpec   *pspec)
 162 {
 163   GConverterInputStream *cstream;
 164
 165   cstream = G_CONVERTER_INPUT_STREAM (object);
 166
 167    switch (prop_id)
 168     {
 169     case PROP_CONVERTER:
 170       cstream->priv->converter = g_value_dup_object (value);
 171       break;
 172
 173     default:
 174       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
 175       break;
 176     }
 177
 178 }
 179
 180 static void
 181 g_converter_input_stream_get_property (GObject    *object,
 182                                        guint       prop_id,
 183                                        GValue     *value,
 184                                        GParamSpec *pspec)
 185 {
 186   GConverterInputStreamPrivate *priv;
 187   GConverterInputStream        *cstream;
 188
 189   cstream = G_CONVERTER_INPUT_STREAM (object);
 190   priv = cstream->priv;
 191
 192   switch (prop_id)
 193     {
 194     case PROP_CONVERTER:
 195       g_value_set_object (value, priv->converter);
 196       break;
 197
 198     default:
 199       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
 200       break;
 201     }
 202
 203 }
 204 static void
 205 g_converter_input_stream_init (GConverterInputStream *stream)
 206 {
 207   stream->priv = g_converter_input_stream_get_instance_private (stream);
 208 }
 209
 210 /**
 211  * g_converter_input_stream_new:
 212  * @base_stream: a #GInputStream
 213  * @converter: a #GConverter
 214  *
 215  * Creates a new converter input stream for the @base_stream.
 216  *
 217  * Returns: a new #GInputStream.
 218  **/
 219 GInputStream *
 220 g_converter_input_stream_new (GInputStream *base_stream,
 221                               GConverter   *converter)
 222 {
 223   GInputStream *stream;
 224
 225   g_return_val_if_fail (G_IS_INPUT_STREAM (base_stream), NULL);
 226
 227   stream = g_object_new (G_TYPE_CONVERTER_INPUT_STREAM,
 228                          "base-stream", base_stream,
 229                          "converter", converter,
 230                          NULL);
 231
 232   return stream;
 233 }
 234
 235 static gsize
 236 buffer_data_size (Buffer *buffer)
 237 {
 238   return buffer->end - buffer->start;
 239 }
 240
 241 static gsize
 242 buffer_tailspace (Buffer *buffer)
 243 {
 244   return buffer->size - buffer->end;
 245 }
 246
 247 static char *
 248 buffer_data (Buffer *buffer)
 249 {
 250   return buffer->data + buffer->start;
 251 }
 252
 253 static void
 254 buffer_consumed (Buffer *buffer,
 255                  gsize count)
 256 {
 257   buffer->start += count;
 258   if (buffer->start == buffer->end)
 259     buffer->start = buffer->end = 0;
 260 }
 261
 262 static void
 263 buffer_read (Buffer *buffer,
 264              char *dest,
 265              gsize count)
 266 {
 267   if (count != 0)
 268     memcpy (dest, buffer->data + buffer->start, count);
 269
 270   buffer_consumed (buffer, count);
 271 }
 272
 273 static void
 274 compact_buffer (Buffer *buffer)
 275 {
 276   gsize in_buffer;
 277
 278   in_buffer = buffer_data_size (buffer);
 279   memmove (buffer->data,
 280            buffer->data + buffer->start,
 281            in_buffer);
 282   buffer->end -= buffer->start;
 283   buffer->start = 0;
 284 }
 285
 286 static void
 287 grow_buffer (Buffer *buffer)
 288 {
 289   char *data;
 290   gsize size, in_buffer;
 291
 292   if (buffer->size == 0)
 293     size = INITIAL_BUFFER_SIZE;
 294   else
 295     size = buffer->size * 2;
 296
 297   data = g_malloc (size);
 298   in_buffer = buffer_data_size (buffer);
 299
 300   if (in_buffer != 0)
 301     memcpy (data,
 302             buffer->data + buffer->start,
 303             in_buffer);
 304
 305   g_free (buffer->data);
 306   buffer->data = data;
 307   buffer->end -= buffer->start;
 308   buffer->start = 0;
 309   buffer->size = size;
 310 }
 311
 312 /* Ensures that the buffer can fit at_least_size bytes,
 313  * *including* the current in-buffer data */
 314 static void
 315 buffer_ensure_space (Buffer *buffer,
 316                      gsize at_least_size)
 317 {
 318   gsize in_buffer, left_to_fill;
 319
 320   in_buffer = buffer_data_size (buffer);
 321
