From f2592ef0e113aef0e8e7141cab2b17521760b064 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Wed, 25 Jan 2023 11:54:44 +0100
Subject: [PATCH] dlfcn: add new safe_dclose() helper

Let's allow destructing loaded module handles in our usual way that is
fine with NULL handles, and also returns the NULL handle again.
---
 src/shared/dlfcn-util.h | 8 ++++++++
 src/shared/tpm2-util.c  | 6 +-----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/shared/dlfcn-util.h b/src/shared/dlfcn-util.h
index f8a16433fc..ca632f4e1f 100644
--- a/src/shared/dlfcn-util.h
+++ b/src/shared/dlfcn-util.h
@@ -24,3 +24,11 @@ int dlopen_many_sym_or_warn_sentinel(void **dlp, const char *filename, int log_l
 /* libbpf is a bit confused about type-safety and API compatibility. Provide a macro that can tape over that mess. Sad. */
 #define DLSYM_ARG_FORCE(arg) \
         &sym_##arg, STRINGIFY(arg)
+
+static inline void *safe_dlclose(void *p) {
+        if (!p)
+                return NULL;
+
+        assert_se(dlclose(p) == 0);
+        return NULL;
+}
diff --git a/src/shared/tpm2-util.c b/src/shared/tpm2-util.c
index 3870f0401b..974b14439c 100644
--- a/src/shared/tpm2-util.c
+++ b/src/shared/tpm2-util.c
@@ -111,11 +111,7 @@ void tpm2_context_destroy(struct tpm2_context *c) {
                 sym_Esys_Finalize(&c->esys_context);
 
         c->tcti_context = mfree(c->tcti_context);
-
-        if (c->tcti_dl) {
-                dlclose(c->tcti_dl);
-                c->tcti_dl = NULL;
-        }
+        c->tcti_dl = safe_dlclose(c->tcti_dl);
 }
 
 static inline void Esys_Finalize_wrapper(ESYS_CONTEXT **c) {