Merge branch 'tb/commit-graph-object-dir'

The code to compute the commit-graph has been taught to use a more
robust way to tell if two object directories refer to the same
thing.

* tb/commit-graph-object-dir:
  commit-graph.h: use odb in 'load_commit_graph_one_fd_st'
  commit-graph.c: remove path normalization, comparison
  commit-graph.h: store object directory in 'struct commit_graph'
  commit-graph.h: store an odb in 'struct write_commit_graph_context'
  t5318: don't pass non-object directory to '--object-dir'
diff --git a/Documentation/git-commit-graph.txt b/Documentation/git-commit-graph.txt
index bcd85c1..28d1fee 100644
--- a/Documentation/git-commit-graph.txt
+++ b/Documentation/git-commit-graph.txt
@@ -26,7 +26,10 @@
 	file. This parameter exists to specify the location of an alternate
 	that only has the objects directory, not a full `.git` directory. The
 	commit-graph file is expected to be in the `<dir>/info` directory and
-	the packfiles are expected to be in `<dir>/pack`.
+	the packfiles are expected to be in `<dir>/pack`. If the directory
+	could not be made into an absolute path, or does not match any known
+	object directory, `git commit-graph ...` will exit with non-zero
+	status.
 
 --[no-]progress::
 	Turn progress on/off explicitly. If neither is specified, progress is
diff --git a/builtin/commit-graph.c b/builtin/commit-graph.c
index e0c6fc4..4a70b33 100644
--- a/builtin/commit-graph.c
+++ b/builtin/commit-graph.c
@@ -34,9 +34,29 @@
 	int progress;
 } opts;
 
+static struct object_directory *find_odb(struct repository *r,
+					 const char *obj_dir)
+{
+	struct object_directory *odb;
+	char *obj_dir_real = real_pathdup(obj_dir, 1);
+
+	prepare_alt_odb(r);
+	for (odb = r->objects->odb; odb; odb = odb->next) {
+		if (!strcmp(obj_dir_real, real_path(odb->path)))
+			break;
+	}
+
+	free(obj_dir_real);
+
+	if (!odb)
+		die(_("could not find object directory matching %s"), obj_dir);
+	return odb;
+}
+
 static int graph_verify(int argc, const char **argv)
 {
 	struct commit_graph *graph = NULL;
+	struct object_directory *odb = NULL;
 	char *graph_name;
 	int open_ok;
 	int fd;
@@ -67,7 +87,8 @@
 	if (opts.progress)
 		flags |= COMMIT_GRAPH_WRITE_PROGRESS;
 
-	graph_name = get_commit_graph_filename(opts.obj_dir);
+	odb = find_odb(the_repository, opts.obj_dir);
+	graph_name = get_commit_graph_filename(odb);
 	open_ok = open_commit_graph(graph_name, &fd, &st);
 	if (!open_ok && errno != ENOENT)
 		die_errno(_("Could not open commit-graph '%s'"), graph_name);
@@ -75,9 +96,9 @@
 	FREE_AND_NULL(graph_name);
 
 	if (open_ok)
-		graph = load_commit_graph_one_fd_st(fd, &st);
-	 else
-		graph = read_commit_graph_one(the_repository, opts.obj_dir);
+		graph = load_commit_graph_one_fd_st(fd, &st, odb);
+	else
+		graph = read_commit_graph_one(the_repository, odb);
 
 	/* Return failure if open_ok predicted success */
 	if (!graph)
@@ -94,6 +115,7 @@
 {
 	struct string_list *pack_indexes = NULL;
 	struct string_list *commit_hex = NULL;
+	struct object_directory *odb = NULL;
 	struct string_list lines;
 	int result = 0;
 	enum commit_graph_write_flags flags = 0;
@@ -145,9 +167,10 @@
 		flags |= COMMIT_GRAPH_WRITE_PROGRESS;
 
 	read_replace_refs = 0;
+	odb = find_odb(the_repository, opts.obj_dir);
 
 	if (opts.reachable) {
-		if (write_commit_graph_reachable(opts.obj_dir, flags, &split_opts))
+		if (write_commit_graph_reachable(odb, flags, &split_opts))
 			return 1;
 		return 0;
 	}
@@ -169,7 +192,7 @@
 		UNLEAK(buf);
 	}
 