 322   if (in_buffer >= at_least_size)
 323     return;
 324
 325   left_to_fill = buffer_tailspace (buffer);
 326
 327   if (in_buffer + left_to_fill >= at_least_size)
 328     {
 329       /* We fit in remaining space at end */
 330       /* If the copy is small, compact now anyway so we can fill more */
 331       if (in_buffer < 256)
 332         compact_buffer (buffer);
 333     }
 334   else if (buffer->size >= at_least_size)
 335     {
 336       /* We fit, but only if we compact */
 337       compact_buffer (buffer);
 338     }
 339   else
 340     {
 341       /* Need to grow buffer */
 342       while (buffer->size < at_least_size)
 343         grow_buffer (buffer);
 344     }
 345 }
 346
 347 static gssize
 348 fill_input_buffer (GConverterInputStream  *stream,
 349                    gsize                   at_least_size,
 350                    gboolean                blocking,
 351                    GCancellable           *cancellable,
 352                    GError                **error)
 353 {
 354   GConverterInputStreamPrivate *priv;
 355   GInputStream *base_stream;
 356   gssize nread;
 357
 358   priv = stream->priv;
 359
 360   buffer_ensure_space (&priv->input_buffer, at_least_size);
 361
 362   base_stream = G_FILTER_INPUT_STREAM (stream)->base_stream;
 363   nread = g_pollable_stream_read (base_stream,
 364                                   priv->input_buffer.data + priv->input_buffer.end,
 365                                   buffer_tailspace (&priv->input_buffer),
 366                                   blocking,
 367                                   cancellable,
 368                                   error);
 369
 370   if (nread > 0)
 371     {
 372       priv->input_buffer.end += nread;
 373       priv->need_input = FALSE;
 374     }
 375
 376   return nread;
 377 }
 378
 379
 380 static gssize
 381 read_internal (GInputStream *stream,
 382                void         *buffer,
 383                gsize         count,
 384                gboolean      blocking,
 385                GCancellable *cancellable,
 386                GError      **error)
 387 {
 388   GConverterInputStream *cstream;
 389   GConverterInputStreamPrivate *priv;
 390   gsize available, total_bytes_read;
 391   gssize nread;
 392   GConverterResult res;
 393   gsize bytes_read;
 394   gsize bytes_written;
 395   GError *my_error;
 396   GError *my_error2;
 397
 398   cstream = G_CONVERTER_INPUT_STREAM (stream);
 399   priv = cstream->priv;
 400
 401   available = buffer_data_size (&priv->converted_buffer);
 402
 403   if (available > 0 &&
 404       count <= available)
 405     {
 406       /* Converted data available, return that */
 407       buffer_read (&priv->converted_buffer, buffer, count);
 408       return count;
 409     }
 410
 411   /* Full request not available, read all currently available and request
 412      refill/conversion for more */
 413
 414   buffer_read (&priv->converted_buffer, buffer, available);
 415
 416   total_bytes_read = available;
 417   buffer = (char *) buffer + available;
 418   count -= available;
 419
 420   /* If there is no data to convert, and no pre-converted data,
 421      do some i/o for more input */
 422   if (buffer_data_size (&priv->input_buffer) == 0 &&
 423       total_bytes_read == 0 &&
 424       !priv->at_input_end)
 425     {
 426       nread = fill_input_buffer (cstream, count, blocking, cancellable, error);
 427       if (nread < 0)
 428         return -1;
 429       if (nread == 0)
 430         priv->at_input_end = TRUE;
 431     }
 432
 433   /* First try to convert any available data (or state) directly to the user buffer: */
 434   if (!priv->finished)
 435     {
 436       my_error = NULL;
 437       res = g_converter_convert (priv->converter,
 438                                  buffer_data (&priv->input_buffer),
 439                                  buffer_data_size (&priv->input_buffer),
 440                                  buffer, count,
 441                                  priv->at_input_end ? G_CONVERTER_INPUT_AT_END : 0,
 442                                  &bytes_read,
 443                                  &bytes_written,
