Update from chromium 62675d9fb31fb8cedc40f68e78e8445a74f362e7

sandbox/linux/bpf_dsl/trap_registry.h

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SANDBOX_LINUX_BPF_DSL_TRAP_REGISTRY_H_
+#define SANDBOX_LINUX_BPF_DSL_TRAP_REGISTRY_H_
+
+#include <stdint.h>
+
+#include "base/macros.h"
+#include "sandbox/sandbox_export.h"
+
+namespace sandbox {
+
+// This must match the kernel's seccomp_data structure.
+struct arch_seccomp_data {
+  int nr;
+  uint32_t arch;
+  uint64_t instruction_pointer;
+  uint64_t args[6];
+};
+
+namespace bpf_dsl {
+
+// TrapRegistry provides an interface for registering "trap handlers"
+// by associating them with non-zero 16-bit trap IDs. Trap IDs should
+// remain valid for the lifetime of the trap registry.
+class SANDBOX_EXPORT TrapRegistry {
+ public:
+  // TrapFnc is a pointer to a function that fulfills the trap handler
+  // function signature.
+  //
+  // Trap handlers follow the calling convention of native system
+  // calls; e.g., to report an error, they return an exit code in the
+  // range -1..-4096 instead of directly modifying errno. However,
+  // modifying errno is harmless, as the original value will be
+  // restored afterwards.
+  //
+  // Trap handlers are executed from signal context and possibly an
+  // async-signal context, so they must be async-signal safe:
+  // http://pubs.opengroup.org/onlinepubs/009695399/functions/xsh_chap02_04.html
+  typedef intptr_t (*TrapFnc)(const struct arch_seccomp_data& args, void* aux);
+
+  // Add registers the specified trap handler tuple and returns a
+  // non-zero trap ID that uniquely identifies the tuple for the life
+  // time of the trap registry. If the same tuple is registered
+  // multiple times, the same value will be returned each time.
+  virtual uint16_t Add(TrapFnc fnc, const void* aux, bool safe) = 0;
+
+  // EnableUnsafeTraps tries to enable unsafe traps and returns
+  // whether it was successful. This is a one-way operation.
+  virtual bool EnableUnsafeTraps() = 0;
+
+ protected:
+  TrapRegistry() {}
+  ~TrapRegistry() {}
+
+  DISALLOW_COPY_AND_ASSIGN(TrapRegistry);
+};
+
+}  // namespace bpf_dsl
+}  // namespace sandbox
+
+#endif  // SANDBOX_LINUX_BPF_DSL_TRAP_REGISTRY_H_