Make pthread_mutex static initialisation work on Windows.

This takes the dynamic initialisation code added to CRYPTO_lock() in e5081719
and applies it to the Window's pthread_mutex implementation. This allows for
PTHREAD_MUTEX_INITIALIZER to be used on Windows.

bcook has agreed to place this code in the public domain (as per the rest of
the code in pthread.h).

1 files changed, 23 insertions, 5 deletions

diff --git a/include/compat/pthread.h b/include/compat/pthread.h
index b2a42a6..1527d3c 100644..100755
--- a/include/compat/pthread.h
+++ b/include/compat/pthread.h
@@ -8,6 +8,8 @@
 
 #ifdef _WIN32
 
+#include <malloc.h>
+#include <stdlib.h>
 #include <windows.h>
 
 /*
@@ -18,7 +20,7 @@
 /*
  * Static mutex initialization values.
  */
-#define PTHREAD_MUTEX_INITIALIZER       { 0, 0, 0, 0, 0, 0 }
+#define PTHREAD_MUTEX_INITIALIZER       { .lock = NULL }
 
 /*
  * Once definitions.
@@ -60,27 +62,43 @@ pthread_equal(pthread_t t1, pthread_t t2)
         return t1 == t2;
 }
 
-typedef CRITICAL_SECTION pthread_mutex_t;
+struct pthread_mutex {
+        volatile LPCRITICAL_SECTION lock;
+};
+typedef struct pthread_mutex pthread_mutex_t;
 typedef void pthread_mutexattr_t;
 
 static inline int
 pthread_mutex_init(pthread_mutex_t *mutex, const pthread_mutexattr_t *attr)
 {
-        InitializeCriticalSection(mutex);
+        if ((mutex->lock = malloc(sizeof(CRITICAL_SECTION))) == NULL)
+                exit(ENOMEM);
+        InitializeCriticalSection(mutex->lock);
         return 0;
 }
 
 static inline int
 pthread_mutex_lock(pthread_mutex_t *mutex)
 {
-        EnterCriticalSection(mutex);
+        if (mutex->lock == NULL) {
+                LPCRITICAL_SECTION lcs;
+
+                if ((lcs = malloc(sizeof(CRITICAL_SECTION))) == NULL)
+                        exit(ENOMEM);
+                InitializeCriticalSection(lcs);
+                if (InterlockedCompareExchangePointer((PVOID*)&mutex->lock, (PVOID)lcs, NULL) != NULL) {
+                        DeleteCriticalSection(lcs);
+                        free(lcs);
+                }
+        }
+        EnterCriticalSection(mutex->lock);
         return 0;
 }
 
 static inline int
 pthread_mutex_unlock(pthread_mutex_t *mutex)
 {
-        LeaveCriticalSection(mutex);
+        LeaveCriticalSection(mutex->lock);
         return 0;
 }