| 1 | /* libFLAC - Free Lossless Audio Codec library |
| 2 | * Copyright (C) 2004-2009 Josh Coalson |
| 3 | * Copyright (C) 2011-2016 Xiph.Org Foundation |
| 4 | * |
| 5 | * Redistribution and use in source and binary forms, with or without |
| 6 | * modification, are permitted provided that the following conditions |
| 7 | * are met: |
| 8 | * |
| 9 | * - Redistributions of source code must retain the above copyright |
| 10 | * notice, this list of conditions and the following disclaimer. |
| 11 | * |
| 12 | * - Redistributions in binary form must reproduce the above copyright |
| 13 | * notice, this list of conditions and the following disclaimer in the |
| 14 | * documentation and/or other materials provided with the distribution. |
| 15 | * |
| 16 | * - Neither the name of the Xiph.org Foundation nor the names of its |
| 17 | * contributors may be used to endorse or promote products derived from |
| 18 | * this software without specific prior written permission. |
| 19 | * |
| 20 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 21 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 22 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 23 | * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR |
| 24 | * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| 25 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| 26 | * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| 27 | * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
| 28 | * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
| 29 | * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
| 30 | * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 31 | */ |
| 32 | |
| 33 | #ifndef FLAC__CALLBACK_H |
| 34 | #define FLAC__CALLBACK_H |
| 35 | |
| 36 | #include "ordinals.h" |
| 37 | #include <stdlib.h> /* for size_t */ |
| 38 | |
| 39 | /** \file include/FLAC/callback.h |
| 40 | * |
| 41 | * \brief |
| 42 | * This module defines the structures for describing I/O callbacks |
| 43 | * to the other FLAC interfaces. |
| 44 | * |
| 45 | * See the detailed documentation for callbacks in the |
| 46 | * \link flac_callbacks callbacks \endlink module. |
| 47 | */ |
| 48 | |
| 49 | /** \defgroup flac_callbacks FLAC/callback.h: I/O callback structures |
| 50 | * \ingroup flac |
| 51 | * |
| 52 | * \brief |
| 53 | * This module defines the structures for describing I/O callbacks |
| 54 | * to the other FLAC interfaces. |
| 55 | * |
| 56 | * The purpose of the I/O callback functions is to create a common way |
| 57 | * for the metadata interfaces to handle I/O. |
| 58 | * |
| 59 | * Originally the metadata interfaces required filenames as the way of |
| 60 | * specifying FLAC files to operate on. This is problematic in some |
| 61 | * environments so there is an additional option to specify a set of |
| 62 | * callbacks for doing I/O on the FLAC file, instead of the filename. |
| 63 | * |
| 64 | * In addition to the callbacks, a FLAC__IOHandle type is defined as an |
| 65 | * opaque structure for a data source. |
| 66 | * |
| 67 | * The callback function prototypes are similar (but not identical) to the |
| 68 | * stdio functions fread, fwrite, fseek, ftell, feof, and fclose. If you use |
| 69 | * stdio streams to implement the callbacks, you can pass fread, fwrite, and |
| 70 | * fclose anywhere a FLAC__IOCallback_Read, FLAC__IOCallback_Write, or |
| 71 | * FLAC__IOCallback_Close is required, and a FILE* anywhere a FLAC__IOHandle |
| 72 | * is required. \warning You generally CANNOT directly use fseek or ftell |
| 73 | * for FLAC__IOCallback_Seek or FLAC__IOCallback_Tell since on most systems |
| 74 | * these use 32-bit offsets and FLAC requires 64-bit offsets to deal with |
| 75 | * large files. You will have to find an equivalent function (e.g. ftello), |
| 76 | * or write a wrapper. The same is true for feof() since this is usually |
| 77 | * implemented as a macro, not as a function whose address can be taken. |
| 78 | * |
| 79 | * \{ |
| 80 | */ |
| 81 | |
| 82 | #ifdef __cplusplus |
| 83 | extern "C" { |
| 84 | #endif |
| 85 | |
| 86 | /** This is the opaque handle type used by the callbacks. Typically |
| 87 | * this is a \c FILE* or address of a file descriptor. |
| 88 | */ |
