read-cache: refactor read_index_from()

It looks better and is simpler to review when we don't compute
the same things many times in the function.

It will also help make the following commit simpler.

Signed-off-by: Christian Couder <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: chriscool

read-cache.c

@@ -1699,6 +1699,8 @@ int read_index_from(struct index_state *istate, const char *path)
 {
 	struct split_index *split_index;
 	int ret;
+	char *base_sha1_hex;
+	const char *base_path;
 
 	/* istate->initialized covers both .git/index and .git/sharedindex.xxx */
 	if (istate->initialized)
@@ -1716,15 +1718,15 @@ int read_index_from(struct index_state *istate, const char *path)
 		discard_index(split_index->base);
 	else
 		split_index->base = xcalloc(1, sizeof(*split_index->base));
-	ret = do_read_index(split_index->base,
-			    git_path("sharedindex.%s",
-				     sha1_to_hex(split_index->base_sha1)), 1);
+
+	base_sha1_hex = sha1_to_hex(split_index->base_sha1);
+	base_path = git_path("sharedindex.%s", base_sha1_hex);
+	ret = do_read_index(split_index->base, base_path, 1);
 	if (hashcmp(split_index->base_sha1, split_index->base->sha1))
 		die("broken index, expect %s in %s, got %s",
-		    sha1_to_hex(split_index->base_sha1),
-		    git_path("sharedindex.%s",
-			     sha1_to_hex(split_index->base_sha1)),
+		    base_sha1_hex, base_path,
 		    sha1_to_hex(split_index->base->sha1));
+
 	merge_base_index(istate);
 	post_read_index_from(istate);
 	return ret;