1 /* GIO - GLib Input, Output and Streaming Library
3 * Copyright (C) 2009 Red Hat, Inc.
5 * SPDX-License-Identifier: LGPL-2.1-or-later
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.
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.
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/>.
20 * Author: Alexander Larsson <alexl@redhat.com>
24 #include "gconverter.h"
30 * @short_description: Data conversion interface
32 * @see_also: #GInputStream, #GOutputStream
34 * #GConverter is implemented by objects that convert
35 * binary data in various ways. The conversion can be
36 * stateful and may fail at any place.
38 * Some example conversions are: character set conversion,
39 * compression, decompression and regular expression
46 typedef GConverterIface GConverterInterface;
47 G_DEFINE_INTERFACE (GConverter, g_converter, G_TYPE_OBJECT)
50 g_converter_default_init (GConverterInterface *iface)
55 * g_converter_convert:
56 * @converter: a #GConverter.
57 * @inbuf: (array length=inbuf_size) (element-type guint8): the buffer
58 * containing the data to convert.
59 * @inbuf_size: the number of bytes in @inbuf
60 * @outbuf: (element-type guint8) (array length=outbuf_size) (not nullable): a
61 * buffer to write converted data in.
62 * @outbuf_size: the number of bytes in @outbuf, must be at least one
63 * @flags: a #GConverterFlags controlling the conversion details
64 * @bytes_read: (out) (not nullable): will be set to the number of bytes read
65 * from @inbuf on success
66 * @bytes_written: (out) (not nullable): will be set to the number of bytes
67 * written to @outbuf on success
68 * @error: location to store the error occurring, or %NULL to ignore
70 * This is the main operation used when converting data. It is to be called
71 * multiple times in a loop, and each time it will do some work, i.e.
72 * producing some output (in @outbuf) or consuming some input (from @inbuf) or
73 * both. If its not possible to do any work an error is returned.
75 * Note that a single call may not consume all input (or any input at all).
76 * Also a call may produce output even if given no input, due to state stored
77 * in the converter producing output.
79 * If any data was either produced or consumed, and then an error happens, then
80 * only the successful conversion is reported and the error is returned on the
83 * A full conversion loop involves calling this method repeatedly, each time
84 * giving it new input and space output space. When there is no more input
85 * data after the data in @inbuf, the flag %G_CONVERTER_INPUT_AT_END must be set.
86 * The loop will be (unless some error happens) returning %G_CONVERTER_CONVERTED
87 * each time until all data is consumed and all output is produced, then
88 * %G_CONVERTER_FINISHED is returned instead. Note, that %G_CONVERTER_FINISHED
89 * may be returned even if %G_CONVERTER_INPUT_AT_END is not set, for instance
90 * in a decompression converter where the end of data is detectable from the
91 * data (and there might even be other data after the end of the compressed data).
93 * When some data has successfully been converted @bytes_read and is set to
94 * the number of bytes read from @inbuf, and @bytes_written is set to indicate
95 * how many bytes was written to @outbuf. If there are more data to output
96 * or consume (i.e. unless the %G_CONVERTER_INPUT_AT_END is specified) then
97 * %G_CONVERTER_CONVERTED is returned, and if no more data is to be output
98 * then %G_CONVERTER_FINISHED is returned.
100 * On error %G_CONVERTER_ERROR is returned and @error is set accordingly.
101 * Some errors need special handling:
103 * %G_IO_ERROR_NO_SPACE is returned if there is not enough space
104 * to write the resulting converted data, the application should
105 * call the function again with a larger @outbuf to continue.
107 * %G_IO_ERROR_PARTIAL_INPUT is returned if there is not enough
108 * input to fully determine what the conversion should produce,
109 * and the %G_CONVERTER_INPUT_AT_END flag is not set. This happens for
110 * example with an incomplete multibyte sequence when converting text,
111 * or when a regexp matches up to the end of the input (and may match
112 * further input). It may also happen when @inbuf_size is zero and
113 * there is no more data to produce.
115 * When this happens the application should read more input and then
116 * call the function again. If further input shows that there is no
117 * more data call the function again with the same data but with
118 * the %G_CONVERTER_INPUT_AT_END flag set. This may cause the conversion
119 * to finish as e.g. in the regexp match case (or, to fail again with
120 * %G_IO_ERROR_PARTIAL_INPUT in e.g. a charset conversion where the
121 * input is actually partial).
123 * After g_converter_convert() has returned %G_CONVERTER_FINISHED the
124 * converter object is in an invalid state where its not allowed
125 * to call g_converter_convert() anymore. At this time you can only
126 * free the object or call g_converter_reset() to reset it to the
129 * If the flag %G_CONVERTER_FLUSH is set then conversion is modified
130 * to try to write out all internal state to the output. The application
131 * has to call the function multiple times with the flag set, and when
132 * the available input has been consumed and all internal state has
133 * been produced then %G_CONVERTER_FLUSHED (or %G_CONVERTER_FINISHED if
134 * really at the end) is returned instead of %G_CONVERTER_CONVERTED.
135 * This is somewhat similar to what happens at the end of the input stream,
136 * but done in the middle of the data.
138 * This has different meanings for different conversions. For instance
139 * in a compression converter it would mean that we flush all the
140 * compression state into output such that if you uncompress the
141 * compressed data you get back all the input data. Doing this may
142 * make the final file larger due to padding though. Another example
143 * is a regexp conversion, where if you at the end of the flushed data
144 * have a match, but there is also a potential longer match. In the
145 * non-flushed case we would ask for more input, but when flushing we
146 * treat this as the end of input and do the match.
148 * Flushing is not always possible (like if a charset converter flushes
149 * at a partial multibyte sequence). Converters are supposed to try
150 * to produce as much output as possible and then return an error
151 * (typically %G_IO_ERROR_PARTIAL_INPUT).
153 * Returns: a #GConverterResult, %G_CONVERTER_ERROR on error.
158 g_converter_convert (GConverter *converter,
163 GConverterFlags flags,
165 gsize *bytes_written,
168 GConverterIface *iface;
170 g_return_val_if_fail (G_IS_CONVERTER (converter), G_CONVERTER_ERROR);
171 g_return_val_if_fail (inbuf != NULL || inbuf_size == 0, G_CONVERTER_ERROR);
172 g_return_val_if_fail (outbuf != NULL, G_CONVERTER_ERROR);
173 g_return_val_if_fail (outbuf_size > 0, G_CONVERTER_ERROR);
174 g_return_val_if_fail (bytes_read != NULL, G_CONVERTER_ERROR);
175 g_return_val_if_fail (bytes_written != NULL, G_CONVERTER_ERROR);
176 g_return_val_if_fail (error == NULL || *error == NULL, G_CONVERTER_ERROR);
181 iface = G_CONVERTER_GET_IFACE (converter);
183 return (* iface->convert) (converter,
187 bytes_read, bytes_written, error);
192 * @converter: a #GConverter.
194 * Resets all internal state in the converter, making it behave
195 * as if it was just created. If the converter has any internal
196 * state that would produce output then that output is lost.
201 g_converter_reset (GConverter *converter)
203 GConverterIface *iface;
205 g_return_if_fail (G_IS_CONVERTER (converter));
207 iface = G_CONVERTER_GET_IFACE (converter);
209 (* iface->reset) (converter);