Merge branch 'ds/disable-replace-refs'

Introduce a mechanism to disable replace refs globally and per
repository.

* ds/disable-replace-refs:
  repository: create read_replace_refs setting
  replace-objects: create wrapper around setting
  repository: create disable_replace_refs()

builtin/cat-file.c

@@ -805,7 +805,7 @@ static int batch_objects(struct batch_options *opt)
 		if (repo_has_promisor_remote(the_repository))
 			warning("This repository uses promisor remotes. Some objects may not be loaded.");
 
-		read_replace_refs = 0;
+		disable_replace_refs();
 
 		cb.opt = opt;
 		cb.expand = &data;

builtin/commit-graph.c

@@ -324,7 +324,7 @@ int cmd_commit_graph(int argc, const char **argv, const char *prefix)
 
 	git_config(git_default_config, NULL);
 
-	read_replace_refs = 0;
+	disable_replace_refs();
 	save_commit_buffer = 0;
 
 	argc = parse_options(argc, argv, prefix, options,

builtin/fsck.c

@@ -929,7 +929,7 @@ int cmd_fsck(int argc, const char **argv, const char *prefix)
 	fetch_if_missing = 0;
 
 	errors_found = 0;
-	read_replace_refs = 0;
+	disable_replace_refs();
 	save_commit_buffer = 0;
 
 	argc = parse_options(argc, argv, prefix, fsck_opts, fsck_usage, 0);

builtin/index-pack.c

@@ -1752,7 +1752,7 @@ int cmd_index_pack(int argc, const char **argv, const char *prefix)
 	if (argc == 2 && !strcmp(argv[1], "-h"))
 		usage(index_pack_usage);
 
-	read_replace_refs = 0;
+	disable_replace_refs();
 	fsck_options.walk = mark_link;
 
 	reset_pack_idx_option(&opts);

builtin/pack-objects.c

@@ -4284,7 +4284,7 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 	if (DFS_NUM_STATES > (1 << OE_DFS_STATE_BITS))
 		BUG("too many dfs states, increase OE_DFS_STATE_BITS");
 
-	read_replace_refs = 0;
+	disable_replace_refs();
 
 	sparse = git_env_bool("GIT_TEST_PACK_SPARSE", -1);
 	if (the_repository->gitdir) {

builtin/prune.c

@@ -164,7 +164,7 @@ int cmd_prune(int argc, const char **argv, const char *prefix)
 
 	expire = TIME_MAX;
 	save_commit_buffer = 0;
-	read_replace_refs = 0;
+	disable_replace_refs();
 	repo_init_revisions(the_repository, &revs, prefix);
 
 	argc = parse_options(argc, argv, prefix, options, prune_usage, 0);

builtin/replace.c

@@ -566,7 +566,7 @@ int cmd_replace(int argc, const char **argv, const char *prefix)
 		OPT_END()
 	};
 
-	read_replace_refs = 0;
+	disable_replace_refs();
 	git_config(git_default_config, NULL);
 
 	argc = parse_options(argc, argv, prefix, options, git_replace_usage, 0);

builtin/unpack-objects.c

@@ -609,7 +609,7 @@ int cmd_unpack_objects(int argc, const char **argv, const char *prefix UNUSED)
 	int i;
 	struct object_id oid;
 
-	read_replace_refs = 0;
+	disable_replace_refs();
 
 	git_config(git_default_config, NULL);
 

builtin/upload-pack.c

@@ -36,7 +36,7 @@ int cmd_upload_pack(int argc, const char **argv, const char *prefix)
 	};
 
 	packet_trace_identity("upload-pack");
-	read_replace_refs = 0;
+	disable_replace_refs();
 
 	argc = parse_options(argc, argv, prefix, options, upload_pack_usage, 0);
 

commit-graph.c

@@ -204,14 +204,12 @@ static struct commit_graph *alloc_commit_graph(void)
 	return g;
 }
 
-extern int read_replace_refs;
-
 static int commit_graph_compatible(struct repository *r)
 {
 	if (!r->gitdir)
 		return 0;
 
