Eliminate cyclic locks in runtime

This change introduces a new deadlock detector for Cosmo's POSIX threads
implementation. Error check mutexes will now track a DAG of nested locks
and report EDEADLK when a deadlock is theoretically possible. These will
occur rarely, but it's important for production hardening your code. You
don't even need to change your mutexes to use the POSIX error check mode
because `cosmocc -mdbg` will enable error checking on mutexes by default
globally. When cycles are found, an error message showing your demangled
symbols describing the strongly connected component are printed and then
the SIGTRAP is raised, which means you'll also get a backtrace if you're
using ShowCrashReports() too. This new error checker is so low-level and
so pure that it's able to verify the relationships of every libc runtime
lock, including those locks upon which the mutex implementation depends.

third_party/dlmalloc/README.cosmo

@@ -9,6 +9,7 @@ LICENSE
 
 LOCAL CHANGES
 
+  - Fix MT-safety bugs in DEBUG mode
   - Fix bug in dlmalloc_inspect_all()
   - Define dlmalloc_requires_more_vespene_gas()
   - Make dlmalloc scalable using sched_getcpu()

third_party/dlmalloc/dlmalloc.c

@@ -31,13 +31,14 @@
 #define FOOTERS 1
 #define MSPACES 1
 #define ONLY_MSPACES 1 // enables scalable multi-threaded malloc
-#define USE_SPIN_LOCKS 0 // only profitable using sched_getcpu()
+#define USE_SPIN_LOCKS 0 // set to 0 to use scalable nsync locks
 #else
 #define INSECURE 1
 #define PROCEED_ON_ERROR 1
 #define FOOTERS 0
 #define MSPACES 0
 #define ONLY_MSPACES 0
+#define USE_SPIN_LOCKS 1
 #endif
 
 #define HAVE_MMAP 1
@@ -1263,12 +1264,15 @@ void* dlrealloc_single(void* oldmem, size_t bytes) {
 #endif /* FOOTERS */
     if (!PREACTION(m)) {
       mchunkptr newp = try_realloc_chunk(m, oldp, nb, MREMAP_MAYMOVE);
-      POSTACTION(m);
       if (newp != 0) {
+        /* [jart] fix realloc MT bug in DEBUG mode
+                  https://github.com/intel/linux-sgx/issues/534 */
         check_inuse_chunk(m, newp);
+        POSTACTION(m);
         mem = chunk2mem(newp);
       }
       else {
+        POSTACTION(m);
         mem = internal_malloc(m, bytes);
         if (mem != 0) {
           size_t oc = chunksize(oldp) - overhead_for(oldp);
@@ -1301,11 +1305,13 @@ void* dlrealloc_in_place(void* oldmem, size_t bytes) {
 #endif /* FOOTERS */
       if (!PREACTION(m)) {
         mchunkptr newp = try_realloc_chunk(m, oldp, nb, 0);
-        POSTACTION(m);
         if (newp == oldp) {
+          /* [jart] fix realloc MT bug in DEBUG mode
+                    https://github.com/intel/linux-sgx/issues/534 */
           check_inuse_chunk(m, newp);
           mem = oldmem;
         }
+        POSTACTION(m);
       }
     }
   }
@@ -1319,13 +1325,6 @@ void* dlmemalign_single(size_t alignment, size_t bytes) {
   return internal_memalign(gm, alignment, bytes);
 }
 
