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 2.1 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: (element-type guint8) (array length=outbuf_size): a buffer to write
  59  *    converted data in.
  60  * @outbuf_size: the number of bytes in @outbuf, must be at least one
  61  * @flags: a #GConverterFlags controlling the conversion details
  62  * @bytes_read: (out): will be set to the number of bytes read from @inbuf on success
  63  * @bytes_written: (out): will be set to the number of bytes written to @outbuf on success
  64  * @error: location to store the error occurring, or %NULL to ignore
  65  *
  66  * This is the main operation used when converting data. It is to be called
  67  * multiple times in a loop, and each time it will do some work, i.e.
  68  * producing some output (in @outbuf) or consuming some input (from @inbuf) or
  69  * both. If its not possible to do any work an error is returned.
  70  *
  71  * Note that a single call may not consume all input (or any input at all).
  72  * Also a call may produce output even if given no input, due to state stored
  73  * in the converter producing output.
  74  *
  75  * If any data was either produced or consumed, and then an error happens, then
  76  * only the successful conversion is reported and the error is returned on the
  77  * next call.
  78  *
  79  * A full conversion loop involves calling this method repeatedly, each time
  80  * giving it new input and space output space. When there is no more input
  81  * data after the data in @inbuf, the flag %G_CONVERTER_INPUT_AT_END must be set.
  82  * The loop will be (unless some error happens) returning %G_CONVERTER_CONVERTED
  83  * each time until all data is consumed and all output is produced, then
  84  * %G_CONVERTER_FINISHED is returned instead. Note, that %G_CONVERTER_FINISHED
  85  * may be returned even if %G_CONVERTER_INPUT_AT_END is not set, for instance
  86  * in a decompression converter where the end of data is detectable from the
  87  * data (and there might even be other data after the end of the compressed data).
  88  *
  89  * When some data has successfully been converted @bytes_read and is set to
  90  * the number of bytes read from @inbuf, and @bytes_written is set to indicate
  91  * how many bytes was written to @outbuf. If there are more data to output
  92  * or consume (i.e. unless the %G_CONVERTER_INPUT_AT_END is specified) then
  93  * %G_CONVERTER_CONVERTED is returned, and if no more data is to be output
  94  * then %G_CONVERTER_FINISHED is returned.
  95  *
  96  * On error %G_CONVERTER_ERROR is returned and @error is set accordingly.
  97  * Some errors need special handling:
  98  *
  99  * %G_IO_ERROR_NO_SPACE is returned if there is not enough space
 100  * to write the resulting converted data, the application should
 101  * call the function again with a larger @outbuf to continue.
 102  *
 103  * %G_IO_ERROR_PARTIAL_INPUT is returned if there is not enough
 104  * input to fully determine what the conversion should produce,
 105  * and the %G_CONVERTER_INPUT_AT_END flag is not set. This happens for
 106  * example with an incomplete multibyte sequence when converting text,
 107  * or when a regexp matches up to the end of the input (and may match
 108  * further input). It may also happen when @inbuf_size is zero and
 109  * there is no more data to produce.
 110  *
 111  * When this happens the application should read more input and then
 112  * call the function again. If further input shows that there is no
 113  * more data call the function again with the same data but with
 114  * the %G_CONVERTER_INPUT_AT_END flag set. This may cause the conversion
 115  * to finish as e.g. in the regexp match case (or, to fail again with
 116  * %G_IO_ERROR_PARTIAL_INPUT in e.g. a charset conversion where the
 117  * input is actually partial).
 118  *
 119  * After g_converter_convert() has returned %G_CONVERTER_FINISHED the
 120  * converter object is in an invalid state where its not allowed
 121  * to call g_converter_convert() anymore. At this time you can only
 122  * free the object or call g_converter_reset() to reset it to the
 123  * initial state.
 124  *
 125  * If the flag %G_CONVERTER_FLUSH is set then conversion is modified
 126  * to try to write out all internal state to the output. The application
 127  * has to call the function multiple times with the flag set, and when
 128  * the available input has been consumed and all internal state has
 129  * been produced then %G_CONVERTER_FLUSHED (or %G_CONVERTER_FINISHED if
 130  * really at the end) is returned instead of %G_CONVERTER_CONVERTED.
 131  * This is somewhat similar to what happens at the end of the input stream,
 132  * but done in the middle of the data.
 133  *
 134  * This has different meanings for different conversions. For instance
 135  * in a compression converter it would mean that we flush all the
 136  * compression state into output such that if you uncompress the
 137  * compressed data you get back all the input data. Doing this may
 138  * make the final file larger due to padding though. Another example
 139  * is a regexp conversion, where if you at the end of the flushed data
 140  * have a match, but there is also a potential longer match. In the
 141  * non-flushed case we would ask for more input, but when flushing we
 142  * treat this as the end of input and do the match.
 143  *
 144  * Flushing is not always possible (like if a charset converter flushes
 145  * at a partial multibyte sequence). Converters are supposed to try
 146  * to produce as much output as possible and then return an error
 147  * (typically %G_IO_ERROR_PARTIAL_INPUT).
 148  *
 149  * Returns: a #GConverterResult, %G_CONVERTER_ERROR on error.
 150  *
 151  * Since: 2.24
 152  **/
 153 GConverterResult
 154 g_converter_convert (GConverter *converter,
 155                      const void *inbuf,
 156                      gsize       inbuf_size,
 157                      void       *outbuf,
 158                      gsize       outbuf_size,
 159                      GConverterFlags flags,
 160                      gsize      *bytes_read,
 161                      gsize      *bytes_written,
 162                      GError    **error)
 163 {
 164   GConverterIface *iface;
 165
 166   g_return_val_if_fail (G_IS_CONVERTER (converter), G_CONVERTER_ERROR);
 167   g_return_val_if_fail (outbuf_size > 0, G_CONVERTER_ERROR);
 168
 169   *bytes_read = 0;
 170   *bytes_written = 0;
 171
 172   iface = G_CONVERTER_GET_IFACE (converter);
 173
 174   return (* iface->convert) (converter,
 175                              inbuf, inbuf_size,
 176                              outbuf, outbuf_size,
 177                              flags,
 178                              bytes_read, bytes_written, error);
 179 }
 180
 181 /**
 182  * g_converter_reset:
 183  * @converter: a #GConverter.
 184  *
 185  * Resets all internal state in the converter, making it behave
 186  * as if it was just created. If the converter has any internal
 187  * state that would produce output then that output is lost.
 188  *
 189  * Since: 2.24
 190  **/
 191 void
 192 g_converter_reset (GConverter *converter)
 193 {
 194   GConverterIface *iface;
 195
 196   g_return_if_fail (G_IS_CONVERTER (converter));
 197
 198   iface = G_CONVERTER_GET_IFACE (converter);
 199
 200   (* iface->reset) (converter);
 201 }