1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef SANDBOX_LINUX_SECCOMP_BPF_SYSCALL_ITERATOR_H__
6#define SANDBOX_LINUX_SECCOMP_BPF_SYSCALL_ITERATOR_H__
7
8#include <stdint.h>
9
10namespace playground2 {
11
12// Iterates over the entire system call range from 0..0xFFFFFFFFu. This
13// iterator is aware of how system calls look like and will skip quickly
14// over ranges that can't contain system calls. It iterates more slowly
15// whenever it reaches a range that is potentially problematic, returning
16// the last invalid value before a valid range of system calls, and the
17// first invalid value after a valid range of syscalls. It iterates over
18// individual values whenever it is in the normal range for system calls
19// (typically MIN_SYSCALL..MAX_SYSCALL).
20// If |invalid_only| is true, this iterator will only return invalid
21// syscall numbers, but will still skip quickly over invalid ranges,
22// returning the first invalid value in the range and then skipping
23// to the last invalid value in the range.
24//
25// Example usage:
26//   for (SyscallIterator iter(false); !iter.Done(); ) {
27//     uint32_t sysnum = iter.Next();
28//     // Do something with sysnum.
29//   }
30//
31// TODO(markus): Make this a classic C++ iterator.
32class SyscallIterator {
33 public:
34  explicit SyscallIterator(bool invalid_only)
35      : invalid_only_(invalid_only),
36        done_(false),
37        num_(0) {}
38
39  bool Done() const { return done_; }
40  uint32_t Next();
41  static bool IsValid(uint32_t num);
42
43 private:
44  static bool IsArmPrivate(uint32_t num);
45
46  bool     invalid_only_;
47  bool     done_;
48  uint32_t num_;
49
50  DISALLOW_IMPLICIT_CONSTRUCTORS(SyscallIterator);
51};
52
53}  // namespace playground2
54
55#endif  // SANDBOX_LINUX_SECCOMP_BPF_SYSCALL_ITERATOR_H__
56
57