-#if USE_LOCKS
-void dlmalloc_atfork(void) {
-  bzero(&gm->mutex, sizeof(gm->mutex));
-  bzero(&malloc_global_mutex, sizeof(malloc_global_mutex));
-}
-#endif
-
 void** dlindependent_calloc(size_t n_elements, size_t elem_size,
                             void* chunks[]) {
   size_t sz = elem_size; /* serves as 1-element array */

third_party/dlmalloc/dlmalloc.h

@@ -9,7 +9,6 @@
 #define dlmallinfo                   __dlmallinfo
 #define dlmalloc                     __dlmalloc
 #define dlmalloc_abort               __dlmalloc_abort
-#define dlmalloc_atfork              __dlmalloc_atfork
 #define dlmalloc_footprint           __dlmalloc_footprint
 #define dlmalloc_footprint_limit     __dlmalloc_footprint_limit
 #define dlmalloc_inspect_all         __dlmalloc_inspect_all
@@ -527,7 +526,10 @@ void mspace_inspect_all(mspace msp,
                         void (*handler)(void*, void*, size_t, void*),
                         void* arg);
 
-void dlmalloc_atfork(void);
+void dlmalloc_pre_fork(void) libcesque;
+void dlmalloc_post_fork_parent(void) libcesque;
+void dlmalloc_post_fork_child(void) libcesque;
+
 void dlmalloc_abort(void) relegated wontreturn;
 
 COSMOPOLITAN_C_END_

third_party/dlmalloc/init.inc

@@ -7,31 +7,34 @@
 #if LOCK_AT_FORK
 #if ONLY_MSPACES
 
-static void dlmalloc_pre_fork(void) {
+void dlmalloc_pre_fork(void) {
   mstate h;
-  for (unsigned i = 0; i < ARRAYLEN(g_heaps); ++i)
+  ACQUIRE_MALLOC_GLOBAL_LOCK();
+  for (unsigned i = ARRAYLEN(g_heaps); i--;)
     if ((h = atomic_load_explicit(&g_heaps[i], memory_order_acquire)))
       ACQUIRE_LOCK(&h->mutex);
 }
 
-static void dlmalloc_post_fork_parent(void) {
+void dlmalloc_post_fork_parent(void) {
   mstate h;
   for (unsigned i = 0; i < ARRAYLEN(g_heaps); ++i)
     if ((h = atomic_load_explicit(&g_heaps[i], memory_order_acquire)))
       RELEASE_LOCK(&h->mutex);
+  RELEASE_MALLOC_GLOBAL_LOCK();
 }
 
-static void dlmalloc_post_fork_child(void) {
+void dlmalloc_post_fork_child(void) {
   mstate h;
   for (unsigned i = 0; i < ARRAYLEN(g_heaps); ++i)
     if ((h = atomic_load_explicit(&g_heaps[i], memory_order_acquire)))
-      (void)INITIAL_LOCK(&h->mutex);
+      (void)REFRESH_LOCK(&h->mutex);
+  (void)REFRESH_MALLOC_GLOBAL_LOCK();
 }
 
 #else
-static void dlmalloc_pre_fork(void)         { ACQUIRE_LOCK(&(gm)->mutex); }
-static void dlmalloc_post_fork_parent(void) { RELEASE_LOCK(&(gm)->mutex); }
-static void dlmalloc_post_fork_child(void)  { (void)INITIAL_LOCK(&(gm)->mutex); }
+void dlmalloc_pre_fork(void)         { ACQUIRE_LOCK(&(gm)->mutex); }
+void dlmalloc_post_fork_parent(void) { RELEASE_LOCK(&(gm)->mutex); }
+void dlmalloc_post_fork_child(void)  { (void)REFRESH_LOCK(&(gm)->mutex); }
 #endif /* ONLY_MSPACES */
 #endif /* LOCK_AT_FORK */
 
@@ -95,12 +98,6 @@ __attribute__((__constructor__(49))) int init_mparams(void) {
     (void)INITIAL_LOCK(&gm->mutex);
 #endif
 
-#if LOCK_AT_FORK
-    pthread_atfork(&dlmalloc_pre_fork,
-                   &dlmalloc_post_fork_parent,
-                   &dlmalloc_post_fork_child);
-#endif
-
     {
 #if USE_DEV_RANDOM
       int fd;

third_party/dlmalloc/locks.inc

@@ -1,3 +1,7 @@
+#include "libc/cosmo.h"
+#include "libc/intrin/kprintf.h"
+#include "libc/intrin/maps.h"
+#include "libc/thread/thread.h"
 