-	if (read_replace_refs) {
+	if (replace_refs_enabled(r)) {
 		prepare_replace_object(r);
 		if (hashmap_get_size(&r->objects->replace_map->map))
 			return 0;

config.c

@@ -1841,11 +1841,6 @@ static int git_default_core_config(const char *var, const char *value, void *cb)
 		return 0;
 	}
 
-	if (!strcmp(var, "core.usereplacerefs")) {
-		read_replace_refs = git_config_bool(var, value);
-		return 0;
-	}
-
 	/* Add other config variables here and to Documentation/config.txt. */
 	return platform_core_config(var, value, cb);
 }

environment.c

@@ -62,7 +62,6 @@ const char *editor_program;
 const char *askpass_program;
 const char *excludes_file;
 enum auto_crlf auto_crlf = AUTO_CRLF_FALSE;
-int read_replace_refs = 1;
 enum eol core_eol = EOL_UNSET;
 int global_conv_flags_eol = CONV_EOL_RNDTRP_WARN;
 char *check_roundtrip_encoding = "SHIFT-JIS";
@@ -183,7 +182,7 @@ void setup_git_env(const char *git_dir)
 	strvec_clear(&to_free);
 
 	if (getenv(NO_REPLACE_OBJECTS_ENVIRONMENT))
-		read_replace_refs = 0;
+		disable_replace_refs();
 	replace_ref_base = getenv(GIT_REPLACE_REF_BASE_ENVIRONMENT);
 	git_replace_ref_base = xstrdup(replace_ref_base ? replace_ref_base
 							  : "refs/replace/");

git.c

@@ -186,7 +186,7 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
 			if (envchanged)
 				*envchanged = 1;
 		} else if (!strcmp(cmd, "--no-replace-objects")) {
-			read_replace_refs = 0;
+			disable_replace_refs();
 			setenv(NO_REPLACE_OBJECTS_ENVIRONMENT, "1", 1);
 			if (envchanged)
 				*envchanged = 1;

log-tree.c

@@ -156,7 +156,7 @@ static int add_ref_decoration(const char *refname, const struct object_id *oid,
 
 	if (starts_with(refname, git_replace_ref_base)) {
 		struct object_id original_oid;
-		if (!read_replace_refs)
+		if (!replace_refs_enabled(the_repository))
 			return 0;
 		if (get_oid_hex(refname + strlen(git_replace_ref_base),
 				&original_oid)) {

replace-object.c

@@ -64,7 +64,7 @@ void prepare_replace_object(struct repository *r)
  * replacement object's name (replaced recursively, if necessary).
  * The return value is either oid or a pointer to a
  * permanently-allocated value.  This function always respects replace
- * references, regardless of the value of read_replace_refs.
+ * references, regardless of the value of r->settings.read_replace_refs.
  */
 const struct object_id *do_lookup_replace_object(struct repository *r,
 						 const struct object_id *oid)
@@ -84,3 +84,29 @@ const struct object_id *do_lookup_replace_object(struct repository *r,
 	}
 	die(_("replace depth too high for object %s"), oid_to_hex(oid));
 }
+
+/*
+ * This indicator determines whether replace references should be
+ * respected process-wide, regardless of which repository is being
+ * using at the time.
+ */
+static int read_replace_refs = 1;
+
+void disable_replace_refs(void)
+{
+	read_replace_refs = 0;
+}
+
+int replace_refs_enabled(struct repository *r)
+{
+	if (!read_replace_refs)
+		return 0;
+
+	if (r->gitdir) {
+		prepare_repo_settings(r);
+		return r->settings.read_replace_refs;
+	}
+
+	/* repository has no objects or refs. */
+	return 0;
+}

replace-object.h

@@ -5,14 +5,6 @@
 #include "repository.h"
 #include "object-store.h"
 
-/*
- * Do replace refs need to be checked this run?  This variable is
- * initialized to true unless --no-replace-object is used or
- * $GIT_NO_REPLACE_OBJECTS is set, but is set to false by some
- * commands that do not want replace references to be active.
- */
-extern int read_replace_refs;
-
 struct replace_object {
 	struct oidmap_entry original;
 	struct object_id replacement;
@@ -27,6 +19,18 @@ void prepare_replace_object(struct repository *r);
 const struct object_id *do_lookup_replace_object(struct repository *r,
 						 const struct object_id *oid);
 
