[libFuzzer] introduce LLVMFuzzerInitialize

llvm-svn: 257980
diff --git a/llvm/lib/Fuzzer/test/CMakeLists.txt b/llvm/lib/Fuzzer/test/CMakeLists.txt
index 91a61f4..3533d3b 100644
--- a/llvm/lib/Fuzzer/test/CMakeLists.txt
+++ b/llvm/lib/Fuzzer/test/CMakeLists.txt
@@ -18,6 +18,7 @@
   CounterTest
   FourIndependentBranchesTest
   FullCoverageSetTest
+  InitializeTest
   MemcmpTest
   NullDerefTest
   RepeatedMemcmp
diff --git a/llvm/lib/Fuzzer/test/InitializeTest.cpp b/llvm/lib/Fuzzer/test/InitializeTest.cpp
new file mode 100644
index 0000000..1462747
--- /dev/null
+++ b/llvm/lib/Fuzzer/test/InitializeTest.cpp
@@ -0,0 +1,23 @@
+// Make sure LLVMFuzzerInitialize is called.
+#include <assert.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static char *argv0;
+
+extern "C" int LLVMFuzzerInitialize(int *argc, char ***argv) {
+  assert(argc > 0);
+  argv0 = **argv;
+  return 0;
+}
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
+  if (strncmp(reinterpret_cast<const char*>(Data), argv0, Size)) {
+    fprintf(stderr, "BINGO\n");
+    exit(1);
+  }
+  return 0;
+}
diff --git a/llvm/lib/Fuzzer/test/fuzzer.test b/llvm/lib/Fuzzer/test/fuzzer.test
index 5b98fde..c8a17f5 100644
--- a/llvm/lib/Fuzzer/test/fuzzer.test
+++ b/llvm/lib/Fuzzer/test/fuzzer.test
@@ -37,3 +37,5 @@
 RUN: not LLVMFuzzer-BufferOverflowOnInput 2>&1 | FileCheck %s --check-prefix=OOB
 OOB: AddressSanitizer: heap-buffer-overflow
 OOB: is located 0 bytes to the right of 3-byte region
+
+RUN: not LLVMFuzzer-InitializeTest 2>&1 | FileCheck %s