test,static-destruct: Use retain attribute to prevent linker garbage collection

medhefgo · yuwata · commit a3aff1c47f61 · 2021-12-22T12:14:08.000+09:00
Fixes: systemd#21847
diff --git a/src/basic/static-destruct.h b/src/basic/static-destruct.h
@@ -24,12 +24,16 @@ typedef struct StaticDestructor {
                 typeof(variable) *q = p;                                \
                 func(q);                                                \
         }                                                               \
+        /* Older compilers don't know retain attribute. */              \
+        _Pragma("GCC diagnostic ignored \"-Wattributes\"")              \
         /* The actual destructor structure we place in a special section to find it */ \
         _section_("SYSTEMD_STATIC_DESTRUCT")                            \
         /* We pick pointer alignment, since that is apparently what gcc does for static variables */ \
         _alignptr_                                                      \
         /* Make sure this is not dropped from the image because not explicitly referenced */ \
         _used_                                                          \
+        /* Prevent linker from garbage collection. */                   \
+        _retain_                                                        \
         /* Make sure that AddressSanitizer doesn't pad this variable: we want everything in this section
          * packed next to each other so that we can enumerate it. */     \
         _variable_no_sanitize_address_                                  \
diff --git a/src/fundamental/macro-fundamental.h b/src/fundamental/macro-fundamental.h
@@ -13,6 +13,7 @@
 #define _pure_ __attribute__((__pure__))
 #define _section_(x) __attribute__((__section__(x)))
 #define _packed_ __attribute__((__packed__))
+#define _retain_ __attribute__((__retain__))
 #define _used_ __attribute__((__used__))
 #define _unused_ __attribute__((__unused__))
 #define _cleanup_(x) __attribute__((__cleanup__(x)))
diff --git a/src/libsystemd/sd-bus/bus-error.h b/src/libsystemd/sd-bus/bus-error.h
@@ -38,7 +38,7 @@ int bus_error_set_errnofv(sd_bus_error *e, int error, const char *format, va_lis
         _Pragma("GCC diagnostic ignored \"-Wattributes\"")              \
         _section_("SYSTEMD_BUS_ERROR_MAP")                              \
         _used_                                                          \
-        __attribute__((retain))                                         \
+        _retain_                                                        \
         _alignptr_                                                      \
         _variable_no_sanitize_address_
 
diff --git a/src/shared/tests.h b/src/shared/tests.h
@@ -57,7 +57,8 @@ typedef struct TestFunc {
 
 /* See static-destruct.h for an explanation of how this works. */
 #define REGISTER_TEST(func, ...)                                                                        \
-        _section_("SYSTEMD_TEST_TABLE") _alignptr_ _used_ _variable_no_sanitize_address_                \
+        _Pragma("GCC diagnostic ignored \"-Wattributes\"")                                              \
+        _section_("SYSTEMD_TEST_TABLE") _alignptr_ _used_ _retain_ _variable_no_sanitize_address_       \
         static const TestFunc UNIQ_T(static_test_table_entry, UNIQ) = {                                 \
                 .f = (union f) &(func),                                                                 \
                 .name = STRINGIFY(func),                                                                \
