read-cache: factor out get_sha1_from_index() helper

Factor out the retrieval of the sha1 for a given path in
read_blob_data_from_index() into the function get_sha1_from_index().

This will be used in the next commit, when convert.c can do the
analyze for "text=auto" without slurping the whole blob into memory
at once.

Add a wrapper definition get_sha1_from_cache().

Signed-off-by: Torsten Bögershausen <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: tboegi

cache.h

@@ -380,6 +380,7 @@ extern void free_name_hash(struct index_state *istate);
 #define unmerge_cache_entry_at(at) unmerge_index_entry_at(&the_index, at)
 #define unmerge_cache(pathspec) unmerge_index(&the_index, pathspec)
 #define read_blob_data_from_cache(path, sz) read_blob_data_from_index(&the_index, (path), (sz))
+#define get_sha1_from_cache(path)  get_sha1_from_index (&the_index, (path))
 #endif
 
 enum object_type {
@@ -1089,6 +1090,8 @@ static inline void *read_sha1_file(const unsigned char *sha1, enum object_type *
 	return read_sha1_file_extended(sha1, type, size, LOOKUP_REPLACE_OBJECT);
 }
 
+const unsigned char *get_sha1_from_index(struct index_state *istate, const char *path);
+
 /*
  * This internal function is only declared here for the benefit of
  * lookup_replace_object().  Please do not call it directly.

read-cache.c

@@ -2290,13 +2290,27 @@ int index_name_is_other(const struct index_state *istate, const char *name,
 
 void *read_blob_data_from_index(struct index_state *istate, const char *path, unsigned long *size)
 {
-	int pos, len;
+	const unsigned char *sha1;
 	unsigned long sz;
 	enum object_type type;
 	void *data;
 
-	len = strlen(path);
-	pos = index_name_pos(istate, path, len);
+	sha1 = get_sha1_from_index(istate, path);
+	if (!sha1)
+		return NULL;
+	data = read_sha1_file(sha1, &type, &sz);
+	if (!data || type != OBJ_BLOB) {
+		free(data);
+		return NULL;
+	}
+	if (size)
+		*size = sz;
+	return data;
+}
+
+const unsigned char *get_sha1_from_index(struct index_state *istate, const char *path)
+{
+	int pos = index_name_pos(istate, path, strlen(path));
 	if (pos < 0) {
 		/*
 		 * We might be in the middle of a merge, in which
@@ -2312,14 +2326,7 @@ void *read_blob_data_from_index(struct index_state *istate, const char *path, un
 	}
 	if (pos < 0)
 		return NULL;
-	data = read_sha1_file(istate->cache[pos]->oid.hash, &type, &sz);
-	if (!data || type != OBJ_BLOB) {
-		free(data);
-		return NULL;
-	}
-	if (size)
-		*size = sz;
-	return data;
+	return istate->cache[pos]->oid.hash;
 }
 
 void stat_validity_clear(struct stat_validity *sv)