Refactorise the policy_path_parser framework

This CL performs a refactorisation of the policy path parser framework.

BUG=352627

Review URL: https://codereview.chromium.org/214233003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@261370 0039d316-1c4b-4281-b951-d872f2087c98

7 files changed, 309 insertions, 195 deletions

diff --git a/chrome/browser/policy/policy_path_parser.cc b/chrome/browser/policy/policy_path_parser.cc
new file mode 100644
index 0000000..cb64af9
--- /dev/null
+++ b/chrome/browser/policy/policy_path_parser.cc
@@ -0,0 +1,67 @@
+// Copyright 2014 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 "chrome/browser/policy/policy_path_parser.h"
+
+#include "base/bind.h"
+#include "base/files/file_path.h"
+
+namespace {
+
+void TrimQuotes(base::FilePath::StringType* path) {
+  if (path->length() > 1 &&
+      (((*path)[0] == FILE_PATH_LITERAL('"') &&
+        (*path)[path->length() - 1] == FILE_PATH_LITERAL('"')) ||
+       ((*path)[0] == FILE_PATH_LITERAL('\'') &&
+        (*path)[path->length() - 1] == FILE_PATH_LITERAL('\'')))) {
+    // Strip first and last char which should be matching quotes now.
+    *path = path->substr(1, path->length() - 2);
+  }
+}
+
+}  // namespace
+
+namespace policy {
+
+namespace path_parser {
+
+// This function performs a lazy call to the GetValueCallback, that is the
+// callback is invoked only if the variable is found in the path. This is done
+// to reduce the overhead during initialization.
+void ReplaceVariableInPathWithValue(
+    const base::FilePath::StringType& variable,
+    const policy::path_parser::internal::GetValueFuncPtr& value_func_ptr,
+    base::FilePath::StringType* path) {
+  size_t position = path->find(variable);
+  base::FilePath::StringType value;
+  if (position != base::FilePath::StringType::npos && value_func_ptr(&value))
+    path->replace(position, variable.length(), value);
+}
+
+// Replaces all variable occurrences in the policy string with the respective
+// system settings values.
+base::FilePath::StringType ExpandPathVariables(
+    const base::FilePath::StringType& untranslated_string) {
+  base::FilePath::StringType result(untranslated_string);
+
+  if (result.length() == 0)
+    return result;
+
+  // Sanitize quotes in case of any around the whole string.
+  TrimQuotes(&result);
+
+  base::FilePath::StringType variable;
+  internal::GetValueFuncPtr val_func_ptr;
+  for (int i = 0; i < internal::kNoOfVariables; ++i) {
+    variable = internal::kVariableNameAndValueCallbacks[i].name;
+    val_func_ptr = internal::kVariableNameAndValueCallbacks[i].value_func_ptr;
+    ReplaceVariableInPathWithValue(variable, val_func_ptr, &result);
+  }
+
+  return result;
+}
+
+}  // namespace path_parser
+
+}  // namespace policy
diff --git a/chrome/browser/policy/policy_path_parser.h b/chrome/browser/policy/policy_path_parser.h
index 5bf0345..c0d4c22 100644
--- a/chrome/browser/policy/policy_path_parser.h
+++ b/chrome/browser/policy/policy_path_parser.h
@@ -7,12 +7,31 @@
 
 #include <string>
 
+#include "base/bind.h"
 #include "base/files/file_path.h"
 
 namespace policy {
 
 namespace path_parser {
 
+namespace internal {
+
+typedef bool (*GetValueFuncPtr)(base::FilePath::StringType*);
+
+struct VariableNameAndValueCallback {
+  const base::FilePath::CharType* name;
+  const GetValueFuncPtr value_func_ptr;
+};
+
+// Different set of variables are supported in each platform (see below). Hence
+// this table is filled in with different elements in each platform.
+extern const VariableNameAndValueCallback kVariableNameAndValueCallbacks[];
+
+// Since the number of elements in the table could vary for each platform, this
+// variable is used to keep track of it.
+extern const int kNoOfVariables;
+}
+
 // This function is used to expand the variables in policy strings that
 // represent paths. The set of supported variables differs between platforms
 // but generally covers most standard locations that might be needed in the
diff --git a/chrome/browser/policy/policy_path_parser_linux.cc b/chrome/browser/policy/policy_path_parser_linux.cc
index e0bed09..4509f18 100644
--- a/chrome/browser/policy/policy_path_parser_linux.cc
+++ b/chrome/browser/policy/policy_path_parser_linux.cc
@@ -8,51 +8,47 @@
 