-	if (write_commit_graph(opts.obj_dir,
+	if (write_commit_graph(odb,
 			       pack_indexes,
 			       commit_hex,
 			       flags,
diff --git a/builtin/commit.c b/builtin/commit.c
index c70ad01..7ba33a3 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1693,7 +1693,7 @@
 		      "not exceeded, and then \"git restore --staged :/\" to recover."));
 
 	if (git_env_bool(GIT_TEST_COMMIT_GRAPH, 0) &&
-	    write_commit_graph_reachable(get_object_directory(), 0, NULL))
+	    write_commit_graph_reachable(the_repository->objects->odb, 0, NULL))
 		return 1;
 
 	repo_rerere(the_repository, 0);
diff --git a/builtin/fetch.c b/builtin/fetch.c
index 6fb5032..ab7e4b1 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -1879,7 +1879,7 @@
 		if (progress)
 			commit_graph_flags |= COMMIT_GRAPH_WRITE_PROGRESS;
 
-		write_commit_graph_reachable(get_object_directory(),
+		write_commit_graph_reachable(the_repository->objects->odb,
 					     commit_graph_flags,
 					     NULL);
 	}
diff --git a/builtin/gc.c b/builtin/gc.c
index 3f76bf4..8e0b9cf 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -686,7 +686,7 @@
 
 	prepare_repo_settings(the_repository);
 	if (the_repository->settings.gc_write_commit_graph == 1)
-		write_commit_graph_reachable(get_object_directory(),
+		write_commit_graph_reachable(the_repository->objects->odb,
 					     !quiet && !daemonized ? COMMIT_GRAPH_WRITE_PROGRESS : 0,
 					     NULL);
 
diff --git a/commit-graph.c b/commit-graph.c
index b205e65..656dd64 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -44,30 +44,21 @@
 /* Remember to update object flag allocation in object.h */
 #define REACHABLE       (1u<<15)
 
-char *get_commit_graph_filename(const char *obj_dir)
+char *get_commit_graph_filename(struct object_directory *odb)
 {
-	char *filename = xstrfmt("%s/info/commit-graph", obj_dir);
-	char *normalized = xmalloc(strlen(filename) + 1);
-	normalize_path_copy(normalized, filename);
-	free(filename);
-	return normalized;
+	return xstrfmt("%s/info/commit-graph", odb->path);
 }
 
-static char *get_split_graph_filename(const char *obj_dir,
+static char *get_split_graph_filename(struct object_directory *odb,
 				      const char *oid_hex)
 {
-	char *filename = xstrfmt("%s/info/commit-graphs/graph-%s.graph",
-				 obj_dir,
-				 oid_hex);
-	char *normalized = xmalloc(strlen(filename) + 1);
-	normalize_path_copy(normalized, filename);
-	free(filename);
-	return normalized;
+	return xstrfmt("%s/info/commit-graphs/graph-%s.graph", odb->path,
+		       oid_hex);
 }
 
-static char *get_chain_filename(const char *obj_dir)
+static char *get_chain_filename(struct object_directory *odb)
 {
-	return xstrfmt("%s/info/commit-graphs/commit-graph-chain", obj_dir);
+	return xstrfmt("%s/info/commit-graphs/commit-graph-chain", odb->path);
 }
 
 static uint8_t oid_version(void)
@@ -117,7 +108,8 @@
 	return 1;
 }
 
-struct commit_graph *load_commit_graph_one_fd_st(int fd, struct stat *st)
+struct commit_graph *load_commit_graph_one_fd_st(int fd, struct stat *st,
+						 struct object_directory *odb)
 {
 	void *graph_map;
 	size_t graph_size;
@@ -133,7 +125,9 @@
 	graph_map = xmmap(NULL, graph_size, PROT_READ, MAP_PRIVATE, fd, 0);
 	ret = parse_commit_graph(graph_map, fd, graph_size);
 
