sandbox/linux/seccomp-bpf/basicblock.h

   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_BASICBLOCK_H__
   6 #define SANDBOX_LINUX_SECCOMP_BPF_BASICBLOCK_H__
   7
   8 #include <vector>
   9
  10 #include "sandbox/linux/seccomp-bpf/instruction.h"
  11
  12 namespace sandbox {
  13
  14 struct BasicBlock {
  15   BasicBlock();
  16   ~BasicBlock();
  17
  18   // Our implementation of the code generator uses a "Less" operator to
  19   // identify common sequences of basic blocks. This would normally be
  20   // really easy to do, but STL requires us to wrap the comparator into
  21   // a class. We begrudgingly add some code here that provides this wrapping.
  22   template <class T>
  23   class Less {
  24    public:
  25     Less(const T& data,
  26          int (*cmp)(const BasicBlock*, const BasicBlock*, const T& data))
  27         : data_(data), cmp_(cmp) {}
  28
  29     bool operator()(const BasicBlock* a, const BasicBlock* b) const {
  30       return cmp_(a, b, data_) < 0;
  31     }
  32
  33    private:
  34     const T& data_;
  35     int (*cmp_)(const BasicBlock*, const BasicBlock*, const T&);
  36   };
  37
  38   // Basic blocks are essentially nothing more than a set of instructions.
  39   std::vector<Instruction*> instructions;
  40
  41   // In order to compute relative branch offsets we need to keep track of
  42   // how far our block is away from the very last basic block. The "offset_"
  43   // is measured in number of BPF instructions.
  44   int offset;
  45 };
  46
  47 }  // namespace sandbox
  48
  49 #endif  // SANDBOX_LINUX_SECCOMP_BPF_BASICBLOCK_H__