/* GIO - GLib Input, Output and Streaming Library

 *

 * Copyright (C) 2009 Red Hat, Inc.

 *

 * SPDX-License-Identifier: LGPL-2.1-or-later

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General

 * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.

 *

 * Author: Alexander Larsson <alexl@redhat.com>

 */

#include "config.h"

#include "gconverter.h"

#include "glibintl.h"

/**

 * GConverter:

 *

 * `GConverter` is an interface for streaming conversions.

 *

 * `GConverter` is implemented by objects that convert

 * binary data in various ways. The conversion can be

 * stateful and may fail at any place.

 *

 * Some example conversions are: character set conversion,

 * compression, decompression and regular expression

 * replace.

 *

 * Since: 2.24

 */

typedef GConverterIface GConverterInterface;

G_DEFINE_INTERFACE (GConverter, g_converter, G_TYPE_OBJECT)

static void

g_converter_default_init (GConverterInterface *iface)

{

}

/**

 * g_converter_convert:

 * @converter: a #GConverter.

 * @inbuf: (array length=inbuf_size) (element-type guint8): the buffer

 *         containing the data to convert.

 * @inbuf_size: the number of bytes in @inbuf

 * @outbuf: (element-type guint8) (array length=outbuf_size) (not nullable): a

 *    buffer to write converted data in.

 * @outbuf_size: the number of bytes in @outbuf, must be at least one

 * @flags: a #GConverterFlags controlling the conversion details

 * @bytes_read: (out) (not nullable): will be set to the number of bytes read

 *    from @inbuf on success

 * @bytes_written: (out) (not nullable): will be set to the number of bytes

 *    written to @outbuf on success

 * @error: location to store the error occurring, or %NULL to ignore

 *

 * This is the main operation used when converting data. It is to be called

 * multiple times in a loop, and each time it will do some work, i.e.

 * producing some output (in @outbuf) or consuming some input (from @inbuf) or

 * both. If its not possible to do any work an error is returned.

 *

 * Note that a single call may not consume all input (or any input at all).

 * Also a call may produce output even if given no input, due to state stored

 * in the converter producing output.

 *

 * If any data was either produced or consumed, and then an error happens, then

 * only the successful conversion is reported and the error is returned on the

 * next call.

 *

 * A full conversion loop involves calling this method repeatedly, each time

 * giving it new input and space output space. When there is no more input

 * data after the data in @inbuf, the flag %G_CONVERTER_INPUT_AT_END must be set.

 * The loop will be (unless some error happens) returning %G_CONVERTER_CONVERTED

 * each time until all data is consumed and all output is produced, then

 * %G_CONVERTER_FINISHED is returned instead. Note, that %G_CONVERTER_FINISHED

 * may be returned even if %G_CONVERTER_INPUT_AT_END is not set, for instance

 * in a decompression converter where the end of data is detectable from the

 * data (and there might even be other data after the end of the compressed data).

 *

 * When some data has successfully been converted @bytes_read and is set to

 * the number of bytes read from @inbuf, and @bytes_written is set to indicate

 * how many bytes was written to @outbuf. If there are more data to output

 * or consume (i.e. unless the %G_CONVERTER_INPUT_AT_END is specified) then

 * %G_CONVERTER_CONVERTED is returned, and if no more data is to be output

 * then %G_CONVERTER_FINISHED is returned.

 *

 * On error %G_CONVERTER_ERROR is returned and @error is set accordingly.

 * Some errors need special handling:

 *

 * %G_IO_ERROR_NO_SPACE is returned if there is not enough space

 * to write the resulting converted data, the application should

 * call the function again with a larger @outbuf to continue.

 *

 * %G_IO_ERROR_PARTIAL_INPUT is returned if there is not enough

 * input to fully determine what the conversion should produce,

 * and the %G_CONVERTER_INPUT_AT_END flag is not set. This happens for

 * example with an incomplete multibyte sequence when converting text,

 * or when a regexp matches up to the end of the input (and may match

 * further input). It may also happen when @inbuf_size is zero and

 * there is no more data to produce.