 444                                  &my_error);
 445       if (res != G_CONVERTER_ERROR)
 446         {
 447           total_bytes_read += bytes_written;
 448           buffer_consumed (&priv->input_buffer, bytes_read);
 449           if (res == G_CONVERTER_FINISHED)
 450             priv->finished = TRUE; /* We're done converting */
 451         }
 452       else if (total_bytes_read == 0 &&
 453                !g_error_matches (my_error,
 454                                  G_IO_ERROR,
 455                                  G_IO_ERROR_PARTIAL_INPUT) &&
 456                !g_error_matches (my_error,
 457                                  G_IO_ERROR,
 458                                  G_IO_ERROR_NO_SPACE))
 459         {
 460           /* No previously read data and no "special" error, return error */
 461           g_propagate_error (error, my_error);
 462           return -1;
 463         }
 464       else
 465         g_error_free (my_error);
 466     }
 467
 468   /* We had some pre-converted data and/or we converted directly to the
 469      user buffer */
 470   if (total_bytes_read > 0)
 471     return total_bytes_read;
 472
 473   /* If there is no more to convert, return EOF */
 474   if (priv->finished)
 475     {
 476       g_assert (buffer_data_size (&priv->converted_buffer) == 0);
 477       return 0;
 478     }
 479
 480   /* There was "complexity" in the straight-to-buffer conversion,
 481    * convert to our own buffer and write from that.
 482    * At this point we didn't produce any data into @buffer.
 483    */
 484
 485   /* Ensure we have *some* initial target space */
 486   buffer_ensure_space (&priv->converted_buffer, count);
 487
 488   while (TRUE)
 489     {
 490       g_assert (!priv->finished);
 491
 492       /* Try to convert to our buffer */
 493       my_error = NULL;
 494       res = g_converter_convert (priv->converter,
 495                                  buffer_data (&priv->input_buffer),
 496                                  buffer_data_size (&priv->input_buffer),
 497                                  buffer_data (&priv->converted_buffer),
 498                                  buffer_tailspace (&priv->converted_buffer),
 499                                  priv->at_input_end ? G_CONVERTER_INPUT_AT_END : 0,
 500                                  &bytes_read,
 501                                  &bytes_written,
 502                                  &my_error);
 503       if (res != G_CONVERTER_ERROR)
 504         {
 505           priv->converted_buffer.end += bytes_written;
 506           buffer_consumed (&priv->input_buffer, bytes_read);
 507
 508           /* Maybe we consumed without producing any output */
 509           if (buffer_data_size (&priv->converted_buffer) == 0 && res != G_CONVERTER_FINISHED)
 510             continue; /* Convert more */
 511
 512           if (res == G_CONVERTER_FINISHED)
 513             priv->finished = TRUE;
 514
 515           total_bytes_read = MIN (count, buffer_data_size (&priv->converted_buffer));
 516           buffer_read (&priv->converted_buffer, buffer, total_bytes_read);
 517
 518           g_assert (priv->finished || total_bytes_read > 0);
 519
 520           return total_bytes_read;
 521         }
 522
 523       /* There was some kind of error filling our buffer */
 524
 525       if (g_error_matches (my_error,
 526                            G_IO_ERROR,
 527                            G_IO_ERROR_PARTIAL_INPUT) &&
 528           !priv->at_input_end)
 529         {
 530           /* Need more data */
 531           my_error2 = NULL;
 532           nread = fill_input_buffer (cstream,
 533                                      buffer_data_size (&priv->input_buffer) + 4096,
 534                                      blocking,
 535                                      cancellable,
 536                                      &my_error2);
 537           if (nread < 0)
 538             {
 539               /* Can't read any more data, return that error */
 540               g_error_free (my_error);
 541               g_propagate_error (error, my_error2);
 542               priv->need_input = TRUE;
