Merge branch 'ab/fewer-the-index-macros'

Progress on removing 'the_index' convenience wrappers.

* ab/fewer-the-index-macros:
  cocci: apply "pending" index-compatibility to some "builtin/*.c"
  cache.h & test-tool.h: add & use "USE_THE_INDEX_VARIABLE"
  {builtin/*,repository}.c: add & use "USE_THE_INDEX_VARIABLE"
  cocci: apply "pending" index-compatibility to "t/helper/*.c"
  cocci & cache.h: apply variable section of "pending" index-compatibility
  cocci & cache.h: apply a selection of "pending" index-compatibility
  cocci: add a index-compatibility.pending.cocci
  read-cache API & users: make discard_index() return void
  cocci & cache.h: remove rarely used "the_index" compat macros
  builtin/{grep,log}.: don't define "USE_THE_INDEX_COMPATIBILITY_MACROS"
  cache.h: remove unused "the_index" compat macros

33 files changed, 317 insertions, 295 deletions

diff --git a/builtin/add.c b/builtin/add.c
index 626c71e..76277df 100644
--- a/builtin/add.c
+++ b/builtin/add.c
@@ -3,7 +3,7 @@
  *
  * Copyright (C) 2006 Linus Torvalds
  */
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "cache.h"
 #include "config.h"
 #include "builtin.h"
@@ -42,8 +42,8 @@ static int chmod_pathspec(struct pathspec *pathspec, char flip, int show_only)
 {
 	int i, ret = 0;
 
-	for (i = 0; i < active_nr; i++) {
-		struct cache_entry *ce = active_cache[i];
+	for (i = 0; i < the_index.cache_nr; i++) {
+		struct cache_entry *ce = the_index.cache[i];
 		int err;
 
 		if (!include_sparse &&
@@ -55,7 +55,7 @@ static int chmod_pathspec(struct pathspec *pathspec, char flip, int show_only)
 			continue;
 
 		if (!show_only)
-			err = chmod_cache_entry(ce, flip);
+			err = chmod_index_entry(&the_index, ce, flip);
 		else
 			err = S_ISREG(ce->ce_mode) ? 0 : -1;
 
@@ -159,8 +159,8 @@ static int renormalize_tracked_files(const struct pathspec *pathspec, int flags)
 {
 	int i, retval = 0;
 
-	for (i = 0; i < active_nr; i++) {
-		struct cache_entry *ce = active_cache[i];
+	for (i = 0; i < the_index.cache_nr; i++) {
+		struct cache_entry *ce = the_index.cache[i];
 
 		if (!include_sparse &&
 		    (ce_skip_worktree(ce) ||
@@ -172,7 +172,8 @@ static int renormalize_tracked_files(const struct pathspec *pathspec, int flags)
 			continue; /* do not touch non blobs */
 		if (pathspec && !ce_path_match(&the_index, ce, pathspec, NULL))
 			continue;
-		retval |= add_file_to_cache(ce->name, flags | ADD_CACHE_RENORMALIZE);
+		retval |= add_file_to_index(&the_index, ce->name,
+					    flags | ADD_CACHE_RENORMALIZE);
 	}
 
 	return retval;
@@ -311,7 +312,7 @@ static int edit_patch(int argc, const char **argv, const char *prefix)
 
 	git_config(git_diff_basic_config, NULL); /* no "diff" UI options */
 
-	if (read_cache() < 0)
+	if (repo_read_index(the_repository) < 0)
 		die(_("Could not read the index"));
 
 	repo_init_revisions(the_repository, &rev, prefix);
@@ -543,7 +544,7 @@ int cmd_add(int argc, const char **argv, const char *prefix)
 	prepare_repo_settings(the_repository);
 	the_repository->settings.command_requires_full_index = 0;
 
-	hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
+	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
 
 	/*
 	 * Check the "pathspec '%s' did not match any files" block
@@ -586,7 +587,7 @@ int cmd_add(int argc, const char **argv, const char *prefix)
 		 (!(addremove || take_worktree_changes)
 		  ? ADD_CACHE_IGNORE_REMOVAL : 0));
 
-	if (read_cache_preload(&pathspec) < 0)
+	if (repo_read_index_preload(the_repository, &pathspec, 0) < 0)
 		die(_("index file corrupt"));
 
 	die_in_unpopulated_submodule(&the_index, prefix);
diff --git a/builtin/am.c b/builtin/am.c
index 20aea0d..30c9b3a 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -1519,8 +1519,8 @@ static int run_apply(const struct am_state *state, const char *index_file)
 
 	if (index_file) {
 		/* Reload index as apply_all_patches() will have modified it. */
-		discard_cache();
-		read_cache_from(index_file);
+		discard_index(&the_index);
+		read_index_from(&the_index, index_file, get_git_dir());
 	}
 
 	return 0;
@@ -1562,8 +1562,8 @@ static int fall_back_threeway(const struct am_state *state, const char *index_pa
 	if (build_fake_ancestor(state, index_path))
 		return error("could not build fake ancestor");
 
-	discard_cache();
-	read_cache_from(index_path);
+	discard_index(&the_index);
+	read_index_from(&the_index, index_path, get_git_dir());
 
 	if (write_index_as_tree(&orig_tree, &the_index, index_path, 0, NULL))
 		return error(_("Repository lacks necessary blobs to fall back on 3-way merge."));
@@ -1596,8 +1596,8 @@ static int fall_back_threeway(const struct am_state *state, const char *index_pa
 
 	say(state, stdout, _("Falling back to patching base and 3-way merge..."));
 
-	discard_cache();
-	read_cache();
+	discard_index(&the_index);
+	repo_read_index(the_repository);
 
 	/*
 	 * This is not so wrong. Depending on which base we picked, orig_tree
@@ -1781,7 +1781,8 @@ static void am_run(struct am_state *state, int resume)
 
 	unlink(am_path(state, "dirtyindex"));
 
-	if (refresh_and_write_cache(REFRESH_QUIET, 0, 0) < 0)
+	if (repo_refresh_and_write_index(the_repository, REFRESH_QUIET, 0, 0,
+					 NULL, NULL, NULL) < 0)
 		die(_("unable to write index file"));
 
 	if (repo_index_has_changes(the_repository, NULL, &sb)) {
@@ -1930,7 +1931,7 @@ static void am_resolve(struct am_state *state, int allow_empty)
 		}
 	}
 
-	if (unmerged_cache()) {
+	if (unmerged_index(&the_index)) {
 		printf_ln(_("You still have unmerged paths in your index.\n"
 			"You should 'git add' each file with resolved conflicts to mark them as such.\n"
 			"You might run `git rm` on a file to accept \"deleted by them\" for it."));
@@ -1967,9 +1968,9 @@ static int fast_forward_to(struct tree *head, struct tree *remote, int reset)
 	if (parse_tree(head) || parse_tree(remote))
 		return -1;
 
-	hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
+	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
 
-	refresh_cache(REFRESH_QUIET);
+	refresh_index(&the_index, REFRESH_QUIET, NULL, NULL, NULL);
 
 	memset(&opts, 0, sizeof(opts));
 	opts.head_idx = 1;
@@ -2007,7 +2008,7 @@ static int merge_tree(struct tree *tree)
 	if (parse_tree(tree))
 		return -1;
 
-	hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
+	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
 
 	memset(&opts, 0, sizeof(opts));
 	opts.head_idx = 1;
@@ -2045,7 +2046,7 @@ static int clean_index(const struct object_id *head, const struct object_id *rem
 	if (!remote_tree)
 		return error(_("Could not parse object '%s'."), oid_to_hex(remote));
 
-	read_cache_unmerged();
+	repo_read_index_unmerged(the_repository);
 
 	if (fast_forward_to(head_tree, head_tree, 1))
 		return -1;
diff --git a/builtin/cat-file.c b/builtin/cat-file.c
index fa7bd89..b3be58b 100644
--- a/builtin/cat-file.c
+++ b/builtin/cat-file.c
@@ -3,7 +3,7 @@
  *
  * Copyright (C) Linus Torvalds, 2005
  */
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "cache.h"
 #include "config.h"
 #include "builtin.h"
diff --git a/builtin/check-attr.c b/builtin/check-attr.c
index dd83397..0fef10e 100644
--- a/builtin/check-attr.c
+++ b/builtin/check-attr.c
@@ -1,4 +1,4 @@
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "builtin.h"
 #include "cache.h"
 #include "config.h"
@@ -115,7 +115,7 @@ int cmd_check_attr(int argc, const char **argv, const char *prefix)
 	argc = parse_options(argc, argv, prefix, check_attr_options,
 			     check_attr_usage, PARSE_OPT_KEEP_DASHDASH);
 
-	if (read_cache() < 0) {
+	if (repo_read_index(the_repository) < 0) {
 		die("invalid cache");
 	}
 
diff --git a/builtin/check-ignore.c b/builtin/check-ignore.c
index 2191256..ab77606 100644
--- a/builtin/check-ignore.c
+++ b/builtin/check-ignore.c
@@ -1,4 +1,4 @@
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "builtin.h"
 #include "cache.h"
 #include "config.h"
@@ -179,7 +179,7 @@ int cmd_check_ignore(int argc, const char **argv, const char *prefix)
 		die(_("--non-matching is only valid with --verbose"));
 
 	/* read_cache() is only necessary so we can watch out for submodules. */
-	if (!no_index && read_cache() < 0)
+	if (!no_index && repo_read_index(the_repository) < 0)
 		die(_("index file corrupt"));
 
 	setup_standard_excludes(&dir);
diff --git a/builtin/checkout-index.c b/builtin/checkout-index.c
index 97e06e8..cf6fba9 100644
--- a/builtin/checkout-index.c
+++ b/builtin/checkout-index.c
@@ -4,7 +4,7 @@
  * Copyright (C) 2005 Linus Torvalds
  *
  */
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "builtin.h"
 #include "config.h"
 #include "dir.h"
@@ -65,7 +65,7 @@ static void write_tempfile_record(const char *name, const char *prefix)
 static int checkout_file(const char *name, const char *prefix)
 {
 	int namelen = strlen(name);
-	int pos = cache_name_pos(name, namelen);
+	int pos = index_name_pos(&the_index, name, namelen);
 	int has_same_name = 0;
 	int is_file = 0;
 	int is_skipped = 1;
@@ -75,8 +75,8 @@ static int checkout_file(const char *name, const char *prefix)
 	if (pos < 0)
 		pos = -pos - 1;
 
-	while (pos < active_nr) {
-		struct cache_entry *ce = active_cache[pos];
+	while (pos < the_index.cache_nr) {
+		struct cache_entry *ce = the_index.cache[pos];
 		if (ce_namelen(ce) != namelen ||
 		    memcmp(ce->name, name, namelen))
 			break;
@@ -136,8 +136,8 @@ static int checkout_all(const char *prefix, int prefix_length)
 	int i, errs = 0;
 	struct cache_entry *last_ce = NULL;
 
