Courgette: Add static method QuickDetect() to optimize program detection.

courgette/disassembler_elf_32_x86.h

 // Copyright (c) 2011 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 COURGETTE_DISASSEMBLER_ELF_32_X86_H_
 #define COURGETTE_DISASSEMBLER_ELF_32_X86_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <map>
 
 #include "base/macros.h"
 #include "courgette/disassembler_elf_32.h"
 #include "courgette/types_elf.h"
 
 namespace courgette {
 
 class AssemblyProgram;
 
 class DisassemblerElf32X86 : public DisassemblerElf32 {
  public:
+  // Returns 'true' if an valid executable is detected using only quick checks.

[huangs, 2016/06/17 15:21:57]

NIT: true does not need ''
NIT: *a* valid executable.

+  static bool QuickDetect(const uint8_t* start, size_t length) {
+    return DisassemblerElf32::QuickDetect(start, length, EM_386);
+  }
+
   class TypedRVAX86 : public TypedRVA {
    public:
     explicit TypedRVAX86(RVA rva) : TypedRVA(rva) { }
     ~TypedRVAX86() override { }
 
     // TypedRVA interfaces.
     CheckBool ComputeRelativeTarget(const uint8_t* op_pointer) override;
     CheckBool EmitInstruction(AssemblyProgram* program,
                               Label* label) override;
     uint16_t op_size() const override;
   };
 
-  DisassemblerElf32X86(const void* start, size_t length);
+  DisassemblerElf32X86(const uint8_t* start, size_t length);
 
   ~DisassemblerElf32X86() override { }
 
   // DisassemblerElf32 interfaces.
   ExecutableType kind() const override { return EXE_ELF_32_X86; }
   e_machine_values ElfEM() const override { return EM_386; }
 
  protected:
   // DisassemblerElf32 interfaces.
   CheckBool RelToRVA(Elf32_Rel rel,
                      RVA* result) const override WARN_UNUSED_RESULT;
   CheckBool ParseRelocationSection(const Elf32_Shdr* section_header,
                                    AssemblyProgram* program)
       override WARN_UNUSED_RESULT;
   CheckBool ParseRel32RelocsFromSection(const Elf32_Shdr* section)
       override WARN_UNUSED_RESULT;
 
 #if COURGETTE_HISTOGRAM_TARGETS
   std::map<RVA, int> rel32_target_rvas_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(DisassemblerElf32X86);
 };
 
 }  // namespace courgette
 
 #endif  // COURGETTE_DISASSEMBLER_ELF_32_X86_H_