 /* --------------------------- Lock preliminaries ------------------------ */
 
@@ -33,11 +37,20 @@
 
 #define MLOCK_T atomic_uint
 
+static int malloc_inlk(MLOCK_T *lk) {
+  atomic_store_explicit(lk, 0, memory_order_relaxed);
+  return 0;
+}
+
 static int malloc_wipe(MLOCK_T *lk) {
   atomic_store_explicit(lk, 0, memory_order_relaxed);
   return 0;
 }
 
+static int malloc_kilk(MLOCK_T *lk) {
+  return 0;
+}
+
 static int malloc_lock(MLOCK_T *lk) {
   for (;;) {
     if (!atomic_exchange_explicit(lk, 1, memory_order_acquire))
@@ -49,36 +62,71 @@ static int malloc_lock(MLOCK_T *lk) {
   return 0;
 }
 
-static int malloc_unlock(MLOCK_T *lk) {
+static int malloc_unlk(MLOCK_T *lk) {
   atomic_store_explicit(lk, 0, memory_order_release);
   return 0;
 }
 
 #else
 
-#define MLOCK_T nsync_mu
+#define MLOCK_T struct MallocLock
 
-static int malloc_wipe(MLOCK_T *lk) {
+struct MallocLock {
+#if DEBUG
+  void *edges;
+#endif
+  nsync_mu mu;
+};
+
+static int malloc_inlk(MLOCK_T *lk) {
   bzero(lk, sizeof(*lk));
   return 0;
 }
 
-static int malloc_lock(MLOCK_T *lk) {
-  nsync_mu_lock(lk);
+static int malloc_wipe(MLOCK_T *lk) {
+  bzero(&lk->mu, sizeof(lk->mu));
   return 0;
 }
 
-static int malloc_unlock(MLOCK_T *lk) {
-  nsync_mu_unlock(lk);
+static int malloc_kilk(MLOCK_T *lk) {
+  return 0;
+}
+
+static int malloc_lock(MLOCK_T *lk) {
+#if DEBUG
+  __deadlock_check(lk, 0);
+#endif
+  nsync_mu_lock(&lk->mu);
+#if DEBUG
+  __deadlock_record(lk, 0);
+  __deadlock_track(lk, 0);
+#endif
+  return 0;
+}
+
+static int malloc_unlk(MLOCK_T *lk) {
+#if DEBUG
+  if (__deadlock_tracked(lk) == 0) {
+    kprintf("error: unlock malloc mutex not owned by caller: %t\n", lk);
+    DebugBreak();
+  }
+#endif
+  nsync_mu_unlock(&lk->mu);
+#if DEBUG
+  __deadlock_untrack(lk);
+#endif
   return 0;
 }
 
 #endif
 
 #define ACQUIRE_LOCK(lk) malloc_lock(lk)
-#define RELEASE_LOCK(lk) malloc_unlock(lk)
-#define INITIAL_LOCK(lk) malloc_wipe(lk)
-#define DESTROY_LOCK(lk) malloc_wipe(lk)
+#define RELEASE_LOCK(lk) malloc_unlk(lk)
+#define INITIAL_LOCK(lk) malloc_inlk(lk)
+#define REFRESH_LOCK(lk) malloc_wipe(lk)
+#define DESTROY_LOCK(lk) malloc_kilk(lk)
+#define INITIAL_MALLOC_GLOBAL_LOCK() INITIAL_LOCK(&malloc_global_mutex);
+#define REFRESH_MALLOC_GLOBAL_LOCK() REFRESH_LOCK(&malloc_global_mutex);
 #define ACQUIRE_MALLOC_GLOBAL_LOCK() ACQUIRE_LOCK(&malloc_global_mutex);
 #define RELEASE_MALLOC_GLOBAL_LOCK() RELEASE_LOCK(&malloc_global_mutex);
 

