[scudo][standalone] Introduce the C & C++ wrappers [fixed]

Summary:
This is a redo of D63612.

Two problems came up on some bots:
- `__builtin_umull_overflow` was not declared. This is likely due to an
  older clang or gcc, so add a guard with `__has_builtin` and fallback
  to a division in the event the builtin doesn't exist;
- contradicting definition for `malloc`, etc. This is AFAIU due to the
  fact that we ended up transitively including `stdlib.h` in the `.inc`
  due to it being the flags parser header: so move the include to the
  cc instead.

This should fix the issues, but since those didn't come up in my local
tests it's mostly guesswork.

Rest is the same!

Reviewers: morehouse, hctim, eugenis, vitalybuka, dyung, hans

Reviewed By: morehouse, dyung, hans

Subscribers: srhines, mgorny, delcypher, jfb, #sanitizers, llvm-commits

Tags: #llvm, #sanitizers

Differential Revision: https://reviews.llvm.org/D63831

llvm-svn: 364547

1 files changed, 39 insertions, 0 deletions

diff --git a/compiler-rt/lib/scudo/standalone/wrappers_c.cc b/compiler-rt/lib/scudo/standalone/wrappers_c.cc
new file mode 100644
index 00000000000..5908c600be3
--- /dev/null
+++ b/compiler-rt/lib/scudo/standalone/wrappers_c.cc
@@ -0,0 +1,39 @@
+//===-- wrappers_c.cc -------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "platform.h"
+
+// Skip this compilation unit if compiled as part of Bionic.
+#if !SCUDO_ANDROID || !_BIONIC
+
+#include "allocator_config.h"
+#include "wrappers_c.h"
+#include "wrappers_c_checks.h"
+
+#include <stdint.h>
+#include <stdio.h>
+
+static scudo::Allocator<scudo::Config> Allocator;
+// Pointer to the static allocator so that the C++ wrappers can access it.
+// Technically we could have a completely separated heap for C & C++ but in
+// reality the amount of cross pollination between the two is staggering.
+scudo::Allocator<scudo::Config> *AllocatorPtr = &Allocator;
+
+extern "C" {
+
+#define SCUDO_PREFIX(name) name
+#define SCUDO_ALLOCATOR Allocator
+#include "wrappers_c.inc"
+#undef SCUDO_ALLOCATOR
+#undef SCUDO_PREFIX
+
+INTERFACE void __scudo_print_stats(void) { Allocator.printStats(); }
+
+} // extern "C"
+
+#endif // !SCUDO_ANDROID || !_BIONIC