-	for (i = 0; i < active_nr ; i++) {
-		struct cache_entry *ce = active_cache[i];
+	for (i = 0; i < the_index.cache_nr ; i++) {
+		struct cache_entry *ce = the_index.cache[i];
 
 		if (S_ISSPARSEDIR(ce->ce_mode)) {
 			if (!ce_skip_worktree(ce))
@@ -151,7 +151,7 @@ static int checkout_all(const char *prefix, int prefix_length)
 			 */
 			if (ignore_skip_worktree) {
 				ensure_full_index(&the_index);
-				ce = active_cache[i];
+				ce = the_index.cache[i];
 			}
 		}
 
@@ -249,7 +249,7 @@ int cmd_checkout_index(int argc, const char **argv, const char *prefix)
 	prepare_repo_settings(the_repository);
 	the_repository->settings.command_requires_full_index = 0;
 
-	if (read_cache() < 0) {
+	if (repo_read_index(the_repository) < 0) {
 		die("invalid cache");
 	}
 
@@ -270,7 +270,8 @@ int cmd_checkout_index(int argc, const char **argv, const char *prefix)
 	if (index_opt && !state.base_dir_len && !to_tempfile) {
 		state.refresh_cache = 1;
 		state.istate = &the_index;
-		hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
+		repo_hold_locked_index(the_repository, &lock_file,
+				       LOCK_DIE_ON_ERROR);
 	}
 
 	get_parallel_checkout_configs(&pc_workers, &pc_threshold);
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 2a13239..3fa29a0 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -1,4 +1,4 @@
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "builtin.h"
 #include "advice.h"
 #include "blob.h"
@@ -148,9 +148,9 @@ static int update_some(const struct object_id *oid, struct strbuf *base,
 	 * entry in place. Whether it is UPTODATE or not, checkout_entry will
 	 * do the right thing.
 	 */
-	pos = cache_name_pos(ce->name, ce->ce_namelen);
+	pos = index_name_pos(&the_index, ce->name, ce->ce_namelen);
 	if (pos >= 0) {
-		struct cache_entry *old = active_cache[pos];
+		struct cache_entry *old = the_index.cache[pos];
 		if (ce->ce_mode == old->ce_mode &&
 		    !ce_intent_to_add(old) &&
 		    oideq(&ce->oid, &old->oid)) {
@@ -160,7 +160,8 @@ static int update_some(const struct object_id *oid, struct strbuf *base,
 		}
 	}
 
-	add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
+	add_index_entry(&the_index, ce,
+			ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 	return 0;
 }
 
@@ -178,8 +179,8 @@ static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
 
 static int skip_same_name(const struct cache_entry *ce, int pos)
 {
-	while (++pos < active_nr &&
-	       !strcmp(active_cache[pos]->name, ce->name))
+	while (++pos < the_index.cache_nr &&
+	       !strcmp(the_index.cache[pos]->name, ce->name))
 		; /* skip */
 	return pos;
 }
@@ -187,9 +188,9 @@ static int skip_same_name(const struct cache_entry *ce, int pos)
 static int check_stage(int stage, const struct cache_entry *ce, int pos,
 		       int overlay_mode)
 {
-	while (pos < active_nr &&
-	       !strcmp(active_cache[pos]->name, ce->name)) {
-		if (ce_stage(active_cache[pos]) == stage)
+	while (pos < the_index.cache_nr &&
+	       !strcmp(the_index.cache[pos]->name, ce->name)) {
+		if (ce_stage(the_index.cache[pos]) == stage)
 			return 0;
 		pos++;
 	}
@@ -206,8 +207,8 @@ static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 	unsigned seen = 0;
 	const char *name = ce->name;
 
-	while (pos < active_nr) {
-		ce = active_cache[pos];
+	while (pos < the_index.cache_nr) {
+		ce = the_index.cache[pos];
 		if (strcmp(name, ce->name))
 			break;
 		seen |= (1 << ce_stage(ce));
@@ -223,10 +224,10 @@ static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
 			  const struct checkout *state, int *nr_checkouts,
 			  int overlay_mode)
 {
-	while (pos < active_nr &&
-	       !strcmp(active_cache[pos]->name, ce->name)) {
-		if (ce_stage(active_cache[pos]) == stage)
-			return checkout_entry(active_cache[pos], state,
+	while (pos < the_index.cache_nr &&
+	       !strcmp(the_index.cache[pos]->name, ce->name)) {
+		if (ce_stage(the_index.cache[pos]) == stage)
+			return checkout_entry(the_index.cache[pos], state,
 					      NULL, nr_checkouts);
 		pos++;
 	}
@@ -243,7 +244,7 @@ static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
 static int checkout_merged(int pos, const struct checkout *state,
 			   int *nr_checkouts, struct mem_pool *ce_mem_pool)
 {
-	struct cache_entry *ce = active_cache[pos];
+	struct cache_entry *ce = the_index.cache[pos];
 	const char *path = ce->name;
 	mmfile_t ancestor, ours, theirs;
 	enum ll_merge_result merge_status;
@@ -256,7 +257,7 @@ static int checkout_merged(int pos, const struct checkout *state,
 	int renormalize = 0;
 
 	memset(threeway, 0, sizeof(threeway));
-	while (pos < active_nr) {
+	while (pos < the_index.cache_nr) {
 		int stage;
 		stage = ce_stage(ce);
 		if (!stage || strcmp(path, ce->name))
@@ -265,7 +266,7 @@ static int checkout_merged(int pos, const struct checkout *state,
 		if (stage == 2)
 			mode = create_ce_mode(ce->ce_mode);
 		pos++;
-		ce = active_cache[pos];
+		ce = the_index.cache[pos];
 	}
 	if (is_null_oid(&threeway[1]) || is_null_oid(&threeway[2]))
 		return error(_("path '%s' does not have necessary versions"), path);
@@ -391,8 +392,8 @@ static int checkout_worktree(const struct checkout_opts *opts,
 	if (pc_workers > 1)
 		init_parallel_checkout();
 
-	for (pos = 0; pos < active_nr; pos++) {
-		struct cache_entry *ce = active_cache[pos];
+	for (pos = 0; pos < the_index.cache_nr; pos++) {
+		struct cache_entry *ce = the_index.cache[pos];
 		if (ce->ce_flags & CE_MATCHED) {
 			if (!ce_stage(ce)) {
 				errs |= checkout_entry(ce, &state,
@@ -528,7 +529,7 @@ static int checkout_paths(const struct checkout_opts *opts,
 	}
 
 	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
-	if (read_cache_preload(&opts->pathspec) < 0)
+	if (repo_read_index_preload(the_repository, &opts->pathspec, 0) < 0)
 		return error(_("index file corrupt"));
 
 	if (opts->source_tree)
@@ -540,13 +541,13 @@ static int checkout_paths(const struct checkout_opts *opts,
 	 * Make sure all pathspecs participated in locating the paths
 	 * to be checked out.
 	 */
-	for (pos = 0; pos < active_nr; pos++)
+	for (pos = 0; pos < the_index.cache_nr; pos++)
 		if (opts->overlay_mode)
-			mark_ce_for_checkout_overlay(active_cache[pos],
+			mark_ce_for_checkout_overlay(the_index.cache[pos],
 						     ps_matched,
 						     opts);
 		else
-			mark_ce_for_checkout_no_overlay(active_cache[pos],
+			mark_ce_for_checkout_no_overlay(the_index.cache[pos],
 							ps_matched,
 							opts);
 
@@ -561,8 +562,8 @@ static int checkout_paths(const struct checkout_opts *opts,
 		unmerge_marked_index(&the_index);
 
 	/* Any unmerged paths? */
-	for (pos = 0; pos < active_nr; pos++) {
-		const struct cache_entry *ce = active_cache[pos];
+	for (pos = 0; pos < the_index.cache_nr; pos++) {
+		const struct cache_entry *ce = the_index.cache[pos];
 		if (ce->ce_flags & CE_MATCHED) {
 			if (!ce_stage(ce))
 				continue;
@@ -722,7 +723,7 @@ static void init_topts(struct unpack_trees_options *topts, int merge,
 
 	setup_unpack_trees_porcelain(topts, "checkout");
 
-	topts->initial_checkout = is_cache_unborn();
+	topts->initial_checkout = is_index_unborn(&the_index);
 	topts->update = 1;
 	topts->merge = 1;
 	topts->quiet = merge && old_commit;
@@ -740,11 +741,11 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	struct lock_file lock_file = LOCK_INIT;
 	struct tree *new_tree;
 
-	hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
-	if (read_cache_preload(NULL) < 0)
+	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
+	if (repo_read_index_preload(the_repository, NULL, 0) < 0)
 		return error(_("index file corrupt"));
 
-	resolve_undo_clear();
+	resolve_undo_clear_index(&the_index);
 	if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
 		if (new_branch_info->commit)
 			BUG("'switch --orphan' should never accept a commit as starting point");
@@ -761,9 +762,9 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		struct unpack_trees_options topts;
 		const struct object_id *old_commit_oid;
 
-		refresh_cache(REFRESH_QUIET);
+		refresh_index(&the_index, REFRESH_QUIET, NULL, NULL, NULL);
 
-		if (unmerged_cache()) {
+		if (unmerged_index(&the_index)) {
 			error(_("you need to resolve your current index first"));
 			return 1;
 		}
@@ -867,7 +868,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		}
 	}
 
-	if (!cache_tree_fully_valid(active_cache_tree))
+	if (!cache_tree_fully_valid(the_index.cache_tree))
 		cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 
 	if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
diff --git a/builtin/clean.c b/builtin/clean.c
index 40ff2c5..b2701a2 100644
--- a/builtin/clean.c
+++ b/builtin/clean.c
@@ -6,7 +6,7 @@
  * Based on git-clean.sh by Pavel Roskin
  */
 
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "builtin.h"
 #include "cache.h"
 #include "config.h"
@@ -1012,7 +1012,7 @@ int cmd_clean(int argc, const char **argv, const char *prefix)
 	prepare_repo_settings(the_repository);
 	the_repository->settings.command_requires_full_index = 0;
 
-	if (read_cache() < 0)
+	if (repo_read_index(the_repository) < 0)
 		die(_("index file corrupt"));
 
 	pl = add_pattern_list(&dir, EXC_CMDL, "--exclude option");
@@ -1031,7 +1031,7 @@ int cmd_clean(int argc, const char **argv, const char *prefix)
 		struct stat st;
 		const char *rel;
 
-		if (!cache_name_is_other(ent->name, ent->len))
+		if (!index_name_is_other(&the_index, ent->name, ent->len))
 			continue;
 
 		if (lstat(ent->name, &st))
diff --git a/builtin/clone.c b/builtin/clone.c
index 0e43486..f518bb2 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -8,7 +8,7 @@
  * Clone a repository into a different directory that does not yet exist.
  */
 
