static int mxf_read_local_tags(MXFContext *mxf, KLVPacket *klv, MXFMetadataReadFunc *read_child, int ctx_size, enum MXFMetadataSetType type)
{
    AVIOContext *pb = mxf->fc->pb;
    MXFMetadataSet *ctx = ctx_size ? av_mallocz(ctx_size) : mxf;
    uint64_t klv_end = avio_tell(pb) + klv->length;

    if (!ctx)
        return AVERROR(ENOMEM);
    while (avio_tell(pb) + 4 < klv_end && !avio_feof(pb)) {
        int ret;
        int tag = avio_rb16(pb);
        int size = avio_rb16(pb); /* KLV specified by 0x53 */
        uint64_t next = avio_tell(pb) + size;
        UID uid = {0};

        av_dlog(mxf->fc, "local tag %#04x size %d\n", tag, size);
        if (!size) { /* ignore empty tag, needed for some files with empty UMID tag */
            av_log(mxf->fc, AV_LOG_ERROR, "local tag %#04x with 0 size\n", tag);
            continue;
        }
        if (tag > 0x7FFF) { /* dynamic tag */
            int i;
            for (i = 0; i < mxf->local_tags_count; i++) {
                int local_tag = AV_RB16(mxf->local_tags+i*18);
                if (local_tag == tag) {
                    memcpy(uid, mxf->local_tags+i*18+2, 16);
                    av_dlog(mxf->fc, "local tag %#04x\n", local_tag);
                    PRINT_KEY(mxf->fc, "uid", uid);
                }
            }
        }
        if (ctx_size && tag == 0x3C0A)
            avio_read(pb, ctx->uid, 16);
        else if ((ret = read_child(ctx, pb, tag, size, uid, -1)) < 0)
            return ret;

        /* Accept the 64k local set limit being exceeded (Avid). Don't accept
         * it extending past the end of the KLV though (zzuf5.mxf). */
        if (avio_tell(pb) > klv_end) {
            if (ctx_size)
                av_free(ctx);

            av_log(mxf->fc, AV_LOG_ERROR,
                   "local tag %#04x extends past end of local set @ %#"PRIx64"\n",
                   tag, klv->offset);
            return AVERROR_INVALIDDATA;
        } else if (avio_tell(pb) <= next)   /* only seek forward, else this can loop for a long time */
            avio_seek(pb, next, SEEK_SET);
    }
    if (ctx_size) ctx->type = type;
    return ctx_size ? mxf_add_metadata_set(mxf, ctx) : 0;
}
Unknown