gio/gconverter.c

   1 /* GIO - GLib Input, Output and Streaming Library
   2  *
   3  * Copyright (C) 2009 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, see <http://www.gnu.org/licenses/>.
  17  *
  18  * Author: Alexander Larsson <alexl@redhat.com>
  19  */
  20
  21 #include "config.h"
  22 #include "gconverter.h"
  23 #include "glibintl.h"
  24
  25
  26 /**
  27  * SECTION:gconverter
  28  * @short_description: Data conversion interface
  29  * @include: gio/gio.h
  30  * @see_also: #GInputStream, #GOutputStream
  31  *
  32  * #GConverter is implemented by objects that convert
  33  * binary data in various ways. The conversion can be
  34  * stateful and may fail at any place.
  35  *
  36  * Some example conversions are: character set conversion,
  37  * compression, decompression and regular expression
  38  * replace.
  39  *
  40  * Since: 2.24
  41  **/
  42
  43
  44 typedef GConverterIface GConverterInterface;
  45 G_DEFINE_INTERFACE (GConverter, g_converter, G_TYPE_OBJECT)
  46
  47 static void
  48 g_converter_default_init (GConverterInterface *iface)
  49 {
  50 }
  51
  52 /**
  53  * g_converter_convert:
  54  * @converter: a #GConverter.
  55  * @inbuf: (array length=inbuf_size) (element-type guint8): the buffer
  56  *         containing the data to convert.
  57  * @inbuf_size: the number of bytes in @inbuf
  58  * @outbuf: a buffer to write converted data in.
  59  * @outbuf_size: the number of bytes in @outbuf, must be at least one
  60  * @flags: a #GConverterFlags controlling the conversion details
  61  * @bytes_read: (out): will be set to the number of bytes read from @inbuf on success
  62  * @bytes_written: (out): will be set to the number of bytes written to @outbuf on success
  63  * @error: location to store the error occurring, or %NULL to ignore
  64  *
  65  * This is the main operation used when converting data. It is to be called
  66  * multiple times in a loop, and each time it will do some work, i.e.
  67  * producing some output (in @outbuf) or consuming some input (from @inbuf) or
  68  * both. If its not possible to do any work an error is returned.
  69  *
  70  * Note that a single call may not consume all input (or any input at all).
  71  * Also a call may produce output even if given no input, due to state stored
  72  * in the converter producing output.
  73  *
  74  * If any data was either produced or consumed, and then an error happens, then
  75  * only the successful conversion is reported and the error is returned on the
  76  * next call.
  77  *
  78  * A full conversion loop involves calling this method repeatedly, each time
  79  * giving it new input and space output space. When there is no more input
  80  * data after the data in @inbuf, the flag %G_CONVERTER_INPUT_AT_END must be set.
  81  * The loop will be (unless some error happens) returning %G_CONVERTER_CONVERTED
  82  * each time until all data is consumed and all output is produced, then
  83  * %G_CONVERTER_FINISHED is returned instead. Note, that %G_CONVERTER_FINISHED
  84  * may be returned even if %G_CONVERTER_INPUT_AT_END is not set, for instance
  85  * in a decompression converter where the end of data is detectable from the
  86  * data (and there might even be other data after the end of the compressed data).
  87  *
  88  * When some data has successfully been converted @bytes_read and is set to
  89  * the number of bytes read from @inbuf, and @bytes_written is set to indicate
  90  * how many bytes was written to @outbuf. If there are more data to output
  91  * or consume (i.e. unless the %G_CONVERTER_INPUT_AT_END is specified) then
  92  * %G_CONVERTER_CONVERTED is returned, and if no more data is to be output
  93  * then %G_CONVERTER_FINISHED is returned.
  94  *
  95  * On error %G_CONVERTER_ERROR is returned and @error is set accordingly.
  96  * Some errors need special handling:
  97  *
  98  * %G_IO_ERROR_NO_SPACE is returned if there is not enough space
  99  * to write the resulting converted data, the application should
 100  * call the function again with a larger @outbuf to continue.
