rockbox/apps/metadata/metadata_common.c

/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2005 Dave Chapman
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include <inttypes.h>

#include "system.h"
#include "metadata.h"
#include "metadata_common.h"
#include "metadata_parsers.h"
#include "replaygain.h"
#include "misc.h"

/* Skip an ID3v2 tag if it can be found. We assume the tag is located at the
 * start of the file, which should be true in all cases where we need to skip it.
 * Returns true if successfully skipped or not skipped, and false if
 * something went wrong while skipping.
 */
bool skip_id3v2(int fd, struct mp3entry *id3)
{
    char buf[4];

    read(fd, buf, 4);
    if (memcmp(buf, "ID3", 3) == 0)
    {
        /* We have found an ID3v2 tag at the start of the file - find its
           length and then skip it. */
        if ((id3->first_frame_offset = getid3v2len(fd)) == 0)
            return false;

        if ((lseek(fd, id3->first_frame_offset, SEEK_SET) < 0)) 
            return false;
        
        return true;
    } else {
        lseek(fd, 0, SEEK_SET);
        id3->first_frame_offset = 0;
        return true;
    }
}


/* Read a string from the file. Read up to size bytes, or, if eos != -1, 
 * until the eos character is found (eos is not stored in buf, unless it is
 * nil). Writes up to buf_size chars to buf, always terminating with a nil.
 * Returns number of chars read or -1 on read error.
 */
long read_string(int fd, char* buf, long buf_size, int eos, long size)
{
    long read_bytes = 0;
    char c;
    
    while (size != 0)
    {
        if (read(fd, &c, 1) != 1)
        {
            read_bytes = -1;
            break;
        }
        
        read_bytes++;
        size--;
        
        if ((eos != -1) && (eos == (unsigned char) c))
        {
            break;
        }
        
        if (buf_size > 1)
        {
            *buf++ = c;
            buf_size--;
        }
    }
    
    *buf = 0;
    return read_bytes;
}
/* Read an unsigned 8-bit integer from a file. */
int read_uint8(int fd, uint8_t* buf)
{
  size_t n;

  n = read(fd, (char*) buf, 1);
  return n;
}

#ifdef ROCKBOX_LITTLE_ENDIAN
/* Read an unsigned 16-bit integer from a big-endian file. */
int read_uint16be(int fd, uint16_t* buf)
{
  size_t n;

  n = read(fd, (char*) buf, 2);
  *buf = betoh16(*buf);
  return n;
}
/* Read an unsigned 32-bit integer from a big-endian file. */
int read_uint32be(int fd, uint32_t* buf)
{
  size_t n;

  n = read(fd, (char*) buf, 4);
  *buf = betoh32(*buf);
  return n;
}
/* Read an unsigned 64-bit integer from a big-endian file. */
int read_uint64be(int fd, uint64_t* buf)
{
  size_t n;
  uint8_t data[8];
  int i;

  n = read(fd, data, 8);

  for (i=0, *buf=0; i<=7; i++) {
       *buf <<= 8;
       *buf |= data[i];
  }
  return n;
}
#else
/* Read unsigned integers from a little-endian file. */
int read_uint16le(int fd, uint16_t* buf)
{
  size_t n;

  n = read(fd, (char*) buf, 2);
  *buf = letoh16(*buf);
  return n;
}
int read_uint32le(int fd, uint32_t* buf)
{
  size_t n;

  n = read(fd, (char*) buf, 4);
  *buf = letoh32(*buf);
  return n;
}
int read_uint64le(int fd, uint64_t* buf)
{
  size_t n;
  uint8_t data[8];
  int i;

  n = read(fd, data, 8);

  for (i=7, *buf=0; i>=0; i--) {
       *buf <<= 8;
       *buf |= data[i];
  }

  return n;
}
#endif

/* Read an unaligned 32-bit little endian long from buffer. */
unsigned long get_long_le(void* buf)
{
    unsigned char* p = (unsigned char*) buf;

    return p[0] | (p[1] << 8) | (p[2] << 16) | (p[3] << 24);
}

/* Read an unaligned 16-bit little endian short from buffer. */
unsigned short get_short_le(void* buf)
{
    unsigned char* p = (unsigned char*) buf;

