Introduce __cxa_thread_atexit()

libc/intrin/cxaatexit.internal.h

@@ -21,7 +21,10 @@ extern struct CxaAtexitBlocks __cxa_blocks;
 
 void __cxa_lock(void);
 void __cxa_unlock(void);
+void __cxa_thread_finalize(void);
 void __cxa_printexits(FILE *, void *);
+int __cxa_thread_atexit(void *, void *, void *);
+int __cxa_thread_atexit_impl(void *, void *, void *);
 
 COSMOPOLITAN_C_END_
 #endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */

libc/log/leaks.c

@@ -20,6 +20,7 @@
 #include "libc/intrin/asan.internal.h"
 #include "libc/intrin/bits.h"
 #include "libc/intrin/cmpxchg.h"
+#include "libc/intrin/cxaatexit.internal.h"
 #include "libc/intrin/kprintf.h"
 #include "libc/intrin/strace.internal.h"
 #include "libc/mem/mem.h"
@@ -94,6 +95,7 @@ dontasan void CheckForMemoryLeaks(void) {
     exit(0);
   }
   _pthread_unwind(_pthread_self());
+  __cxa_thread_finalize();
   _pthread_unkey(__get_tls());
   _pthread_ungarbage();
   __cxa_finalize(0);

libc/thread/__cxa_thread_atexit.c

@@ -0,0 +1,23 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2023 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/intrin/cxaatexit.internal.h"
+
+int __cxa_thread_atexit(void *fun, void *arg, void *dso_symbol) {
+  return __cxa_thread_atexit_impl(fun, arg, dso_symbol);
+}

libc/thread/__cxa_thread_atexit_impl.c

@@ -0,0 +1,47 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2023 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/intrin/cxaatexit.internal.h"
+#include "libc/mem/mem.h"
+
+struct Dtor {
+  void *fun;
+  void *arg;
+  struct Dtor *next;
+};
+
+static _Thread_local struct Dtor *__cxa_thread_atexit_list;
+
+void __cxa_thread_finalize(void) {
+  struct Dtor *dtor;
+  while ((dtor = __cxa_thread_atexit_list)) {
+    __cxa_thread_atexit_list = dtor->next;
+    ((void (*)(void *))dtor->fun)(dtor->arg);
+    free(dtor);
+  }
+}
+
+int __cxa_thread_atexit_impl(void *fun, void *arg, void *dso_symbol) {
+  struct Dtor *dtor;
+  if (!(dtor = malloc(sizeof(struct Dtor)))) return -1;
+  dtor->fun = fun;
+  dtor->arg = arg;
+  dtor->next = __cxa_thread_atexit_list;
+  __cxa_thread_atexit_list = dtor;
+  return 0;
+}

libc/thread/pthread_exit.c

@@ -20,6 +20,7 @@
 #include "libc/atomic.h"
 #include "libc/dce.h"
 #include "libc/intrin/atomic.h"
+#include "libc/intrin/cxaatexit.internal.h"
 #include "libc/intrin/strace.internal.h"
 #include "libc/intrin/weaken.h"
 #include "libc/limits.h"
@@ -110,6 +111,9 @@ wontreturn void pthread_exit(void *rc) {
 
   // free resources
   _pthread_unwind(pt);
+  if (_weaken(__cxa_thread_finalize)) {
+    _weaken(__cxa_thread_finalize)();
+  }
   _pthread_unkey(tib);
   _pthread_ungarbage();
   _pthread_decimate();

test/libc/thread/pthread_exit_test.c

@@ -16,6 +16,7 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/intrin/cxaatexit.internal.h"
 #include "libc/runtime/runtime.h"
 #include "libc/testlib/subprocess.h"
 #include "libc/testlib/testlib.h"
@@ -66,3 +67,21 @@ TEST(pthread_exit, detachedOrphanedChild_runsAtexitHandlers) {
   pthread_exit(0);
   EXITS(CHILD);
 }
+
+void OnMainThreadExit(void *arg) {
+  _Exit((long)arg);
+}
+
+TEST(__cxa_thread_atexit, exit_wontInvokeThreadDestructors) {
+  SPAWN(fork);
+  __cxa_thread_atexit(OnMainThreadExit, (void *)123L, 0);
+  exit(0);
+  EXITS(0);
+}
+
+TEST(__cxa_thread_atexit, pthread_exit_willInvokeThreadDestructors) {
+  SPAWN(fork);
+  __cxa_thread_atexit(OnMainThreadExit, (void *)123L, 0);
+  pthread_exit(0);
+  EXITS(123);
+}