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

courgette/program_detector.cc

Index: courgette/program_detector.cc
diff --git a/courgette/program_detector.cc b/courgette/program_detector.cc
index 60b295fef7a82825c7e2f097c22c9fd55b87446c..71021cc3f7a397a78457609c223d7cd3e32cf88a 100644
--- a/courgette/program_detector.cc
+++ b/courgette/program_detector.cc
@@ -19,32 +19,36 @@ namespace {
 
 // Returns a new instance of Disassembler subclass if binary data given in
 // |buffer| and |length| matches a known binary format, otherwise null.
-std::unique_ptr<Disassembler> DetectDisassembler(const void* buffer,
+std::unique_ptr<Disassembler> DetectDisassembler(const uint8_t* buffer,
                                                  size_t length) {
   std::unique_ptr<Disassembler> disassembler;
 
-  disassembler.reset(new DisassemblerWin32X86(buffer, length));
-  if (disassembler->ParseHeader())
-    return disassembler;
-
-  disassembler.reset(new DisassemblerWin32X64(buffer, length));
-  if (disassembler->ParseHeader())
-    return disassembler;
-
-  disassembler.reset(new DisassemblerElf32X86(buffer, length));
-  if (disassembler->ParseHeader())
-    return disassembler;
-
-  disassembler.reset(new DisassemblerElf32ARM(buffer, length));
-  if (disassembler->ParseHeader())
-    return disassembler;
-
+  if (DisassemblerWin32X86::QuickDetect(buffer, length)) {
+    disassembler.reset(new DisassemblerWin32X86(buffer, length));
+    if (disassembler->ParseHeader())
+      return disassembler;
+  }
+  if (DisassemblerWin32X64::QuickDetect(buffer, length)) {
+    disassembler.reset(new DisassemblerWin32X64(buffer, length));
+    if (disassembler->ParseHeader())
+      return disassembler;
+  }
+  if (DisassemblerElf32X86::QuickDetect(buffer, length)) {
+    disassembler.reset(new DisassemblerElf32X86(buffer, length));
+    if (disassembler->ParseHeader())
+      return disassembler;
+  }
+  if (DisassemblerElf32ARM::QuickDetect(buffer, length)) {
+    disassembler.reset(new DisassemblerElf32ARM(buffer, length));
+    if (disassembler->ParseHeader())
+      return disassembler;
+  }
   return nullptr;
 }
 
 }  // namespace
 
-Status DetectExecutableType(const void* buffer,
+Status DetectExecutableType(const uint8_t* buffer,
                             size_t length,
                             ExecutableType* type,
                             size_t* detected_length) {
@@ -62,7 +66,7 @@ Status DetectExecutableType(const void* buffer,
   return C_OK;
 }
 
-Status ParseDetectedExecutable(const void* buffer,
+Status ParseDetectedExecutable(const uint8_t* buffer,
                                size_t length,
                                std::unique_ptr<AssemblyProgram>* output) {
   output->reset();