-	if (!ret) {
+	if (ret)
+		ret->odb = odb;
+	else {
 		munmap(graph_map, graph_size);
 		close(fd);
 	}
@@ -308,7 +302,8 @@
 	return graph;
 }
 
-static struct commit_graph *load_commit_graph_one(const char *graph_file)
+static struct commit_graph *load_commit_graph_one(const char *graph_file,
+						  struct object_directory *odb)
 {
 
 	struct stat st;
@@ -319,7 +314,7 @@
 	if (!open_ok)
 		return NULL;
 
-	g = load_commit_graph_one_fd_st(fd, &st);
+	g = load_commit_graph_one_fd_st(fd, &st, odb);
 
 	if (g)
 		g->filename = xstrdup(graph_file);
@@ -327,15 +322,13 @@
 	return g;
 }
 
-static struct commit_graph *load_commit_graph_v1(struct repository *r, const char *obj_dir)
+static struct commit_graph *load_commit_graph_v1(struct repository *r,
+						 struct object_directory *odb)
 {
-	char *graph_name = get_commit_graph_filename(obj_dir);
-	struct commit_graph *g = load_commit_graph_one(graph_name);
+	char *graph_name = get_commit_graph_filename(odb);
+	struct commit_graph *g = load_commit_graph_one(graph_name, odb);
 	free(graph_name);
 
-	if (g)
-		g->obj_dir = obj_dir;
-
 	return g;
 }
 
@@ -372,14 +365,15 @@
 	return 1;
 }
 
-static struct commit_graph *load_commit_graph_chain(struct repository *r, const char *obj_dir)
+static struct commit_graph *load_commit_graph_chain(struct repository *r,
+						    struct object_directory *odb)
 {
 	struct commit_graph *graph_chain = NULL;
 	struct strbuf line = STRBUF_INIT;
 	struct stat st;
 	struct object_id *oids;
 	int i = 0, valid = 1, count;
-	char *chain_name = get_chain_filename(obj_dir);
+	char *chain_name = get_chain_filename(odb);
 	FILE *fp;
 	int stat_res;
 
@@ -412,14 +406,12 @@
 
 		valid = 0;
 		for (odb = r->objects->odb; odb; odb = odb->next) {
-			char *graph_name = get_split_graph_filename(odb->path, line.buf);
-			struct commit_graph *g = load_commit_graph_one(graph_name);
+			char *graph_name = get_split_graph_filename(odb, line.buf);
+			struct commit_graph *g = load_commit_graph_one(graph_name, odb);
 
 			free(graph_name);
 
 			if (g) {
-				g->obj_dir = odb->path;
-
 				if (add_graph_to_chain(g, graph_chain, oids, i)) {
 					graph_chain = g;
 					valid = 1;
@@ -442,23 +434,25 @@
 	return graph_chain;
 }
 
-struct commit_graph *read_commit_graph_one(struct repository *r, const char *obj_dir)
+struct commit_graph *read_commit_graph_one(struct repository *r,
+					   struct object_directory *odb)
 {
-	struct commit_graph *g = load_commit_graph_v1(r, obj_dir);
+	struct commit_graph *g = load_commit_graph_v1(r, odb);
 
 	if (!g)
-		g = load_commit_graph_chain(r, obj_dir);
+		g = load_commit_graph_chain(r, odb);
 
 	return g;
 }
 
-static void prepare_commit_graph_one(struct repository *r, const char *obj_dir)
+static void prepare_commit_graph_one(struct repository *r,
+				     struct object_directory *odb)
 {
 
 	if (r->objects->commit_graph)
 		return;
 
