[PATCH 19/20] submodule--helper: don't exit() on failure, return

[Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx>]

Change code downstream of module_update() to short-circuit and return
to the top-level on failure, rather than calling exit().

To do so we need to diligently check whether we "must_die_on_failure",
which is a pattern started in c51f8f94e5b (submodule--helper: run
update procedures from C, 2021-08-24), but which hadn't been completed
to the point where we could avoid calling exit() here.

This introduces no functional changes, but makes it easier to both
call these routines as a library in the future, and to eventually
avoid leaking memory.

This and similar control flow in submodule--helper.c could be made
simpler by properly "libifying" it, i.e. to have it consistently
return -1 on failures, and to early return on any non-success.

But let's leave that larger project for now, and (mostly) emulate what
were doing with the "exit(128)" before this change.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx>
---
 builtin/submodule--helper.c | 36 ++++++++++++++++++++++++++----------
 1 file changed, 26 insertions(+), 10 deletions(-)

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index 68aa10a26cd..d3f22f03766 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -2121,7 +2121,8 @@ static int fetch_in_submodule(const char *module_path, int depth, int quiet, str
 	return run_command(&cp);
 }
 
-static int run_update_command(struct update_data *ud, int subforce)
+static int run_update_command(struct update_data *ud, int subforce,
+			      int *must_die_on_failurep)
 {
 	struct child_process cp = CHILD_PROCESS_INIT;
 	char *oid = oid_to_hex(&ud->oid);
@@ -2183,8 +2184,10 @@ static int run_update_command(struct update_data *ud, int subforce)
 			BUG("unexpected update strategy type: %s",
 			    submodule_strategy_to_string(&ud->update_strategy));
 		}
-		if (must_die_on_failure)
-			exit(128);
+		if (must_die_on_failure) {
+			*must_die_on_failurep = 1;
+			return 128;
+		}
 
 		/* the command failed, but update must continue */
 		return 1;
@@ -2218,7 +2221,8 @@ static int run_update_command(struct update_data *ud, int subforce)
 	return 0;
 }
 
-static int run_update_procedure(struct update_data *ud)
+static int run_update_procedure(struct update_data *ud,
+				int *must_die_on_failure)
 {
 	int subforce = is_null_oid(&ud->suboid) || ud->force;
 
@@ -2245,7 +2249,7 @@ static int run_update_procedure(struct update_data *ud)
 			    ud->displaypath, oid_to_hex(&ud->oid));
 	}
 
-	return run_update_command(ud, subforce);
+	return run_update_command(ud, subforce, must_die_on_failure);
 }
 
 static const char *remote_submodule_branch(const char *path)
@@ -2381,7 +2385,8 @@ static void update_data_to_args(struct update_data *update_data, struct strvec *
 				    "--no-single-branch");
 }
 
-static int update_submodule(struct update_data *update_data)
+static int update_submodule(struct update_data *update_data,
+			    int *must_die_on_failure)
 {
 	int ret = 1;
 
@@ -2420,8 +2425,13 @@ static int update_submodule(struct update_data *update_data)
 	}
 
 	if (!oideq(&update_data->oid, &update_data->suboid) || update_data->force) {
-		if (run_update_procedure(update_data))
+		ret = run_update_procedure(update_data, must_die_on_failure);
+		if (ret && *must_die_on_failure) {
+			goto cleanup;
+		} else if (ret) {
+			ret = 1;
 			goto cleanup;
+		}
 	}
 
 	if (update_data->recursive) {
@@ -2444,7 +2454,8 @@ static int update_submodule(struct update_data *update_data)
 		die_message(_("Failed to recurse into submodule path '%s'"),
 			    update_data->displaypath);
 		if (ret == 128) {
-			exit(ret);
+			*must_die_on_failure = 1;
+			goto cleanup;
 		} else if (ret) {
 			ret = 1;
 			goto cleanup;
@@ -2482,13 +2493,18 @@ static int update_submodules(struct update_data *update_data)
 
 	for (i = 0; i < suc.update_clone_nr; i++) {
 		struct update_clone_data ucd = suc.update_clone[i];
+		int code;
+		int must_die_on_failure = 0;
 
 		oidcpy(&update_data->oid, &ucd.oid);
 		update_data->just_cloned = ucd.just_cloned;
 		update_data->sm_path = ucd.sub->path;
 
-		if (update_submodule(update_data))
-			res = 1;
+		code = update_submodule(update_data, &must_die_on_failure);
+		if (code)
+			res = code;
+		if (must_die_on_failure)
+			goto cleanup;
 	}
 
 cleanup:
-- 
2.37.1.1167.g38fda70d8c4