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "builtin.h"
 #include "config.h"
 #include "lockfile.h"
@@ -703,7 +703,7 @@ static int checkout(int submodule_progress, int filter_submodules)
 	/* We need to be in the new work tree for the checkout */
 	setup_work_tree();
 
-	hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
+	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
 
 	memset(&opts, 0, sizeof opts);
 	opts.update = 1;
diff --git a/builtin/commit.c b/builtin/commit.c
index e22bdf2..06b1330 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -272,8 +272,8 @@ static int list_paths(struct string_list *list, const char *with_tree,
 
 	/* TODO: audit for interaction with sparse-index. */
 	ensure_full_index(&the_index);
-	for (i = 0; i < active_nr; i++) {
-		const struct cache_entry *ce = active_cache[i];
+	for (i = 0; i < the_index.cache_nr; i++) {
+		const struct cache_entry *ce = the_index.cache[i];
 		struct string_list_item *item;
 
 		if (ce->ce_flags & CE_UPDATE)
@@ -302,10 +302,10 @@ static void add_remove_files(struct string_list *list)
 			continue;
 
 		if (!lstat(p->string, &st)) {
-			if (add_to_cache(p->string, &st, 0))
+			if (add_to_index(&the_index, p->string, &st, 0))
 				die(_("updating files failed"));
 		} else
-			remove_file_from_cache(p->string);
+			remove_file_from_index(&the_index, p->string);
 	}
 }
 
@@ -316,7 +316,7 @@ static void create_base_index(const struct commit *current_head)
 	struct tree_desc t;
 
 	if (!current_head) {
-		discard_cache();
+		discard_index(&the_index);
 		return;
 	}
 
@@ -343,7 +343,7 @@ static void refresh_cache_or_die(int refresh_flags)
 	 * refresh_flags contains REFRESH_QUIET, so the only errors
 	 * are for unmerged entries.
 	 */
-	if (refresh_cache(refresh_flags | REFRESH_IN_PORCELAIN))
+	if (refresh_index(&the_index, refresh_flags | REFRESH_IN_PORCELAIN, NULL, NULL, NULL))
 		die_resolve_conflict("commit");
 }
 
@@ -382,12 +382,13 @@ static const char *prepare_index(const char **argv, const char *prefix,
 	    (!amend || (fixup_message && strcmp(fixup_prefix, "amend"))))))
 		die(_("No paths with --include/--only does not make sense."));
 
-	if (read_cache_preload(&pathspec) < 0)
+	if (repo_read_index_preload(the_repository, &pathspec, 0) < 0)
 		die(_("index file corrupt"));
 
 	if (interactive) {
 		char *old_index_env = NULL, *old_repo_index_file;
-		hold_locked_index(&index_lock, LOCK_DIE_ON_ERROR);
+		repo_hold_locked_index(the_repository, &index_lock,
+				       LOCK_DIE_ON_ERROR);
 
 		refresh_cache_or_die(refresh_flags);
 
@@ -410,8 +411,9 @@ static const char *prepare_index(const char **argv, const char *prefix,
 			unsetenv(INDEX_ENVIRONMENT);
 		FREE_AND_NULL(old_index_env);
 
-		discard_cache();
-		read_cache_from(get_lock_file_path(&index_lock));
+		discard_index(&the_index);
+		read_index_from(&the_index, get_lock_file_path(&index_lock),
+				get_git_dir());
 		if (update_main_cache_tree(WRITE_TREE_SILENT) == 0) {
 			if (reopen_lock_file(&index_lock) < 0)
 				die(_("unable to write index file"));
@@ -438,7 +440,8 @@ static const char *prepare_index(const char **argv, const char *prefix,
 	 * (B) on failure, rollback the real index.
 	 */
 	if (all || (also && pathspec.nr)) {
-		hold_locked_index(&index_lock, LOCK_DIE_ON_ERROR);
+		repo_hold_locked_index(the_repository, &index_lock,
+				       LOCK_DIE_ON_ERROR);
 		add_files_to_cache(also ? prefix : NULL, &pathspec, 0);
 		refresh_cache_or_die(refresh_flags);
 		update_main_cache_tree(WRITE_TREE_SILENT);
@@ -459,10 +462,11 @@ static const char *prepare_index(const char **argv, const char *prefix,
 	 * We still need to refresh the index here.
 	 */
 	if (!only && !pathspec.nr) {
-		hold_locked_index(&index_lock, LOCK_DIE_ON_ERROR);
+		repo_hold_locked_index(the_repository, &index_lock,
+				       LOCK_DIE_ON_ERROR);
 		refresh_cache_or_die(refresh_flags);
-		if (active_cache_changed
-		    || !cache_tree_fully_valid(active_cache_tree))
+		if (the_index.cache_changed
+		    || !cache_tree_fully_valid(the_index.cache_tree))
 			update_main_cache_tree(WRITE_TREE_SILENT);
 		if (write_locked_index(&the_index, &index_lock,
 				       COMMIT_LOCK | SKIP_IF_UNCHANGED))
@@ -505,13 +509,13 @@ static const char *prepare_index(const char **argv, const char *prefix,
 	if (list_paths(&partial, !current_head ? NULL : "HEAD", &pathspec))
 		exit(1);
 
-	discard_cache();
-	if (read_cache() < 0)
+	discard_index(&the_index);
+	if (repo_read_index(the_repository) < 0)
 		die(_("cannot read the index"));
 
-	hold_locked_index(&index_lock, LOCK_DIE_ON_ERROR);
+	repo_hold_locked_index(the_repository, &index_lock, LOCK_DIE_ON_ERROR);
 	add_remove_files(&partial);
-	refresh_cache(REFRESH_QUIET);
+	refresh_index(&the_index, REFRESH_QUIET, NULL, NULL, NULL);
 	update_main_cache_tree(WRITE_TREE_SILENT);
 	if (write_locked_index(&the_index, &index_lock, 0))
 		die(_("unable to write new_index file"));
@@ -523,14 +527,14 @@ static const char *prepare_index(const char **argv, const char *prefix,
 
 	create_base_index(current_head);
 	add_remove_files(&partial);
-	refresh_cache(REFRESH_QUIET);
+	refresh_index(&the_index, REFRESH_QUIET, NULL, NULL, NULL);
 
 	if (write_locked_index(&the_index, &false_lock, 0))
 		die(_("unable to write temporary index file"));
 
-	discard_cache();
+	discard_index(&the_index);
 	ret = get_lock_file_path(&false_lock);
-	read_cache_from(ret);
+	read_index_from(&the_index, ret, get_git_dir());
 out:
 	string_list_clear(&partial, 0);
 	clear_pathspec(&pathspec);
@@ -998,10 +1002,10 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 
 			/* TODO: audit for interaction with sparse-index. */
 			ensure_full_index(&the_index);
-			for (i = 0; i < active_nr; i++)
-				if (ce_intent_to_add(active_cache[i]))
+			for (i = 0; i < the_index.cache_nr; i++)
+				if (ce_intent_to_add(the_index.cache[i]))
 					ita_nr++;
-			committable = active_nr - ita_nr > 0;
+			committable = the_index.cache_nr - ita_nr > 0;
 		} else {
 			/*
 			 * Unless the user did explicitly request a submodule
@@ -1068,9 +1072,9 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 		 * and could have updated it. We must do this before we invoke
 		 * the editor and after we invoke run_status above.
 		 */
-		discard_cache();
+		discard_index(&the_index);
 	}
-	read_cache_from(index_file);
+	read_index_from(&the_index, index_file, get_git_dir());
 
 	if (update_main_cache_tree(0)) {
 		error(_("Error building trees"));
@@ -1556,7 +1560,7 @@ int cmd_status(int argc, const char **argv, const char *prefix)
 		      &s.pathspec, NULL, NULL);
 
 	if (use_optional_locks())
-		fd = hold_locked_index(&index_lock, 0);
+		fd = repo_hold_locked_index(the_repository, &index_lock, 0);
 	else
 		fd = -1;
 
@@ -1823,7 +1827,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 		append_merge_tag_headers(parents, &tail);
 	}
 
-	if (commit_tree_extended(sb.buf, sb.len, &active_cache_tree->oid,
+	if (commit_tree_extended(sb.buf, sb.len, &the_index.cache_tree->oid,
 				 parents, &oid, author_ident.buf, NULL,
 				 sign_commit, extra)) {
 		rollback_index_files();
diff --git a/builtin/describe.c b/builtin/describe.c
index 23e3f05..eea1e33 100644
--- a/builtin/describe.c
+++ b/builtin/describe.c
@@ -1,4 +1,4 @@
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "cache.h"
 #include "config.h"
 #include "lockfile.h"
@@ -653,10 +653,11 @@ int cmd_describe(int argc, const char **argv, const char *prefix)
 			int fd, result;
 
 			setup_work_tree();
-			read_cache();
+			repo_read_index(the_repository);
 			refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED,
 				      NULL, NULL, NULL);
-			fd = hold_locked_index(&index_lock, 0);
+			fd = repo_hold_locked_index(the_repository,
+						    &index_lock, 0);
 			if (0 <= fd)
 				repo_update_index_if_able(the_repository, &index_lock);
 
diff --git a/builtin/diff-files.c b/builtin/diff-files.c
index 096ea2f..dc991f7 100644
--- a/builtin/diff-files.c
+++ b/builtin/diff-files.c
@@ -3,7 +3,6 @@
  *
  * Copyright (C) Linus Torvalds, 2005
  */
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
 #include "cache.h"
 #include "config.h"
 #include "diff.h"
@@ -76,8 +75,8 @@ int cmd_diff_files(int argc, const char **argv, const char *prefix)
 	    (rev.diffopt.output_format & DIFF_FORMAT_PATCH))
 		diff_merges_set_dense_combined_if_unset(&rev);
 
