Add implementation of pthread_rwlock based on NaCl futexs

src/untrusted/pthread/pthread.h

Index: src/untrusted/pthread/pthread.h
diff --git a/src/untrusted/pthread/pthread.h b/src/untrusted/pthread/pthread.h
index eb495280aba765a6f5329e9cd36f57b433fd0b8d..18afd25699354c35f0cbb7468d44bc10743027bc 100644
--- a/src/untrusted/pthread/pthread.h
+++ b/src/untrusted/pthread/pthread.h
@@ -129,6 +129,24 @@ typedef struct {
   int dummy; /**< Reserved; condition variables don't have attributes */
 } pthread_condattr_t;
 
+/**
+ * A structure representing rwlock attributes. It should be considered an
+ * opaque record.
+ */
+typedef int32_t pthread_rwlockattr_t;
+
+/**
+ * A structure representing a rwlock. It should be considered an
+ * opaque record; the names of the fields can change anytime.
+ */
+typedef struct {
+  volatile int32_t state;  /* 0=unlock, -1=writer lock, +n=reader lock */
+  struct __nc_basic_thread_data *volatile writer_thread_id;
+  volatile int32_t pending_readers;
+  volatile int32_t pending_writers;
+  pthread_rwlockattr_t attr;
+} pthread_rwlock_t;
+
 /** A value that represents an uninitialized handle. */
 #define NC_INVALID_HANDLE -1
 
@@ -153,7 +171,8 @@ typedef struct {
 /** Statically initializes a condition variable (pthread_cond_t). */
 #define PTHREAD_COND_INITIALIZER {0, NC_INVALID_HANDLE}
 
-
+#define PTHREAD_PROCESS_PRIVATE  0
+#define PTHREAD_PROCESS_SHARED   1
 
 /* Functions for mutex handling.  */
 
@@ -376,6 +395,30 @@ int pthread_cond_timedwait_rel(pthread_cond_t *cond,
  */
 #define pthread_cond_timedwait pthread_cond_timedwait_abs
 
+/* Functions for rwlock handling.  */
+
+int pthread_rwlockattr_init(pthread_rwlockattr_t *attr);
+int pthread_rwlockattr_getpshared(const pthread_rwlockattr_t *attr,
+                                  int *pshared);
+int pthread_rwlockattr_setpshared(pthread_rwlockattr_t *attr, int pshared);
+int pthread_rwlockattr_destroy(pthread_rwlockattr_t *attr);
+
+int pthread_rwlock_init(pthread_rwlock_t *rwlock,
+                        const pthread_rwlockattr_t *attr);
+
+int pthread_rwlock_rdlock(pthread_rwlock_t *rwlock);
+int pthread_rwlock_tryrdlock(pthread_rwlock_t *rwlock);
+int pthread_rwlock_timedrdlock(pthread_rwlock_t *rwlock,
+                               const struct timespec *abstime);
+
+
+int pthread_rwlock_wrlock(pthread_rwlock_t *rwlock);
+int pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock);
+int pthread_rwlock_timedwrlock(pthread_rwlock_t *rwlock,
+                               const struct timespec *abstime);
+
+int pthread_rwlock_unlock(pthread_rwlock_t *rwlock);
+int pthread_rwlock_destroy(pthread_rwlock_t *rwlock);
 
 /* Threads */
 /** Thread entry function type. */