mp3utils.c
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/*
SDL_mixer: An audio mixer library based on the SDL library
Copyright (C) 1997-2012 Sam Lantinga <slouken@libsdl.org>
This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
*/
#include "SDL_stdinc.h"
#include "SDL_rwops.h"
#include "mp3utils.h"
#if defined(MP3_MAD_MUSIC) || defined(MP3_MUSIC)
/*********************** SDL_RW WITH BOOKKEEPING ************************/
int MP3_RWread(struct mp3file_t *fil, void *ptr, int size, int maxnum) {
int remaining = fil->length - fil->pos;
int ret;
maxnum *= size;
if (maxnum > remaining) maxnum = remaining;
ret = SDL_RWread(fil->rw, ptr, 1, maxnum);
if (ret > 0) fil->pos += ret;
return ret;
}
int MP3_RWseek(struct mp3file_t *fil, int offset, int whence) {
int ret;
switch (whence) { /* assumes a legal whence value */
case RW_SEEK_CUR:
offset += fil->pos;
break;
case RW_SEEK_END:
offset = fil->length + offset;
break;
}
if (offset < 0) return -1;
if (offset > fil->length)
offset = fil->length;
ret = SDL_RWseek(fil->rw, fil->start + offset, RW_SEEK_SET);
if (ret < 0) return ret;
fil->pos = offset;
return (fil->pos - fil->start);
}
/*************************** TAG HANDLING: ******************************/
static __inline__ SDL_bool is_id3v1(const unsigned char *data, int length)
{
/* http://id3.org/ID3v1 : 3 bytes "TAG" identifier and 125 bytes tag data */
if (length < 3 || SDL_memcmp(data,"TAG",3) != 0) {
return SDL_FALSE;
}
return SDL_TRUE;
}
static __inline__ SDL_bool is_id3v2(const unsigned char *data, int length)
{
/* ID3v2 header is 10 bytes: http://id3.org/id3v2.4.0-structure */
/* bytes 0-2: "ID3" identifier */
if (length < 10 || SDL_memcmp(data,"ID3",3) != 0) {
return SDL_FALSE;
}
/* bytes 3-4: version num (major,revision), each byte always less than 0xff. */
if (data[3] == 0xff || data[4] == 0xff) {
return SDL_FALSE;
}
/* bytes 6-9 are the ID3v2 tag size: a 32 bit 'synchsafe' integer, i.e. the
* highest bit 7 in each byte zeroed. i.e.: 7 bit information in each byte ->
* effectively a 28 bit value. */
if (data[6] >= 0x80 || data[7] >= 0x80 || data[8] >= 0x80 || data[9] >= 0x80) {
return SDL_FALSE;
}
return SDL_TRUE;
}
static __inline__ int get_id3v2_len(const unsigned char *data, int length)
{
/* size is a 'synchsafe' integer (see above) */
int size = (int)((data[6]<<21) + (data[7]<<14) + (data[8]<<7) + data[9]);
size += 10; /* header size */
/* ID3v2 header[5] is flags (bits 4-7 only, 0-3 are zero).
* bit 4 set: footer is present (a copy of the header but
* with "3DI" as ident.) */
if (data[5] & 0x10) {
size += 10; /* footer size */
}
/* optional padding (always zeroes) */
while (size < length && data[size] == 0) {
++size;
}
return size;
}
static __inline__ SDL_bool is_apetag(const unsigned char *data, int length)
{
/* http://wiki.hydrogenaud.io/index.php?title=APEv2_specification
* Header/footer is 32 bytes: bytes 0-7 ident, bytes 8-11 version,
* bytes 12-17 size. bytes 24-31 are reserved: must be all zeroes. */
Uint32 v;
if (length < 32 || SDL_memcmp(data,"APETAGEX",8) != 0) {
return SDL_FALSE;
}
v = (Uint32)((data[11]<<24) | (data[10]<<16) | (data[9]<<8) | data[8]); /* version */
if (v != 2000U && v != 1000U) {
return SDL_FALSE;
}
v = 0; /* reserved bits : */
if (SDL_memcmp(&data[24],&v,4) != 0 || SDL_memcmp(&data[28],&v,4) != 0) {
return SDL_FALSE;
}
return SDL_TRUE;
}
static __inline__ int get_ape_len(const unsigned char *data)
{
Uint32 flags, version;
int size = (int)((data[15]<<24) | (data[14]<<16) | (data[13]<<8) | data[12]);
version = (Uint32)((data[11]<<24) | (data[10]<<16) | (data[9]<<8) | data[8]);