-	if (read_cache_preload(&rev.diffopt.pathspec) < 0) {
-		perror("read_cache_preload");
+	if (repo_read_index_preload(the_repository, &rev.diffopt.pathspec, 0) < 0) {
+		perror("repo_read_index_preload");
 		result = -1;
 		goto cleanup;
 	}
diff --git a/builtin/diff-index.c b/builtin/diff-index.c
index aea139b..35dc9b2 100644
--- a/builtin/diff-index.c
+++ b/builtin/diff-index.c
@@ -1,4 +1,3 @@
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
 #include "cache.h"
 #include "config.h"
 #include "diff.h"
@@ -62,12 +61,12 @@ int cmd_diff_index(int argc, const char **argv, const char *prefix)
 		usage(diff_cache_usage);
 	if (!(option & DIFF_INDEX_CACHED)) {
 		setup_work_tree();
-		if (read_cache_preload(&rev.diffopt.pathspec) < 0) {
-			perror("read_cache_preload");
+		if (repo_read_index_preload(the_repository, &rev.diffopt.pathspec, 0) < 0) {
+			perror("repo_read_index_preload");
 			return -1;
 		}
-	} else if (read_cache() < 0) {
-		perror("read_cache");
+	} else if (repo_read_index(the_repository) < 0) {
+		perror("repo_read_index");
 		return -1;
 	}
 	result = run_diff_index(&rev, option);
diff --git a/builtin/diff-tree.c b/builtin/diff-tree.c
index 85e8c81..25b853b 100644
--- a/builtin/diff-tree.c
+++ b/builtin/diff-tree.c
@@ -1,4 +1,4 @@
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "cache.h"
 #include "config.h"
 #include "diff.h"
@@ -120,7 +120,7 @@ int cmd_diff_tree(int argc, const char **argv, const char *prefix)
 
 	git_config(git_diff_basic_config, NULL); /* no "diff" UI options */
 	repo_init_revisions(the_repository, opt, prefix);
-	if (read_cache() < 0)
+	if (repo_read_index(the_repository) < 0)
 		die(_("index file corrupt"));
 	opt->abbrev = 0;
 	opt->diff = 1;
diff --git a/builtin/diff.c b/builtin/diff.c
index 854d2c5..163f2c6 100644
--- a/builtin/diff.c
+++ b/builtin/diff.c
@@ -3,7 +3,7 @@
  *
  * Copyright (c) 2006 Junio C Hamano
  */
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "cache.h"
 #include "config.h"
 #include "ewah/ewok.h"
@@ -157,12 +157,13 @@ static int builtin_diff_index(struct rev_info *revs,
 		usage(builtin_diff_usage);
 	if (!(option & DIFF_INDEX_CACHED)) {
 		setup_work_tree();
-		if (read_cache_preload(&revs->diffopt.pathspec) < 0) {
-			perror("read_cache_preload");
+		if (repo_read_index_preload(the_repository,
+					    &revs->diffopt.pathspec, 0) < 0) {
+			perror("repo_read_index_preload");
 			return -1;
 		}
-	} else if (read_cache() < 0) {
-		perror("read_cache");
+	} else if (repo_read_index(the_repository) < 0) {
+		perror("repo_read_cache");
 		return -1;
 	}
 	return run_diff_index(revs, option);
@@ -239,12 +240,13 @@ static void refresh_index_quietly(void)
 	struct lock_file lock_file = LOCK_INIT;
 	int fd;
 
-	fd = hold_locked_index(&lock_file, 0);
+	fd = repo_hold_locked_index(the_repository, &lock_file, 0);
 	if (fd < 0)
 		return;
-	discard_cache();
-	read_cache();
-	refresh_cache(REFRESH_QUIET|REFRESH_UNMERGED);
+	discard_index(&the_index);
+	repo_read_index(the_repository);
+	refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL,
+		      NULL);
 	repo_update_index_if_able(the_repository, &lock_file);
 }
 
@@ -279,8 +281,9 @@ static int builtin_diff_files(struct rev_info *revs, int argc, const char **argv
 		diff_merges_set_dense_combined_if_unset(revs);
 
 	setup_work_tree();
-	if (read_cache_preload(&revs->diffopt.pathspec) < 0) {
-		perror("read_cache_preload");
+	if (repo_read_index_preload(the_repository, &revs->diffopt.pathspec,
+				    0) < 0) {
+		perror("repo_read_index_preload");
 		return -1;
 	}
 	return run_diff_files(revs, options);
diff --git a/builtin/difftool.c b/builtin/difftool.c
index d7f08c8..d9b7622 100644
--- a/builtin/difftool.c
+++ b/builtin/difftool.c
@@ -11,7 +11,7 @@
  *
  * Copyright (C) 2016 Johannes Schindelin
  */
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "cache.h"
 #include "config.h"
 #include "builtin.h"
diff --git a/builtin/fsck.c b/builtin/fsck.c
index 7436e1a..d207bd9 100644
--- a/builtin/fsck.c
+++ b/builtin/fsck.c
@@ -1,4 +1,4 @@
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "builtin.h"
 #include "cache.h"
 #include "repository.h"
@@ -958,29 +958,29 @@ int cmd_fsck(int argc, const char **argv, const char *prefix)
 	if (keep_cache_objects) {
 		verify_index_checksum = 1;
 		verify_ce_order = 1;
-		read_cache();
+		repo_read_index(the_repository);
 		/* TODO: audit for interaction with sparse-index. */
 		ensure_full_index(&the_index);
-		for (i = 0; i < active_nr; i++) {
+		for (i = 0; i < the_index.cache_nr; i++) {
 			unsigned int mode;
 			struct blob *blob;
 			struct object *obj;
 
-			mode = active_cache[i]->ce_mode;
+			mode = the_index.cache[i]->ce_mode;
 			if (S_ISGITLINK(mode))
 				continue;
 			blob = lookup_blob(the_repository,
-					   &active_cache[i]->oid);
+					   &the_index.cache[i]->oid);
 			if (!blob)
 				continue;
 			obj = &blob->object;
 			obj->flags |= USED;
 			fsck_put_object_name(&fsck_walk_options, &obj->oid,
-					     ":%s", active_cache[i]->name);
+					     ":%s", the_index.cache[i]->name);
 			mark_object_reachable(obj);
 		}
-		if (active_cache_tree)
-			fsck_cache_tree(active_cache_tree);
+		if (the_index.cache_tree)
+			fsck_cache_tree(the_index.cache_tree);
 		fsck_resolve_undo(&the_index);
 	}
 
diff --git a/builtin/grep.c b/builtin/grep.c
index 5fa927d..f7821c5 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -3,7 +3,6 @@
  *
  * Copyright (c) 2006 Junio C Hamano
  */
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
 #include "cache.h"
 #include "repository.h"
 #include "config.h"
diff --git a/builtin/log.c b/builtin/log.c
index 5eafcf2..89447a5 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -4,7 +4,6 @@
  * (C) Copyright 2006 Linus Torvalds
  *		 2006 Junio Hamano
  */
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
 #include "cache.h"
 #include "config.h"
 #include "refs.h"
diff --git a/builtin/merge-index.c b/builtin/merge-index.c
index 012f52b..452f833 100644
--- a/builtin/merge-index.c
+++ b/builtin/merge-index.c
@@ -1,4 +1,4 @@
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "builtin.h"
 #include "run-command.h"
 
@@ -14,11 +14,11 @@ static int merge_entry(int pos, const char *path)
 	char ownbuf[4][60];
 	struct child_process cmd = CHILD_PROCESS_INIT;
 
-	if (pos >= active_nr)
+	if (pos >= the_index.cache_nr)
 		die("git merge-index: %s not in the cache", path);
 	found = 0;
 	do {
-		const struct cache_entry *ce = active_cache[pos];
+		const struct cache_entry *ce = the_index.cache[pos];
 		int stage = ce_stage(ce);
 
 		if (strcmp(ce->name, path))
@@ -28,7 +28,7 @@ static int merge_entry(int pos, const char *path)
 		xsnprintf(ownbuf[stage], sizeof(ownbuf[stage]), "%o", ce->ce_mode);
 		arguments[stage] = hexbuf[stage];
 		arguments[stage + 4] = ownbuf[stage];
-	} while (++pos < active_nr);
+	} while (++pos < the_index.cache_nr);
 	if (!found)
 		die("git merge-index: %s not in the cache", path);
 
@@ -47,7 +47,7 @@ static int merge_entry(int pos, const char *path)
 
 static void merge_one_path(const char *path)
 {
-	int pos = cache_name_pos(path, strlen(path));
+	int pos = index_name_pos(&the_index, path, strlen(path));
 
 	/*
 	 * If it already exists in the cache as stage0, it's
@@ -62,8 +62,8 @@ static void merge_all(void)
 	int i;
 	/* TODO: audit for interaction with sparse-index. */
 	ensure_full_index(&the_index);
-	for (i = 0; i < active_nr; i++) {
-		const struct cache_entry *ce = active_cache[i];
+	for (i = 0; i < the_index.cache_nr; i++) {
+		const struct cache_entry *ce = the_index.cache[i];
 		if (!ce_stage(ce))
 			continue;
 		i += merge_entry(i, ce->name)-1;
@@ -82,7 +82,7 @@ int cmd_merge_index(int argc, const char **argv, const char *prefix)
 	if (argc < 3)
 		usage("git merge-index [-o] [-q] <merge-program> (-a | [--] [<filename>...])");
 
-	read_cache();
+	repo_read_index(the_repository);
 
 	/* TODO: audit for interaction with sparse-index. */
 	ensure_full_index(&the_index);
diff --git a/builtin/merge-ours.c b/builtin/merge-ours.c
index 3583cff..284eb48 100644
--- a/builtin/merge-ours.c
+++ b/builtin/merge-ours.c
@@ -7,7 +7,6 @@
  *
  * Pretend we resolved the heads, but declare our tree trumps everybody else.
  */
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
 #include "git-compat-util.h"
 #include "builtin.h"
 #include "diff.h"
@@ -25,7 +24,7 @@ int cmd_merge_ours(int argc, const char **argv, const char *prefix)
 	 * commit.  The index must match HEAD, or this merge cannot go
 	 * through.
 	 */
-	if (read_cache() < 0)
+	if (repo_read_index(the_repository) < 0)
 		die_errno("read_cache failed");
 	if (index_differs_from(the_repository, "HEAD", NULL, 0))
 		return 2;
diff --git a/builtin/merge-tree.c b/builtin/merge-tree.c
index fe853aa..e376708 100644
--- a/builtin/merge-tree.c
+++ b/builtin/merge-tree.c
@@ -1,4 +1,4 @@
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "builtin.h"
 #include "tree-walk.h"
 #include "xdiff-interface.h"
diff --git a/builtin/merge.c b/builtin/merge.c
index b3f75f5..dd47437 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -318,7 +318,7 @@ static int save_state(struct object_id *stash)
 	int rc = -1;
 
 	fd = repo_hold_locked_index(the_repository, &lock_file, 0);
-	refresh_cache(REFRESH_QUIET);
+	refresh_index(&the_index, REFRESH_QUIET, NULL, NULL, NULL);
 	if (0 <= fd)
 		repo_update_index_if_able(the_repository, &lock_file);
 	rollback_lock_file(&lock_file);
@@ -390,7 +390,8 @@ static void restore_state(const struct object_id *head,
 	run_command(&cmd);
 
 refresh_cache:
-	if (discard_cache() < 0 || read_cache() < 0)
+	discard_cache();
+	if (read_cache() < 0)
 		die(_("could not read index"));
 }
 
@@ -693,7 +694,7 @@ static int read_tree_trivial(struct object_id *common, struct object_id *head,
 	if (!trees[nr_trees++])
 		return -1;
 	opts.fn = threeway_merge;
-	cache_tree_free(&active_cache_tree);
+	cache_tree_free(&the_index.cache_tree);
 	for (i = 0; i < nr_trees; i++) {
 		parse_tree(trees[i]);
 		init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
@@ -715,7 +716,9 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
 {
 	const char *head_arg = "HEAD";
 
