Function zap_leaf_array_read

freebsd/contrib/openzfs/module/zfs/zap_leaf.c:278–334

array_len and buf_len are in integers, not bytes */

/* array_len and buf_len are in integers, not bytes */
static void
zap_leaf_array_read(zap_leaf_t *l, uint16_t chunk,
    int array_int_len, int array_len, int buf_int_len, uint64_t buf_len,
    void *buf)
{
	int len = MIN(array_len, buf_len);
	int byten = 0;
	uint64_t value = 0;
	char *p = buf;

	ASSERT3U(array_int_len, <=, buf_int_len);

	/* Fast path for one 8-byte integer */
	if (array_int_len == 8 && buf_int_len == 8 && len == 1) {
		struct zap_leaf_array *la = &ZAP_LEAF_CHUNK(l, chunk).l_array;
		uint8_t *ip = la->la_array;
		uint64_t *buf64 = buf;

		*buf64 = (uint64_t)ip[0] << 56 | (uint64_t)ip[1] << 48 |
		    (uint64_t)ip[2] << 40 | (uint64_t)ip[3] << 32 |
		    (uint64_t)ip[4] << 24 | (uint64_t)ip[5] << 16 |
		    (uint64_t)ip[6] << 8 | (uint64_t)ip[7];
		return;
	}

	/* Fast path for an array of 1-byte integers (eg. the entry name) */
	if (array_int_len == 1 && buf_int_len == 1 &&
	    buf_len > array_len + ZAP_LEAF_ARRAY_BYTES) {
		while (chunk != CHAIN_END) {
			struct zap_leaf_array *la =
			    &ZAP_LEAF_CHUNK(l, chunk).l_array;
			bcopy(la->la_array, p, ZAP_LEAF_ARRAY_BYTES);
			p += ZAP_LEAF_ARRAY_BYTES;
			chunk = la->la_next;
		}
		return;
	}

	while (len > 0) {
		struct zap_leaf_array *la = &ZAP_LEAF_CHUNK(l, chunk).l_array;

		ASSERT3U(chunk, <, ZAP_LEAF_NUMCHUNKS(l));
		for (int i = 0; i < ZAP_LEAF_ARRAY_BYTES && len > 0; i++) {
			value = (value << 8) | la->la_array[i];
			byten++;
			if (byten == array_int_len) {
				stv(buf_int_len, p, value);
				byten = 0;
				len--;
				if (len == 0)
					return;
				p += buf_int_len;
			}
		}
		chunk = la->la_next;
	}
}