[2/6] repo-settings: add submodule_propagate_branches

Commit Message

Glen Choo Aug. 29, 2022, 8:54 p.m. UTC

From: Glen Choo <[e-mail]>

When processes recurse into submodules, the child processes have to
use the same value of "submodule.propagateBranches" as the parent
process regardless of whether the process is spawned in the superproject
or submodule, otherwise the behavior may be inconsistent if the
repositories don't agree on the config.

We haven't needed a way to propagate the config because because the only
command that reads "submodule.propagateBranches" is "git branch", which
only has one mode of operation with "--recurse-submodules". However, a
future commit will teach "submodule.propagateBranches" to "git submodule
update", making this necessary.

Propagate "submodule.propagateBranches" to child processes by adding a
corresponding GIT_INTERNAL_* environment variable and repository
setting, and setting the environment variable inside
prepare_submodule_repo_env(). Then, refactor builtin/branch.c to read
the repository setting.

Using an internal environment variable is a potentially leaky
abstraction because environment variables can come from sources besides
the parent process. A more robust solution would be to teach Git that
the repository is a submodule and to only read
"submodule.propagateBranches" from the superproject config. There is WIP
for this on the ML [1].

Another alternative would be to pass "-c submodule.propagateBranches" to
all child processes. This is error-prone because many different
processes are invoked directly or indirectly by "git submodule update"
(e.g. "git submodule--helper clone", "git clone", "git checkout"). With
an environment variable, we can avoid this work because
prepare_submodule_repo_env() is already called for submodule child
processes.

[1] https://lore.kernel.org/git/[e-mail]/

Signed-off-by: Glen Choo <[e-mail]>
---
 builtin/branch.c | 11 +++--------
 cache.h          |  1 +
 repo-settings.c  | 11 ++++++-----
 repository.h     |  1 +
 submodule.c      |  2 ++
 5 files changed, 13 insertions(+), 13 deletions(-)

Comments

Philippe Blain Aug. 30, 2022, 4:02 a.m. UTC | #1

Le 2022-08-29 à 16:54, Glen Choo via GitGitGadget a écrit :
> From: Glen Choo <[e-mail]>
> 
> When processes recurse into submodules, the child processes have to
> use the same value of "submodule.propagateBranches" as the parent
> process regardless of whether the process is spawned in the superproject
> or submodule, otherwise the behavior may be inconsistent if the
> repositories don't agree on the config.
> 
> We haven't needed a way to propagate the config because because the only

"because because"

> command that reads "submodule.propagateBranches" is "git branch", which
> only has one mode of operation with "--recurse-submodules". However, a
> future commit will teach "submodule.propagateBranches" to "git submodule
> update", making this necessary.
> 
> Propagate "submodule.propagateBranches" to child processes by adding a
> corresponding GIT_INTERNAL_* environment variable and repository
> setting, and setting the environment variable inside
> prepare_submodule_repo_env(). Then, refactor builtin/branch.c to read
> the repository setting.
> 
> Using an internal environment variable is a potentially leaky
> abstraction because environment variables can come from sources besides
> the parent process. A more robust solution would be to teach Git that
> the repository is a submodule and to only read
> "submodule.propagateBranches" from the superproject config. There is WIP
> for this on the ML [1].
> 
> Another alternative would be to pass "-c submodule.propagateBranches" to
> all child processes. This is error-prone because many different
> processes are invoked directly or indirectly by "git submodule update"
> (e.g. "git submodule--helper clone", "git clone", "git checkout"). With
> an environment variable, we can avoid this work because
> prepare_submodule_repo_env() is already called for submodule child
> processes.

I think this is a good justification. I agree adding '-c' everywhere would be
error-prone.

Patch

diff --git a/builtin/branch.c b/builtin/branch.c
index 55cd9a6e998..1201e41ef8c 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -40,7 +40,6 @@  static const char * const builtin_branch_usage[] = {
 static const char *head;
 static struct object_id head_oid;
 static int recurse_submodules = 0;
-static int submodule_propagate_branches = 0;
 
 static int branch_use_color = -1;
 static char branch_colors[][COLOR_MAXLEN] = {
@@ -106,10 +105,6 @@  static int git_branch_config(const char *var, const char *value, void *cb)
 		recurse_submodules = git_config_bool(var, value);
 		return 0;
 	}
-	if (!strcasecmp(var, "submodule.propagateBranches")) {
-		submodule_propagate_branches = git_config_bool(var, value);
-		return 0;
-	}
 
 	return git_color_default_config(var, value, cb);
 }
@@ -714,7 +709,7 @@  int cmd_branch(int argc, const char **argv, const char *prefix)
 
