read-cache.c: kill read_index()

read_index() shares the same problem as hold_locked_index(): it
assumes $GIT_DIR/index. Move all call sites to repo_read_index()
instead. read_index_preload() and read_index_unmerged() are also
killed as a consequence.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/am.c b/builtin/am.c
index d320445..901dc55 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -2278,7 +2278,7 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 	/* Ensure a valid committer ident can be constructed */
 	git_committer_info(IDENT_STRICT);
 
-	if (read_index_preload(&the_index, NULL, 0) < 0)
+	if (repo_read_index_preload(the_repository, NULL, 0) < 0)
 		die(_("failed to read the index"));
 
 	if (in_progress) {
diff --git a/builtin/commit.c b/builtin/commit.c
index e29fb5e..19eb6cf 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1367,7 +1367,7 @@ int cmd_status(int argc, const char **argv, const char *prefix)
 	if (status_format != STATUS_FORMAT_PORCELAIN &&
 	    status_format != STATUS_FORMAT_PORCELAIN_V2)
 		progress_flag = REFRESH_PROGRESS;
-	read_index(&the_index);
+	repo_read_index(the_repository);
 	refresh_index(&the_index,
 		      REFRESH_QUIET|REFRESH_UNMERGED|progress_flag,
 		      &s.pathspec, NULL, NULL);
diff --git a/builtin/diff-tree.c b/builtin/diff-tree.c
index ef99612..42bc1eb 100644
--- a/builtin/diff-tree.c
+++ b/builtin/diff-tree.c
@@ -165,7 +165,7 @@ int cmd_diff_tree(int argc, const char **argv, const char *prefix)
 
 		if (opt->diffopt.detect_rename) {
 			if (!the_index.cache)
-				read_index(&the_index);
+				repo_read_index(the_repository);
 			opt->diffopt.setup |= DIFF_SETUP_USE_SIZE_CACHE;
 		}
 		while (fgets(line, sizeof(line), stdin)) {
diff --git a/builtin/rebase.c b/builtin/rebase.c
index 00de703..ce5f5b5 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -576,7 +576,7 @@ static int reset_head(struct object_id *oid, const char *action,
 	if (!detach_head)
 		unpack_tree_opts.reset = 1;
 
-	if (read_index_unmerged(the_repository->index) < 0) {
+	if (repo_read_index_unmerged(the_repository) < 0) {
 		ret = error(_("could not read index"));
 		goto leave_reset_head;
 	}
@@ -1015,7 +1015,7 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 			die(_("Cannot read HEAD"));
 
 		fd = hold_locked_index(&lock_file, 0);
-		if (read_index(the_repository->index) < 0)
+		if (repo_read_index(the_repository) < 0)
 			die(_("could not read index"));
 		refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL,
 			      NULL);
@@ -1368,7 +1368,7 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 			get_fork_point(options.upstream_name, head);
 	}
 
-	if (read_index(the_repository->index) < 0)
+	if (repo_read_index(the_repository) < 0)
 		die(_("could not read index"));
 
 	if (options.autostash) {
@@ -1423,7 +1423,7 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 			putchar('\n');
 
 			if (discard_index(the_repository->index) < 0 ||
-				read_index(the_repository->index) < 0)
+				repo_read_index(the_repository) < 0)
 				die(_("could not read index"));
 		}
 	}