Add American Fuzzy Lop (afl) to third_party/afl/

third_party/afl/src/experimental/persistent_demo/persistent_demo.c

+/*
+   american fuzzy lop - persistent mode example
+   --------------------------------------------
+
+   Written and maintained by Michal Zalewski <lcamtuf@google.com>
+
+   Copyright 2015 Google Inc. All rights reserved.
+
+   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
+
+   This file demonstrates the high-performance "persistent mode" that may be
+   suitable for fuzzing certain fast and well-behaved libraries, provided that
+   they are stateless or that their internal state can be easily reset
+   across runs.
+
+   To make this work, the library and this shim need to be compiled in LLVM
+   mode using afl-clang-fast (other compiler wrappers will *not* work).
+
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <signal.h>
+#include <string.h>
+
+
+/* Main entry point. */
+
+int main(int argc, char** argv) {
+
+  char buf[100]; /* Example-only buffer, you'd replace it with other global or
+                    local variables appropriate for your use case. */
+
+  /* The number passed to __AFL_LOOP() controls the maximum number of
+     iterations before the loop exits and the program is allowed to
+     terminate normally. This limits the impact of accidental memory leaks
+     and similar hiccups. */
+
+  while (__AFL_LOOP(1000)) {
+
+    /*** PLACEHOLDER CODE ***/
+
+    /* STEP 1: Fully re-initialize all critical variables. In our example, this
+               involves zeroing buf[], our input buffer. */
+
+    memset(buf, 0, 100);
+
+    /* STEP 2: Read input data. When reading from stdin, no special preparation
+               is required. When reading from a named file, you need to close
+               the old descriptor and reopen the file first!
+
+               Beware of reading from buffered FILE* objects such as stdin. Use
+               raw file descriptors or call fopen() / fdopen() in every pass. */
+
+    read(0, buf, 100);
+
+    /* STEP 3: This is where we'd call the tested library on the read data.
+               We just have some trivial inline code that faults on 'foo!'. */
+
+    if (buf[0] == 'f') {
+      printf("one\n");
+      if (buf[1] == 'o') {
+        printf("two\n");
+        if (buf[2] == 'o') {
+          printf("three\n");
+          if (buf[3] == '!') {
+            printf("four\n");
+            abort();
+          }
+        }
+      }
+    }
+
+    /*** END PLACEHOLDER CODE ***/
+
+  }
+
+  /* Once the loop is exited, terminate normally - AFL will restart the process
+     when this happens, with a clean slate when it comes to allocated memory,
+     leftover file descriptors, etc. */
+
+  return 0;
+
+}