-	if (refresh_and_write_cache(REFRESH_QUIET, SKIP_IF_UNCHANGED, 0) < 0)
+	if (repo_refresh_and_write_index(the_repository, REFRESH_QUIET,
+					 SKIP_IF_UNCHANGED, 0, NULL, NULL,
+					 NULL) < 0)
 		return error(_("Unable to write index."));
 
 	if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree") ||
@@ -749,7 +752,8 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
 		for (j = common; j; j = j->next)
 			commit_list_insert(j->item, &reversed);
 
-		hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
+		repo_hold_locked_index(the_repository, &lock,
+				       LOCK_DIE_ON_ERROR);
 		if (!strcmp(strategy, "ort"))
 			clean = merge_ort_recursive(&o, head, remoteheads->item,
 						    reversed, &result);
@@ -783,8 +787,8 @@ static int count_unmerged_entries(void)
 {
 	int i, ret = 0;
 
-	for (i = 0; i < active_nr; i++)
-		if (ce_stage(active_cache[i]))
+	for (i = 0; i < the_index.cache_nr; i++)
+		if (ce_stage(the_index.cache[i]))
 			ret++;
 
 	return ret;
@@ -858,9 +862,9 @@ static void prepare_to_commit(struct commit_list *remoteheads)
 		 * the editor and after we invoke run_status above.
 		 */
 		if (invoked_hook)
-			discard_cache();
+			discard_index(&the_index);
 	}
-	read_cache_from(index_file);
+	read_index_from(&the_index, index_file, get_git_dir());
 	strbuf_addbuf(&msg, &merge_msg);
 	if (squash)
 		BUG("the control must not reach here under --squash");
@@ -909,7 +913,9 @@ static int merge_trivial(struct commit *head, struct commit_list *remoteheads)
 	struct object_id result_tree, result_commit;
 	struct commit_list *parents, **pptr = &parents;
 
-	if (refresh_and_write_cache(REFRESH_QUIET, SKIP_IF_UNCHANGED, 0) < 0)
+	if (repo_refresh_and_write_index(the_repository, REFRESH_QUIET,
+					 SKIP_IF_UNCHANGED, 0, NULL, NULL,
+					 NULL) < 0)
 		return error(_("Unable to write index."));
 
 	write_tree_trivial(&result_tree);
@@ -1375,7 +1381,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		goto done;
 	}
 
-	if (read_cache_unmerged())
+	if (repo_read_index_unmerged(the_repository))
 		die_resolve_conflict("merge");
 
 	if (file_exists(git_path_merge_head(the_repository))) {
@@ -1396,7 +1402,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		else
 			die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists)."));
 	}
-	resolve_undo_clear();
+	resolve_undo_clear_index(&the_index);
 
 	if (option_edit < 0)
 		option_edit = default_edit_option();
@@ -1601,7 +1607,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		 * We are not doing octopus, not fast-forward, and have
 		 * only one common.
 		 */
-		refresh_cache(REFRESH_QUIET);
+		refresh_index(&the_index, REFRESH_QUIET, NULL, NULL, NULL);
 		if (allow_trivial && fast_forward != FF_ONLY) {
 			/*
 			 * Must first ensure that index matches HEAD before
diff --git a/builtin/mv.c b/builtin/mv.c
index 3413ad1..19790ce 100644
--- a/builtin/mv.c
+++ b/builtin/mv.c
@@ -87,7 +87,7 @@ static void prepare_move_submodule(const char *src, int first,
 				   const char **submodule_gitfile)
 {
 	struct strbuf submodule_dotgit = STRBUF_INIT;
-	if (!S_ISGITLINK(active_cache[first]->ce_mode))
+	if (!S_ISGITLINK(the_index.cache[first]->ce_mode))
 		die(_("Directory %s is in index and no submodule?"), src);
 	if (!is_staging_gitmodules_ok(&the_index))
 		die(_("Please stage your changes to .gitmodules or stash them to proceed"));
@@ -106,13 +106,13 @@ static int index_range_of_same_dir(const char *src, int length,
 	const char *src_w_slash = add_slash(src);
 	int first, last, len_w_slash = length + 1;
 
-	first = cache_name_pos(src_w_slash, len_w_slash);
+	first = index_name_pos(&the_index, src_w_slash, len_w_slash);
 	if (first >= 0)
 		die(_("%.*s is in index"), len_w_slash, src_w_slash);
 
 	first = -1 - first;
-	for (last = first; last < active_nr; last++) {
-		const char *path = active_cache[last]->name;
+	for (last = first; last < the_index.cache_nr; last++) {
+		const char *path = the_index.cache[last]->name;
 		if (strncmp(path, src_w_slash, len_w_slash))
 			break;
 	}
@@ -136,14 +136,14 @@ static int empty_dir_has_sparse_contents(const char *name)
 	const char *with_slash = add_slash(name);
 	int length = strlen(with_slash);
 
-	int pos = cache_name_pos(with_slash, length);
+	int pos = index_name_pos(&the_index, with_slash, length);
 	const struct cache_entry *ce;
 
 	if (pos < 0) {
 		pos = -pos - 1;
 		if (pos >= the_index.cache_nr)
 			goto free_return;
-		ce = active_cache[pos];
+		ce = the_index.cache[pos];
 		if (strncmp(with_slash, ce->name, length))
 			goto free_return;
 		if (ce_skip_worktree(ce))
@@ -189,8 +189,8 @@ int cmd_mv(int argc, const char **argv, const char *prefix)
 	if (--argc < 1)
 		usage_with_options(builtin_mv_usage, builtin_mv_options);
 
-	hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
-	if (read_cache() < 0)
+	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
+	if (repo_read_index(the_repository) < 0)
 		die(_("index file corrupt"));
 
 	source = internal_prefix_pathspec(prefix, argv, argc, 0);
@@ -255,7 +255,7 @@ int cmd_mv(int argc, const char **argv, const char *prefix)
 			int pos;
 			const struct cache_entry *ce;
 
-			pos = cache_name_pos(src, length);
+			pos = index_name_pos(&the_index, src, length);
 			if (pos < 0) {
 				const char *src_w_slash = add_slash(src);
 				if (!path_in_sparse_checkout(src_w_slash, &the_index) &&
@@ -268,7 +268,7 @@ int cmd_mv(int argc, const char **argv, const char *prefix)
 					bad = _("bad source");
 				goto act_on_entry;
 			}
-			ce = active_cache[pos];
+			ce = the_index.cache[pos];
 			if (!ce_skip_worktree(ce)) {
 				bad = _("bad source");
 				goto act_on_entry;
@@ -278,7 +278,7 @@ int cmd_mv(int argc, const char **argv, const char *prefix)
 				goto act_on_entry;
 			}
 			/* Check if dst exists in index */
-			if (cache_name_pos(dst, strlen(dst)) < 0) {
+			if (index_name_pos(&the_index, dst, strlen(dst)) < 0) {
 				modes[i] |= SPARSE;
 				goto act_on_entry;
 			}
@@ -303,7 +303,7 @@ int cmd_mv(int argc, const char **argv, const char *prefix)
 dir_check:
 		if (S_ISDIR(st.st_mode)) {
 			int j, dst_len, n;
-			int first = cache_name_pos(src, length), last;
+			int first = index_name_pos(&the_index, src, length), last;
 
 			if (first >= 0) {
 				prepare_move_submodule(src, first,
@@ -331,7 +331,7 @@ dir_check:
 			dst_len = strlen(dst);
 
 			for (j = 0; j < last - first; j++) {
-				const struct cache_entry *ce = active_cache[first + j];
+				const struct cache_entry *ce = the_index.cache[first + j];
 				const char *path = ce->name;
 				source[argc + j] = path;
 				destination[argc + j] =
@@ -343,7 +343,7 @@ dir_check:
 			argc += last - first;
 			goto act_on_entry;
 		}
-		if (!(ce = cache_file_exists(src, length, 0))) {
+		if (!(ce = index_file_exists(&the_index, src, length, 0))) {
 			bad = _("not under version control");
 			goto act_on_entry;
 		}
@@ -468,11 +468,14 @@ remove_entry:
 		if (mode & (WORKING_DIRECTORY | SKIP_WORKTREE_DIR))
 			continue;
 
-		pos = cache_name_pos(src, strlen(src));
+		pos = index_name_pos(&the_index, src, strlen(src));
 		assert(pos >= 0);
 		if (!(mode & SPARSE) && !lstat(src, &st))
-			sparse_and_dirty = ce_modified(active_cache[pos], &st, 0);
-		rename_cache_entry_at(pos, dst);
+			sparse_and_dirty = ie_modified(&the_index,
+						       the_index.cache[pos],
+						       &st,
+						       0);
+		rename_index_entry_at(&the_index, pos, dst);
 
 		if (ignore_sparse &&
 		    core_apply_sparse_checkout &&
@@ -487,7 +490,7 @@ remove_entry:
 			    path_in_sparse_checkout(dst, &the_index)) {
 				/* from out-of-cone to in-cone */
 				int dst_pos = cache_name_pos(dst, strlen(dst));
-				struct cache_entry *dst_ce = active_cache[dst_pos];
+				struct cache_entry *dst_ce = the_index.cache[dst_pos];
 
 				dst_ce->ce_flags &= ~CE_SKIP_WORKTREE;
 
@@ -498,7 +501,7 @@ remove_entry:
 				   !path_in_sparse_checkout(dst, &the_index)) {
 				/* from in-cone to out-of-cone */
 				int dst_pos = cache_name_pos(dst, strlen(dst));
-				struct cache_entry *dst_ce = active_cache[dst_pos];
+				struct cache_entry *dst_ce = the_index.cache[dst_pos];
 
 				/*
 				 * if src is clean, it will suffice to remove it
diff --git a/builtin/pull.c b/builtin/pull.c
index b21edd7..1ab4de0 100644
--- a/builtin/pull.c
+++ b/builtin/pull.c
@@ -5,7 +5,7 @@
  *
  * Fetch one or more remote refs and merge it/them into the current HEAD.
  */
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "cache.h"
 #include "config.h"
 #include "builtin.h"
@@ -1030,7 +1030,7 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 	if (opt_rebase < 0)
 		opt_rebase = config_get_rebase(&rebase_unspecified);
 
-	if (read_cache_unmerged())
+	if (repo_read_index_unmerged(the_repository))
 		die_resolve_conflict("pull");
 
 	if (file_exists(git_path_merge_head(the_repository)))
@@ -1043,7 +1043,7 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 		if (opt_autostash == -1)
 			opt_autostash = config_autostash;
 
