1 files changed, 102 insertions, 0 deletions
diff --git a/memory/replace/phc/PHC.h b/memory/replace/phc/PHC.h
new file mode 100644
index 0000000000..139a0e81c9
--- /dev/null
+++ b/memory/replace/phc/PHC.h
@@ -0,0 +1,102 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef PHC_h
+#define PHC_h
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Maybe.h"
+#include <stdint.h>
+#include <stdlib.h>
+
+namespace mozilla {
+namespace phc {
+
+// Note: a stack trace may have no frames due to a collection problem.
+//
+// Also note: a more compact stack trace representation could be achieved with
+// some effort.
+struct StackTrace {
+ public:
+  static const size_t kMaxFrames = 16;
+
+  // The number of PCs in the stack trace.
+  size_t mLength;
+
+  // The PCs in the stack trace. Only the first mLength are initialized.
+  const void* mPcs[kMaxFrames];
+
+ public:
+  StackTrace() : mLength(0) {}
+};
+
+// Info from PHC about an address in memory.
+class AddrInfo {
+ public:
+  enum class Kind {
+    // The address is not in PHC-managed memory.
+    Unknown = 0,
+
+    // The address is within a PHC page that has never been allocated. A crash
+    // involving such an address is unlikely in practice, because it would
+    // require the crash to happen quite early.
+    NeverAllocatedPage = 1,
+
+    // The address is within a PHC page that is in use.
+    InUsePage = 2,
+
+    // The address is within a PHC page that has been allocated and then freed.
+    // A crash involving such an address most likely indicates a
+    // use-after-free. (A sufficiently wild write -- e.g. a large buffer
+    // overflow -- could also trigger it, but this is less likely.)
+    FreedPage = 3,
+
+    // The address is within a PHC guard page. A crash involving such an
+    // address most likely indicates a buffer overflow. (Again, a sufficiently
+    // wild write could unluckily trigger it, but this is less likely.)
+    GuardPage = 4,
+  };
+
+  // The page kind.
+  Kind mKind;
+
+  // The starting address of the allocation.
+  // - Unknown | NeverAllocatedPage: nullptr.
+  // - InUsePage | FreedPage: the address of the allocation within the page.
+  // - GuardPage: the mBaseAddr value from the preceding allocation page.
+  const void* mBaseAddr;
+
+  // The usable size, which could be bigger than the requested size.
+  // - Unknown | NeverAllocatePage: 0.
+  // - InUsePage | FreedPage: the usable size of the allocation within the page.
+  // - GuardPage: the mUsableSize value from the preceding allocation page.
+  size_t mUsableSize;
+
+  // The allocation stack.
+  // - Unknown | NeverAllocatedPage: Nothing.
+  // - InUsePage | FreedPage: Some.
+  // - GuardPage: the mAllocStack value from the preceding allocation page.
+  mozilla::Maybe<StackTrace> mAllocStack;
+
+  // The free stack.
+  // - Unknown | NeverAllocatedPage | InUsePage: Nothing.
+  // - FreedPage: Some.
+  // - GuardPage: the mFreeStack value from the preceding allocation page.
+  mozilla::Maybe<StackTrace> mFreeStack;
+
+  // Default to no PHC info.
+  AddrInfo()
+      : mKind(Kind::Unknown),
+        mBaseAddr(nullptr),
+        mUsableSize(0),
+        mAllocStack(),
+        mFreeStack() {}
+};
+
+}  // namespace phc
+}  // namespace mozilla
+
+#endif /* PHC_h */