    return p[0] | (p[1] << 8);
}

/* Read an unaligned 32-bit big endian long from buffer. */
unsigned long get_long_be(void* buf)
{
    unsigned char* p = (unsigned char*) buf;

    return (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
}

/* Read an unaligned 32-bit little endian long from buffer. */
long get_slong(void* buf)
{
    unsigned char* p = (unsigned char*) buf;

    return p[0] | (p[1] << 8) | (p[2] << 16) | (p[3] << 24);
}

unsigned long get_itunes_int32(char* value, int count)
{
    static const char hexdigits[] = "0123456789ABCDEF";
    const char* c;
    int r = 0;
    
    while (count-- > 0)
    {
        value = skip_whitespace(value);
        
        while (*value && !isspace(*value))
        {
            value++;
        }
    }
    
    value = skip_whitespace(value);
    
    while (*value && ((c = strchr(hexdigits, toupper(*value))) != NULL))
    {
        r = (r << 4) | (c - hexdigits);
        value++;
    }
    
    return r;
}
 
/* Parse the tag (the name-value pair) and fill id3 and buffer accordingly.
 * String values to keep are written to buf. Returns number of bytes written
 * to buf (including end nil).
 */
long parse_tag(const char* name, char* value, struct mp3entry* id3,
    char* buf, long buf_remaining, enum tagtype type)
{
    long len = 0;
    char** p;

    if ((((strcasecmp(name, "track") == 0) && (type == TAGTYPE_APE)))
        || ((strcasecmp(name, "tracknumber") == 0) && (type == TAGTYPE_VORBIS)))
    {
        id3->tracknum = atoi(value);
        p = &(id3->track_string);
    }
    else if (strcasecmp(name, "discnumber") == 0 || strcasecmp(name, "disc") == 0)
    {
        id3->discnum = atoi(value);
        p = &(id3->disc_string);
    }
    else if (((strcasecmp(name, "year") == 0) && (type == TAGTYPE_APE))
        || ((strcasecmp(name, "date") == 0) && (type == TAGTYPE_VORBIS)))
    {
        /* Date's can be in any format in Vorbis. However most of them 
         * are in ISO8601 format so if we try and parse the first part
         * of the tag as a number, we should get the year. If we get crap,
         * then act like we never parsed it.
         */
        id3->year = atoi(value);
        if (id3->year < 1900)
        { /* yeah, not likely */
            id3->year = 0;
        }
        p = &(id3->year_string);
    }
    else if (strcasecmp(name, "title") == 0)
    {
        p = &(id3->title);
    }
    else if (strcasecmp(name, "artist") == 0)
    {
        p = &(id3->artist);
    }
    else if (strcasecmp(name, "album") == 0)
    {
        p = &(id3->album);
    }
    else if (strcasecmp(name, "genre") == 0)
    {
        p = &(id3->genre_string);
    }
    else if (strcasecmp(name, "composer") == 0)
    {
        p = &(id3->composer);
    }
    else if (strcasecmp(name, "comment") == 0)
    {
        p = &(id3->comment);
    }
    else if (strcasecmp(name, "albumartist") == 0)
    {
        p = &(id3->albumartist);
    }
    else if (strcasecmp(name, "album artist") == 0)
    {
        p = &(id3->albumartist);
    }
    else if (strcasecmp(name, "ensemble") == 0)
    {
        p = &(id3->albumartist);
    }
    else if (strcasecmp(name, "grouping") == 0)
    {
        p = &(id3->grouping);
    }
    else if (strcasecmp(name, "content group") == 0)
    {
        p = &(id3->grouping);
    }
    else if (strcasecmp(name, "contentgroup") == 0) 
    {
        p = &(id3->grouping);
    }
    else if (strcasecmp(name, "musicbrainz_trackid") == 0
        || strcasecmp(name, "http://musicbrainz.org") == 0 )
    {
        p = &(id3->mb_track_id);
    }
    else
    {
        len = parse_replaygain(name, value, id3, buf, buf_remaining);
        p = NULL;
    }
    
    if (p)
    {
        len = strlen(value);
        len = MIN(len, buf_remaining - 1);

        if (len > 0)
        {
            len++;
            strlcpy(buf, value, len);
            *p = buf;
        }
        else
        {
            len = 0;
        }
    }
    
    return len;
}