 #include "chrome/browser/policy/policy_path_parser.h"
 
+#include "base/bind.h"
 #include "base/logging.h"
 
 namespace policy {
 
 namespace path_parser {
 
+namespace internal {
+
 const char* kMachineNamePolicyVarName = "${machine_name}";
 const char* kUserNamePolicyVarName = "${user_name}";
 
-// Replaces all variable occurrences in the policy string with the respective
-// system settings values.
-base::FilePath::StringType ExpandPathVariables(
-    const base::FilePath::StringType& untranslated_string) {
-  base::FilePath::StringType result(untranslated_string);
-  if (result.length() == 0)
-    return result;
-  // Sanitize quotes in case of any around the whole string.
-  if (result.length() > 1 &&
-      ((result[0] == '"' && result[result.length() - 1] == '"') ||
-      (result[0] == '\'' && result[result.length() - 1] == '\''))) {
-    // Strip first and last char which should be matching quotes now.
-    result = result.substr(1, result.length() - 2);
-  }
-  // Translate two special variables ${user_name} and ${machine_name}
-  size_t position = result.find(kUserNamePolicyVarName);
-  if (position != std::string::npos) {
-    struct passwd* user = getpwuid(geteuid());
-    if (user) {
-      result.replace(position, strlen(kUserNamePolicyVarName), user->pw_name);
-    } else {
-      LOG(ERROR) << "Username variable can not be resolved. ";
-    }
-  }
-  position = result.find(kMachineNamePolicyVarName);
-  if (position != std::string::npos) {
-    char machinename[255];
-    if (gethostname(machinename, 255) == 0) {
-      result.replace(position, strlen(kMachineNamePolicyVarName), machinename);
-    } else {
-      LOG(ERROR) << "Machine name variable can not be resolved.";
-    }
-  }
-  return result;
+bool GetUserName(base::FilePath::StringType* value) {
+  struct passwd* user = getpwuid(geteuid());
+  if (user)
+    *value = base::FilePath::StringType(user->pw_name);
+  else
+    LOG(ERROR) << "Username variable can not be resolved. ";
+  return (user != NULL);
+}
+
+bool GetMachineName(base::FilePath::StringType* value) {
+  char machinename[255];
+  int status;
+  if ((status = gethostname(machinename, 255)) == 0)
+    *value = base::FilePath::StringType(machinename);
+  else
+    LOG(ERROR) << "Machine name variable can not be resolved.";
+  return (status == 0);
 }
 
+// A table mapping variable name to their respective getvalue callbacks.
+const VariableNameAndValueCallback kVariableNameAndValueCallbacks[] = {
+    {kUserNamePolicyVarName, &GetUserName},
+    {kMachineNamePolicyVarName, &GetMachineName}};
+
+// Total number of entries in the mapping table.
+const int kNoOfVariables = arraysize(kVariableNameAndValueCallbacks);
+
+}  // namespace internal
+
 void CheckUserDataDirPolicy(base::FilePath* user_data_dir) {
   // This function is not implemented in Linux because we don't support the
   // policy on this platform.
diff --git a/chrome/browser/policy/policy_path_parser_mac.mm b/chrome/browser/policy/policy_path_parser_mac.mm
index b734faa3..9be470a 100644
--- a/chrome/browser/policy/policy_path_parser_mac.mm
+++ b/chrome/browser/policy/policy_path_parser_mac.mm
@@ -4,7 +4,7 @@
 
 #include "chrome/browser/policy/policy_path_parser.h"
 
-#include "base/basictypes.h"
+#include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #import "base/mac/scoped_nsautorelease_pool.h"
@@ -21,79 +21,72 @@ namespace policy {
 
 namespace path_parser {
 
-const char* kUserNamePolicyVarName = "${user_name}";
-const char* kMachineNamePolicyVarName = "${machine_name}";
-const char* kMacUsersDirectory = "${users}";
-const char* kMacDocumentsFolderVarName = "${documents}";
+namespace internal {
 
