installer/util/shell_util.h

// Copyright (c) 2012 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.
//
// This file declares methods that are useful for integrating Chrome in
// Windows shell. These methods are all static and currently part of
// ShellUtil class.

#ifndef CHROME_INSTALLER_UTIL_SHELL_UTIL_H_
#define CHROME_INSTALLER_UTIL_SHELL_UTIL_H_

#include <windows.h>

#include <stddef.h>
#include <stdint.h>

#include <map>
#include <memory>
#include <set>
#include <utility>
#include <vector>

#include "base/check.h"
#include "base/files/file_path.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/strings/string16.h"
#include "chrome/installer/util/work_item_list.h"

class RegistryEntry;

namespace base {
class AtomicFlag;
class CommandLine;
}  // namespace base

// This is a utility class that provides common shell integration methods
// that can be used by installer as well as Chrome.
class ShellUtil {
 public:
  // Input to any methods that make changes to OS shell.
  enum ShellChange {
    CURRENT_USER = 0x1,  // Make any shell changes only at the user level
    SYSTEM_LEVEL = 0x2   // Make any shell changes only at the system level
  };

  // Chrome's default handler state for a given protocol. If the current install
  // mode is not default, the brand's other modes are checked. This allows
  // callers to take specific action in case the current mode (e.g., Chrome Dev)
  // is not the default handler, but another of the brand's modes (e.g., stable
  // Chrome) is.
  enum DefaultState {
    // An error occurred while attempting to check the default handler for the
    // protocol.
    UNKNOWN_DEFAULT,
    // No install mode for the brand is default for the protocol.
    NOT_DEFAULT,
    // The current install mode is default.
    IS_DEFAULT,
    // The current install mode is not default, although one of the brand's
    // other install modes is.
    OTHER_MODE_IS_DEFAULT,
  };

  // Typical shortcut directories. Resolved in GetShortcutPath().
  // Also used in ShortcutLocationIsSupported().
  enum ShortcutLocation {
    SHORTCUT_LOCATION_FIRST = 0,
    SHORTCUT_LOCATION_DESKTOP = SHORTCUT_LOCATION_FIRST,
    SHORTCUT_LOCATION_QUICK_LAUNCH,
    SHORTCUT_LOCATION_START_MENU_ROOT,
    SHORTCUT_LOCATION_START_MENU_CHROME_DIR_DEPRECATED,  // now placed in root
    SHORTCUT_LOCATION_START_MENU_CHROME_APPS_DIR,
    SHORTCUT_LOCATION_TASKBAR_PINS,   // base::win::Version::WIN7 +
    SHORTCUT_LOCATION_APP_SHORTCUTS,  // base::win::Version::WIN8 +
    SHORTCUT_LOCATION_STARTUP,
    NUM_SHORTCUT_LOCATIONS
  };

  enum ShortcutOperation {
    // Create a new shortcut (overwriting if necessary).
    SHELL_SHORTCUT_CREATE_ALWAYS,
    // Create the per-user shortcut only if its system-level equivalent (with
    // the same name) is not present.
    SHELL_SHORTCUT_CREATE_IF_NO_SYSTEM_LEVEL,
    // Overwrite an existing shortcut (fail if the shortcut doesn't exist).
    // If the arguments are not specified on the new shortcut, keep the old
    // shortcut's arguments.
    SHELL_SHORTCUT_REPLACE_EXISTING,
    // Update specified properties only on an existing shortcut.
    SHELL_SHORTCUT_UPDATE_EXISTING,
  };

  // Properties for shortcuts. Properties set will be applied to
  // the shortcut on creation/update. On update, unset properties are ignored;
  // on create (and replaced) unset properties might have a default value (see
  // individual property setters below for details).
  // Callers are encouraged to use the setters provided which take care of
  // setting |options| as desired.
  struct ShortcutProperties {
    enum IndividualProperties {
      PROPERTIES_TARGET = 1 << 0,
      PROPERTIES_ARGUMENTS = 1 << 1,
      PROPERTIES_DESCRIPTION = 1 << 2,
      PROPERTIES_ICON = 1 << 3,
      PROPERTIES_APP_ID = 1 << 4,
      PROPERTIES_SHORTCUT_NAME = 1 << 5,
      PROPERTIES_DUAL_MODE = 1 << 6,
      PROPERTIES_TOAST_ACTIVATOR_CLSID = 1 << 7,
    };

    explicit ShortcutProperties(ShellChange level_in);
    ShortcutProperties(const ShortcutProperties& other);
    ~ShortcutProperties();

    // Sets the target executable to launch from this shortcut.
    // This is mandatory when creating a shortcut.
    void set_target(const base::FilePath& target_in) {
      target = target_in;
      options |= PROPERTIES_TARGET;
    }

    // Sets the arguments to be passed to |target| when launching from this
    // shortcut.
    // The length of this string must be less than MAX_PATH.
    void set_arguments(const base::string16& arguments_in) {
      // Size restriction as per MSDN at
      // http://msdn.microsoft.com/library/windows/desktop/bb774954.aspx.
      DCHECK(arguments_in.length() < MAX_PATH);
      arguments = arguments_in;
      options |= PROPERTIES_ARGUMENTS;
    }

    // Sets the localized description of the shortcut.
    // The length of this string must be less than MAX_PATH.
    void set_description(const base::string16& description_in) {
      // Size restriction as per MSDN at
      // http://msdn.microsoft.com/library/windows/desktop/bb774955.aspx.
      DCHECK(description_in.length() < MAX_PATH);
      description = description_in;
      options |= PROPERTIES_DESCRIPTION;
    }