-		if (is_null_oid(&orig_head) && !is_cache_unborn())
+		if (is_null_oid(&orig_head) && !is_index_unborn(&the_index))
 			die(_("Updating an unborn branch with changes added to the index."));
 
 		if (!opt_autostash)
diff --git a/builtin/read-tree.c b/builtin/read-tree.c
index 45c6652..f702f9d 100644
--- a/builtin/read-tree.c
+++ b/builtin/read-tree.c
@@ -4,7 +4,7 @@
  * Copyright (C) Linus Torvalds, 2005
  */
 
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "cache.h"
 #include "config.h"
 #include "lockfile.h"
@@ -176,7 +176,7 @@ int cmd_read_tree(int argc, const char **argv, const char *cmd_prefix)
 	prepare_repo_settings(the_repository);
 	the_repository->settings.command_requires_full_index = 0;
 
-	hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
+	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
 
 	/*
 	 * NEEDSWORK
@@ -188,11 +188,11 @@ int cmd_read_tree(int argc, const char **argv, const char *cmd_prefix)
 	 */
 
 	if (opts.reset || opts.merge || opts.prefix) {
-		if (read_cache_unmerged() && (opts.prefix || opts.merge))
+		if (repo_read_index_unmerged(the_repository) && (opts.prefix || opts.merge))
 			die(_("You need to resolve your current index first"));
 		stage = opts.merge = 1;
 	}
-	resolve_undo_clear();
+	resolve_undo_clear_index(&the_index);
 
 	for (i = 0; i < argc; i++) {
 		const char *arg = argv[i];
@@ -232,7 +232,7 @@ int cmd_read_tree(int argc, const char **argv, const char *cmd_prefix)
 			break;
 		case 2:
 			opts.fn = twoway_merge;
-			opts.initial_checkout = is_cache_unborn();
+			opts.initial_checkout = is_index_unborn(&the_index);
 			break;
 		case 3:
 		default:
@@ -253,7 +253,7 @@ int cmd_read_tree(int argc, const char **argv, const char *cmd_prefix)
 	if (nr_trees == 1 && !opts.prefix)
 		opts.skip_cache_tree_update = 1;
 
-	cache_tree_free(&active_cache_tree);
+	cache_tree_free(&the_index.cache_tree);
 	for (i = 0; i < nr_trees; i++) {
 		struct tree *tree = trees[i];
 		parse_tree(tree);
diff --git a/builtin/rebase.c b/builtin/rebase.c
index 4d6839a..b22768c 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -4,7 +4,7 @@
  * Copyright (c) 2018 Pratik Karki
  */
 
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "builtin.h"
 #include "run-command.h"
 #include "exec-cmd.h"
@@ -292,7 +292,7 @@ static int do_interactive_rebase(struct rebase_options *opts, unsigned flags)
 	if (ret)
 		error(_("could not generate todo list"));
 	else {
-		discard_cache();
+		discard_index(&the_index);
 		if (todo_list_parse_insn_buffer(the_repository, todo_list.buf.buf,
 						&todo_list))
 			BUG("unusable todo list");
@@ -1270,7 +1270,7 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 		if (get_oid("HEAD", &head))
 			die(_("Cannot read HEAD"));
 
-		fd = hold_locked_index(&lock_file, 0);
+		fd = repo_hold_locked_index(the_repository, &lock_file, 0);
 		if (repo_read_index(the_repository) < 0)
 			die(_("could not read index"));
 		refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL,
diff --git a/builtin/reset.c b/builtin/reset.c
index ab02777..1fa86ed 100644
--- a/builtin/reset.c
+++ b/builtin/reset.c
@@ -7,7 +7,7 @@
  *
  * Copyright (c) 2005, 2006 Linus Torvalds and Junio C Hamano
  */
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "builtin.h"
 #include "config.h"
 #include "lockfile.h"
@@ -84,7 +84,7 @@ static int reset_index(const char *ref, const struct object_id *oid, int reset_t
 		BUG("invalid reset_type passed to reset_index");
 	}
 
-	read_cache_unmerged();
+	repo_read_index_unmerged(the_repository);
 
 	if (reset_type == KEEP) {
 		struct object_id head_oid;
@@ -145,7 +145,7 @@ static void update_index_from_diff(struct diff_queue_struct *q,
 		struct cache_entry *ce;
 
 		if (!is_in_reset_tree && !intent_to_add) {
-			remove_file_from_cache(one->path);
+			remove_file_from_index(&the_index, one->path);
 			continue;
 		}
 
@@ -160,8 +160,8 @@ static void update_index_from_diff(struct diff_queue_struct *q,
 		 * if this entry is outside the sparse cone - this is necessary
 		 * to properly construct the reset sparse directory.
 		 */
-		pos = cache_name_pos(one->path, strlen(one->path));
-		if ((pos >= 0 && ce_skip_worktree(active_cache[pos])) ||
+		pos = index_name_pos(&the_index, one->path, strlen(one->path));
+		if ((pos >= 0 && ce_skip_worktree(the_index.cache[pos])) ||
 		    (pos < 0 && !path_in_sparse_checkout(one->path, &the_index)))
 			ce->ce_flags |= CE_SKIP_WORKTREE;
 
@@ -172,7 +172,8 @@ static void update_index_from_diff(struct diff_queue_struct *q,
 			ce->ce_flags |= CE_INTENT_TO_ADD;
 			set_object_name_for_intent_to_add_entry(ce);
 		}
-		add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
+		add_index_entry(&the_index, ce,
+				ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 	}
 }
 
@@ -220,7 +221,7 @@ static void set_reflog_message(struct strbuf *sb, const char *action,
 
 static void die_if_unmerged_cache(int reset_type)
 {
-	if (is_merge() || unmerged_cache())
+	if (is_merge() || unmerged_index(&the_index))
 		die(_("Cannot do a %s reset in the middle of a merge."),
 		    _(reset_type_names[reset_type]));
 
@@ -422,7 +423,7 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 	prepare_repo_settings(the_repository);
 	the_repository->settings.command_requires_full_index = 0;
 
-	if (read_cache() < 0)
+	if (repo_read_index(the_repository) < 0)
 		die(_("index file corrupt"));
 
 	/* Soft reset does not touch the index file nor the working tree
@@ -433,7 +434,8 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 
 	if (reset_type != SOFT) {
 		struct lock_file lock = LOCK_INIT;
-		hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
+		repo_hold_locked_index(the_repository, &lock,
+				       LOCK_DIE_ON_ERROR);
 		if (reset_type == MIXED) {
 			int flags = quiet ? REFRESH_QUIET : REFRESH_IN_PORCELAIN;
 			if (read_from_tree(&pathspec, &oid, intent_to_add))
diff --git a/builtin/rev-parse.c b/builtin/rev-parse.c
index b5666a0..1c344d7 100644
--- a/builtin/rev-parse.c
+++ b/builtin/rev-parse.c
@@ -3,7 +3,7 @@
  *
  * Copyright (C) Linus Torvalds, 2005
  */
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "cache.h"
 #include "config.h"
 #include "commit.h"
@@ -1007,7 +1007,7 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
 				continue;
 			}
 			if (!strcmp(arg, "--shared-index-path")) {
-				if (read_cache() < 0)
+				if (repo_read_index(the_repository) < 0)
 					die(_("Could not read the index"));
 				if (the_index.split_index) {
 					const struct object_id *oid = &the_index.split_index->base_oid;
diff --git a/builtin/rm.c b/builtin/rm.c
index 05bfe20..d4989d4 100644
--- a/builtin/rm.c
+++ b/builtin/rm.c
@@ -35,8 +35,8 @@ static int get_ours_cache_pos(const char *path, int pos)
 {
 	int i = -pos - 1;
 
-	while ((i < active_nr) && !strcmp(active_cache[i]->name, path)) {
-		if (ce_stage(active_cache[i]) == 2)
+	while ((i < the_index.cache_nr) && !strcmp(the_index.cache[i]->name, path)) {
+		if (ce_stage(the_index.cache[i]) == 2)
 			return i;
 		i++;
 	}
@@ -72,13 +72,13 @@ static void submodules_absorb_gitdir_if_needed(void)
 		int pos;
 		const struct cache_entry *ce;
 
-		pos = cache_name_pos(name, strlen(name));
+		pos = index_name_pos(&the_index, name, strlen(name));
 		if (pos < 0) {
 			pos = get_ours_cache_pos(name, pos);
 			if (pos < 0)
 				continue;
 		}
-		ce = active_cache[pos];
+		ce = the_index.cache[pos];
 
 		if (!S_ISGITLINK(ce->ce_mode) ||
 		    !file_exists(ce->name) ||
@@ -116,7 +116,7 @@ static int check_local_mod(struct object_id *head, int index_only)
 		int local_changes = 0;
 		int staged_changes = 0;
 
-		pos = cache_name_pos(name, strlen(name));
+		pos = index_name_pos(&the_index, name, strlen(name));
 		if (pos < 0) {
 			/*
 			 * Skip unmerged entries except for populated submodules
@@ -126,11 +126,11 @@ static int check_local_mod(struct object_id *head, int index_only)
 			if (pos < 0)
 				continue;
 
-			if (!S_ISGITLINK(active_cache[pos]->ce_mode) ||
+			if (!S_ISGITLINK(the_index.cache[pos]->ce_mode) ||
 			    is_empty_dir(name))
 				continue;
 		}
-		ce = active_cache[pos];
+		ce = the_index.cache[pos];
 
 		if (lstat(ce->name, &st) < 0) {
 			if (!is_missing_file_error(errno))
@@ -167,7 +167,7 @@ static int check_local_mod(struct object_id *head, int index_only)
 		 * Is the index different from the file in the work tree?
 		 * If it's a submodule, is its work tree modified?
 		 */
-		if (ce_match_stat(ce, &st, 0) ||
+		if (ie_match_stat(&the_index, ce, &st, 0) ||
 		    (S_ISGITLINK(ce->ce_mode) &&
 		     bad_to_remove_submodule(ce->name,
 				SUBMODULE_REMOVAL_DIE_ON_ERROR |
@@ -290,9 +290,9 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 
 	prepare_repo_settings(the_repository);
 	the_repository->settings.command_requires_full_index = 0;
-	hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
+	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
 
-	if (read_cache() < 0)
+	if (repo_read_index(the_repository) < 0)
 		die(_("index file corrupt"));
 
 	refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, &pathspec, NULL, NULL);
@@ -302,8 +302,8 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 	if (pathspec_needs_expanded_index(&the_index, &pathspec))
 		ensure_full_index(&the_index);
 
-	for (i = 0; i < active_nr; i++) {
-		const struct cache_entry *ce = active_cache[i];
+	for (i = 0; i < the_index.cache_nr; i++) {
+		const struct cache_entry *ce = the_index.cache[i];
 
 		if (!include_sparse &&
 		    (ce_skip_worktree(ce) ||
@@ -385,7 +385,7 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 		if (!quiet)
 			printf("rm '%s'\n", path);
 