+/*
+ * Some commands disable replace-refs unconditionally, and otherwise each
+ * repository could alter the core.useReplaceRefs config value.
+ *
+ * Return 1 if and only if all of the following are true:
+ *
+ *  a. disable_replace_refs() has not been called.
+ *  b. GIT_NO_REPLACE_OBJECTS is unset or zero.
+ *  c. the given repository does not have core.useReplaceRefs=false.
+ */
+int replace_refs_enabled(struct repository *r);
+
 /*
  * If object sha1 should be replaced, return the replacement object's
  * name (replaced recursively, if necessary).  The return value is
@@ -41,11 +45,19 @@ const struct object_id *do_lookup_replace_object(struct repository *r,
 static inline const struct object_id *lookup_replace_object(struct repository *r,
 							    const struct object_id *oid)
 {
-	if (!read_replace_refs ||
+	if (!replace_refs_enabled(r) ||
 	    (r->objects->replace_map_initialized &&
 	     r->objects->replace_map->map.tablesize == 0))
 		return oid;
 	return do_lookup_replace_object(r, oid);
 }
 
+/*
+ * Some commands override config and environment settings for using
+ * replace references. Use this method to disable the setting and ensure
+ * those other settings will not override this choice. This applies
+ * globally to all in-process repositories.
+ */
+void disable_replace_refs(void);
+
 #endif /* REPLACE_OBJECT_H */

repo-settings.c

@@ -67,6 +67,7 @@ void prepare_repo_settings(struct repository *r)
 	repo_cfg_bool(r, "pack.usebitmapboundarytraversal",
 		      &r->settings.pack_use_bitmap_boundary_traversal,
 		      r->settings.pack_use_bitmap_boundary_traversal);
+	repo_cfg_bool(r, "core.usereplacerefs", &r->settings.read_replace_refs, 1);
 
 	/*
 	 * The GIT_TEST_MULTI_PACK_INDEX variable is special in that

repository.h

@@ -39,6 +39,15 @@ struct repo_settings {
 	int pack_read_reverse_index;
 	int pack_use_bitmap_boundary_traversal;
 
+	/*
+	 * Does this repository have core.useReplaceRefs=true (on by
+	 * default)? This provides a repository-scoped version of this
+	 * config, though it could be disabled process-wide via some Git
+	 * builtins or the --no-replace-objects option. See
+	 * replace_refs_enabled() for more details.
+	 */
+	int read_replace_refs;
+
 	struct fsmonitor_settings *fsmonitor; /* lazily loaded */
 
 	int index_version;

t/t7814-grep-recurse-submodules.sh

@@ -594,4 +594,44 @@ test_expect_success 'grep partially-cloned submodule' '
 	)
 '
 
+test_expect_success 'check scope of core.useReplaceRefs' '
+	git init base &&
+	git init base/sub &&
+
+	echo A >base/a &&
+	echo B >base/b &&
+	echo C >base/sub/c &&
+	echo D >base/sub/d &&
+
+	git -C base/sub add c d &&
+	git -C base/sub commit -m "Add files" &&
+
+	git -C base submodule add ./sub &&
+	git -C base add a b sub &&
+	git -C base commit -m "Add files and submodule" &&
+
+	A=$(git -C base rev-parse HEAD:a) &&
+	B=$(git -C base rev-parse HEAD:b) &&
+	C=$(git -C base/sub rev-parse HEAD:c) &&
+	D=$(git -C base/sub rev-parse HEAD:d) &&
+
+	git -C base replace $A $B &&
+	git -C base/sub replace $C $D &&
+
+	test_must_fail git -C base grep --cached --recurse-submodules A &&
+	test_must_fail git -C base grep --cached --recurse-submodules C &&
+
+	git -C base config core.useReplaceRefs false &&
+	git -C base grep --recurse-submodules A &&
+	test_must_fail git -C base grep --cached --recurse-submodules C &&
+
+	git -C base/sub config core.useReplaceRefs false &&
+	git -C base grep --cached --recurse-submodules A &&
+	git -C base grep --cached --recurse-submodules C &&
+
+	git -C base config --unset core.useReplaceRefs &&
+	test_must_fail git -C base grep --cached --recurse-submodules A &&
+	git -C base grep --cached --recurse-submodules C
+'
+
 test_done