Make "index_name_exists()" return the cache_entry it found

This allows verify_absent() in unpack_trees() to use the hash chains
rather than looking it up using the binary search.

Perhaps more importantly, it's also going to be useful for the next phase,
where we actually start looking at the cache entry when we do
case-insensitive lookups and checking the result.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

cache.h

@@ -353,7 +353,7 @@ extern int write_index(const struct index_state *, int newfd);
 extern int discard_index(struct index_state *);
 extern int unmerged_index(const struct index_state *);
 extern int verify_path(const char *path);
-extern int index_name_exists(struct index_state *istate, const char *name, int namelen);
+extern struct cache_entry *index_name_exists(struct index_state *istate, const char *name, int namelen);
 extern int index_name_pos(const struct index_state *, const char *name, int namelen);
 #define ADD_CACHE_OK_TO_ADD 1		/* Ok to add */
 #define ADD_CACHE_OK_TO_REPLACE 2	/* Ok to replace file/directory */

name-hash.c

@@ -54,7 +54,7 @@ void add_name_hash(struct index_state *istate, struct cache_entry *ce)
 		hash_index_entry(istate, ce);
 }
 
-int index_name_exists(struct index_state *istate, const char *name, int namelen)
+struct cache_entry *index_name_exists(struct index_state *istate, const char *name, int namelen)
 {
 	unsigned int hash = hash_name(name, namelen);
 	struct cache_entry *ce;
@@ -65,9 +65,9 @@ int index_name_exists(struct index_state *istate, const char *name, int namelen)
 	while (ce) {
 		if (!(ce->ce_flags & CE_UNHASHED)) {
 			if (!cache_name_compare(name, namelen, ce->name, ce->ce_flags))
-				return 1;
+				return ce;
 		}
 		ce = ce->next;
 	}
-	return 0;
+	return NULL;
 }

unpack-trees.c

@@ -538,6 +538,7 @@ static int verify_absent(struct cache_entry *ce, const char *action,
 	if (!lstat(ce->name, &st)) {
 		int cnt;
 		int dtype = ce_to_dtype(ce);
+		struct cache_entry *result;
 
 		if (o->dir && excluded(o->dir, ce->name, &dtype))
 			/*
@@ -581,10 +582,9 @@ static int verify_absent(struct cache_entry *ce, const char *action,
 		 * delete this path, which is in a subdirectory that
 		 * is being replaced with a blob.
 		 */
-		cnt = index_name_pos(&o->result, ce->name, strlen(ce->name));
-		if (0 <= cnt) {
-			struct cache_entry *ce = o->result.cache[cnt];
-			if (ce->ce_flags & CE_REMOVE)
+		result = index_name_exists(&o->result, ce->name, ce_namelen(ce));
+		if (result) {
+			if (result->ce_flags & CE_REMOVE)
 				return 0;
 		}