third_party/dlmalloc/mspaces.inc

@@ -368,12 +368,15 @@ void* mspace_realloc(mspace msp, void* oldmem, size_t bytes) {
 #endif /* FOOTERS */
     if (!PREACTION(m)) {
       mchunkptr newp = try_realloc_chunk(m, oldp, nb, 1);
-      POSTACTION(m);
       if (newp != 0) {
+        /* [jart] fix realloc MT bug in DEBUG mode
+                  https://github.com/intel/linux-sgx/issues/534 */
         check_inuse_chunk(m, newp);
+        POSTACTION(m);
         mem = chunk2mem(newp);
       }
       else {
+        POSTACTION(m);
         mem = mspace_malloc(m, bytes);
         if (mem != 0) {
           size_t oc = chunksize(oldp) - overhead_for(oldp);
@@ -407,11 +410,13 @@ void* mspace_realloc_in_place(mspace msp, void* oldmem, size_t bytes) {
 #endif /* FOOTERS */
       if (!PREACTION(m)) {
         mchunkptr newp = try_realloc_chunk(m, oldp, nb, 0);
-        POSTACTION(m);
         if (newp == oldp) {
+          /* [jart] fix realloc_in_place MT bug in DEBUG mode
+                    https://github.com/intel/linux-sgx/issues/534 */
           check_inuse_chunk(m, newp);
           mem = oldmem;
         }
+        POSTACTION(m);
       }
     }
   }

third_party/gdtoa/lock.c

@@ -0,0 +1,59 @@
+/*-*- mode:c;indent-tabs-mode:t;c-basic-offset:8;tab-width:8;coding:utf-8   -*-│
+│ vi: set noet ft=c ts=8 sw=8 fenc=utf-8                                   :vi │
+╚──────────────────────────────────────────────────────────────────────────────╝
+│                                                                              │
+│  The author of this software is David M. Gay.                                │
+│  Please send bug reports to David M. Gay <dmg@acm.org>                       │
+│                          or Justine Tunney <jtunney@gmail.com>               │
+│                                                                              │
+│  Copyright (C) 1998, 1999 by Lucent Technologies                             │
+│  All Rights Reserved                                                         │
+│                                                                              │
+│  Permission to use, copy, modify, and distribute this software and           │
+│  its documentation for any purpose and without fee is hereby                 │
+│  granted, provided that the above copyright notice appear in all             │
+│  copies and that both that the copyright notice and this                     │
+│  permission notice and warranty disclaimer appear in supporting              │
+│  documentation, and that the name of Lucent or any of its entities           │
+│  not be used in advertising or publicity pertaining to                       │
+│  distribution of the software without specific, written prior                │
+│  permission.                                                                 │
+│                                                                              │
+│  LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,               │
+│  INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.            │
+│  IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY           │
+│  SPECIAL, 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 "third_party/gdtoa/lock.h"
+
+pthread_mutex_t __gdtoa_lock_obj = PTHREAD_MUTEX_INITIALIZER;
+pthread_mutex_t __gdtoa_lock1_obj = PTHREAD_MUTEX_INITIALIZER;
+
+void
+__gdtoa_lock(void)
+{
+	pthread_mutex_lock(&__gdtoa_lock_obj);
+}
+
+void
+__gdtoa_unlock(void)
+{
+	pthread_mutex_unlock(&__gdtoa_lock_obj);
+}
+
+void
+__gdtoa_lock1(void)
+{
+	pthread_mutex_lock(&__gdtoa_lock1_obj);
+}
+
+void
+__gdtoa_unlock1(void)
+{
+	pthread_mutex_unlock(&__gdtoa_lock1_obj);
+}

