prefer memcpy to strcpy

When we already know the length of a string (e.g., because
we just malloc'd to fit it), it's nicer to use memcpy than
strcpy, as it makes it more obvious that we are not going to
overflow the buffer (because the size we pass matches the
size in the allocation).

This also eliminates calls to strcpy, which make auditing
the code base harder.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
static int parse_from(struct branch *b)
{
	const char *from;
	struct branch *s;
	unsigned char sha1[20];

	if (!skip_prefix(command_buf.buf, "from ", &from))
		return 0;

	hashcpy(sha1, b->branch_tree.versions[1].sha1);

	s = lookup_branch(from);
	if (b == s)
		die("Can't create a branch from itself: %s", b->name);
	else if (s) {
		unsigned char *t = s->branch_tree.versions[1].sha1;
		hashcpy(b->sha1, s->sha1);
		hashcpy(b->branch_tree.versions[0].sha1, t);
		hashcpy(b->branch_tree.versions[1].sha1, t);
	} else if (*from == ':') {
		uintmax_t idnum = parse_mark_ref_eol(from);
		struct object_entry *oe = find_mark(idnum);
		if (oe->type != OBJ_COMMIT)
			die("Mark :%" PRIuMAX " not a commit", idnum);
		if (hashcmp(b->sha1, oe->idx.sha1)) {
			hashcpy(b->sha1, oe->idx.sha1);
			if (oe->pack_id != MAX_PACK_ID) {
				unsigned long size;
				char *buf = gfi_unpack_entry(oe, &size);
				parse_from_commit(b, buf, size);
				free(buf);
			} else
				parse_from_existing(b);
		}
	} else if (!get_sha1(from, b->sha1)) {
		parse_from_existing(b);
		if (is_null_sha1(b->sha1))
			b->delete = 1;
	}
	else
		die("Invalid ref name or SHA1 expression: %s", from);

	if (b->branch_tree.tree && hashcmp(sha1, b->branch_tree.versions[1].sha1)) {
		release_tree_content_recursive(b->branch_tree.tree);
		b->branch_tree.tree = NULL;
	}

	read_next_command();
	return 1;
}

static int parse_from(struct branch *b)
{
	const char *from;
	struct branch *s;
	unsigned char sha1[20];

	if (!skip_prefix(command_buf.buf, "from ", &from))
		return 0;

	hashcpy(sha1, b->branch_tree.versions[1].sha1);

	s = lookup_branch(from);
	if (b == s)
		die("Can't create a branch from itself: %s", b->name);
	else if (s) {
		unsigned char *t = s->branch_tree.versions[1].sha1;
		hashcpy(b->sha1, s->sha1);
		hashcpy(b->branch_tree.versions[0].sha1, t);
		hashcpy(b->branch_tree.versions[1].sha1, t);
	} else if (*from == ':') {
		uintmax_t idnum = parse_mark_ref_eol(from);
		struct object_entry *oe = find_mark(idnum);
		if (oe->type != OBJ_COMMIT)
			die("Mark :%" PRIuMAX " not a commit", idnum);
		if (hashcmp(b->sha1, oe->idx.sha1)) {
			hashcpy(b->sha1, oe->idx.sha1);
			if (oe->pack_id != MAX_PACK_ID) {
				unsigned long size;
				char *buf = gfi_unpack_entry(oe, &size);
				parse_from_commit(b, buf, size);
				free(buf);
			} else
				parse_from_existing(b);
		}
	} else if (!get_sha1(from, b->sha1)) {
		parse_from_existing(b);
		if (is_null_sha1(b->sha1))
			b->delete = 1;
	}
	else
		die("Invalid ref name or SHA1 expression: %s", from);

	if (b->branch_tree.tree && hashcmp(sha1, b->branch_tree.versions[1].sha1)) {
		release_tree_content_recursive(b->branch_tree.tree);
		b->branch_tree.tree = NULL;
	}

	read_next_command();
	return 1;
}
