Add missing include and function prototype for sched_getaffinity.

Change-Id: I649633c8d074def5d05bd0c8b92fb680d9d11d51
diff --git a/libc/bionic/sched_getaffinity.cpp b/libc/bionic/sched_getaffinity.cpp
new file mode 100644
index 0000000..26f22b1
--- /dev/null
+++ b/libc/bionic/sched_getaffinity.cpp
@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#define _GNU_SOURCE 1
+#include <sched.h>
+#include <string.h>
+
+extern "C" int __sched_getaffinity(pid_t, size_t, cpu_set_t*);
+
+int sched_getaffinity(pid_t pid, size_t set_size, cpu_set_t* set) {
+  int rc = __sched_getaffinity(pid, set_size, set);
+  if (rc == -1) {
+      return -1;
+  }
+
+  // Clear any bytes the kernel didn't touch.
+  // (The kernel returns the number of bytes written on success.)
+  memset(reinterpret_cast<char*>(set) + rc, 0, set_size - rc);
+  return 0;
+}