third_party/gdtoa/lock.h

@@ -0,0 +1,15 @@
+#ifndef COSMOPOLITAN_THIRD_PARTY_GDTOA_LOCK_H_
+#define COSMOPOLITAN_THIRD_PARTY_GDTOA_LOCK_H_
+#include "libc/thread/thread.h"
+COSMOPOLITAN_C_START_
+
+extern pthread_mutex_t __gdtoa_lock_obj;
+extern pthread_mutex_t __gdtoa_lock1_obj;
+
+void __gdtoa_lock(void);
+void __gdtoa_unlock(void);
+void __gdtoa_lock1(void);
+void __gdtoa_unlock1(void);
+
+COSMOPOLITAN_C_END_
+#endif /* COSMOPOLITAN_THIRD_PARTY_GDTOA_LOCK_H_ */

third_party/gdtoa/misc.c

@@ -35,46 +35,9 @@
 #include "libc/thread/thread.h"
 #include "libc/thread/tls.h"
 #include "third_party/gdtoa/gdtoa.internal.h"
+#include "third_party/gdtoa/lock.h"
 
 static ThInfo TI0;
-static pthread_mutex_t __gdtoa_lock_obj;
-static pthread_mutex_t __gdtoa_lock1_obj;
-
-static void
-__gdtoa_lock(void)
-{
-	pthread_mutex_lock(&__gdtoa_lock_obj);
-}
-
-static void
-__gdtoa_unlock(void)
-{
-	pthread_mutex_unlock(&__gdtoa_lock_obj);
-}
-
-static void
-__gdtoa_initlock(void)
-{
-	pthread_mutex_init(&__gdtoa_lock_obj, 0);
-}
-
-static void
-__gdtoa_lock1(void)
-{
-	pthread_mutex_lock(&__gdtoa_lock1_obj);
-}
-
-static void
-__gdtoa_unlock1(void)
-{
-	pthread_mutex_unlock(&__gdtoa_lock1_obj);
-}
-
-static void
-__gdtoa_initlock1(void)
-{
-	pthread_mutex_init(&__gdtoa_lock1_obj, 0);
-}
 
 static void
 __gdtoa_Brelease(Bigint *rv)
@@ -88,24 +51,20 @@ static void
 __gdtoa_Bclear(void)
 {
 	int i;
-	__gdtoa_lock();
+	__gdtoa_lock1();
 	for (i = 0; i < ARRAYLEN(TI0.Freelist); ++i)
 		__gdtoa_Brelease(TI0.Freelist[i]);
-	__gdtoa_lock1();
+	__gdtoa_lock();
 	__gdtoa_Brelease(TI0.P5s);
-	__gdtoa_unlock1();
-	bzero(&TI0, sizeof(TI0));
 	__gdtoa_unlock();
+	bzero(&TI0, sizeof(TI0));
+	__gdtoa_unlock1();
 }
 
 __attribute__((__constructor__(60))) static void
 __gdtoa_Binit(void)
 {
-	__gdtoa_initlock();
-	__gdtoa_initlock1();
 	atexit(__gdtoa_Bclear);
-	pthread_atfork(__gdtoa_lock1, __gdtoa_unlock1, __gdtoa_initlock1);
-	pthread_atfork(__gdtoa_lock, __gdtoa_unlock, __gdtoa_initlock);
 }
 
 static ThInfo *

third_party/lua/llock.c

@@ -19,12 +19,16 @@
 #include "libc/thread/thread.h"
 #include "third_party/lua/lrepl.h"
 
-static pthread_mutex_t lua_repl_lock_obj;
+static pthread_mutex_t lua_repl_lock_obj = PTHREAD_MUTEX_INITIALIZER;
 
-void(lua_repl_lock)(void) {
+void lua_repl_wock(void) {
+  lua_repl_lock_obj = (pthread_mutex_t)PTHREAD_MUTEX_INITIALIZER;
+}
+
+void lua_repl_lock(void) {
   pthread_mutex_lock(&lua_repl_lock_obj);
 }
 