flags = (Uint32)((data[23]<<24) | (data[22]<<16) | (data[21]<<8) | data[20]);
if (version == 2000U && (flags & (1U<<31))) size += 32; /* header present. */
return size;
}
static __inline__ int is_lyrics3tag(const unsigned char *data, int length) {
/* http://id3.org/Lyrics3
* http://id3.org/Lyrics3v2 */
if (length < 15) return 0;
if (SDL_memcmp(data+6,"LYRICS200",9) == 0) return 2; /* v2 */
if (SDL_memcmp(data+6,"LYRICSEND",9) == 0) return 1; /* v1 */
return 0;
}
static __inline__ int get_lyrics3v1_len(struct mp3file_t *m) {
const char *p; int i, len;
char buf[5104];
/* needs manual search: http://id3.org/Lyrics3 */
if (m->length < 20) return -1;
len = (m->length > 5109)? 5109 : m->length;
MP3_RWseek(m, -len, RW_SEEK_END);
MP3_RWread(m, buf, 1, (len -= 9)); /* exclude footer */
/* strstr() won't work here. */
for (i = len - 11, p = buf; i >= 0; --i, ++p) {
if (SDL_memcmp(p, "LYRICSBEGIN", 11) == 0)
break;
}
if (i < 0) return -1;
return len - (int)(p - buf) + 9 /* footer */;
}
static __inline__ int get_lyrics3v2_len(const unsigned char *data, int length) {
/* 6 bytes before the end marker is size in decimal format -
* does not include the 9 bytes end marker and size field. */
if (length != 6) return 0;
return SDL_strtol((const char *)data, NULL, 10) + 15;
}
static __inline__ SDL_bool verify_lyrics3v2(const unsigned char *data, int length) {
if (length < 11) return SDL_FALSE;
if (SDL_memcmp(data,"LYRICSBEGIN",11) == 0) return SDL_TRUE;
return SDL_FALSE;
}
#define MMTAG_PARANOID
static __inline__ SDL_bool is_musicmatch(const unsigned char *data, int length) {
/* From docs/musicmatch.txt in id3lib: https://sourceforge.net/projects/id3lib/
Overall tag structure:
+-----------------------------+
| Header |
| (256 bytes, OPTIONAL) |
+-----------------------------+
| Image extension (4 bytes) |
+-----------------------------+
| Image binary |
| (var. length >= 4 bytes) |
+-----------------------------+
| Unused (4 bytes) |
+-----------------------------+
| Version info (256 bytes) |
+-----------------------------+
| Audio meta-data |
| (var. length >= 7868 bytes) |
+-----------------------------+
| Data offsets (20 bytes) |
+-----------------------------+
| Footer (48 bytes) |
+-----------------------------+
*/
if (length < 48) return SDL_FALSE;
/* sig: 19 bytes company name + 13 bytes space */
if (SDL_memcmp(data,"Brava Software Inc. ",32) != 0) {
return SDL_FALSE;
}
/* 4 bytes version: x.xx */
if (!SDL_isdigit(data[32]) || data[33] != '.' ||
!SDL_isdigit(data[34]) ||!SDL_isdigit(data[35])) {
return SDL_FALSE;
}
#ifdef MMTAG_PARANOID
/* [36..47]: 12 bytes trailing space */
for (length = 36; length < 48; ++length) {
if (data[length] != ' ') return SDL_FALSE;
}
#endif
return SDL_TRUE;
}
static __inline__ int get_musicmatch_len(struct mp3file_t *m) {
const Sint32 metasizes[4] = { 7868, 7936, 8004, 8132 };
const unsigned char syncstr[10] = {'1','8','2','7','3','6','4','5',0,0};
unsigned char buf[256];
Sint32 i, j, imgext_ofs, version_ofs;
int len;
MP3_RWseek(m, -68, RW_SEEK_END);
MP3_RWread(m, buf, 1, 20);
imgext_ofs = (Sint32)((buf[3] <<24) | (buf[2] <<16) | (buf[1] <<8) | buf[0] );
version_ofs = (Sint32)((buf[15]<<24) | (buf[14]<<16) | (buf[13]<<8) | buf[12]);
if (version_ofs <= imgext_ofs) return -1;
if (version_ofs <= 0 || imgext_ofs <= 0) return -1;
/* Try finding the version info section:
* Because metadata section comes after it, and because metadata section
* has different sizes across versions (format ver. <= 3.00: always 7868
* bytes), we can _not_ directly calculate using deltas from the offsets
