Make locks more reliable

This change switches most of the core locks to be re-entrant, in order
to reduce the chance of deadlocking code that does, clever things with
asynchronous signal handlers. This change implements it it in pthreads
so we're one step closer to having a standardized threading primitives

libc/stdio/fflush.internal.h

@@ -1,5 +1,6 @@
 #ifndef COSMOPOLITAN_LIBC_STDIO_FFLUSH_H_
 #define COSMOPOLITAN_LIBC_STDIO_FFLUSH_H_
+#include "libc/intrin/pthread.h"
 #include "libc/stdio/stdio.h"
 #if !(__ASSEMBLER__ + __LINKER__ + 0)
 COSMOPOLITAN_C_START_
@@ -10,7 +11,7 @@ struct StdioFlushHandles {
 };
 
 struct StdioFlush {
-  int lock;
+  pthread_mutex_t lock;
   struct StdioFlushHandles handles;
   FILE *handles_initmem[8];
 };

libc/stdio/fflush_unlocked.c

@@ -21,6 +21,7 @@
 #include "libc/bits/pushpop.h"
 #include "libc/calls/calls.h"
 #include "libc/errno.h"
+#include "libc/intrin/pthread.h"
 #include "libc/intrin/spinlock.h"
 #include "libc/macros.internal.h"
 #include "libc/mem/mem.h"
@@ -40,7 +41,7 @@ int fflush_unlocked(FILE *f) {
   int rc = 0;
   size_t i;
   if (!f) {
-    _spinlock(&__fflush.lock);
+    pthread_mutex_lock(&__fflush.lock);
     for (i = __fflush.handles.i; i; --i) {
       if ((f = __fflush.handles.p[i - 1])) {
         if (fflush(f) == -1) {
@@ -48,7 +49,7 @@ int fflush_unlocked(FILE *f) {
         }
       }
     }
-    _spunlock(&__fflush.lock);
+    pthread_mutex_unlock(&__fflush.lock);
   } else if (f->fd != -1) {
     if (__fflush_impl(f) == -1) {
       rc = -1;
@@ -63,7 +64,7 @@ textstartup int __fflush_register(FILE *f) {
   int rc;
   size_t i;
   struct StdioFlush *sf;
-  _spinlock(&__fflush.lock);
+  pthread_mutex_lock(&__fflush.lock);
   sf = &__fflush;
   if (!sf->handles.p) {
     sf->handles.p = sf->handles_initmem;
@@ -73,19 +74,19 @@ textstartup int __fflush_register(FILE *f) {
   for (i = sf->handles.i; i; --i) {
     if (!sf->handles.p[i - 1]) {
       sf->handles.p[i - 1] = f;
-      _spunlock(&__fflush.lock);
+      pthread_mutex_unlock(&__fflush.lock);
       return 0;
     }
   }
   rc = append(&sf->handles, &f);
-  _spunlock(&__fflush.lock);
+  pthread_mutex_unlock(&__fflush.lock);
   return rc;
 }
 
 void __fflush_unregister(FILE *f) {
   size_t i;
   struct StdioFlush *sf;
-  _spinlock(&__fflush.lock);
+  pthread_mutex_lock(&__fflush.lock);
   sf = &__fflush;
   sf = pushpop(sf);
   for (i = sf->handles.i; i; --i) {
@@ -94,5 +95,5 @@ void __fflush_unregister(FILE *f) {
       break;
     }
   }
-  _spunlock(&__fflush.lock);
+  pthread_mutex_unlock(&__fflush.lock);
 }

libc/stdio/flockfile.c

@@ -16,30 +16,11 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
-#include "libc/calls/calls.h"
-#include "libc/intrin/cmpxchg.h"
-#include "libc/intrin/lockcmpxchgp.h"
-#include "libc/nexgen32e/threaded.h"
 #include "libc/stdio/stdio.h"
 