-struct MacFolderNamesToSPDMaping {
-  const char* name;
-  NSSearchPathDirectory id;
-};
-
-// Mapping from variable names to MacOS NSSearchPathDirectory ids.
-const MacFolderNamesToSPDMaping mac_folder_mapping[] = {
-    { kMacUsersDirectory, NSUserDirectory},
-    { kMacDocumentsFolderVarName, NSDocumentDirectory}
-};
-
-// Replaces all variable occurrences in the policy string with the respective
-// system settings values.
-base::FilePath::StringType ExpandPathVariables(
-    const base::FilePath::StringType& untranslated_string) {
-  base::FilePath::StringType result(untranslated_string);
-  if (result.length() == 0)
-    return result;
-  // Sanitize quotes in case of any around the whole string.
-  if (result.length() > 1 &&
-      ((result[0] == '"' && result[result.length() - 1] == '"') ||
-      (result[0] == '\'' && result[result.length() - 1] == '\''))) {
-    // Strip first and last char which should be matching quotes now.
-    result = result.substr(1, result.length() - 2);
-  }
-  // First translate all path variables we recognize.
-  for (size_t i = 0; i < arraysize(mac_folder_mapping); ++i) {
-    size_t position = result.find(mac_folder_mapping[i].name);
-    if (position != std::string::npos) {
-      NSArray* searchpaths = NSSearchPathForDirectoriesInDomains(
-          mac_folder_mapping[i].id, NSAllDomainsMask, true);
-      if ([searchpaths count] > 0) {
-        NSString *variable_value = [searchpaths objectAtIndex:0];
-        result.replace(position, strlen(mac_folder_mapping[i].name),
-                       base::SysNSStringToUTF8(variable_value));
-      }
-    }
+bool GetFolder(NSSearchPathDirectory id, base::FilePath::StringType* value) {
+  NSArray* searchpaths =
+      NSSearchPathForDirectoriesInDomains(id, NSAllDomainsMask, true);
+  if ([searchpaths count] > 0) {
+    NSString* variable_value = [searchpaths objectAtIndex:0];
+    *value = base::SysNSStringToUTF8(variable_value);
+    return true;
   }
-  // Next translate two special variables ${user_name} and ${machine_name}
-  size_t position = result.find(kUserNamePolicyVarName);
-  if (position != std::string::npos) {
-    NSString* username = NSUserName();
-    if (username) {
-      result.replace(position, strlen(kUserNamePolicyVarName),
-                     base::SysNSStringToUTF8(username));
-    } else {
-      LOG(ERROR) << "Username variable can not be resolved.";
-    }
+  return false;
+}
+
+// The wrapper is used instead of callbacks since these function are
+// initialized in a global table and using callbacks in the table results in
+// the increase in size of static initializers.
+#define WRAP_GET_FORLDER_FUNCTION(FunctionName, FolderId)   \
+  bool FunctionName(base::FilePath::StringType* value) { \
+    return GetFolder(FolderId, value);                      \
   }
-  position = result.find(kMachineNamePolicyVarName);
-  if (position != std::string::npos) {
-    SCDynamicStoreContext context = { 0, NULL, NULL, NULL };
-    SCDynamicStoreRef store = SCDynamicStoreCreate(kCFAllocatorDefault,
-                                                   CFSTR("policy_subsystem"),
-                                                   NULL, &context);
-    CFStringRef machinename = SCDynamicStoreCopyLocalHostName(store);
-    if (machinename) {
-      result.replace(position, strlen(kMachineNamePolicyVarName),
-                     base::SysCFStringRefToUTF8(machinename));
-      CFRelease(machinename);
-    } else {
-      LOG(ERROR) << "Machine name variable can not be resolved.";
-    }
-    CFRelease(store);
+
+WRAP_GET_FORLDER_FUNCTION(GetMacUserFolderPath, NSUserDirectory)
+WRAP_GET_FORLDER_FUNCTION(GetMacDocumentsFolderPath, NSDocumentDirectory)
+
+bool GetUserName(base::FilePath::StringType* value) {
+  NSString* username = NSUserName();
+  if (username)
+    *value = base::SysNSStringToUTF8(username);
+  else
+    LOG(ERROR) << "Username variable can not be resolved.";
+  return (username != NULL);
+}
+
+bool GetMachineName(base::FilePath::StringType* value) {
+  SCDynamicStoreContext context = {0, NULL, NULL, NULL};
+  SCDynamicStoreRef store = SCDynamicStoreCreate(
+      kCFAllocatorDefault, CFSTR("policy_subsystem"), NULL, &context);
+  CFStringRef machinename = SCDynamicStoreCopyLocalHostName(store);
+  if (machinename) {
+    *value = base::SysCFStringRefToUTF8(machinename);
+    CFRelease(machinename);
+  } else {
+    LOG(ERROR) << "Machine name variable can not be resolved.";
   }
-  return result;
+  CFRelease(store);
+  return (machinename != NULL);
 }
 