-void(lua_repl_unlock)(void) {
+void lua_repl_unlock(void) {
   pthread_mutex_unlock(&lua_repl_lock_obj);
 }

third_party/lua/lrepl.h

@@ -11,6 +11,7 @@ extern struct linenoiseState *lua_repl_linenoise;
 extern linenoiseCompletionCallback *lua_repl_completions_callback;
 
 void lua_freerepl(void);
+void lua_repl_wock(void);
 void lua_repl_lock(void);
 void lua_repl_unlock(void);
 int lua_loadline(lua_State *);

third_party/lua/lunix.c

@@ -2959,7 +2959,7 @@ static int LuaUnixMapshared(lua_State *L) {
   m->mapsize = c;
   m->lock = (pthread_mutex_t *)p;
   pthread_mutexattr_init(&mattr);
-  pthread_mutexattr_settype(&mattr, PTHREAD_MUTEX_NORMAL);
+  pthread_mutexattr_settype(&mattr, PTHREAD_MUTEX_DEFAULT);
   pthread_mutexattr_setpshared(&mattr, PTHREAD_PROCESS_SHARED);
   pthread_mutex_init(m->lock, &mattr);
   pthread_mutexattr_destroy(&mattr);

third_party/nsync/common.c

@@ -39,6 +39,7 @@
 #include "third_party/nsync/common.internal.h"
 #include "third_party/nsync/mu_semaphore.h"
 #include "third_party/nsync/mu_semaphore.internal.h"
+#include "libc/intrin/kprintf.h"
 #include "third_party/nsync/wait_s.internal.h"
 __static_yoink("nsync_notice");
 

third_party/nsync/mu_semaphore_sem.c

@@ -78,7 +78,7 @@ static bool nsync_mu_semaphore_sem_create (struct sem *f) {
 	return true;
 }
 
-static void nsync_mu_semaphore_sem_fork_child (void) {
+void nsync_mu_semaphore_sem_fork_child (void) {
 	struct sem *f;
 	for (f = atomic_load_explicit (&g_sems, memory_order_relaxed); f; f = f->next) {
 		int rc = sys_close (f->id);
@@ -87,17 +87,11 @@ static void nsync_mu_semaphore_sem_fork_child (void) {
 	}
 }
 
-static void nsync_mu_semaphore_sem_init (void) {
-	pthread_atfork (0, 0, nsync_mu_semaphore_sem_fork_child);
-}
-
 /* Initialize *s; the initial value is 0. */
 bool nsync_mu_semaphore_init_sem (nsync_semaphore *s) {
-	static atomic_uint once;
 	struct sem *f = (struct sem *) s;
 	if (!nsync_mu_semaphore_sem_create (f))
 		return false;
-	cosmo_once (&once, nsync_mu_semaphore_sem_init);
 	sems_push(f);
 	return true;
 }

third_party/nsync/panic.c

@@ -28,5 +28,5 @@ void nsync_panic_ (const char *s) {
 		   "cosmoaddr2line ", program_invocation_name, " ",
 		   DescribeBacktrace (__builtin_frame_address (0)), "\n",
 		   NULL);
-	_Exit (44);
+	__builtin_trap ();
 }

third_party/tz/localtime.c

@@ -2,6 +2,10 @@
 │ vi: set noet ft=c ts=8 sw=8 fenc=utf-8                                   :vi │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #define LOCALTIME_IMPLEMENTATION
+#include "lock.h"
+#include "tzdir.h"
+#include "tzfile.h"
+#include "private.h"
 #include "libc/calls/blockcancel.internal.h"
 #include "libc/calls/calls.h"
 #include "libc/cxxabi.h"
@@ -10,20 +14,15 @@
 #include "libc/serialize.h"
 #include "libc/str/str.h"
 #include "libc/sysv/consts/o.h"
-#include "libc/thread/thread.h"
-#include "libc/thread/tls.h"
 #include "libc/time.h"
 #include "libc/inttypes.h"
 #include "libc/sysv/consts/ok.h"
 #include "libc/runtime/runtime.h"
 #include "libc/stdckdint.h"
 #include "libc/time.h"
-#include "tzdir.h"
-#include "tzfile.h"
 #include "libc/nt/struct/timezoneinformation.h"
 #include "libc/nt/time.h"
 #include "libc/dce.h"
-#include "private.h"
 
