Fix pthreads functions that should return ESRCH.

imgtec pointed out that pthread_kill(3) was broken, but most of the
other functions that ought to return ESRCH for invalid/exited threads
were equally broken.

Change-Id: I96347f6195549aee0c72dc39063e6c5d06d2e01f

libc/bionic/pthread_accessor.h

@@ -0,0 +1,65 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef PTHREAD_ACCESSOR_H
+#define PTHREAD_ACCESSOR_H
+
+#include <pthread.h>
+
+#include "pthread_internal.h"
+
+class pthread_accessor {
+ public:
+  explicit pthread_accessor(pthread_t desired_thread) {
+    Lock();
+    for (thread_ = gThreadList; thread_ != NULL; thread_ = thread_->next) {
+      if (thread_ == reinterpret_cast<pthread_internal_t*>(desired_thread)) {
+        break;
+      }
+    }
+  }
+
+  ~pthread_accessor() {
+    Unlock();
+  }
+
+  pthread_internal_t& operator*() const { return *thread_; }
+  pthread_internal_t* operator->() const { return thread_; }
+  pthread_internal_t* get() const { return thread_; }
+
+ private:
+  pthread_internal_t* thread_;
+  bool is_locked_;
+
+  void Lock() {
+    pthread_mutex_lock(&gThreadListLock);
+    is_locked_ = true;
+  }
+
+  void Unlock() {
+    if (is_locked_) {
+      is_locked_ = false;
+      thread_ = NULL;
+      pthread_mutex_unlock(&gThreadListLock);
+    }
+  }
+
+  // Disallow copy and assignment.
+  pthread_accessor(const pthread_accessor&);
+  void operator=(const pthread_accessor&);
+};
+
+#endif // PTHREAD_ACCESSOR_H