| 89 | typedef void* FLAC__IOHandle; |
| 90 | |
| 91 | /** Signature for the read callback. |
| 92 | * The signature and semantics match POSIX fread() implementations |
| 93 | * and can generally be used interchangeably. |
| 94 | * |
| 95 | * \param ptr The address of the read buffer. |
| 96 | * \param size The size of the records to be read. |
| 97 | * \param nmemb The number of records to be read. |
| 98 | * \param handle The handle to the data source. |
| 99 | * \retval size_t |
| 100 | * The number of records read. |
| 101 | */ |
| 102 | typedef size_t (*FLAC__IOCallback_Read) (void *ptr, size_t size, size_t nmemb, FLAC__IOHandle handle); |
| 103 | |
| 104 | /** Signature for the write callback. |
| 105 | * The signature and semantics match POSIX fwrite() implementations |
| 106 | * and can generally be used interchangeably. |
| 107 | * |
| 108 | * \param ptr The address of the write buffer. |
| 109 | * \param size The size of the records to be written. |
| 110 | * \param nmemb The number of records to be written. |
| 111 | * \param handle The handle to the data source. |
| 112 | * \retval size_t |
| 113 | * The number of records written. |
| 114 | */ |
| 115 | typedef size_t (*FLAC__IOCallback_Write) (const void *ptr, size_t size, size_t nmemb, FLAC__IOHandle handle); |
| 116 | |
| 117 | /** Signature for the seek callback. |
| 118 | * The signature and semantics mostly match POSIX fseek() WITH ONE IMPORTANT |
| 119 | * EXCEPTION: the offset is a 64-bit type whereas fseek() is generally 'long' |
| 120 | * and 32-bits wide. |
| 121 | * |
| 122 | * \param handle The handle to the data source. |
| 123 | * \param offset The new position, relative to \a whence |
| 124 | * \param whence \c SEEK_SET, \c SEEK_CUR, or \c SEEK_END |
| 125 | * \retval int |
| 126 | * \c 0 on success, \c -1 on error. |
| 127 | */ |
| 128 | typedef int (*FLAC__IOCallback_Seek) (FLAC__IOHandle handle, FLAC__int64 offset, int whence); |
| 129 | |
| 130 | /** Signature for the tell callback. |
| 131 | * The signature and semantics mostly match POSIX ftell() WITH ONE IMPORTANT |
| 132 | * EXCEPTION: the offset is a 64-bit type whereas ftell() is generally 'long' |
| 133 | * and 32-bits wide. |
| 134 | * |
| 135 | * \param handle The handle to the data source. |
| 136 | * \retval FLAC__int64 |
| 137 | * The current position on success, \c -1 on error. |
| 138 | */ |
| 139 | typedef FLAC__int64 (*FLAC__IOCallback_Tell) (FLAC__IOHandle handle); |
| 140 | |
| 141 | /** Signature for the EOF callback. |
| 142 | * The signature and semantics mostly match POSIX feof() but WATCHOUT: |
| 143 | * on many systems, feof() is a macro, so in this case a wrapper function |
| 144 | * must be provided instead. |
| 145 | * |
| 146 | * \param handle The handle to the data source. |
| 147 | * \retval int |
| 148 | * \c 0 if not at end of file, nonzero if at end of file. |
| 149 | */ |
| 150 | typedef int (*FLAC__IOCallback_Eof) (FLAC__IOHandle handle); |
| 151 | |
| 152 | /** Signature for the close callback. |
| 153 | * The signature and semantics match POSIX fclose() implementations |
| 154 | * and can generally be used interchangeably. |
| 155 | * |
| 156 | * \param handle The handle to the data source. |
| 157 | * \retval int |
| 158 | * \c 0 on success, \c EOF on error. |
| 159 | */ |
| 160 | typedef int (*FLAC__IOCallback_Close) (FLAC__IOHandle handle); |
| 161 | |
| 162 | /** A structure for holding a set of callbacks. |
| 163 | * Each FLAC interface that requires a FLAC__IOCallbacks structure will |
| 164 | * describe which of the callbacks are required. The ones that are not |
| 165 | * required may be set to NULL. |
| 166 | * |
| 167 | * If the seek requirement for an interface is optional, you can signify that |
| 168 | * a data sorce is not seekable by setting the \a seek field to \c NULL. |
| 169 | */ |
| 170 | typedef struct { |
| 171 | FLAC__IOCallback_Read read; |
| 172 | FLAC__IOCallback_Write write; |
| 173 | FLAC__IOCallback_Seek seek; |
| 174 | FLAC__IOCallback_Tell tell; |
| 175 | FLAC__IOCallback_Eof eof; |
| 176 | FLAC__IOCallback_Close close; |
| 177 | } FLAC__IOCallbacks; |
| 178 | |
| 179 | /* \} */ |
| 180 | |
| 181 | #ifdef __cplusplus |
| 182 | } |
| 183 | #endif |
| 184 | |
| 185 | #endif |