 	argc = parse_options(argc, argv, prefix, options, builtin_branch_usage,
 			     0);
-
+	prepare_repo_settings(the_repository);
 	if (!delete && !rename && !copy && !edit_description && !new_upstream &&
 	    !show_current && !unset_upstream && argc == 0)
 		list = 1;
@@ -730,7 +725,7 @@  int cmd_branch(int argc, const char **argv, const char *prefix)
 		usage_with_options(builtin_branch_usage, options);
 
 	if (recurse_submodules_explicit) {
-		if (!submodule_propagate_branches)
+		if (!the_repository->settings.submodule_propagate_branches)
 			die(_("branch with --recurse-submodules can only be used if submodule.propagateBranches is enabled"));
 		if (noncreate_actions)
 			die(_("--recurse-submodules can only be used to create branches"));
@@ -738,7 +733,7 @@  int cmd_branch(int argc, const char **argv, const char *prefix)
 
 	recurse_submodules =
 		(recurse_submodules || recurse_submodules_explicit) &&
-		submodule_propagate_branches;
+		the_repository->settings.submodule_propagate_branches;
 
 	if (filter.abbrev == -1)
 		filter.abbrev = DEFAULT_ABBREV;
diff --git a/cache.h b/cache.h
index 302810b353a..023f8feba42 100644
--- a/cache.h
+++ b/cache.h
@@ -505,6 +505,7 @@  static inline enum object_type object_type(unsigned int mode)
 #define GIT_WORK_TREE_ENVIRONMENT "GIT_WORK_TREE"
 #define GIT_PREFIX_ENVIRONMENT "GIT_PREFIX"
 #define GIT_SUPER_PREFIX_ENVIRONMENT "GIT_INTERNAL_SUPER_PREFIX"
+#define GIT_SUBMODULE_PROPAGATE_BRANCHES_ENVIRONMENT "GIT_INTERNAL_SUBMODULE_PROPAGATE_BRANCHES"
 #define DEFAULT_GIT_DIR_ENVIRONMENT ".git"
 #define DB_ENVIRONMENT "GIT_OBJECT_DIRECTORY"
 #define INDEX_ENVIRONMENT "GIT_INDEX_FILE"
diff --git a/repo-settings.c b/repo-settings.c
index 43bc881bfc9..2fde9bcdbf6 100644
--- a/repo-settings.c
+++ b/repo-settings.c
@@ -60,16 +60,17 @@  void prepare_repo_settings(struct repository *r)
 	repo_cfg_bool(r, "pack.usesparse", &r->settings.pack_use_sparse, 1);
 	repo_cfg_bool(r, "core.multipackindex", &r->settings.core_multi_pack_index, 1);
 	repo_cfg_bool(r, "index.sparse", &r->settings.sparse_index, 0);
+	repo_cfg_bool(r, "submodule.propagateBranches", &r->settings.submodule_propagate_branches, 0);
 
 	/*
-	 * The GIT_TEST_MULTI_PACK_INDEX variable is special in that
-	 * either it *or* the config sets
-	 * r->settings.core_multi_pack_index if true. We don't take
-	 * the environment variable if it exists (even if false) over
-	 * any config, as in most other cases.
+	 * Boolean settings from config and environment variables. Only
+	 * take the environment variable if it is true, otherwise, use
+	 * the config.
 	 */
 	if (git_env_bool(GIT_TEST_MULTI_PACK_INDEX, 0))
 		r->settings.core_multi_pack_index = 1;
+	if (git_env_bool(GIT_SUBMODULE_PROPAGATE_BRANCHES_ENVIRONMENT, 0))
+		r->settings.submodule_propagate_branches = 1;
 
 	/*
 	 * Non-boolean config
diff --git a/repository.h b/repository.h
index 797f471cce9..bf36b9ee6d7 100644
--- a/repository.h
+++ b/repository.h
@@ -36,6 +36,7 @@  struct repo_settings {
 	int fetch_write_commit_graph;
 	int command_requires_full_index;
 	int sparse_index;
+	int submodule_propagate_branches;
 
 	struct fsmonitor_settings *fsmonitor; /* lazily loaded */
 
diff --git a/submodule.c b/submodule.c
index 3fa5db3ecdf..510c1b04a76 100644
--- a/submodule.c
+++ b/submodule.c
@@ -504,6 +504,8 @@  static void print_submodule_diff_summary(struct repository *r, struct rev_info *
 
 void prepare_submodule_repo_env(struct strvec *out)
 {
+	if (the_repository->settings.submodule_propagate_branches)
+		strvec_pushf(out, "%s=1", GIT_SUBMODULE_PROPAGATE_BRANCHES_ENVIRONMENT);
 	prepare_other_repo_env(out, DEFAULT_GIT_DIR_ENVIRONMENT);
 }