Add interrupter library to simulate EINTR

To check for robustness against EINTR from syscalls, add an
interrupter library that can be preloaded with LD_PRELOAD.

Change-Id: I0a6cd8702ec5bc6b2927a5e223ee3cdc033860a2
diff --git a/cmds/interrupter/interrupter.c b/cmds/interrupter/interrupter.c
new file mode 100644
index 0000000..ae55515
--- /dev/null
+++ b/cmds/interrupter/interrupter.c
@@ -0,0 +1,53 @@
+/*
+ * Copyright 2012, 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.
+ */
+
+
+/**
+ * The probability of a syscall failing from 0.0 to 1.0
+ */
+#define PROBABILITY 0.9
+
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+
+/* for various intercepted calls */
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+/* For builds on glibc */
+#define __USE_GNU
+#include <dlfcn.h>
+
+#include "interrupter.h"
+
+static int probability = PROBABILITY * RAND_MAX;
+
+static int maybe_interrupt() {
+    if (rand() < probability) {
+        return 1;
+    }
+    return 0;
+}
+
+DEFINE_INTERCEPT(read, ssize_t, int, void*, size_t);
+DEFINE_INTERCEPT(write, ssize_t, int, const void*, size_t);
+DEFINE_INTERCEPT(accept, int, int, struct sockaddr*, socklen_t*);
+DEFINE_INTERCEPT(creat, int, const char*, mode_t);