-	r->objects->commit_graph = read_commit_graph_one(r, obj_dir);
+	r->objects->commit_graph = read_commit_graph_one(r, odb);
 }
 
 /*
@@ -505,7 +499,7 @@
 	for (odb = r->objects->odb;
 	     !r->objects->commit_graph && odb;
 	     odb = odb->next)
-		prepare_commit_graph_one(r, odb->path);
+		prepare_commit_graph_one(r, odb);
 	return !!r->objects->commit_graph;
 }
 
@@ -772,7 +766,7 @@
 
 struct write_commit_graph_context {
 	struct repository *r;
-	char *obj_dir;
+	struct object_directory *odb;
 	char *graph_name;
 	struct packed_oid_list oids;
 	struct packed_commit_list commits;
@@ -1149,7 +1143,7 @@
 	return 0;
 }
 
-int write_commit_graph_reachable(const char *obj_dir,
+int write_commit_graph_reachable(struct object_directory *odb,
 				 enum commit_graph_write_flags flags,
 				 const struct split_commit_graph_opts *split_opts)
 {
@@ -1157,7 +1151,7 @@
 	int result;
 
 	for_each_ref(add_ref_to_list, &list);
-	result = write_commit_graph(obj_dir, NULL, &list,
+	result = write_commit_graph(odb, NULL, &list,
 				    flags, split_opts);
 
 	string_list_clear(&list, 0);
@@ -1172,7 +1166,7 @@
 	struct strbuf packname = STRBUF_INIT;
 	int dirlen;
 
-	strbuf_addf(&packname, "%s/pack/", ctx->obj_dir);
+	strbuf_addf(&packname, "%s/pack/", ctx->odb->path);
 	dirlen = packname.len;
 	if (ctx->report_progress) {
 		strbuf_addf(&progress_title,
@@ -1368,10 +1362,10 @@
 
 		strbuf_addf(&tmp_file,
 			    "%s/info/commit-graphs/tmp_graph_XXXXXX",
-			    ctx->obj_dir);
+			    ctx->odb->path);
 		ctx->graph_name = strbuf_detach(&tmp_file, NULL);
 	} else {
-		ctx->graph_name = get_commit_graph_filename(ctx->obj_dir);
+		ctx->graph_name = get_commit_graph_filename(ctx->odb);
 	}
 
 	if (safe_create_leading_directories(ctx->graph_name)) {
@@ -1382,7 +1376,7 @@
 	}
 
 	if (ctx->split) {
-		char *lock_name = get_chain_filename(ctx->obj_dir);
+		char *lock_name = get_chain_filename(ctx->odb);
 
 		hold_lock_file_for_update(&lk, lock_name, LOCK_DIE_ON_ERROR);
 
@@ -1470,7 +1464,7 @@
 
 	if (ctx->split && ctx->base_graph_name && ctx->num_commit_graphs_after > 1) {
 		char *new_base_hash = xstrdup(oid_to_hex(&ctx->new_base_graph->oid));
-		char *new_base_name = get_split_graph_filename(ctx->new_base_graph->obj_dir, new_base_hash);
+		char *new_base_name = get_split_graph_filename(ctx->new_base_graph->odb, new_base_hash);
 
 		free(ctx->commit_graph_filenames_after[ctx->num_commit_graphs_after - 2]);
 		free(ctx->commit_graph_hash_after[ctx->num_commit_graphs_after - 2]);
@@ -1506,12 +1500,12 @@
 				}
 			}
 		} else {
-			char *graph_name = get_commit_graph_filename(ctx->obj_dir);
+			char *graph_name = get_commit_graph_filename(ctx->odb);
 			unlink(graph_name);
 		}
 
 		ctx->commit_graph_hash_after[ctx->num_commit_graphs_after - 1] = xstrdup(oid_to_hex(&file_hash));
-		final_graph_name = get_split_graph_filename(ctx->obj_dir,
+		final_graph_name = get_split_graph_filename(ctx->odb,
 					ctx->commit_graph_hash_after[ctx->num_commit_graphs_after - 1]);
 		ctx->commit_graph_filenames_after[ctx->num_commit_graphs_after - 1] = final_graph_name;
 