-		if (remove_file_from_cache(path))
+		if (remove_file_from_index(&the_index, path))
 			die(_("git rm: unable to remove %s"), path);
 	}
 
diff --git a/builtin/stash.c b/builtin/stash.c
index bb5485b..62e3671 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -261,11 +261,11 @@ static int reset_tree(struct object_id *i_tree, int update, int reset)
 	struct tree *tree;
 	struct lock_file lock_file = LOCK_INIT;
 
-	read_cache_preload(NULL);
-	if (refresh_cache(REFRESH_QUIET))
+	repo_read_index_preload(the_repository, NULL, 0);
+	if (refresh_index(&the_index, REFRESH_QUIET, NULL, NULL, NULL))
 		return -1;
 
-	hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
+	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
 
 	memset(&opts, 0, sizeof(opts));
 
@@ -454,10 +454,10 @@ static void unstage_changes_unless_new(struct object_id *orig_tree)
 		 * path, but left it out of the working tree, then clear the
 		 * SKIP_WORKTREE bit and write it to the working tree.
 		 */
-		if (pos >= 0 && ce_skip_worktree(active_cache[pos])) {
+		if (pos >= 0 && ce_skip_worktree(the_index.cache[pos])) {
 			struct stat st;
 
-			ce = active_cache[pos];
+			ce = the_index.cache[pos];
 			if (!lstat(ce->name, &st)) {
 				/* Conflicting path present; relocate it */
 				struct strbuf new_path = STRBUF_INIT;
@@ -523,8 +523,9 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 	struct tree *head, *merge, *merge_base;
 	struct lock_file lock = LOCK_INIT;
 
-	read_cache_preload(NULL);
-	if (refresh_and_write_cache(REFRESH_QUIET, 0, 0))
+	repo_read_index_preload(the_repository, NULL, 0);
+	if (repo_refresh_and_write_index(the_repository, REFRESH_QUIET, 0, 0,
+					 NULL, NULL, NULL))
 		return -1;
 
 	if (write_cache_as_tree(&c_tree, 0, NULL))
@@ -549,14 +550,14 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 				return error(_("conflicts in index. "
 					       "Try without --index."));
 
-			discard_cache();
-			read_cache();
+			discard_index(&the_index);
+			repo_read_index(the_repository);
 			if (write_cache_as_tree(&index_tree, 0, NULL))
 				return error(_("could not save index tree"));
 
 			reset_head();
-			discard_cache();
-			read_cache();
+			discard_index(&the_index);
+			repo_read_index(the_repository);
 		}
 	}
 
@@ -1082,7 +1083,7 @@ static int check_changes_tracked_files(const struct pathspec *ps)
 	if (get_oid("HEAD", &dummy))
 		return -1;
 
-	if (read_cache() < 0)
+	if (repo_read_index(the_repository) < 0)
 		return -1;
 
 	init_revisions(&rev, NULL);
@@ -1286,7 +1287,7 @@ static int stash_working_tree(struct stash_info *info, const struct pathspec *ps
 	rev.diffopt.format_callback = add_diff_to_buf;
 	rev.diffopt.format_callback_data = &diff_output;
 
-	if (read_cache_preload(&rev.diffopt.pathspec) < 0) {
+	if (repo_read_index_preload(the_repository, &rev.diffopt.pathspec, 0) < 0) {
 		ret = -1;
 		goto done;
 	}
@@ -1344,8 +1345,9 @@ static int do_create_stash(const struct pathspec *ps, struct strbuf *stash_msg_b
 
 	prepare_fallback_ident("git stash", "git@stash");
 
-	read_cache_preload(NULL);
-	if (refresh_and_write_cache(REFRESH_QUIET, 0, 0) < 0) {
+	repo_read_index_preload(the_repository, NULL, 0);
+	if (repo_refresh_and_write_index(the_repository, REFRESH_QUIET, 0, 0,
+					 NULL, NULL, NULL) < 0) {
 		ret = -1;
 		goto done;
 	}
@@ -1513,15 +1515,15 @@ static int do_push_stash(const struct pathspec *ps, const char *stash_msg, int q
 		goto done;
 	}
 
-	read_cache_preload(NULL);
+	repo_read_index_preload(the_repository, NULL, 0);
 	if (!include_untracked && ps->nr) {
 		int i;
 		char *ps_matched = xcalloc(ps->nr, 1);
 
 		/* TODO: audit for interaction with sparse-index. */
 		ensure_full_index(&the_index);
-		for (i = 0; i < active_nr; i++)
-			ce_path_match(&the_index, active_cache[i], ps,
+		for (i = 0; i < the_index.cache_nr; i++)
+			ce_path_match(&the_index, the_index.cache[i], ps,
 				      ps_matched);
 
 		if (report_path_error(ps_matched, ps)) {
@@ -1533,7 +1535,8 @@ static int do_push_stash(const struct pathspec *ps, const char *stash_msg, int q
 		free(ps_matched);
 	}
 
-	if (refresh_and_write_cache(REFRESH_QUIET, 0, 0)) {
+	if (repo_refresh_and_write_index(the_repository, REFRESH_QUIET, 0, 0,
+					 NULL, NULL, NULL)) {
 		ret = -1;
 		goto done;
 	}
@@ -1590,7 +1593,7 @@ static int do_push_stash(const struct pathspec *ps, const char *stash_msg, int q
 				goto done;
 			}
 		}
-		discard_cache();
+		discard_index(&the_index);
 		if (ps->nr) {
 			struct child_process cp_add = CHILD_PROCESS_INIT;
 			struct child_process cp_diff = CHILD_PROCESS_INIT;
diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index c75e9e8..05f2c9b 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -1,4 +1,4 @@
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "builtin.h"
 #include "repository.h"
 #include "cache.h"
@@ -196,11 +196,11 @@ static int module_list_compute(const char **argv,
 	if (pathspec->nr)
 		ps_matched = xcalloc(pathspec->nr, 1);
 
-	if (read_cache() < 0)
+	if (repo_read_index(the_repository) < 0)
 		die(_("index file corrupt"));
 
-	for (i = 0; i < active_nr; i++) {
-		const struct cache_entry *ce = active_cache[i];
+	for (i = 0; i < the_index.cache_nr; i++) {
+		const struct cache_entry *ce = the_index.cache[i];
 
 		if (!match_pathspec(&the_index, pathspec, ce->name, ce_namelen(ce),
 				    0, ps_matched, 1) ||
@@ -209,8 +209,8 @@ static int module_list_compute(const char **argv,
 
 		ALLOC_GROW(list->entries, list->nr + 1, list->alloc);
 		list->entries[list->nr++] = ce;
-		while (i + 1 < active_nr &&
-		       !strcmp(ce->name, active_cache[i + 1]->name))
+		while (i + 1 < the_index.cache_nr &&
+		       !strcmp(ce->name, the_index.cache[i + 1]->name))
 			/*
 			 * Skip entries with the same name in different stages
 			 * to make sure an entry is returned only once.
@@ -1110,13 +1110,13 @@ static int compute_summary_module_list(struct object_id *head_oid,
 	if (!info->cached) {
 		if (diff_cmd == DIFF_INDEX)
 			setup_work_tree();
-		if (read_cache_preload(&rev.diffopt.pathspec) < 0) {
-			perror("read_cache_preload");
+		if (repo_read_index_preload(the_repository, &rev.diffopt.pathspec, 0) < 0) {
+			perror("repo_read_index_preload");
 			ret = -1;
 			goto cleanup;
 		}
-	} else if (read_cache() < 0) {
-		perror("read_cache");
+	} else if (repo_read_index(the_repository) < 0) {
+		perror("repo_read_cache");
 		ret = -1;
 		goto cleanup;
 	}
@@ -3187,7 +3187,7 @@ static void die_on_index_match(const char *path, int force)
 	const char *args[] = { path, NULL };
 	parse_pathspec(&ps, 0, PATHSPEC_PREFER_CWD, NULL, args);
 
-	if (read_cache_preload(NULL) < 0)
+	if (repo_read_index_preload(the_repository, NULL, 0) < 0)
 		die(_("index file corrupt"));
 
 	if (ps.nr) {
@@ -3202,15 +3202,15 @@ static void die_on_index_match(const char *path, int force)
 		 * need to check ps_matched[0] to know if a cache
 		 * entry matched.
 		 */
-		for (i = 0; i < active_nr; i++) {
-			ce_path_match(&the_index, active_cache[i], &ps,
+		for (i = 0; i < the_index.cache_nr; i++) {
+			ce_path_match(&the_index, the_index.cache[i], &ps,
 				      ps_matched);
 
 			if (ps_matched[0]) {
 				if (!force)
 					die(_("'%s' already exists in the index"),
 					    path);
-				if (!S_ISGITLINK(active_cache[i]->ce_mode))
+				if (!S_ISGITLINK(the_index.cache[i]->ce_mode))
 					die(_("'%s' already exists in the index "
 					      "and is not a submodule"), path);
 				break;
diff --git a/builtin/update-index.c b/builtin/update-index.c
index 7b0c924..82d5902 100644
--- a/builtin/update-index.c
+++ b/builtin/update-index.c
@@ -237,16 +237,16 @@ done:
 static int mark_ce_flags(const char *path, int flag, int mark)
 {
 	int namelen = strlen(path);
-	int pos = cache_name_pos(path, namelen);
+	int pos = index_name_pos(&the_index, path, namelen);
 	if (0 <= pos) {
-		mark_fsmonitor_invalid(&the_index, active_cache[pos]);
+		mark_fsmonitor_invalid(&the_index, the_index.cache[pos]);
 		if (mark)
-			active_cache[pos]->ce_flags |= flag;
+			the_index.cache[pos]->ce_flags |= flag;
 		else
-			active_cache[pos]->ce_flags &= ~flag;
-		active_cache[pos]->ce_flags |= CE_UPDATE_IN_BASE;
+			the_index.cache[pos]->ce_flags &= ~flag;
+		the_index.cache[pos]->ce_flags |= CE_UPDATE_IN_BASE;
 		cache_tree_invalidate_path(&the_index, path);
-		active_cache_changed |= CE_ENTRY_CHANGED;
+		the_index.cache_changed |= CE_ENTRY_CHANGED;
 		return 0;
 	}
 	return -1;
@@ -256,7 +256,7 @@ static int remove_one_path(const char *path)
 {
 	if (!allow_remove)
 		return error("%s: does not exist and --remove not passed", path);
-	if (remove_file_from_cache(path))
+	if (remove_file_from_index(&the_index, path))
 		return error("%s: cannot remove from the index", path);
 	return 0;
 }
@@ -281,7 +281,7 @@ static int add_one_path(const struct cache_entry *old, const char *path, int len
 	struct cache_entry *ce;
 
