attr.c: extract read_index_data() as read_blob_data_from_index()

Extract the read_index_data() function from attr.c and move it to
read-cache.c; rename it to read_blob_data_from_index() and update
the function signature of it to align better with index/cache API
functions.

This allows for reusing the function in convert.c later.

Signed-off-by: Lukas Fleischer <git@cryptocrack.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

attr.c

@@ -381,46 +381,13 @@ static struct attr_stack *read_attr_from_file(const char *path, int macro_ok)
 	return res;
 }
 
-static void *read_index_data(const char *path)
-{
-	int pos, len;
-	unsigned long sz;
-	enum object_type type;
-	void *data;
-	struct index_state *istate = use_index ? use_index : &the_index;
-
-	len = strlen(path);
-	pos = index_name_pos(istate, path, len);
-	if (pos < 0) {
-		/*
-		 * We might be in the middle of a merge, in which
-		 * case we would read stage #2 (ours).
-		 */
-		int i;
-		for (i = -pos - 1;
-		     (pos < 0 && i < istate->cache_nr &&
-		      !strcmp(istate->cache[i]->name, path));
-		     i++)
-			if (ce_stage(istate->cache[i]) == 2)
-				pos = i;
-	}
-	if (pos < 0)
-		return NULL;
-	data = read_sha1_file(istate->cache[pos]->sha1, &type, &sz);
-	if (!data || type != OBJ_BLOB) {
-		free(data);
-		return NULL;
-	}
-	return data;
-}
-
 static struct attr_stack *read_attr_from_index(const char *path, int macro_ok)
 {
 	struct attr_stack *res;
 	char *buf, *sp;
 	int lineno = 0;
 
-	buf = read_index_data(path);
+	buf = read_blob_data_from_index(use_index ? use_index : &the_index, path);
 	if (!buf)
 		return NULL;
 

cache.h

@@ -307,6 +307,7 @@ extern void free_name_hash(struct index_state *istate);
 #define resolve_undo_clear() resolve_undo_clear_index(&the_index)
 #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) read_blob_data_from_index(&the_index, (path))
 #endif
 
 enum object_type {
@@ -452,6 +453,7 @@ extern int add_file_to_index(struct index_state *, const char *path, int flags);
 extern struct cache_entry *make_cache_entry(unsigned int mode, const unsigned char *sha1, const char *path, int stage, int refresh);
 extern int ce_same_name(struct cache_entry *a, struct cache_entry *b);
 extern int index_name_is_other(const struct index_state *, const char *, int);
+extern void *read_blob_data_from_index(struct index_state *, const char *);
 
 /* do stat comparison even if CE_VALID is true */
 #define CE_MATCH_IGNORE_VALID		01

read-cache.c

@@ -1895,3 +1895,35 @@ int index_name_is_other(const struct index_state *istate, const char *name,
 	}
 	return 1;
 }
+
+void *read_blob_data_from_index(struct index_state *istate, const char *path)
+{
+	int pos, len;
+	unsigned long sz;
+	enum object_type type;
+	void *data;
+
+	len = strlen(path);
+	pos = index_name_pos(istate, path, len);
+	if (pos < 0) {
+		/*
+		 * We might be in the middle of a merge, in which
+		 * case we would read stage #2 (ours).
+		 */
+		int i;
+		for (i = -pos - 1;
+		     (pos < 0 && i < istate->cache_nr &&
+		      !strcmp(istate->cache[i]->name, path));
+		     i++)
+			if (ce_stage(istate->cache[i]) == 2)
+				pos = i;
+	}
+	if (pos < 0)
+		return NULL;
+	data = read_sha1_file(istate->cache[pos]->sha1, &type, &sz);
+	if (!data || type != OBJ_BLOB) {
+		free(data);
+		return NULL;
+	}
+	return data;
+}