Merge branch 'ds/midx-normalize-pathname-before-comparison' into maint

The path taken by "git multi-pack-index" command from the end user
was compared with path internally prepared by the tool withut first
normalizing, which lead to duplicated paths not being noticed,
which has been corrected.
source: <pull.1221.v2.git.1650911234.gitgitgadget@gmail.com>

* ds/midx-normalize-pathname-before-comparison:
  cache: use const char * for get_object_directory()
  multi-pack-index: use --object-dir real path
  midx: use real paths in lookup_multi_pack_index()

builtin/multi-pack-index.c

@@ -44,7 +44,7 @@ static char const * const builtin_multi_pack_index_usage[] = {
 };
 
 static struct opts_multi_pack_index {
-	const char *object_dir;
+	char *object_dir;
 	const char *preferred_pack;
 	const char *refs_snapshot;
 	unsigned long batch_size;
@@ -52,9 +52,23 @@ static struct opts_multi_pack_index {
 	int stdin_packs;
 } opts;
 
+
+static int parse_object_dir(const struct option *opt, const char *arg,
+			    int unset)
+{
+	free(opts.object_dir);
+	if (unset)
+		opts.object_dir = xstrdup(get_object_directory());
+	else
+		opts.object_dir = real_pathdup(arg, 1);
+	return 0;
+}
+
 static struct option common_opts[] = {
-	OPT_FILENAME(0, "object-dir", &opts.object_dir,
-	  N_("object directory containing set of packfile and pack-index pairs")),
+	OPT_CALLBACK(0, "object-dir", &opts.object_dir,
+	  N_("directory"),
+	  N_("object directory containing set of packfile and pack-index pairs"),
+	  parse_object_dir),
 	OPT_END(),
 };
 
@@ -232,31 +246,40 @@ static int cmd_multi_pack_index_repack(int argc, const char **argv)
 int cmd_multi_pack_index(int argc, const char **argv,
 			 const char *prefix)
 {
+	int res;
 	struct option *builtin_multi_pack_index_options = common_opts;
 
 	git_config(git_default_config, NULL);
 
+	if (the_repository &&
+	    the_repository->objects &&
+	    the_repository->objects->odb)
+		opts.object_dir = xstrdup(the_repository->objects->odb->path);
+
 	argc = parse_options(argc, argv, prefix,
 			     builtin_multi_pack_index_options,
 			     builtin_multi_pack_index_usage,
 			     PARSE_OPT_STOP_AT_NON_OPTION);
 
-	if (!opts.object_dir)
-		opts.object_dir = get_object_directory();
-
 	if (!argc)
 		goto usage;
 
 	if (!strcmp(argv[0], "repack"))
-		return cmd_multi_pack_index_repack(argc, argv);
+		res = cmd_multi_pack_index_repack(argc, argv);
 	else if (!strcmp(argv[0], "write"))
-		return cmd_multi_pack_index_write(argc, argv);
+		res =  cmd_multi_pack_index_write(argc, argv);
 	else if (!strcmp(argv[0], "verify"))
-		return cmd_multi_pack_index_verify(argc, argv);
+		res =  cmd_multi_pack_index_verify(argc, argv);
 	else if (!strcmp(argv[0], "expire"))
-		return cmd_multi_pack_index_expire(argc, argv);
+		res =  cmd_multi_pack_index_expire(argc, argv);
+	else {
+		error(_("unrecognized subcommand: %s"), argv[0]);
+		goto usage;
+	}
+
+	free(opts.object_dir);
+	return res;
 
-	error(_("unrecognized subcommand: %s"), argv[0]);
 usage:
 	usage_with_options(builtin_multi_pack_index_usage,
 			   builtin_multi_pack_index_options);

cache.h

@@ -566,7 +566,7 @@ extern char *git_work_tree_cfg;
 int is_inside_work_tree(void);
 const char *get_git_dir(void);
 const char *get_git_common_dir(void);
-char *get_object_directory(void);
+const char *get_object_directory(void);
 char *get_index_file(void);
 char *get_graft_file(struct repository *r);
 void set_git_dir(const char *path, int make_realpath);

environment.c

@@ -273,7 +273,7 @@ const char *get_git_work_tree(void)
 	return the_repository->worktree;
 }
 
-char *get_object_directory(void)
+const char *get_object_directory(void)
 {
 	if (!the_repository->objects->odb)
 		BUG("git environment hasn't been setup");

midx.c

@@ -1132,17 +1132,26 @@ cleanup:
 static struct multi_pack_index *lookup_multi_pack_index(struct repository *r,
 							const char *object_dir)
 {
+	struct multi_pack_index *result = NULL;
 	struct multi_pack_index *cur;
+	char *obj_dir_real = real_pathdup(object_dir, 1);
+	struct strbuf cur_path_real = STRBUF_INIT;
 
 	/* Ensure the given object_dir is local, or a known alternate. */
-	find_odb(r, object_dir);
+	find_odb(r, obj_dir_real);
 
 	for (cur = get_multi_pack_index(r); cur; cur = cur->next) {
-		if (!strcmp(object_dir, cur->object_dir))
-			return cur;
+		strbuf_realpath(&cur_path_real, cur->object_dir, 1);
+		if (!strcmp(obj_dir_real, cur_path_real.buf)) {
+			result = cur;
+			goto cleanup;
+		}
 	}
 
-	return NULL;
+cleanup:
+	free(obj_dir_real);
+	strbuf_release(&cur_path_real);
+	return result;
 }
 
 static int write_midx_internal(const char *object_dir,