Support: Add CrashRecoveryContext helper object.

 - Designed as a simple wrapper to allow clients to attempt to catch crashes
   (memory errors, assertion violations, etc.) and do some kind of recovery.

 - Currently doesn't actually attempt to catch crashes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109586 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 82 insertions, 0 deletions

diff --git a/include/llvm/Support/CrashRecoveryContext.h b/include/llvm/Support/CrashRecoveryContext.h
new file mode 100644
index 0000000..d44d24a
--- /dev/null
+++ b/include/llvm/Support/CrashRecoveryContext.h
@@ -0,0 +1,82 @@
+//===--- CrashRecoveryContext.h - Crash Recovery ----------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_CRASHRECOVERYCONTEXT_H
+#define LLVM_SUPPORT_CRASHRECOVERYCONTEXT_H
+
+#include <string>
+
+namespace llvm {
+class StringRef;
+
+/// \brief Crash recovery helper object.
+///
+/// This class implements support for running operations in a safe context so
+/// that crashes (memory errors, stack overflow, assertion violations) can be
+/// detected and control restored to the crashing thread. Crash detection is
+/// purely "best effort", the exact set of failures which can be recovered from
+/// is platform dependent.
+///
+/// Clients make use of this code by first calling
+/// CrashRecoveryContext::Enable(), and then executing unsafe operations via a
+/// CrashRecoveryContext object. For example:
+///
+///    void actual_work(void *);
+///
+///    void foo() {
+///      CrashRecoveryContext CRC;
+///
+///      if (!CRC.RunSafely(actual_work, 0)) {
+///         ... a crash was detected, report error to user ...
+///      }
+///
+///      ... no crash was detected ...
+///    }
+///
+/// Crash recovery contexts may not be nested.
+class CrashRecoveryContext {
+  void *Impl;
+
+public:
+  CrashRecoveryContext() : Impl(0) {}
+  ~CrashRecoveryContext();
+
+  /// \brief Enable crash recovery. This function is not thread safe, clients
+  /// should call it during startup or with a lock held.
+  static void Enable();
+
+  /// \brief Disable crash recovery. This function is not thread safe, clients
+  /// should call it during startup or with a lock held.
+  static void Disable();
+
+  /// \brief Execute the provide callback function (with the given arguments) in
+  /// a protected context.
+  ///
+  /// \return True if the function completed successfully, and false if the
+  /// function crashed (or HandleCrash was called explicitly). Clients should
+  /// make as little assumptions as possible about the program state when
+  /// RunSafely has returned false. Clients can use getBacktrace() to retrieve
+  /// the backtrace of the crash on failures.
+  bool RunSafely(void (*Fn)(void*), void *UserData);
+
+  /// \brief Explicitly trigger a crash recovery in the current process, and
+  /// return failure from RunSafely(). This function does not return.
+  void HandleCrash();
+
+  /// \brief Return a string containing the backtrace where the crash was
+  /// detected; or empty if the backtrace wasn't recovered.
+  ///
+  /// This function is only valid when a crash has been detected (i.e.,
+  /// RunSafely() has returned false.
+  const std::string &getBacktrace() const;
+};
+
+}
+
+#endif