 	/* Was the old index entry already up-to-date? */
-	if (old && !ce_stage(old) && !ce_match_stat(old, st, 0))
+	if (old && !ce_stage(old) && !ie_match_stat(&the_index, old, st, 0))
 		return 0;
 
 	ce = make_empty_cache_entry(&the_index, len);
@@ -298,7 +298,7 @@ static int add_one_path(const struct cache_entry *old, const char *path, int len
 	}
 	option = allow_add ? ADD_CACHE_OK_TO_ADD : 0;
 	option |= allow_replace ? ADD_CACHE_OK_TO_REPLACE : 0;
-	if (add_cache_entry(ce, option)) {
+	if (add_index_entry(&the_index, ce, option)) {
 		discard_cache_entry(ce);
 		return error("%s: cannot add to the index - missing --add option?", path);
 	}
@@ -331,11 +331,11 @@ static int add_one_path(const struct cache_entry *old, const char *path, int len
 static int process_directory(const char *path, int len, struct stat *st)
 {
 	struct object_id oid;
-	int pos = cache_name_pos(path, len);
+	int pos = index_name_pos(&the_index, path, len);
 
 	/* Exact match: file or existing gitlink */
 	if (pos >= 0) {
-		const struct cache_entry *ce = active_cache[pos];
+		const struct cache_entry *ce = the_index.cache[pos];
 		if (S_ISGITLINK(ce->ce_mode)) {
 
 			/* Do nothing to the index if there is no HEAD! */
@@ -350,8 +350,8 @@ static int process_directory(const char *path, int len, struct stat *st)
 
 	/* Inexact match: is there perhaps a subdirectory match? */
 	pos = -pos-1;
-	while (pos < active_nr) {
-		const struct cache_entry *ce = active_cache[pos++];
+	while (pos < the_index.cache_nr) {
+		const struct cache_entry *ce = the_index.cache[pos++];
 
 		if (strncmp(ce->name, path, len))
 			break;
@@ -382,7 +382,7 @@ static int process_path(const char *path, struct stat *st, int stat_errno)
 		return error("'%s' is beyond a symbolic link", path);
 
 	pos = cache_name_pos(path, len);
-	ce = pos < 0 ? NULL : active_cache[pos];
+	ce = pos < 0 ? NULL : the_index.cache[pos];
 	if (ce && ce_skip_worktree(ce)) {
 		/*
 		 * working directory version is assumed "good"
@@ -390,7 +390,7 @@ static int process_path(const char *path, struct stat *st, int stat_errno)
 		 * On the other hand, removing it from index should work
 		 */
 		if (!ignore_skip_worktree_entries && allow_remove &&
-		    remove_file_from_cache(path))
+		    remove_file_from_index(&the_index, path))
 			return error("%s: cannot remove from the index", path);
 		return 0;
 	}
@@ -429,7 +429,7 @@ static int add_cacheinfo(unsigned int mode, const struct object_id *oid,
 		ce->ce_flags |= CE_VALID;
 	option = allow_add ? ADD_CACHE_OK_TO_ADD : 0;
 	option |= allow_replace ? ADD_CACHE_OK_TO_REPLACE : 0;
-	if (add_cache_entry(ce, option))
+	if (add_index_entry(&the_index, ce, option))
 		return error("%s: cannot add to the index - missing --add option?",
 			     path);
 	report("add '%s'", path);
@@ -441,11 +441,11 @@ static void chmod_path(char flip, const char *path)
 	int pos;
 	struct cache_entry *ce;
 
-	pos = cache_name_pos(path, strlen(path));
+	pos = index_name_pos(&the_index, path, strlen(path));
 	if (pos < 0)
 		goto fail;
-	ce = active_cache[pos];
-	if (chmod_cache_entry(ce, flip) < 0)
+	ce = the_index.cache[pos];
+	if (chmod_index_entry(&the_index, ce, flip) < 0)
 		goto fail;
 
 	report("chmod %cx '%s'", flip, path);
@@ -488,7 +488,7 @@ static void update_one(const char *path)
 	}
 
 	if (force_remove) {
-		if (remove_file_from_cache(path))
+		if (remove_file_from_index(&the_index, path))
 			die("git update-index: unable to remove %s", path);
 		report("remove '%s'", path);
 		return;
@@ -571,7 +571,7 @@ static void read_index_info(int nul_term_line)
 
 		if (!mode) {
 			/* mode == 0 means there is no such path -- remove */
-			if (remove_file_from_cache(path_name))
+			if (remove_file_from_index(&the_index, path_name))
 				die("git update-index: unable to remove %s",
 				    ptr);
 		}
@@ -638,12 +638,12 @@ static int unresolve_one(const char *path)
 	struct cache_entry *ce_2 = NULL, *ce_3 = NULL;
 
 	/* See if there is such entry in the index. */
-	pos = cache_name_pos(path, namelen);
+	pos = index_name_pos(&the_index, path, namelen);
 	if (0 <= pos) {
 		/* already merged */
-		pos = unmerge_cache_entry_at(pos);
-		if (pos < active_nr) {
-			const struct cache_entry *ce = active_cache[pos];
+		pos = unmerge_index_entry_at(&the_index, pos);
+		if (pos < the_index.cache_nr) {
+			const struct cache_entry *ce = the_index.cache[pos];
 			if (ce_stage(ce) &&
 			    ce_namelen(ce) == namelen &&
 			    !memcmp(ce->name, path, namelen))
@@ -656,8 +656,8 @@ static int unresolve_one(const char *path)
 		 * want to do anything in the former case.
 		 */
 		pos = -pos-1;
-		if (pos < active_nr) {
-			const struct cache_entry *ce = active_cache[pos];
+		if (pos < the_index.cache_nr) {
+			const struct cache_entry *ce = the_index.cache[pos];
 			if (ce_namelen(ce) == namelen &&
 			    !memcmp(ce->name, path, namelen)) {
 				fprintf(stderr,
@@ -686,13 +686,13 @@ static int unresolve_one(const char *path)
 		goto free_return;
 	}
 
-	remove_file_from_cache(path);
-	if (add_cache_entry(ce_2, ADD_CACHE_OK_TO_ADD)) {
+	remove_file_from_index(&the_index, path);
+	if (add_index_entry(&the_index, ce_2, ADD_CACHE_OK_TO_ADD)) {
 		error("%s: cannot add our version to the index.", path);
 		ret = -1;
 		goto free_return;
 	}
-	if (!add_cache_entry(ce_3, ADD_CACHE_OK_TO_ADD))
+	if (!add_index_entry(&the_index, ce_3, ADD_CACHE_OK_TO_ADD))
 		return 0;
 	error("%s: cannot add their version to the index.", path);
 	ret = -1;
@@ -752,8 +752,8 @@ static int do_reupdate(const char **paths,
 		 */
 		has_head = 0;
  redo:
-	for (pos = 0; pos < active_nr; pos++) {
-		const struct cache_entry *ce = active_cache[pos];
+	for (pos = 0; pos < the_index.cache_nr; pos++) {
+		const struct cache_entry *ce = the_index.cache[pos];
 		struct cache_entry *old = NULL;
 		int save_nr;
 		char *path;
@@ -782,12 +782,12 @@ static int do_reupdate(const char **paths,
 		 * path anymore, in which case, under 'allow_remove',
 		 * or worse yet 'allow_replace', active_nr may decrease.
 		 */
-		save_nr = active_nr;
+		save_nr = the_index.cache_nr;
 		path = xstrdup(ce->name);
 		update_one(path);
 		free(path);
 		discard_cache_entry(old);
-		if (save_nr != active_nr)
+		if (save_nr != the_index.cache_nr)
 			goto redo;
 	}
 	clear_pathspec(&pathspec);
@@ -802,18 +802,19 @@ struct refresh_params {
 static int refresh(struct refresh_params *o, unsigned int flag)
 {
 	setup_work_tree();
-	read_cache();
-	*o->has_errors |= refresh_cache(o->flags | flag);
+	repo_read_index(the_repository);
+	*o->has_errors |= refresh_index(&the_index, o->flags | flag, NULL,
+					NULL, NULL);
 	if (has_racy_timestamp(&the_index)) {
 		/*
 		 * Even if nothing else has changed, updating the file
 		 * increases the chance that racy timestamps become
 		 * non-racy, helping future run-time performance.
 		 * We do that even in case of "errors" returned by
-		 * refresh_cache() as these are no actual errors.
+		 * refresh_index() as these are no actual errors.
 		 * cmd_status() does the same.
 		 */
-		active_cache_changed |= SOMETHING_CHANGED;
+		the_index.cache_changed |= SOMETHING_CHANGED;
 	}
 	return 0;
 }
@@ -850,7 +851,7 @@ static int resolve_undo_clear_callback(const struct option *opt,
 {
 	BUG_ON_OPT_NEG(unset);
 	BUG_ON_OPT_ARG(arg);
-	resolve_undo_clear();
+	resolve_undo_clear_index(&the_index);
 	return 0;
 }
 
@@ -951,7 +952,7 @@ static enum parse_opt_result unresolve_callback(
 	*has_errors = do_unresolve(ctx->argc, ctx->argv,
 				prefix, prefix ? strlen(prefix) : 0);
 	if (*has_errors)
-		active_cache_changed = 0;
+		the_index.cache_changed = 0;
 
 	ctx->argv += ctx->argc - 1;
 	ctx->argc = 1;
@@ -972,7 +973,7 @@ static enum parse_opt_result reupdate_callback(
 	setup_work_tree();
 	*has_errors = do_reupdate(ctx->argv + 1, prefix);
 	if (*has_errors)
-		active_cache_changed = 0;
+		the_index.cache_changed = 0;
 
 	ctx->argv += ctx->argc - 1;
 	ctx->argc = 1;
@@ -1109,11 +1110,11 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
 	the_repository->settings.command_requires_full_index = 0;
 
 	/* we will diagnose later if it turns out that we need to update it */
-	newfd = hold_locked_index(&lock_file, 0);
+	newfd = repo_hold_locked_index(the_repository, &lock_file, 0);
 	if (newfd < 0)
 		lock_error = errno;
 
-	entries = read_cache();
+	entries = repo_read_index(the_repository);
 	if (entries < 0)
 		die("cache corrupted");
 
@@ -1178,7 +1179,7 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
 			    INDEX_FORMAT_LB, INDEX_FORMAT_UB);
 
 		if (the_index.version != preferred_index_format)
-			active_cache_changed |= SOMETHING_CHANGED;
+			the_index.cache_changed |= SOMETHING_CHANGED;
 		the_index.version = preferred_index_format;
 	}
 
@@ -1290,7 +1291,7 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
 		report(_("fsmonitor disabled"));
 	}
 
-	if (active_cache_changed || force_write) {
+	if (the_index.cache_changed || force_write) {
 		if (newfd < 0) {
 			if (refresh_args.flags & REFRESH_QUIET)
 				exit(128);