 *

 * When this happens the application should read more input and then

 * call the function again. If further input shows that there is no

 * more data call the function again with the same data but with

 * the %G_CONVERTER_INPUT_AT_END flag set. This may cause the conversion

 * to finish as e.g. in the regexp match case (or, to fail again with

 * %G_IO_ERROR_PARTIAL_INPUT in e.g. a charset conversion where the

 * input is actually partial).

 *

 * After g_converter_convert() has returned %G_CONVERTER_FINISHED the

 * converter object is in an invalid state where its not allowed

 * to call g_converter_convert() anymore. At this time you can only

 * free the object or call g_converter_reset() to reset it to the

 * initial state.

 *

 * If the flag %G_CONVERTER_FLUSH is set then conversion is modified

 * to try to write out all internal state to the output. The application

 * has to call the function multiple times with the flag set, and when

 * the available input has been consumed and all internal state has

 * been produced then %G_CONVERTER_FLUSHED (or %G_CONVERTER_FINISHED if

 * really at the end) is returned instead of %G_CONVERTER_CONVERTED.

 * This is somewhat similar to what happens at the end of the input stream,

 * but done in the middle of the data.

 *

 * This has different meanings for different conversions. For instance

 * in a compression converter it would mean that we flush all the

 * compression state into output such that if you uncompress the

 * compressed data you get back all the input data. Doing this may

 * make the final file larger due to padding though. Another example

 * is a regexp conversion, where if you at the end of the flushed data

 * have a match, but there is also a potential longer match. In the

 * non-flushed case we would ask for more input, but when flushing we

 * treat this as the end of input and do the match.

 *

 * Flushing is not always possible (like if a charset converter flushes

 * at a partial multibyte sequence). Converters are supposed to try

 * to produce as much output as possible and then return an error

 * (typically %G_IO_ERROR_PARTIAL_INPUT).

 *

 * Returns: a #GConverterResult, %G_CONVERTER_ERROR on error.

 *

 * Since: 2.24

 **/

GConverterResult

g_converter_convert (GConverter *converter,

         const void *inbuf,

         gsize       inbuf_size,

         void       *outbuf,

         gsize       outbuf_size,

         GConverterFlags flags,

         gsize      *bytes_read,

         gsize      *bytes_written,

         GError    **error)

{

  GConverterIface *iface;

  g_return_val_if_fail (G_IS_CONVERTER (converter), G_CONVERTER_ERROR);

  g_return_val_if_fail (inbuf != NULL || inbuf_size == 0, G_CONVERTER_ERROR);

  g_return_val_if_fail (outbuf != NULL, G_CONVERTER_ERROR);

  g_return_val_if_fail (outbuf_size > 0, G_CONVERTER_ERROR);

  g_return_val_if_fail (bytes_read != NULL, G_CONVERTER_ERROR);

  g_return_val_if_fail (bytes_written != NULL, G_CONVERTER_ERROR);

  g_return_val_if_fail (error == NULL || *error == NULL, G_CONVERTER_ERROR);

  *bytes_read = 0;

  *bytes_written = 0;

  iface = G_CONVERTER_GET_IFACE (converter);

  return (* iface->convert) (converter,

           inbuf, inbuf_size,

           outbuf, outbuf_size,

           flags,

           bytes_read, bytes_written, error);

}

/**

 * g_converter_reset:

 * @converter: a #GConverter.

 *

 * Resets all internal state in the converter, making it behave

 * as if it was just created. If the converter has any internal

 * state that would produce output then that output is lost.

 *

 * Since: 2.24

 **/

void

g_converter_reset (GConverter *converter)

{

  GConverterIface *iface;

  g_return_if_fail (G_IS_CONVERTER (converter));

  iface = G_CONVERTER_GET_IFACE (converter);

  (* iface->reset) (converter);

}