id3.c

Go to the documentation of this file.

#include "config.h"
#include "id3.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include "len.h"
#include "int_to_bit.h"
#include "ustrncpy.h"

#define ID3_MAJOR_VERSION 3

int ID3_tag_init(ID3_tag *t)
{
        t->version_major = ID3_MAJOR_VERSION;
        t->version_rev = 0;
        t->flags = 0;
        t->size = 0;
        t->size = 0;
        t->frames = malloc(1);
        (t->frames)[0] = '\0';
        return 0;
}

int ID3_tag_add_data(ID3_tag *tag, uint8_t t1, uint8_t t2, uint8_t t3, uint8_t t4, char *data)
{
        if(tag->version_major != ID3_MAJOR_VERSION)
                return -1;

        size_t datalen = str_len(data);
        if(data == NULL || datalen == 0)
                return 0;

        /*  the size of a frame is:
            frame header:       10 bytes
            encoding:           1 byte
            data:               str_len(data) bytes
        */
        size_t newsize = datalen + 10 + 1;
        tag->frames = realloc(tag->frames, tag->size + newsize + 1);

        /* frame id */
        (tag->frames)[tag->size] = t1;
        (tag->frames)[tag->size + 1] = t2;
        (tag->frames)[tag->size + 2] = t3;
        (tag->frames)[tag->size + 3] = t4;

        /* content size */
        unsigned char *tmp = NULL;
        uint8_t n;
        size_t len = int_to_bit1(datalen + 1, &tmp, 128); /* + 1 for the encoding byte */
        for(n = 1; n <= 4; n++)
        {
              if(n <= len)
                      (tag->frames)[tag->size + 4 + (4 - n)] = tmp[len - n];
              else
                      (tag->frames)[tag->size + 4 + (4 - n)] = 0;
        }
        free(tmp);
        tmp = NULL;

        /* frame flags */
        (tag->frames)[tag->size + 8] = 0;
        (tag->frames)[tag->size + 9] = 0;

        /* encoding: 00 (ISO-8859-1) */
        (tag->frames)[tag->size + 10] = 0;

        /* content */
        ustrncpy(tag->frames + tag->size + 11, data, datalen);

        tag->size += newsize;
        (tag->frames)[tag->size] = '\0';

        return 0;
}

int ID3_tag_fwrite(ID3_tag *t, FILE *fp)
{
        if(t->version_major != ID3_MAJOR_VERSION)
                return -1;

        if(t->size == 0)
                return 0;

        unsigned char *tag = malloc(10 + t->size + 1);
        tag[0] = 73; // 'I'
        tag[1] = 68; // 'D'
        tag[2] = 51; // '3'
        tag[3] = t->version_major;
        tag[4] = t->version_rev;
        tag[5] = t->flags;

        unsigned char *tmp = NULL;
        uint8_t n;
        size_t len = int_to_bit1(t->size, &tmp, 128);
        for(n = 1; n <= 4; n++)
        {
              if(n <= len)
                      tag[6 + (4 - n)] = tmp[len - n];
              else
                      tag[6 + (4 - n)] = 0;
        }
        free(tmp);
        tmp = NULL;

        for(n = 0; n < t->size; n++)
                tag[10 + n] = t->frames[n];

        tag[10 + t->size] = '\0';

/* write first 10 + 't->size' bytes of 'tag' to the file */
        fwrite(tag, 1, 10 + t->size, fp);

        t->version_major = 0;
        t->version_rev = 0;
        t->flags = 0;
        t->size = 0;
        free(t->frames);
        t->frames = NULL;

        free(tag);
        tag = NULL;

        return 0;
}

int ID3_tag_write(ID3_tag *tag, char *filename)
{
        FILE *fp = fopen(filename, "w");
        int ret = ID3_tag_fwrite(tag, fp);
        fclose(fp);

        return ret;
}