int bcf_get_format_string(const bcf_hdr_t *hdr, bcf1_t *line, const char *tag, char ***dst, int *ndst)
{
    int i,tag_id = bcf_hdr_id2int(hdr, BCF_DT_ID, tag);
    if ( !bcf_hdr_idinfo_exists(hdr,BCF_HL_FMT,tag_id) ) return -1;    // no such FORMAT field in the header
    if ( bcf_hdr_id2type(hdr,BCF_HL_FMT,tag_id)!=BCF_HT_STR ) return -2;     // expected different type

    if ( !(line->unpacked & BCF_UN_FMT) ) bcf_unpack(line, BCF_UN_FMT);

    for (i=0; i<line->n_fmt; i++)
        if ( line->d.fmt[i].id==tag_id ) break;
    if ( i==line->n_fmt ) return -3;                               // the tag is not present in this record
    bcf_fmt_t *fmt = &line->d.fmt[i];
    if ( !fmt->p ) return -3;                                      // the tag was marked for removal

    int nsmpl = bcf_hdr_nsamples(hdr);
    if ( !*dst )
    {
        *dst = (char**) malloc(sizeof(char*)*nsmpl);
        if ( !*dst ) return -4;     // could not alloc
        (*dst)[0] = NULL;
    }
    int n = (fmt->n+1)*nsmpl;
    if ( *ndst < n )
    {
        (*dst)[0] = realloc((*dst)[0], n);
        if ( !(*dst)[0] ) return -4;    // could not alloc
        *ndst = n;
    }
    for (i=0; i<nsmpl; i++)
    {
        uint8_t *src = fmt->p + i*fmt->n;
        uint8_t *tmp = (uint8_t*)(*dst)[0] + i*(fmt->n+1);
        memcpy(tmp,src,fmt->n);
        tmp[fmt->n] = 0;
        (*dst)[i] = (char*) tmp;
    }
    return n;
}
int bcf_get_format_string(const bcf_hdr_t *hdr, bcf1_t *line, const char *tag, char ***dst, int *ndst)
{
    int i,tag_id = bcf_hdr_id2int(hdr, BCF_DT_ID, tag);
    if ( !bcf_hdr_idinfo_exists(hdr,BCF_HL_FMT,tag_id) ) return -1;     
    if ( bcf_hdr_id2type(hdr,BCF_HL_FMT,tag_id)!=BCF_HT_STR ) return -2;      

    if ( !(line->unpacked & BCF_UN_FMT) ) bcf_unpack(line, BCF_UN_FMT);

    for (i=0; i<line->n_fmt; i++)
        if ( line->d.fmt[i].id==tag_id ) break;
    if ( i==line->n_fmt ) return -3;                                
    bcf_fmt_t *fmt = &line->d.fmt[i];
    if ( !fmt->p ) return -3;                                       

    int nsmpl = bcf_hdr_nsamples(hdr);
    if ( !*dst )
    {
        *dst = (char**) malloc(sizeof(char*)*nsmpl);
        if ( !*dst ) return -4;      
        (*dst)[0] = NULL;
    }
    int n = (fmt->n+1)*nsmpl;
    if ( *ndst < n )
    {
        (*dst)[0] = realloc((*dst)[0], n);
        if ( !(*dst)[0] ) return -4;     
        *ndst = n;
    }
    for (i=0; i<nsmpl; i++)
    {
        uint8_t *src = fmt->p + i*fmt->n;
        uint8_t *tmp = (uint8_t*)(*dst)[0] + i*(fmt->n+1);
        memcpy(tmp,src,fmt->n);
        tmp[fmt->n] = 0;
        (*dst)[i] = (char*) tmp;
    }
    return n;
}