* section. */
for (i = 0; i < 4; ++i) {
/* 48: footer, 20: offsets, 256: version info */
len = metasizes[i] + 48 + 20 + 256;
if (m->length < len) return -1;
MP3_RWseek(m, -len, RW_SEEK_END);
MP3_RWread(m, buf, 1, 256);
/* [0..9]: sync string, [30..255]: 0x20 */
#ifdef MMTAG_PARANOID
for (j = 30; j < 256; ++j) {
if (buf[j] != ' ') break;
}
if (j < 256) continue;
#endif
if (SDL_memcmp(buf, syncstr, 10) == 0) {
break;
}
}
if (i == 4) return -1; /* no luck. */
#ifdef MMTAG_PARANOID
/* unused section: (4 bytes of 0x00) */
MP3_RWseek(m, -(len + 4), RW_SEEK_END);
MP3_RWread(m, buf, 1, 4); j = 0;
if (SDL_memcmp(buf, &j, 4) != 0) return -1;
#endif
len += (version_ofs - imgext_ofs);
if (m->length < len) return -1;
MP3_RWseek(m, -len, RW_SEEK_END);
MP3_RWread(m, buf, 1, 8);
j = (Sint32)((buf[7] <<24) | (buf[6] <<16) | (buf[5] <<8) | buf[4]);
if (j < 0) return -1;
/* verify image size: */
/* without this, we may land at a wrong place. */
if (j + 12 != version_ofs - imgext_ofs) return -1;
/* try finding the optional header */
if (m->length < len + 256) return len;
MP3_RWseek(m, -(len + 256), RW_SEEK_END);
MP3_RWread(m, buf, 1, 256);
/* [0..9]: sync string, [30..255]: 0x20 */
if (SDL_memcmp(buf, syncstr, 10) != 0) {
return len;
}
#ifdef MMTAG_PARANOID
for (j = 30; j < 256; ++j) {
if (buf[j] != ' ') return len;
}
#endif
return len + 256; /* header is present. */
}
int mp3_skiptags(struct mp3file_t *fil)
{
unsigned char buf[128];
int len, readsize;
int rc = -1;
readsize = MP3_RWread(fil, buf, 1, 128);
if (readsize <= 0) goto fail;
/* ID3v2 tag is at the start */
if (is_id3v2(buf, readsize)) {
len = get_id3v2_len(buf, readsize);
if (len >= fil->length) goto fail;
fil->start += len;
fil->length -= len;
}
/* APE tag _might_ be at the start (discouraged
* but not forbidden, either.) read the header. */
else if (is_apetag(buf, readsize)) {
len = get_ape_len(buf);
if (len >= fil->length) goto fail;
fil->start += len;
fil->length -= len;
}
/* ID3v1 tag is at the end */
if (fil->length >= 128) {
MP3_RWseek(fil, -128, RW_SEEK_END);
readsize = MP3_RWread(fil, buf, 1, 128);
if (readsize != 128) goto fail;
if (is_id3v1(buf, 128)) {
fil->length -= 128;
/* FIXME: handle possible double-ID3v1 tags?? */
}
}
/* do we know whether ape or lyrics3 is the first?
* well, we don't: we need to handle that later... */
/* check for the _old_ MusicMatch tag at end. */
if (fil->length >= 68) {
MP3_RWseek(fil, -48, RW_SEEK_END);
readsize = MP3_RWread(fil, buf, 1, 48);
if (readsize != 48) goto fail;
if (is_musicmatch(buf, 48)) {
len = get_musicmatch_len(fil);
if (len < 0) goto fail;
if (len >= fil->length) goto fail;
fil->length -= len;
}
}
/* APE tag may be at the end: read the footer */
if (fil->length >= 32) {
MP3_RWseek(fil, -32, RW_SEEK_END);
readsize = MP3_RWread(fil, buf, 1, 32);
if (readsize != 32) goto fail;
if (is_apetag(buf, 32)) {
len = get_ape_len(buf);
if (len >= fil->length) goto fail;
fil->length -= len;
}
}
if (fil->length >= 15) {
MP3_RWseek(fil, -15, RW_SEEK_END);
readsize = MP3_RWread(fil, buf, 1, 15);
if (readsize != 15) goto fail;
len = is_lyrics3tag(buf, 15);
if (len == 2) {
len = get_lyrics3v2_len(buf, 6);
if (len >= fil->length) goto fail;
if (len < 15) goto fail;
MP3_RWseek(fil, -len, RW_SEEK_END);
readsize = MP3_RWread(fil, buf, 1, 11);
if (readsize != 11) goto fail;
if (!verify_lyrics3v2(buf, 11)) goto fail;
fil->length -= len;
}
else if (len == 1) {
len = get_lyrics3v1_len(fil);
if (len < 0) goto fail;
fil->length -= len;
}
}
rc = (fil->length > 0)? 0 : -1;
fail:
MP3_RWseek(fil, 0, RW_SEEK_SET);
return rc;
}
#endif /* MP3_???_MUSIC */