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

courgette/disassembler_elf_32.cc

 // Copyright 2013 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.
 
 #include "courgette/disassembler_elf_32.h"
 
 #include <algorithm>
 #include <iterator>
 #include <utility>
 
@@ skipping 587 matching lines @@
     found_rel32 = true;
     if (!ParseRel32RelocsFromSection(section_header))
       return false;
   }
   if (!found_rel32)
     VLOG(1) << "Warning: Found no rel32 addresses. Missing .text section?";
 
   return true;
 }
 
+bool DisassemblerElf32::QuickDetects(const uint8_t* start,
+                                     size_t length,
+                                     e_machine_values elf_em) {
+  if (length < sizeof(Elf32_Ehdr))
+    return false;
+
+  const Elf32_Ehdr* header = reinterpret_cast<const Elf32_Ehdr*>(start);
+
+    // Have magic for ELF header?
+  if (header->e_ident[0] != 0x7f || header->e_ident[1] != 'E' ||
+      header->e_ident[2] != 'L' || header->e_ident[3] != 'F')
+    return false;
+
+  if (header->e_type != ET_EXEC && header->e_type != ET_DYN)
+    return false;
+  if (header->e_machine != elf_em)
+    return false;
+  if (header->e_version != 1)
+    return false;
+  if (header->e_shentsize != sizeof(Elf32_Shdr))
+    return false;
+
+  return true;
+}
+
 }  // namespace courgette