 543               return -1;
 544             }
 545           else if (nread == 0)
 546             {
 547               /* End of file, try INPUT_AT_END */
 548               priv->at_input_end = TRUE;
 549             }
 550           g_error_free (my_error);
 551           continue;
 552         }
 553
 554       if (g_error_matches (my_error,
 555                            G_IO_ERROR,
 556                            G_IO_ERROR_NO_SPACE))
 557         {
 558           /* Need more destination space, grow it
 559            * Note: if we actually grow the buffer (as opposed to compacting it),
 560            * this will double the size, not just add one byte. */
 561           buffer_ensure_space (&priv->converted_buffer,
 562                                priv->converted_buffer.size + 1);
 563           g_error_free (my_error);
 564           continue;
 565         }
 566
 567       /* Any other random error, return it */
 568       g_propagate_error (error, my_error);
 569       return -1;
 570     }
 571
 572   g_assert_not_reached ();
 573 }
 574
 575 static gssize
 576 g_converter_input_stream_read (GInputStream *stream,
 577                                void         *buffer,
 578                                gsize         count,
 579                                GCancellable *cancellable,
 580                                GError      **error)
 581 {
 582   return read_internal (stream, buffer, count, TRUE, cancellable, error);
 583 }
 584
 585 static gboolean
 586 g_converter_input_stream_can_poll (GPollableInputStream *stream)
 587 {
 588   GInputStream *base_stream = G_FILTER_INPUT_STREAM (stream)->base_stream;
 589
 590   return (G_IS_POLLABLE_INPUT_STREAM (base_stream) &&
 591           g_pollable_input_stream_can_poll (G_POLLABLE_INPUT_STREAM (base_stream)));
 592 }
 593
 594 static gboolean
 595 g_converter_input_stream_is_readable (GPollableInputStream *stream)
 596 {
 597   GInputStream *base_stream = G_FILTER_INPUT_STREAM (stream)->base_stream;
 598   GConverterInputStream *cstream = G_CONVERTER_INPUT_STREAM (stream);
 599
 600   if (buffer_data_size (&cstream->priv->converted_buffer))
 601     return TRUE;
 602   else if (buffer_data_size (&cstream->priv->input_buffer) &&
 603            !cstream->priv->need_input)
 604     return TRUE;
 605   else
 606     return g_pollable_input_stream_is_readable (G_POLLABLE_INPUT_STREAM (base_stream));
 607 }
 608
 609 static gssize
 610 g_converter_input_stream_read_nonblocking (GPollableInputStream  *stream,
 611                                            void                  *buffer,
 612                                            gsize                  count,
 613                                            GError               **error)
 614 {
 615   return read_internal (G_INPUT_STREAM (stream), buffer, count,
 616                         FALSE, NULL, error);
 617 }
 618
 619 static GSource *
 620 g_converter_input_stream_create_source (GPollableInputStream *stream,
 621                                         GCancellable         *cancellable)
 622 {
 623   GInputStream *base_stream = G_FILTER_INPUT_STREAM (stream)->base_stream;
 624   GSource *base_source, *pollable_source;
 625
 626   if (g_pollable_input_stream_is_readable (stream))
 627     base_source = g_timeout_source_new (0);
 628   else
 629     base_source = g_pollable_input_stream_create_source (G_POLLABLE_INPUT_STREAM (base_stream), NULL);
 630
 631   pollable_source = g_pollable_source_new_full (stream, base_source,
 632                                                 cancellable);
 633   g_source_unref (base_source);
 634
 635   return pollable_source;
 636 }
 637
 638
 639 /**
 640  * g_converter_input_stream_get_converter:
 641  * @converter_stream: a #GConverterInputStream
 642  *
 643  * Gets the #GConverter that is used by @converter_stream.
 644  *
 645  * Returns: (transfer none): the converter of the converter input stream
 646  *
 647  * Since: 2.24
 648  */
 649 GConverter *
 650 g_converter_input_stream_get_converter (GConverterInputStream *converter_stream)
 651 {
 652   return converter_stream->priv->converter;
 653 }