ref: fbdd310a2c207e0c239c1a5d69c313336e61e77b
dir: /src/libflac/FLAC/callback.h/
/* libFLAC - Free Lossless Audio Codec library
* Copyright (C) 2004-2009 Josh Coalson
* Copyright (C) 2011-2016 Xiph.Org Foundation
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of the Xiph.org Foundation nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef FLAC__CALLBACK_H
#define FLAC__CALLBACK_H
#include "ordinals.h"
#include <stdlib.h> /* for size_t */
/** \file include/FLAC/callback.h
*
* \brief
* This module defines the structures for describing I/O callbacks
* to the other FLAC interfaces.
*
* See the detailed documentation for callbacks in the
* \link flac_callbacks callbacks \endlink module.
*/
/** \defgroup flac_callbacks FLAC/callback.h: I/O callback structures
* \ingroup flac
*
* \brief
* This module defines the structures for describing I/O callbacks
* to the other FLAC interfaces.
*
* The purpose of the I/O callback functions is to create a common way
* for the metadata interfaces to handle I/O.
*
* Originally the metadata interfaces required filenames as the way of
* specifying FLAC files to operate on. This is problematic in some
* environments so there is an additional option to specify a set of
* callbacks for doing I/O on the FLAC file, instead of the filename.
*
* In addition to the callbacks, a FLAC__IOHandle type is defined as an
* opaque structure for a data source.
*
* The callback function prototypes are similar (but not identical) to the
* stdio functions fread, fwrite, fseek, ftell, feof, and fclose. If you use
* stdio streams to implement the callbacks, you can pass fread, fwrite, and
* fclose anywhere a FLAC__IOCallback_Read, FLAC__IOCallback_Write, or
* FLAC__IOCallback_Close is required, and a FILE* anywhere a FLAC__IOHandle
* is required. \warning You generally CANNOT directly use fseek or ftell
* for FLAC__IOCallback_Seek or FLAC__IOCallback_Tell since on most systems
* these use 32-bit offsets and FLAC requires 64-bit offsets to deal with
* large files. You will have to find an equivalent function (e.g. ftello),
* or write a wrapper. The same is true for feof() since this is usually
* implemented as a macro, not as a function whose address can be taken.
*
* \{
*/
#ifdef __cplusplus
extern "C" {
#endif
/** This is the opaque handle type used by the callbacks. Typically
* this is a \c FILE* or address of a file descriptor.
*/
typedef void* FLAC__IOHandle;
/** Signature for the read callback.
* The signature and semantics match POSIX fread() implementations
* and can generally be used interchangeably.
*
* \param ptr The address of the read buffer.
* \param size The size of the records to be read.
* \param nmemb The number of records to be read.
* \param handle The handle to the data source.
* \retval size_t
* The number of records read.
*/
typedef size_t (*FLAC__IOCallback_Read) (void *ptr, size_t size, size_t nmemb, FLAC__IOHandle handle);
/** Signature for the write callback.
* The signature and semantics match POSIX fwrite() implementations
* and can generally be used interchangeably.
*
* \param ptr The address of the write buffer.
* \param size The size of the records to be written.
* \param nmemb The number of records to be written.
* \param handle The handle to the data source.
* \retval size_t
* The number of records written.
*/
typedef size_t (*FLAC__IOCallback_Write) (const void *ptr, size_t size, size_t nmemb, FLAC__IOHandle handle);
/** Signature for the seek callback.
* The signature and semantics mostly match POSIX fseek() WITH ONE IMPORTANT
* EXCEPTION: the offset is a 64-bit type whereas fseek() is generally 'long'
* and 32-bits wide.
*
* \param handle The handle to the data source.
* \param offset The new position, relative to \a whence
* \param whence \c SEEK_SET, \c SEEK_CUR, or \c SEEK_END
* \retval int
* \c 0 on success, \c -1 on error.
*/
typedef int (*FLAC__IOCallback_Seek) (FLAC__IOHandle handle, FLAC__int64 offset, int whence);
/** Signature for the tell callback.
* The signature and semantics mostly match POSIX ftell() WITH ONE IMPORTANT
* EXCEPTION: the offset is a 64-bit type whereas ftell() is generally 'long'
* and 32-bits wide.
*
* \param handle The handle to the data source.
* \retval FLAC__int64
* The current position on success, \c -1 on error.
*/
typedef FLAC__int64 (*FLAC__IOCallback_Tell) (FLAC__IOHandle handle);
/** Signature for the EOF callback.
* The signature and semantics mostly match POSIX feof() but WATCHOUT:
* on many systems, feof() is a macro, so in this case a wrapper function
* must be provided instead.
*
* \param handle The handle to the data source.
* \retval int
* \c 0 if not at end of file, nonzero if at end of file.
*/
typedef int (*FLAC__IOCallback_Eof) (FLAC__IOHandle handle);
/** Signature for the close callback.
* The signature and semantics match POSIX fclose() implementations
* and can generally be used interchangeably.
*
* \param handle The handle to the data source.
* \retval int
* \c 0 on success, \c EOF on error.
*/
typedef int (*FLAC__IOCallback_Close) (FLAC__IOHandle handle);
/** A structure for holding a set of callbacks.
* Each FLAC interface that requires a FLAC__IOCallbacks structure will
* describe which of the callbacks are required. The ones that are not
* required may be set to NULL.
*
* If the seek requirement for an interface is optional, you can signify that
* a data source is not seekable by setting the \a seek field to \c NULL.
*/
typedef struct {
FLAC__IOCallback_Read read;
FLAC__IOCallback_Write write;
FLAC__IOCallback_Seek seek;
FLAC__IOCallback_Tell tell;
FLAC__IOCallback_Eof eof;
FLAC__IOCallback_Close close;
} FLAC__IOCallbacks;
/* \} */
#ifdef __cplusplus
}
#endif
#endif