@@ -1553,7 +1547,7 @@
 
 	while (g && (g->num_commits <= size_mult * num_commits ||
 		    (max_commits && num_commits > max_commits))) {
-		if (strcmp(g->obj_dir, ctx->obj_dir))
+		if (g->odb != ctx->odb)
 			break;
 
 		num_commits += g->num_commits;
@@ -1565,10 +1559,10 @@
 	ctx->new_base_graph = g;
 
 	if (ctx->num_commit_graphs_after == 2) {
-		char *old_graph_name = get_commit_graph_filename(g->obj_dir);
+		char *old_graph_name = get_commit_graph_filename(g->odb);
 
 		if (!strcmp(g->filename, old_graph_name) &&
-		    strcmp(g->obj_dir, ctx->obj_dir)) {
+		    g->odb != ctx->odb) {
 			ctx->num_commit_graphs_after = 1;
 			ctx->new_base_graph = NULL;
 		}
@@ -1719,13 +1713,13 @@
 	if (ctx->split_opts && ctx->split_opts->expire_time)
 		expire_time -= ctx->split_opts->expire_time;
 	if (!ctx->split) {
-		char *chain_file_name = get_chain_filename(ctx->obj_dir);
+		char *chain_file_name = get_chain_filename(ctx->odb);
 		unlink(chain_file_name);
 		free(chain_file_name);
 		ctx->num_commit_graphs_after = 0;
 	}
 
-	strbuf_addstr(&path, ctx->obj_dir);
+	strbuf_addstr(&path, ctx->odb->path);
 	strbuf_addstr(&path, "/info/commit-graphs");
 	dir = opendir(path.buf);
 
@@ -1764,7 +1758,7 @@
 	strbuf_release(&path);
 }
 
-int write_commit_graph(const char *obj_dir,
+int write_commit_graph(struct object_directory *odb,
 		       struct string_list *pack_indexes,
 		       struct string_list *commit_hex,
 		       enum commit_graph_write_flags flags,
@@ -1772,7 +1766,6 @@
 {
 	struct write_commit_graph_context *ctx;
 	uint32_t i, count_distinct = 0;
-	size_t len;
 	int res = 0;
 
 	if (!commit_graph_compatible(the_repository))
@@ -1780,14 +1773,7 @@
 
 	ctx = xcalloc(1, sizeof(struct write_commit_graph_context));
 	ctx->r = the_repository;
-
-	/* normalize object dir with no trailing slash */
-	ctx->obj_dir = xmallocz(strlen(obj_dir) + 1);
-	normalize_path_copy(ctx->obj_dir, obj_dir);
-	len = strlen(ctx->obj_dir);
-	if (len && ctx->obj_dir[len - 1] == '/')
-		ctx->obj_dir[len - 1] = 0;
-
+	ctx->odb = odb;
 	ctx->append = flags & COMMIT_GRAPH_WRITE_APPEND ? 1 : 0;
 	ctx->report_progress = flags & COMMIT_GRAPH_WRITE_PROGRESS ? 1 : 0;
 	ctx->split = flags & COMMIT_GRAPH_WRITE_SPLIT ? 1 : 0;
@@ -1824,7 +1810,7 @@
 		ctx->oids.alloc = split_opts->max_commits;
 
 	if (ctx->append) {
-		prepare_commit_graph_one(ctx->r, ctx->obj_dir);
+		prepare_commit_graph_one(ctx->r, ctx->odb);
 		if (ctx->r->objects->commit_graph)
 			ctx->oids.alloc += ctx->r->objects->commit_graph->num_commits;
 	}
@@ -1898,7 +1884,6 @@
 	free(ctx->graph_name);
 	free(ctx->commits.list);
 	free(ctx->oids.list);
-	free(ctx->obj_dir);
 
 	if (ctx->commit_graph_filenames_after) {
 		for (i = 0; i < ctx->num_commit_graphs_after; i++) {
diff --git a/commit-graph.h b/commit-graph.h
index 7f5c933..e87a6f6 100644
--- a/commit-graph.h
+++ b/commit-graph.h
@@ -5,13 +5,14 @@
 #include "repository.h"
 #include "string-list.h"
 #include "cache.h"
+#include "object-store.h"
 
