static unsigned long write_reuse_object(struct sha1file *f, struct object_entry *entry,
					unsigned long limit, int usable_delta)
{
	struct packed_git *p = entry->in_pack;
	struct pack_window *w_curs = NULL;
	struct revindex_entry *revidx;
	off_t offset;
	enum object_type type = entry->type;
	unsigned long datalen;
	unsigned char header[10], dheader[10];
	unsigned hdrlen;

	if (entry->delta)
		type = (allow_ofs_delta && entry->delta->idx.offset) ?
			OBJ_OFS_DELTA : OBJ_REF_DELTA;
	hdrlen = encode_in_pack_object_header(type, entry->size, header);

	offset = entry->in_pack_offset;
	revidx = find_pack_revindex(p, offset);
	datalen = revidx[1].offset - offset;
	if (!pack_to_stdout && p->index_version > 1 &&
	    check_pack_crc(p, &w_curs, offset, datalen, revidx->nr)) {
		error("bad packed object CRC for %s", sha1_to_hex(entry->idx.sha1));
		unuse_pack(&w_curs);
		return write_no_reuse_object(f, entry, limit, usable_delta);
	}

	offset += entry->in_pack_header_size;
	datalen -= entry->in_pack_header_size;

	if (!pack_to_stdout && p->index_version == 1 &&
	    check_pack_inflate(p, &w_curs, offset, datalen, entry->size)) {
		error("corrupt packed object for %s", sha1_to_hex(entry->idx.sha1));
		unuse_pack(&w_curs);
		return write_no_reuse_object(f, entry, limit, usable_delta);
	}

	if (type == OBJ_OFS_DELTA) {
		off_t ofs = entry->idx.offset - entry->delta->idx.offset;
		unsigned pos = sizeof(dheader) - 1;
		dheader[pos] = ofs & 127;
		while (ofs >>= 7)
			dheader[--pos] = 128 | (--ofs & 127);
		if (limit && hdrlen + sizeof(dheader) - pos + datalen + 20 >= limit) {
			unuse_pack(&w_curs);
			return 0;
		}
		sha1write(f, header, hdrlen);
		sha1write(f, dheader + pos, sizeof(dheader) - pos);
		hdrlen += sizeof(dheader) - pos;
		reused_delta++;
	} else if (type == OBJ_REF_DELTA) {
		if (limit && hdrlen + 20 + datalen + 20 >= limit) {
			unuse_pack(&w_curs);
			return 0;
		}
		sha1write(f, header, hdrlen);
		sha1write(f, entry->delta->idx.sha1, 20);
		hdrlen += 20;
		reused_delta++;
	} else {
		if (limit && hdrlen + datalen + 20 >= limit) {
			unuse_pack(&w_curs);
			return 0;
		}
		sha1write(f, header, hdrlen);
	}
	copy_pack_data(f, p, &w_curs, offset, datalen);
	unuse_pack(&w_curs);
	reused++;
	return hdrlen + datalen;
}
static unsigned long write_reuse_object(struct sha1file *f, struct object_entry *entry,
					unsigned long limit, int usable_delta)
{
	struct packed_git *p = entry->in_pack;
	struct pack_window *w_curs = NULL;
	struct revindex_entry *revidx;
	off_t offset;
	enum object_type type = entry->type;
	unsigned long datalen;
	unsigned char header[10], dheader[10];
	unsigned hdrlen;

	if (entry->delta)
		type = (allow_ofs_delta && entry->delta->idx.offset) ?
			OBJ_OFS_DELTA : OBJ_REF_DELTA;
	hdrlen = encode_in_pack_object_header(type, entry->size, header);

	offset = entry->in_pack_offset;
	revidx = find_pack_revindex(p, offset);
	datalen = revidx[1].offset - offset;
	if (!pack_to_stdout && p->index_version > 1 &&
	    check_pack_crc(p, &w_curs, offset, datalen, revidx->nr)) {
		error("bad packed object CRC for %s", sha1_to_hex(entry->idx.sha1));
		unuse_pack(&w_curs);
		return write_no_reuse_object(f, entry, limit, usable_delta);
	}

	offset += entry->in_pack_header_size;
	datalen -= entry->in_pack_header_size;

	if (!pack_to_stdout && p->index_version == 1 &&
	    check_pack_inflate(p, &w_curs, offset, datalen, entry->size)) {
		error("corrupt packed object for %s", sha1_to_hex(entry->idx.sha1));
		unuse_pack(&w_curs);
		return write_no_reuse_object(f, entry, limit, usable_delta);
	}

	if (type == OBJ_OFS_DELTA) {
		off_t ofs = entry->idx.offset - entry->delta->idx.offset;
		unsigned pos = sizeof(dheader) - 1;
		dheader[pos] = ofs & 127;
		while (ofs >>= 7)
			dheader[--pos] = 128 | (--ofs & 127);
		if (limit && hdrlen + sizeof(dheader) - pos + datalen + 20 >= limit) {
			unuse_pack(&w_curs);
			return 0;
		}
		sha1write(f, header, hdrlen);
		sha1write(f, dheader + pos, sizeof(dheader) - pos);
		hdrlen += sizeof(dheader) - pos;
		reused_delta++;
	} else if (type == OBJ_REF_DELTA) {
		if (limit && hdrlen + 20 + datalen + 20 >= limit) {
			unuse_pack(&w_curs);
			return 0;
		}
		sha1write(f, header, hdrlen);
		sha1write(f, entry->delta->idx.sha1, 20);
		hdrlen += 20;
		reused_delta++;
	} else {
		if (limit && hdrlen + datalen + 20 >= limit) {
			unuse_pack(&w_curs);
			return 0;
		}
		sha1write(f, header, hdrlen);
	}
	copy_pack_data(f, p, &w_curs, offset, datalen);
	unuse_pack(&w_curs);
	reused++;
	return hdrlen + datalen;
}