Reset all static variables to NULL in clar's __cleanup

Without this change, any failed assertion in the second (or a later) test
inside a test suite has a chance of double deleting memory, resulting in
a heap corruption. See #1096 for details.

This leaves alone the test cases where we "just" use cl_git_sandbox_init()
and cl_git_sandbox_cleanup(). These methods already take good care to not
double delete a repository.

Fixes #1096

3 files changed, 12 insertions, 0 deletions

diff --git a/tests-clar/stash/drop.c b/tests-clar/stash/drop.c
index b4f73b995..9d1aeda70 100644
--- a/tests-clar/stash/drop.c
+++ b/tests-clar/stash/drop.c
@@ -14,7 +14,11 @@ void test_stash_drop__initialize(void)
 void test_stash_drop__cleanup(void)
 {
 	git_signature_free(signature);
+	signature = NULL;
+
 	git_repository_free(repo);
+	repo = NULL;
+
 	cl_git_pass(git_futils_rmdir_r("stash", NULL, GIT_RMDIR_REMOVE_FILES));
 }
 
diff --git a/tests-clar/stash/foreach.c b/tests-clar/stash/foreach.c
index d7127a9db..c7d59a3a1 100644
--- a/tests-clar/stash/foreach.c
+++ b/tests-clar/stash/foreach.c
@@ -29,7 +29,11 @@ void test_stash_foreach__initialize(void)
 void test_stash_foreach__cleanup(void)
 {
 	git_signature_free(signature);
+	signature = NULL;
+
 	git_repository_free(repo);
+	repo = NULL;
+
 	cl_git_pass(git_futils_rmdir_r(REPO_NAME, NULL, GIT_RMDIR_REMOVE_FILES));
 }
 
diff --git a/tests-clar/stash/save.c b/tests-clar/stash/save.c
index fadb8940b..4eaf2a3c1 100644
--- a/tests-clar/stash/save.c
+++ b/tests-clar/stash/save.c
@@ -26,7 +26,11 @@ void test_stash_save__initialize(void)
 void test_stash_save__cleanup(void)
 {
 	git_signature_free(signature);
+	signature = NULL;
+
 	git_repository_free(repo);
+	repo = NULL;
+
 	cl_git_pass(git_futils_rmdir_r("stash", NULL, GIT_RMDIR_REMOVE_FILES));
 }