 #define GIT_TEST_COMMIT_GRAPH "GIT_TEST_COMMIT_GRAPH"
 #define GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD "GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD"
 
 struct commit;
 
-char *get_commit_graph_filename(const char *obj_dir);
+char *get_commit_graph_filename(struct object_directory *odb);
 int open_commit_graph(const char *graph_file, int *fd, struct stat *st);
 
 /*
@@ -48,7 +49,7 @@
 	uint32_t num_commits;
 	struct object_id oid;
 	char *filename;
-	const char *obj_dir;
+	struct object_directory *odb;
 
 	uint32_t num_commits_in_base;
 	struct commit_graph *base_graph;
@@ -60,8 +61,10 @@
 	const unsigned char *chunk_base_graphs;
 };
 
-struct commit_graph *load_commit_graph_one_fd_st(int fd, struct stat *st);
-struct commit_graph *read_commit_graph_one(struct repository *r, const char *obj_dir);
+struct commit_graph *load_commit_graph_one_fd_st(int fd, struct stat *st,
+						 struct object_directory *odb);
+struct commit_graph *read_commit_graph_one(struct repository *r,
+					   struct object_directory *odb);
 struct commit_graph *parse_commit_graph(void *graph_map, int fd,
 					size_t graph_size);
 
@@ -91,10 +94,10 @@
  * is not compatible with the commit-graph feature, then the
  * methods will return 0 without writing a commit-graph.
  */
-int write_commit_graph_reachable(const char *obj_dir,
+int write_commit_graph_reachable(struct object_directory *odb,
 				 enum commit_graph_write_flags flags,
 				 const struct split_commit_graph_opts *split_opts);
-int write_commit_graph(const char *obj_dir,
+int write_commit_graph(struct object_directory *odb,
 		       struct string_list *pack_indexes,
 		       struct string_list *commit_hex,
 		       enum commit_graph_write_flags flags,
diff --git a/t/helper/test-read-graph.c b/t/helper/test-read-graph.c
index d2884ef..f8a4617 100644
--- a/t/helper/test-read-graph.c
+++ b/t/helper/test-read-graph.c
@@ -11,18 +11,18 @@
 	int open_ok;
 	int fd;
 	struct stat st;
-	const char *object_dir;
+	struct object_directory *odb;
 
 	setup_git_directory();
-	object_dir = get_object_directory();
+	odb = the_repository->objects->odb;
 
-	graph_name = get_commit_graph_filename(object_dir);
+	graph_name = get_commit_graph_filename(odb);
 
 	open_ok = open_commit_graph(graph_name, &fd, &st);
 	if (!open_ok)
 		die_errno(_("Could not open commit-graph '%s'"), graph_name);
 
-	graph = load_commit_graph_one_fd_st(fd, &st);
+	graph = load_commit_graph_one_fd_st(fd, &st, odb);
 	if (!graph)
 		return 1;
 
diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
index 81cf118..07b3207 100755
--- a/t/t5318-commit-graph.sh
+++ b/t/t5318-commit-graph.sh
@@ -19,8 +19,8 @@
 
 test_expect_success 'write graph with no packs' '
 	cd "$TRASH_DIRECTORY/full" &&
-	git commit-graph write --object-dir . &&
-	test_path_is_missing info/commit-graph
+	git commit-graph write --object-dir $objdir &&
+	test_path_is_missing $objdir/info/commit-graph
 '
 
 test_expect_success 'exit with correct error on bad input to --stdin-packs' '