Workaround crash in FreeBSD rand() by avoiding its concurrent usage

Issue #414 (bdwgc).

The standard specifies rand() as not a thread-safe API function.  Thus,
the concurrent usage of libc rand() should be avoided.

Redefine the standard rand() in disclaim_[weakmap_]test with a trivial
(yet sufficient for the test purpose) implementation to avoid crashes
inside rand() on some targets (e.g. FreeBSD 13.0).

* tests/disclaim_test.c [LINT2] (GC_API_PRIV): Do not define.
* tests/disclaim_weakmap_test.c [LINT2] (GC_API_PRIV): Likewise.
* tests/disclaim_test.c [LINT2] (GC_random): Do not declare.
* tests/disclaim_weakmap_test.c [LINT2] (GC_random): Likewise.
* tests/disclaim_test.c [GC_PTHREADS || LINT2] (NOT_GCBUILD): Define.
* tests/disclaim_weakmap_test.c [GC_PTHREADS || LINT2] (NOT_GCBUILD):
Likewise.
* tests/disclaim_test.c [GC_PTHREADS || LINT2]: Include gc_priv.h.
* tests/disclaim_test.c [GC_PTHREADS || LINT2] (GC_rand): New static
function.
* tests/disclaim_weakmap_test.c [GC_PTHREADS || LINT2] (GC_rand):
Likewise.
* tests/disclaim_test.c [GC_PTHREADS || LINT2] (rand): Define to
GC_rand() (instead of (int)GC_random()); add comment.
* tests/disclaim_weakmap_test.c [GC_PTHREADS || LINT2] (rand):
Likewise.
* tests/disclaim_weakmap_test.c [GC_PTHREADS || LINT2]: Include
gc_priv.h before gc/gc_mark.h; add comment.

2 files changed, 38 insertions, 31 deletions

diff --git a/tests/disclaim_test.c b/tests/disclaim_test.c
index 7dca517b..f73c16a7 100644
--- a/tests/disclaim_test.c
+++ b/tests/disclaim_test.c
@@ -28,21 +28,26 @@
 #undef GC_NO_THREAD_REDIRECTS
 #include "gc/gc_disclaim.h"
 
-#ifdef LINT2
-  /* Avoid include gc_priv.h. */
-# ifndef GC_API_PRIV
-#   define GC_API_PRIV GC_API
-# endif
-# ifdef __cplusplus
-    extern "C" {
-# endif
-  GC_API_PRIV long GC_random(void);
-# ifdef __cplusplus
-    } /* extern "C" */
-# endif
+#if defined(GC_PTHREADS) || defined(LINT2)
+# define NOT_GCBUILD
+# include "private/gc_priv.h"
+
+  GC_ATTR_NO_SANITIZE_THREAD
+  static int GC_rand(void) /* nearly identical to GC_random */
+  {
+    static unsigned seed; /* concurrent update does not hurt the test */
+
+    seed = (seed * 1103515245U + 12345) & (~0U >> 1);
+    return (int)seed;
+  }
+
+  /* Redefine the standard rand() with a trivial (yet sufficient for    */
+  /* the test purpose) implementation to avoid crashes inside rand()    */
+  /* on some targets (e.g. FreeBSD 13.0) when used concurrently.        */
+  /* The standard specifies rand() as not a thread-safe API function.   */
 # undef rand
-# define rand() (int)GC_random()
-#endif /* LINT2 */
+# define rand() GC_rand()
+#endif /* GC_PTHREADS || LINT2 */
 
 #define my_assert(e) \
     if (!(e)) { \
diff --git a/tests/disclaim_weakmap_test.c b/tests/disclaim_weakmap_test.c
index a42695fd..68f7c6e5 100644
--- a/tests/disclaim_weakmap_test.c
+++ b/tests/disclaim_weakmap_test.c
@@ -24,7 +24,25 @@
 #endif
 
 #include "gc/gc_disclaim.h" /* includes gc.h */
-#include "gc/gc_mark.h"
+
+#if defined(GC_PTHREADS) || defined(LINT2)
+# define NOT_GCBUILD
+# include "private/gc_priv.h"
+
+  GC_ATTR_NO_SANITIZE_THREAD
+  static int GC_rand(void) /* same as in disclaim_test.c */
+  {
+    static unsigned seed; /* concurrent update does not hurt the test */
+
+    seed = (seed * 1103515245U + 12345) & (~0U >> 1);
+    return (int)seed;
+  }
+
+# undef rand
+# define rand() GC_rand()
+#endif /* GC_PTHREADS || LINT2 */
+
+#include "gc/gc_mark.h" /* should not precede include gc_priv.h */
 
 #ifdef GC_PTHREADS
 # ifndef NTHREADS
@@ -39,22 +57,6 @@
 # define AO_t GC_word
 #endif
 
-#ifdef LINT2
-  /* Avoid include gc_priv.h. */
-# ifndef GC_API_PRIV
-#   define GC_API_PRIV GC_API
-# endif
-# ifdef __cplusplus
-    extern "C" {
-# endif
-  GC_API_PRIV long GC_random(void);
-# ifdef __cplusplus
-    } /* extern "C" */
-# endif
-# undef rand
-# define rand() (int)GC_random()
-#endif /* LINT2 */
-
 #define POP_SIZE 200
 #define MUTATE_CNT (5000000 / NTHREADS)
 #define GROW_LIMIT (MUTATE_CNT / 10)