libyelp/yelp-magic-decompressor.c

   1 /* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * Copyright (C) 2009 Red Hat, Inc.
   4  * Copyright (C) 2009 Shaun McCance <shaunm@gnome.org>
   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: Shaun McCance <shaunm@gnome.org>
  20  */
  21
  22 #include "config.h"
  23
  24 #include <glib/gi18n.h>
  25 #include <string.h>
  26
  27 #include "yelp-magic-decompressor.h"
  28
  29 #ifdef ENABLE_BZ2
  30 #include "yelp-bz2-decompressor.h"
  31 #endif
  32
  33 #ifdef ENABLE_LZMA
  34 #include "yelp-lzma-decompressor.h"
  35 #endif
  36
  37
  38 static void yelp_magic_decompressor_iface_init          (GConverterIface *iface);
  39
  40 struct _YelpMagicDecompressor
  41 {
  42     GObject parent_instance;
  43
  44     GConverter *magic_decoder_ring;
  45
  46     gboolean first;
  47 };
  48
  49 G_DEFINE_TYPE_WITH_CODE (YelpMagicDecompressor, yelp_magic_decompressor, G_TYPE_OBJECT,
  50                          G_IMPLEMENT_INTERFACE (G_TYPE_CONVERTER,
  51                                                 yelp_magic_decompressor_iface_init))
  52
  53 static void
  54 yelp_magic_decompressor_dispose (GObject *object)
  55 {
  56     YelpMagicDecompressor *decompressor = YELP_MAGIC_DECOMPRESSOR (object);
  57
  58     if (decompressor->magic_decoder_ring) {
  59         g_object_unref (decompressor->magic_decoder_ring);
  60         decompressor->magic_decoder_ring = NULL;
  61     }
  62
  63     G_OBJECT_CLASS (yelp_magic_decompressor_parent_class)->dispose (object);
  64 }
  65
  66 static void
  67 yelp_magic_decompressor_init (YelpMagicDecompressor *decompressor)
  68 {
  69     decompressor->magic_decoder_ring = NULL;
  70     decompressor->first = TRUE;
  71 }
  72
  73 static void
  74 yelp_magic_decompressor_class_init (YelpMagicDecompressorClass *klass)
  75 {
  76     GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
  77
  78     gobject_class->dispose = yelp_magic_decompressor_dispose;
  79 }
  80
  81 YelpMagicDecompressor *
  82 yelp_magic_decompressor_new (void)
  83 {
  84     YelpMagicDecompressor *decompressor;
  85
  86     decompressor = g_object_new (YELP_TYPE_MAGIC_DECOMPRESSOR, NULL);
  87
  88     return decompressor;
  89 }
  90
  91 static void
  92 yelp_magic_decompressor_reset (GConverter *converter)
  93 {
  94     YelpMagicDecompressor *decompressor = YELP_MAGIC_DECOMPRESSOR (converter);
  95
  96     if (decompressor->magic_decoder_ring)
  97         g_converter_reset (decompressor->magic_decoder_ring);
  98 }
  99
 100 static GConverter*
 101 yelp_magic_decompressor_choose (const void *inbuf, gsize inbuf_size)
 102 {
 103     /* If input_size is less than two the first time, we end up
 104      * not getting detection.  Might be worth addressing.  Not
 105      * sure I care.
 106      *
 107      * The two-byte magic we're doing here is not sufficient in
 108      * the general case.  It is sufficient for the specific data
 109      * Yelp deals with.
 110      */
 111     if (inbuf_size <= 2)
 112         return NULL;
 113
 114 #ifdef ENABLE_BZ2
 115     if (((gchar *) inbuf)[0] == 'B' && ((gchar *) inbuf)[1] == 'Z') {
 116         return (GConverter *) yelp_bz2_decompressor_new ();
 117     }
 118 #endif
 119 #ifdef ENABLE_LZMA
 120     if (((gchar *) inbuf)[0] == ']' && ((gchar *) inbuf)[1] == '\0') {
 121         return (GConverter *) yelp_lzma_decompressor_new ();
 122     }
 123 #endif
 124     if (((guint8*) inbuf)[0] == 0x1F && ((guint8*) inbuf)[1] == 0x8B) {
 125         return (GConverter *) g_zlib_decompressor_new (G_ZLIB_COMPRESSOR_FORMAT_GZIP);
 126     }
 127
 128     return NULL;
 129 }
 130
 131 static GConverterResult
 132 yelp_magic_decompressor_convert (GConverter *converter,
 133                                  const void *inbuf,
 134                                  gsize       inbuf_size,
 135                                  void       *outbuf,
 136                                  gsize       outbuf_size,
 137                                  GConverterFlags flags,
 138                                  gsize      *bytes_read,
 139                                  gsize      *bytes_written,
 140                                  GError    **error)
 141 {
 142     YelpMagicDecompressor *decompressor;
 143     gsize txfer_size;
 144
 145     decompressor = YELP_MAGIC_DECOMPRESSOR (converter);
 146
 147     if (decompressor->first) {
 148         decompressor->magic_decoder_ring =
 149             yelp_magic_decompressor_choose (inbuf, inbuf_size);
 150         decompressor->first = FALSE;
 151     }
 152
 153     if (decompressor->magic_decoder_ring) {
 154         return g_converter_convert (decompressor->magic_decoder_ring,
 155                                     inbuf, inbuf_size,
 156                                     outbuf, outbuf_size,
 157                                     flags,
 158                                     bytes_read, bytes_written,
 159                                     error);
 160     }
 161
 162     /* If there's no magic_decoder_ring, we just copy the data
 163      * straight through. */
 164     txfer_size = MIN (inbuf_size, outbuf_size);
 165     memcpy (outbuf, inbuf, txfer_size);
 166     *bytes_read = txfer_size;
 167     *bytes_written = txfer_size;
 168
 169     if (flags & G_CONVERTER_INPUT_AT_END)
 170         return G_CONVERTER_FINISHED;
 171     return G_CONVERTER_CONVERTED;
 172 }
 173
 174 static void
 175 yelp_magic_decompressor_iface_init (GConverterIface *iface)
 176 {
 177   iface->convert = yelp_magic_decompressor_convert;
 178   iface->reset = yelp_magic_decompressor_reset;
 179 }