+const char* kUserNamePolicyVarName = "${user_name}";
+const char* kMachineNamePolicyVarName = "${machine_name}";
+const char* kMacUsersDirectory = "${users}";
+const char* kMacDocumentsFolderVarName = "${documents}";
+
+// A table mapping variable names to their respective get value function
+// pointers.
+const VariableNameAndValueCallback kVariableNameAndValueCallbacks[] = {
+    {kUserNamePolicyVarName, &GetUserName},
+    {kMachineNamePolicyVarName, &GetMachineName},
+    {kMacUsersDirectory, &GetMacUserFolderPath},
+    {kMacDocumentsFolderVarName, &GetMacDocumentsFolderPath}};
+
+// Total number of entries in the mapping table.
+const int kNoOfVariables = arraysize(kVariableNameAndValueCallbacks);
+
+}  // namespace internal
+
 void CheckUserDataDirPolicy(base::FilePath* user_data_dir) {
   base::mac::ScopedNSAutoreleasePool pool;
 
diff --git a/chrome/browser/policy/policy_path_parser_unittest.cc b/chrome/browser/policy/policy_path_parser_unittest.cc
index 633ef78..8fec189 100644
--- a/chrome/browser/policy/policy_path_parser_unittest.cc
+++ b/chrome/browser/policy/policy_path_parser_unittest.cc
@@ -20,13 +20,41 @@ class PolicyPathParserTests : public testing::Test {
   }
 };
 
-#if defined(OS_MACOSX)
-// http://crbug.com/327520
-#define MAYBE_AllPlatformVariables DISABLED_AllPlatformVariables
-#else
-#define MAYBE_AllPlatformVariables AllPlatformVariables
-#endif
-TEST_F(PolicyPathParserTests, MAYBE_AllPlatformVariables) {
+namespace path_parser {
+
+// The test needs access to a routine that is not exposed via the public header.
+void ReplaceVariableInPathWithValue(
+    const base::FilePath::StringType& variable,
+    const policy::path_parser::internal::GetValueFuncPtr& value_func_ptr,
+    base::FilePath::StringType* path);
+
+}  // namespace path_parser;
+
+bool GetBuggy(base::FilePath::StringType* value) {
+  *value = base::FilePath::StringType(FILE_PATH_LITERAL("ok"));
+  return true;
+}
+
+TEST_F(PolicyPathParserTests, ReplaceVariableInPathWithValue) {
+  // This is custom variable with custom callback. It should replace ${buggy}
+  // with ok.
+  base::FilePath::StringType custom_vars(FILE_PATH_LITERAL("//$C/${buggy}"));
+  base::FilePath::StringType custom_vars_expected(FILE_PATH_LITERAL("//$C/ok"));
+  base::FilePath::StringType buggy(FILE_PATH_LITERAL("${buggy}"));
+
+  path_parser::ReplaceVariableInPathWithValue(buggy, &GetBuggy, &custom_vars);
+  ASSERT_EQ(custom_vars, custom_vars_expected);
+
+  // There is no ${buggy} in input, so it should remain unchanged.
+  base::FilePath::StringType custom2_vars(FILE_PATH_LITERAL("//$C/ok"));
+  base::FilePath::StringType custom2_vars_expected(
+      FILE_PATH_LITERAL("//$C/ok"));
+
+  path_parser::ReplaceVariableInPathWithValue(buggy, &GetBuggy, &custom2_vars);
+  ASSERT_EQ(custom2_vars, custom2_vars_expected);
+}
+
+TEST_F(PolicyPathParserTests, CommonExpandPathVariables) {
   // No vars whatsoever no substitution should occur.
   base::FilePath::StringType no_vars(FILE_PATH_LITERAL("//$C/shares"));
   base::FilePath::StringType no_vars_result =
@@ -50,7 +78,15 @@ TEST_F(PolicyPathParserTests, MAYBE_AllPlatformVariables) {
   ASSERT_EQ(quotes_result, no_quotes);
   quotes_result = path_parser::ExpandPathVariables(double_quotes);
   ASSERT_EQ(quotes_result, no_quotes);
+}
 