 /**
  * Acquires reentrant lock on stdio object, blocking if needed.
  */
 void flockfile(FILE *f) {
-  int me, owner;
-  unsigned tries;
-  if (__threaded) {
-    for (tries = 0, me = gettid();;) {
-      owner = 0;
-      if (_lockcmpxchgp(&f->lock, &owner, me) || owner == me) {
-        break;
-      }
-      if (++tries & 7) {
-        __builtin_ia32_pause();
-      } else {
-        sched_yield();
-      }
-    }
-  }
-  ++f->reent;
+  pthread_mutex_lock(&f->lock);
 }

libc/stdio/flushlbf.c

@@ -17,6 +17,7 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/calls.h"
+#include "libc/intrin/pthread.h"
 #include "libc/intrin/spinlock.h"
 #include "libc/stdio/fflush.internal.h"
 #include "libc/stdio/stdio.h"
@@ -28,7 +29,7 @@
 void _flushlbf(void) {
   int i;
   FILE *f;
-  _spinlock(&__fflush.lock);
+  pthread_mutex_lock(&__fflush.lock);
   for (i = 0; i < __fflush.handles.i; ++i) {
     if ((f = __fflush.handles.p[i])) {
       flockfile(f);
@@ -38,5 +39,5 @@ void _flushlbf(void) {
       funlockfile(f);
     }
   }
-  _spunlock(&__fflush.lock);
+  pthread_mutex_unlock(&__fflush.lock);
 }

libc/stdio/ftrylockfile.c

@@ -16,9 +16,6 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
-#include "libc/calls/calls.h"
-#include "libc/intrin/lockcmpxchgp.h"
-#include "libc/nexgen32e/threaded.h"
 #include "libc/stdio/stdio.h"
 
 /**
@@ -27,15 +24,5 @@
  * @return 0 on success, or non-zero if another thread owns the lock
  */
 int ftrylockfile(FILE *f) {
-  int me, owner = 0;
-  if (__threaded) {
-    me = gettid();
-    if (!_lockcmpxchgp(&f->lock, &owner, me) && owner == me) {
-      owner = 0;
-    }
-  }
-  if (!owner) {
-    ++f->reent;
-  }
-  return owner;
+  return pthread_mutex_trylock(&f->lock);
 }

libc/stdio/funlockfile.c

@@ -16,24 +16,11 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
-#include "libc/assert.h"
-#include "libc/calls/calls.h"
-#include "libc/nexgen32e/threaded.h"
 #include "libc/stdio/stdio.h"
 
 /**
  * Releases lock on stdio object.
  */
 void funlockfile(FILE *f) {
-  int owner;
-  bool shouldunlock;
-  assert(f->reent > 0);
-  shouldunlock = --f->reent <= 0;
-  if (__threaded) {
-    assert(f->lock == gettid());
-    if (shouldunlock) {
-      owner = 0;
-      __atomic_store(&f->lock, &owner, __ATOMIC_RELAXED);
-    }
-  }
+  pthread_mutex_unlock(&f->lock);
 }

libc/stdio/stdio.h

@@ -1,6 +1,7 @@
 #ifndef COSMOPOLITAN_LIBC_STDIO_STDIO_H_
 #define COSMOPOLITAN_LIBC_STDIO_STDIO_H_
 #include "libc/fmt/pflink.h"
+#include "libc/intrin/pthread.h"
 #include "libc/runtime/symbolic.h"
 
 #define FILENAME_MAX PATH_MAX
@@ -24,9 +25,8 @@ typedef struct FILE {
   uint32_t size;   /* 0x20 */
   uint32_t nofree; /* 0x24 */
   int pid;         /* 0x28 */
-  int lock;        /* 0x2c */
-  int reent;       /* 0x30 */
-  char *getln;     /* 0x38 */
+  char *getln;
+  pthread_mutex_t lock;
 } FILE;
 
 extern FILE *stdin;