[PATCH 1/2] submodule: prevent overwriting .gitmodules on path reuse
- From
K Jayatheerth <jayatheerthkulkarni2005@gmail.com>
- Date
- Jul 24, 2025, 15:24 UTC
- Message-ID
- <20250724152418.45226-2-jayatheerthkulkarni2005@gmail.com>
- In-Reply-To
- <20250724152418.45226-1-jayatheerthkulkarni2005@gmail.com>
Adding a submodule at a path that previously hosted another submodule (e.g., 'child') reuses the submodule name derived from the path. If the original submodule was only moved (e.g., to 'child_old') and not renamed, this silently overwrites its configuration in .gitmodules.
This behavior loses user configuration and causes confusion when the original submodule is expected to remain intact. It assumes that the path-derived name is always safe to reuse, even though the name might still be in use elsewhere in the repository.
Teach module_add() to check if the computed submodule name already exists in the repository's submodule config, and if so, refuse the operation unless the user explicitly renames the submodule or uses the --force option, which will automatically generate a unique name by appending a number (e.g., child1).
Signed-off-by: K Jayatheerth <jayatheerthkulkarni2005@gmail.com> --- Documentation/git-submodule.adoc | 7 +++++++ builtin/submodule--helper.c | 27 +++++++++++++++++++++++++++ t/t7400-submodule-basic.sh | 22 ++++++++++++++++++++++ 3 files changed, 56 insertions(+)
diff --git a/Documentation/git-submodule.adoc b/Documentation/git-submodule.adoc index 87d8e0f0c5..503c84a200 100644 --- a/Documentation/git-submodule.adoc +++ b/Documentation/git-submodule.adoc @@ -307,6 +307,13 @@ OPTIONS --force:: This option is only valid for add, deinit and update commands. When running add, allow adding an otherwise ignored submodule path. + This option is also used to bypass a check that the submodule's name + is not already in use. By default, 'git submodule add' will fail if + the proposed name (which is derived from the path) is already registered + for another submodule in the repository. Using '--force' allows the command + to proceed by automatically generating a unique name by appending a number + to the conflicting name (e.g., if a submodule named 'child' exists, it will + try 'child1', and so on). When running deinit the submodule working trees will be removed even if they contain local changes. When running update (only effective with the checkout procedure), diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c index d8a6fa47e5..b4f5d6e26a 100644 --- a/builtin/submodule--helper.c +++ b/builtin/submodule--helper.c @@ -3423,6 +3423,10 @@ static int module_add(int argc, const char **argv, const char *prefix, struct add_data add_data = ADD_DATA_INIT; const char *ref_storage_format = NULL; char *to_free = NULL; + const struct submodule *existing; + struct strbuf buf = STRBUF_INIT; + int i; + char *sm_name_to_free = NULL; struct option options[] = { OPT_STRING('b', "branch", &add_data.branch, N_("branch"), N_("branch of repository to add as submodule")), @@ -3525,6 +3529,28 @@ static int module_add(int argc, const char **argv, const char *prefix, if(!add_data.sm_name) add_data.sm_name = add_data.sm_path; + existing = submodule_from_name(the_repository, + null_oid(the_hash_algo), + add_data.sm_name); + + if (existing && strcmp(existing->path, add_data.sm_path)) { + if (!force) { + die(_("submodule name '%s' already used for path '%s'"), + add_data.sm_name, existing->path); + } + /* --force: build <name><n> until unique */ + for (i = 1; ; i++) { + strbuf_reset(&buf); + strbuf_addf(&buf, "%s%d", add_data.sm_name, i); + if (!submodule_from_name(the_repository, + null_oid(the_hash_algo), + buf.buf)) { + break; + } + } + add_data.sm_name = sm_name_to_free = strbuf_detach(&buf, NULL); + } + if (check_submodule_name(add_data.sm_name)) die(_("'%s' is not a valid submodule name"), add_data.sm_name); @@ -3540,6 +3566,7 @@ static int module_add(int argc, const char **argv, const char *prefix, ret = 0; cleanup: + free(sm_name_to_free); free(add_data.sm_path); free(to_free); strbuf_release(&sb); diff --git a/t/t7400-submodule-basic.sh b/t/t7400-submodule-basic.sh index d6a501d453..6812df3081 100755 --- a/t/t7400-submodule-basic.sh +++ b/t/t7400-submodule-basic.sh @@ -1482,4 +1482,26 @@ test_expect_success '`submodule init` and `init.templateDir`' ' ) ' +test_expect_success 'submodule add fails when name is reused' ' + git init test-submodule && + ( + cd test-submodule && + git commit --allow-empty -m init && + + git init ../child-origin && + git -C ../child-origin commit --allow-empty -m init && + + git submodule add ../child-origin child && + git commit -m "Add submodule child" && + + git mv child child_old && + git commit -m "Move child to child_old" && + + # Now adding a *new* repo at the old name must fail + git init ../child2-origin && + git -C ../child2-origin commit --allow-empty -m init && + test_must_fail git submodule add ../child2-origin child + ) +' + test_done
-- 2.50.GIT