+#if defined(OS_MACOSX)
+// http://crbug.com/327520
+#define MAYBE_AllPlatformVariables DISABLED_AllPlatformVariables
+#else
+#define MAYBE_AllPlatformVariables AllPlatformVariables
+#endif
+TEST_F(PolicyPathParserTests, MAYBE_AllPlatformVariables) {
   // Both should have been substituted.
   base::FilePath::StringType vars(
       FILE_PATH_LITERAL("${user_name}${machine_name}"));
diff --git a/chrome/browser/policy/policy_path_parser_win.cc b/chrome/browser/policy/policy_path_parser_win.cc
index 71c9011..6f496d8 100644
--- a/chrome/browser/policy/policy_path_parser_win.cc
+++ b/chrome/browser/policy/policy_path_parser_win.cc
@@ -8,6 +8,7 @@
 
 #include "chrome/browser/policy/policy_path_parser.h"
 
+#include "base/bind.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/win/registry.h"
@@ -28,104 +29,105 @@ bool LoadUserDataDirPolicyFromRegistry(HKEY hive, base::FilePath* dir) {
   return false;
 }
 
-const WCHAR* kMachineNamePolicyVarName = L"${machine_name}";
-const WCHAR* kUserNamePolicyVarName = L"${user_name}";
-const WCHAR* kWinDocumentsFolderVarName = L"${documents}";
-const WCHAR* kWinLocalAppDataFolderVarName = L"${local_app_data}";
-const WCHAR* kWinRoamingAppDataFolderVarName = L"${roaming_app_data}";
-const WCHAR* kWinProfileFolderVarName = L"${profile}";
-const WCHAR* kWinProgramDataFolderVarName = L"${global_app_data}";
-const WCHAR* kWinProgramFilesFolderVarName = L"${program_files}";
-const WCHAR* kWinWindowsFolderVarName = L"${windows}";
-const WCHAR* kWinClientName = L"${client_name}";
-
-struct WinFolderNamesToCSIDLMapping {
-  const WCHAR* name;
-  int id;
-};
-
-// Mapping from variable names to Windows CSIDL ids.
-const WinFolderNamesToCSIDLMapping win_folder_mapping[] = {
-    { kWinWindowsFolderVarName,        CSIDL_WINDOWS},
-    { kWinProgramFilesFolderVarName,   CSIDL_PROGRAM_FILES},
-    { kWinProgramDataFolderVarName,    CSIDL_COMMON_APPDATA},
-    { kWinProfileFolderVarName,        CSIDL_PROFILE},
-    { kWinLocalAppDataFolderVarName,   CSIDL_LOCAL_APPDATA},
-    { kWinRoamingAppDataFolderVarName, CSIDL_APPDATA},
-    { kWinDocumentsFolderVarName,      CSIDL_PERSONAL}
-};
-
 }  // namespace
 