 /* Convert timestamp from time_t to struct tm.  */
 
@@ -624,34 +623,10 @@ localtime_windows_init(void)
 	setenv("TZ", buf, true);
 }
 
-static pthread_mutex_t locallock = PTHREAD_MUTEX_INITIALIZER;
-
-static dontinline void
-localtime_wipe(void)
-{
-	pthread_mutex_init(&locallock, 0);
-}
-
-static dontinline void
-localtime_lock(void)
-{
-	pthread_mutex_lock(&locallock);
-}
-
-static dontinline void
-localtime_unlock(void)
-{
-	pthread_mutex_unlock(&locallock);
-}
-
 __attribute__((__constructor__(80)))
 textstartup static void
 localtime_init(void)
 {
-	localtime_wipe();
-	pthread_atfork(localtime_lock,
-		       localtime_unlock,
-		       localtime_wipe);
 	if (IsWindows())
 		localtime_windows_init();
 }
@@ -2052,9 +2027,9 @@ localtime_tzset_unlocked(void)
 void
 tzset(void)
 {
-	localtime_lock();
+	__localtime_lock();
 	localtime_tzset_unlocked();
-	localtime_unlock();
+	__localtime_unlock();
 }
 
 static void
@@ -2067,7 +2042,7 @@ static void
 localtime_gmtcheck(void)
 {
 	static bool gmt_is_set;
-	localtime_lock();
+	__localtime_lock();
 	if (! gmt_is_set) {
 #ifdef ALL_STATE
 		gmtptr = malloc(sizeof *gmtptr);
@@ -2077,7 +2052,7 @@ localtime_gmtcheck(void)
 			localtime_gmtload(gmtptr);
 		gmt_is_set = true;
 	}
-	localtime_unlock();
+	__localtime_unlock();
 }
 
 /*
@@ -2193,11 +2168,11 @@ localsub(struct state const *sp, time_t const *timep, int_fast32_t setname,
 static struct tm *
 localtime_tzset(time_t const *timep, struct tm *tmp, bool setname)
 {
-	localtime_lock();
+	__localtime_lock();
 	if (setname || !lcl_is_set)
 		localtime_tzset_unlocked();
 	tmp = localsub(lclptr, timep, setname, tmp);
-	localtime_unlock();
+	__localtime_unlock();
 	return tmp;
 }
 
@@ -2834,10 +2809,10 @@ time_t
 mktime(struct tm *tmp)
 {
 	time_t t;
-	localtime_lock();
+	__localtime_lock();
 	localtime_tzset_unlocked();
 	t = mktime_tzname(lclptr, tmp, true);
-	localtime_unlock();
+	__localtime_unlock();
 	return t;
 }
 

third_party/tz/lock.h

@@ -0,0 +1,12 @@
+#ifndef COSMOPOLITAN_THIRD_PARTY_TZ_LOCK_H_
+#define COSMOPOLITAN_THIRD_PARTY_TZ_LOCK_H_
+#include "libc/thread/thread.h"
+COSMOPOLITAN_C_START_
+
+extern pthread_mutex_t __localtime_lock_obj;
+
+void __localtime_lock(void);
+void __localtime_unlock(void);
+
+COSMOPOLITAN_C_END_
+#endif /* COSMOPOLITAN_THIRD_PARTY_TZ_LOCK_H_ */