 101  *
 102  * %G_IO_ERROR_PARTIAL_INPUT is returned if there is not enough
 103  * input to fully determine what the conversion should produce,
 104  * and the %G_CONVERTER_INPUT_AT_END flag is not set. This happens for
 105  * example with an incomplete multibyte sequence when converting text,
 106  * or when a regexp matches up to the end of the input (and may match
 107  * further input). It may also happen when @inbuf_size is zero and
 108  * there is no more data to produce.
 109  *
 110  * When this happens the application should read more input and then
 111  * call the function again. If further input shows that there is no
 112  * more data call the function again with the same data but with
 113  * the %G_CONVERTER_INPUT_AT_END flag set. This may cause the conversion
 114  * to finish as e.g. in the regexp match case (or, to fail again with
 115  * %G_IO_ERROR_PARTIAL_INPUT in e.g. a charset conversion where the
 116  * input is actually partial).
 117  *
 118  * After g_converter_convert() has returned %G_CONVERTER_FINISHED the
 119  * converter object is in an invalid state where its not allowed
 120  * to call g_converter_convert() anymore. At this time you can only
 121  * free the object or call g_converter_reset() to reset it to the
 122  * initial state.
 123  *
 124  * If the flag %G_CONVERTER_FLUSH is set then conversion is modified
 125  * to try to write out all internal state to the output. The application
 126  * has to call the function multiple times with the flag set, and when
 127  * the available input has been consumed and all internal state has
 128  * been produced then %G_CONVERTER_FLUSHED (or %G_CONVERTER_FINISHED if
 129  * really at the end) is returned instead of %G_CONVERTER_CONVERTED.
 130  * This is somewhat similar to what happens at the end of the input stream,
 131  * but done in the middle of the data.
 132  *
 133  * This has different meanings for different conversions. For instance
 134  * in a compression converter it would mean that we flush all the
 135  * compression state into output such that if you uncompress the
 136  * compressed data you get back all the input data. Doing this may
 137  * make the final file larger due to padding though. Another example
 138  * is a regexp conversion, where if you at the end of the flushed data
 139  * have a match, but there is also a potential longer match. In the
 140  * non-flushed case we would ask for more input, but when flushing we
 141  * treat this as the end of input and do the match.
 142  *
 143  * Flushing is not always possible (like if a charset converter flushes
 144  * at a partial multibyte sequence). Converters are supposed to try
 145  * to produce as much output as possible and then return an error
 146  * (typically %G_IO_ERROR_PARTIAL_INPUT).
 147  *
 148  * Returns: a #GConverterResult, %G_CONVERTER_ERROR on error.
 149  *
 150  * Since: 2.24
 151  **/
 152 GConverterResult
 153 g_converter_convert (GConverter *converter,
 154                      const void *inbuf,
 155                      gsize       inbuf_size,
 156                      void       *outbuf,
 157                      gsize       outbuf_size,
 158                      GConverterFlags flags,
 159                      gsize      *bytes_read,
 160                      gsize      *bytes_written,
 161                      GError    **error)
 162 {
 163   GConverterIface *iface;
 164
 165   g_return_val_if_fail (G_IS_CONVERTER (converter), G_CONVERTER_ERROR);
 166   g_return_val_if_fail (outbuf_size > 0, G_CONVERTER_ERROR);
 167
 168   *bytes_read = 0;
 169   *bytes_written = 0;
 170
 171   iface = G_CONVERTER_GET_IFACE (converter);
 172
 173   return (* iface->convert) (converter,
 174                              inbuf, inbuf_size,
 175                              outbuf, outbuf_size,
 176                              flags,
 177                              bytes_read, bytes_written, error);
 178 }
 179
 180 /**
 181  * g_converter_reset:
 182  * @converter: a #GConverter.
 183  *
 184  * Resets all internal state in the converter, making it behave
 185  * as if it was just created. If the converter has any internal
 186  * state that would produce output then that output is lost.
 187  *
 188  * Since: 2.24
 189  **/
 190 void
 191 g_converter_reset (GConverter *converter)
 192 {
 193   GConverterIface *iface;
 194
 195   g_return_if_fail (G_IS_CONVERTER (converter));
 196
 197   iface = G_CONVERTER_GET_IFACE (converter);
 198
 199   (* iface->reset) (converter);
 200 }