 namespace policy {
 
 namespace path_parser {
 
-// Replaces all variable occurances in the policy string with the respective
-// system settings values.
-base::FilePath::StringType ExpandPathVariables(
-    const base::FilePath::StringType& untranslated_string) {
-  base::FilePath::StringType result(untranslated_string);
-  if (result.length() == 0)
-    return result;
-  // Sanitize quotes in case of any around the whole string.
-  if (result.length() > 1 &&
-      ((result[0] == L'"' && result[result.length() - 1] == L'"') ||
-       (result[0] == L'\'' && result[result.length() - 1] == L'\''))) {
-    // Strip first and last char which should be matching quotes now.
-    result = result.substr(1, result.length() - 2);
-  }
-  // First translate all path variables we recognize.
-  for (int i = 0; i < arraysize(win_folder_mapping); ++i) {
-    size_t position = result.find(win_folder_mapping[i].name);
-    if (position != std::wstring::npos) {
-      WCHAR path[MAX_PATH];
-      ::SHGetSpecialFolderPath(0, path, win_folder_mapping[i].id, false);
-      std::wstring path_string(path);
-      result.replace(position, wcslen(win_folder_mapping[i].name), path_string);
-    }
-  }
-  // Next translate other windows specific variables.
-  size_t position = result.find(kUserNamePolicyVarName);
-  if (position != std::wstring::npos) {
-    DWORD return_length = 0;
-    ::GetUserName(NULL, &return_length);
-    if (return_length != 0) {
-      scoped_ptr<WCHAR[]> username(new WCHAR[return_length]);
-      ::GetUserName(username.get(), &return_length);
-      std::wstring username_string(username.get());
-      result.replace(position, wcslen(kUserNamePolicyVarName), username_string);
-    }
+namespace internal {
+
+bool GetSpecialFolderPath(int id, base::FilePath::StringType* value) {
+  WCHAR path[MAX_PATH];
+  ::SHGetSpecialFolderPath(0, path, id, false);
+  *value = base::FilePath::StringType(path);
+  return true;
+}
+
+// The wrapper is used instead of callbacks since these function are
+// initialized in a global table and using callbacks in the table results in
+// the increase in size of static initializers.
+#define WRAP_GET_FORLDER_FUNCTION(FunctionName, FolderId) \
+  bool FunctionName(base::FilePath::StringType* value) {   \
+    return GetSpecialFolderPath(FolderId, value);         \
   }
-  position = result.find(kMachineNamePolicyVarName);
-  if (position != std::wstring::npos) {
-    DWORD return_length = 0;
-    ::GetComputerNameEx(ComputerNamePhysicalDnsHostname, NULL, &return_length);
-    if (return_length != 0) {
-      scoped_ptr<WCHAR[]> machinename(new WCHAR[return_length]);
-      ::GetComputerNameEx(ComputerNamePhysicalDnsHostname,
-                          machinename.get(), &return_length);
-      std::wstring machinename_string(machinename.get());
-      result.replace(
-          position, wcslen(kMachineNamePolicyVarName), machinename_string);
-    }
+
+WRAP_GET_FORLDER_FUNCTION(GetWindowsFolderPath, CSIDL_WINDOWS)
+WRAP_GET_FORLDER_FUNCTION(GetProgramFilesFolderPath, CSIDL_PROGRAM_FILES)
+WRAP_GET_FORLDER_FUNCTION(GetProgramDataFolderPath, CSIDL_COMMON_APPDATA)
+WRAP_GET_FORLDER_FUNCTION(GetProfileFolderPath, CSIDL_PROFILE)
+WRAP_GET_FORLDER_FUNCTION(GetLocalAppDataFolderPath, CSIDL_LOCAL_APPDATA)
+WRAP_GET_FORLDER_FUNCTION(GetRoamingAppDataFolderPath, CSIDL_APPDATA)
+WRAP_GET_FORLDER_FUNCTION(GetDocumentsFolderPath, CSIDL_PERSONAL)
+
+bool GetWindowsUserName(base::FilePath::StringType* value) {
+  DWORD return_length = 0;
+  ::GetUserName(NULL, &return_length);
+  if (return_length) {
+    scoped_ptr<WCHAR[]> username(new WCHAR[return_length]);
+    ::GetUserName(username.get(), &return_length);
+    *value = base::FilePath::StringType(username.get());
   }
-  position = result.find(kWinClientName);
-  if (position != std::wstring::npos) {
-    LPWSTR buffer = NULL;
-    DWORD buffer_length = 0;
-    if (::WTSQuerySessionInformation(WTS_CURRENT_SERVER, WTS_CURRENT_SESSION,
-                                     WTSClientName,
-                                     &buffer, &buffer_length)) {
-      std::wstring clientname_string(buffer);
-      result.replace(position, wcslen(kWinClientName), clientname_string);
-      ::WTSFreeMemory(buffer);
-    }
+  return (return_length != 0);
+}
+
+bool GetMachineName(base::FilePath::StringType* value) {
+  DWORD return_length = 0;
+  ::GetComputerNameEx(ComputerNamePhysicalDnsHostname, NULL, &return_length);
+  if (return_length) {
+    scoped_ptr<WCHAR[]> machinename(new WCHAR[return_length]);
+    ::GetComputerNameEx(
+        ComputerNamePhysicalDnsHostname, machinename.get(), &return_length);
+    *value = base::FilePath::StringType(machinename.get());
   }
+  return (return_length != 0);
+}
 
