Use PEImage in ntdll_cache.cc

Use the exported functions iterator in PEImage instead of writing our
own.

BUG=

Review URL: https://codereview.chromium.org/192933003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256424 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 24 insertions, 36 deletions

diff --git a/chrome_elf/chrome_elf.gyp b/chrome_elf/chrome_elf.gyp
index 165507d..21ab568 100644
--- a/chrome_elf/chrome_elf.gyp
+++ b/chrome_elf/chrome_elf.gyp
@@ -124,6 +124,7 @@
       ],
       'dependencies': [
         'chrome_elf_common',
+        '../base/base.gyp:base_static',
       ],
     },
     {
diff --git a/chrome_elf/ntdll_cache.cc b/chrome_elf/ntdll_cache.cc
index e550442..2f4dbdf 100644
--- a/chrome_elf/ntdll_cache.cc
+++ b/chrome_elf/ntdll_cache.cc
@@ -5,47 +5,34 @@
 #include <stdint.h>
 #include <windows.h>
 
+#include "base/win/pe_image.h"
 #include "chrome_elf/ntdll_cache.h"
 
 FunctionLookupTable g_ntdll_lookup;
 
+namespace {
+
+bool EnumExportsCallback(const base::win::PEImage& image,
+                         DWORD ordinal,
+                         DWORD hint,
+                         LPCSTR name,
+                         PVOID function_addr,
+                         LPCSTR forward,
+                         PVOID cookie) {
+  // Our lookup only cares about named functions that are in ntdll, so skip
+  // unnamed or forwarded exports.
+  if (name && function_addr)
+    g_ntdll_lookup[std::string(name)] = function_addr;
+
+  return true;
+}
+
+}  // namespace
+
 void InitCache() {
   HMODULE ntdll_handle = ::GetModuleHandle(L"ntdll.dll");
 
-  // To find the Export Address Table address, we start from the DOS header.
-  // The module handle is actually the address of the header.
-  IMAGE_DOS_HEADER* dos_header =
-      reinterpret_cast<IMAGE_DOS_HEADER*>(ntdll_handle);
-  // The e_lfanew is an offset from the DOS header to the NT header. It should
-  // never be 0.
-  IMAGE_NT_HEADERS* nt_headers = reinterpret_cast<IMAGE_NT_HEADERS*>(
-      ntdll_handle + dos_header->e_lfanew / sizeof(uint32_t));
-  // For modules that have an import address table, its offset from the
-  // DOS header is stored in the second data directory's VirtualAddress.
-  if (!nt_headers->OptionalHeader.DataDirectory[0].VirtualAddress)
-    return;
-
-  BYTE* base_addr = reinterpret_cast<BYTE*>(ntdll_handle);
-
-  IMAGE_DATA_DIRECTORY* exports_data_dir =
-      &nt_headers->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT];
-
-  IMAGE_EXPORT_DIRECTORY* exports = reinterpret_cast<IMAGE_EXPORT_DIRECTORY*>(
-      base_addr + exports_data_dir->VirtualAddress);
-
-  WORD* ordinals = reinterpret_cast<WORD*>(
-      base_addr + exports->AddressOfNameOrdinals);
-  DWORD* names = reinterpret_cast<DWORD*>(
-      base_addr + exports->AddressOfNames);
-  DWORD* funcs = reinterpret_cast<DWORD*>(
-      base_addr + exports->AddressOfFunctions);
-  int num_entries = exports->NumberOfNames;
-
-  for (int i = 0; i < num_entries; i++) {
-    char* name = reinterpret_cast<char*>(base_addr + names[i]);
-    WORD ord =  ordinals[i];
-    DWORD func = funcs[ord];
-    FARPROC func_addr = reinterpret_cast<FARPROC>(func + base_addr);
-    g_ntdll_lookup[std::string(name)] = func_addr;
-  }
+  base::win::PEImage ntdll_image(ntdll_handle);
+
+  ntdll_image.EnumExports(EnumExportsCallback, NULL);
 }