[Mac] if someone overrides FILE_EXE/DIR_EXE in the path service, it can cause...

[Mac] if someone overrides FILE_EXE/DIR_EXE in the path service, it can cause the calculation for DIR_SOURCE_ROOT to go wrong.  Avoid this by not using the value from the path service.

BUG=52918
TEST=green tree
Review URL: http://codereview.chromium.org/3176036

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@57237 0039d316-1c4b-4281-b951-d872f2087c98

base/base_paths_mac.mm

@@ -7,6 +7,7 @@
 #import <Cocoa/Cocoa.h>
 #include <mach-o/dyld.h>
 
+#include "base/compiler_specific.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/logging.h"
@@ -14,48 +15,62 @@
 #include "base/path_service.h"
 #include "base/string_util.h"
 
+namespace {
+
+bool GetNSExecutablePath(FilePath* path) WARN_UNUSED_RESULT;
+
+bool GetNSExecutablePath(FilePath* path) {
+  DCHECK(path);
+  // Executable path can have relative references ("..") depending on
+  // how the app was launched.
+  uint32_t executable_length = 0;
+  _NSGetExecutablePath(NULL, &executable_length);
+  DCHECK_GE(executable_length, 1u);
+  std::string executable_path;
+  char* executable_path_c = WriteInto(&executable_path, executable_length);
+  int rv = _NSGetExecutablePath(executable_path_c, &executable_length);
+  DCHECK_EQ(rv, 0);
+  DCHECK(!executable_path.empty());
+  if ((rv != 0) || (executable_path.empty()))
+    return false;
+  *path = FilePath(executable_path);
+  return true;
+}
+
+}  // namespace
+
 namespace base {
 
 bool PathProviderMac(int key, FilePath* result) {
-  std::string cur;
   switch (key) {
     case base::FILE_EXE:
     case base::FILE_MODULE: {
-      // Executable path can have relative references ("..") depending on
-      // how the app was launched.
-      uint32_t executable_length = 0;
-      _NSGetExecutablePath(NULL, &executable_length);
-      DCHECK_GT(executable_length, 1u);
-      char* executable = WriteInto(&cur, executable_length);
-      int rv = _NSGetExecutablePath(executable, &executable_length);
-      DCHECK_EQ(rv, 0);
-      DCHECK(!cur.empty());
-      break;
+      return GetNSExecutablePath(result);
     }
     case base::DIR_USER_CACHE:
       return mac_util::GetUserDirectory(NSCachesDirectory, result);
     case base::DIR_APP_DATA:
       return mac_util::GetUserDirectory(NSApplicationSupportDirectory, result);
     case base::DIR_SOURCE_ROOT: {
-      PathService::Get(base::DIR_EXE, result);
-      if (mac_util::AmIBundled()) {
-        // The bundled app executables (Chromium, TestShell, etc) live five
-        // levels down, eg:
-        // src/xcodebuild/{Debug|Release}/Chromium.app/Contents/MacOS/Chromium.
-        *result = result->DirName().DirName().DirName().DirName().DirName();
-      } else {
-        // Unit tests execute two levels deep from the source root, eg:
-        // src/xcodebuild/{Debug|Release}/base_unittests
-        *result = result->DirName().DirName();
+      if (GetNSExecutablePath(result)) {
+        // Start with the executable's directory.
+        *result = result->DirName();
+        if (mac_util::AmIBundled()) {
+          // The bundled app executables (Chromium, TestShell, etc) live five
+          // levels down, eg:
+          // src/xcodebuild/{Debug|Release}/Chromium.app/Contents/MacOS/Chromium
+          *result = result->DirName().DirName().DirName().DirName().DirName();
+        } else {
+          // Unit tests execute two levels deep from the source root, eg:
+          // src/xcodebuild/{Debug|Release}/base_unittests
+          *result = result->DirName().DirName();
+        }
       }
       return true;
     }
     default:
       return false;
   }
-
-  *result = FilePath(cur);
-  return true;
 }
 
 }  // namespace base