-  return result;
+bool GetClientName(base::FilePath::StringType* value) {
+  LPWSTR buffer = NULL;
+  DWORD buffer_length = 0;
+  BOOL status;
+  if ((status = ::WTSQuerySessionInformation(WTS_CURRENT_SERVER,
+                                             WTS_CURRENT_SESSION,
+                                             WTSClientName,
+                                             &buffer,
+                                             &buffer_length))) {
+    *value = base::FilePath::StringType(buffer);
+    ::WTSFreeMemory(buffer);
+  }
+  return (status == TRUE);
 }
 
+const WCHAR* kMachineNamePolicyVarName = L"${machine_name}";
+const WCHAR* kUserNamePolicyVarName = L"${user_name}";
+const WCHAR* kWinDocumentsFolderVarName = L"${documents}";
+const WCHAR* kWinLocalAppDataFolderVarName = L"${local_app_data}";
+const WCHAR* kWinRoamingAppDataFolderVarName = L"${roaming_app_data}";
+const WCHAR* kWinProfileFolderVarName = L"${profile}";
+const WCHAR* kWinProgramDataFolderVarName = L"${global_app_data}";
+const WCHAR* kWinProgramFilesFolderVarName = L"${program_files}";
+const WCHAR* kWinWindowsFolderVarName = L"${windows}";
+const WCHAR* kWinClientName = L"${client_name}";
+
+// A table mapping variable names to their respective get value function
+// pointers.
+const VariableNameAndValueCallback kVariableNameAndValueCallbacks[] = {
+    {kWinWindowsFolderVarName, &GetWindowsFolderPath},
+    {kWinProgramFilesFolderVarName, &GetProgramFilesFolderPath},
+    {kWinProgramDataFolderVarName, &GetProgramDataFolderPath},
+    {kWinProfileFolderVarName, &GetProfileFolderPath},
+    {kWinLocalAppDataFolderVarName, &GetLocalAppDataFolderPath},
+    {kWinRoamingAppDataFolderVarName, &GetRoamingAppDataFolderPath},
+    {kWinDocumentsFolderVarName, &GetDocumentsFolderPath},
+    {kUserNamePolicyVarName, &GetWindowsUserName},
+    {kMachineNamePolicyVarName, &GetMachineName},
+    {kWinClientName, &GetClientName}};
+
+// Total number of entries in the mapping table.
+const int kNoOfVariables = arraysize(kVariableNameAndValueCallbacks);
+
+}  // namespace internal
+
 void CheckUserDataDirPolicy(base::FilePath* user_data_dir) {
   DCHECK(user_data_dir);
   // Policy from the HKLM hive has precedence over HKCU.
diff --git a/chrome/policy.gypi b/chrome/policy.gypi
index 79cc543..60de7fe 100644
--- a/chrome/policy.gypi
+++ b/chrome/policy.gypi
@@ -20,6 +20,7 @@
         'browser/policy/policy_path_parser_linux.cc',
         'browser/policy/policy_path_parser_mac.mm',
         'browser/policy/policy_path_parser_win.cc',
+        'browser/policy/policy_path_parser.cc',
       ],
     },
   ],