    // Sets the path to the icon (icon_index set to 0).
    // icon index unless otherwise specified in master_preferences).
    void set_icon(const base::FilePath& icon_in, int icon_index_in) {
      icon = icon_in;
      icon_index = icon_index_in;
      options |= PROPERTIES_ICON;
    }

    // Sets the app model id for the shortcut.
    void set_app_id(const base::string16& app_id_in) {
      app_id = app_id_in;
      options |= PROPERTIES_APP_ID;
    }

    // Forces the shortcut's name to |shortcut_name_in|.
    // Default: InstallUtil::GetShortcutName().
    // The ".lnk" extension will automatically be added to this name.
    void set_shortcut_name(const base::string16& shortcut_name_in) {
      shortcut_name = shortcut_name_in;
      options |= PROPERTIES_SHORTCUT_NAME;
    }

    // Sets the toast activator CLSID to |toast_activator_clsid_in|.
    void set_toast_activator_clsid(const CLSID& toast_activator_clsid_in) {
      toast_activator_clsid = toast_activator_clsid_in;
      options |= PROPERTIES_TOAST_ACTIVATOR_CLSID;
    }

    // Sets whether to pin this shortcut to the taskbar after creating it
    // (ignored if the shortcut is only being updated).
    // Note: This property doesn't have a mask in |options|.
    void set_pin_to_taskbar(bool pin_to_taskbar_in) {
      pin_to_taskbar = pin_to_taskbar_in;
    }

    bool has_target() const { return (options & PROPERTIES_TARGET) != 0; }

    bool has_arguments() const { return (options & PROPERTIES_ARGUMENTS) != 0; }

    bool has_description() const {
      return (options & PROPERTIES_DESCRIPTION) != 0;
    }

    bool has_icon() const { return (options & PROPERTIES_ICON) != 0; }

    bool has_app_id() const { return (options & PROPERTIES_APP_ID) != 0; }

    bool has_shortcut_name() const {
      return (options & PROPERTIES_SHORTCUT_NAME) != 0;
    }

    bool has_toast_activator_clsid() const {
      return (options & PROPERTIES_TOAST_ACTIVATOR_CLSID) != 0;
    }

    // The level to install this shortcut at (CURRENT_USER for a per-user
    // shortcut and SYSTEM_LEVEL for an all-users shortcut).
    ShellChange level;

    base::FilePath target;
    base::string16 arguments;
    base::string16 description;
    base::FilePath icon;
    int icon_index;
    base::string16 app_id;
    base::string16 shortcut_name;
    CLSID toast_activator_clsid;
    bool pin_to_taskbar;
    // Bitfield made of IndividualProperties. Properties set in |options| will
    // be used to create/update the shortcut, others will be ignored on update
    // and possibly replaced by default values on create (see individual
    // property setters above for details on default values).
    uint32_t options;
  };

  struct FileAssociationsAndAppName {
    FileAssociationsAndAppName();
    FileAssociationsAndAppName(FileAssociationsAndAppName&& other);
    ~FileAssociationsAndAppName();

    std::set<base::string16> file_associations;
    base::string16 app_name;
  };

  // Relative path of the URL Protocol registry entry (prefixed with '\').
  static const wchar_t* kRegURLProtocol;

  // Relative path of DefaultIcon registry entry (prefixed with '\').
  static const wchar_t* kRegDefaultIcon;

  // Relative path of "shell" registry key.
  static const wchar_t* kRegShellPath;

  // Relative path of shell open command in Windows registry
  // (i.e. \\shell\\open\\command).
  static const wchar_t* kRegShellOpen;

  // Relative path of registry key under which applications need to register
  // to control Windows Start menu links.
  static const wchar_t* kRegStartMenuInternet;

  // Relative path of Classes registry entry under which file associations
  // are added on Windows.
  static const wchar_t* kRegClasses;

  // Relative path of RegisteredApplications registry entry under which
  // we add Chrome as a Windows application
  static const wchar_t* kRegRegisteredApplications;

  // The key path and key name required to register Chrome on Windows such
  // that it can be launched from Start->Run just by name (chrome.exe).
  static const wchar_t* kAppPathsRegistryKey;
  static const wchar_t* kAppPathsRegistryPathName;

  // Registry path that stores url associations on Vista.
  static const wchar_t* kRegVistaUrlPrefs;

  // File extensions that Chrome registers itself as the default handler
  // for when the user makes Chrome the default browser.
  static const wchar_t* kDefaultFileAssociations[];

  // File extensions that Chrome registers itself as being capable of
  // handling.
  static const wchar_t* kPotentialFileAssociations[];

  // Protocols that Chrome registers itself as the default handler for
  // when the user makes Chrome the default browser.
  static const wchar_t* kBrowserProtocolAssociations[];

  // Protocols that Chrome registers itself as being capable of handling.
  static const wchar_t* kPotentialProtocolAssociations[];

  // Registry value name that is needed for ChromeHTML ProgId
  static const wchar_t* kRegUrlProtocol;

  // Relative registry path from \Software\Classes\ChromeHTML to the ProgId
  // Application definitions.
  static const wchar_t* kRegApplication;

  // Registry value name for the AppUserModelId of an application.
  static const wchar_t* kRegAppUserModelId;

  // Registry value name for the description of an application.
  static const wchar_t* kRegApplicationDescription;

  // Registry value name for an application's name.
  static const wchar_t* kRegApplicationName;

  // Registry value name for the path to an application's icon.
  static const wchar_t* kRegApplicationIcon;

  // Registry value name for an application's company.
  static const wchar_t* kRegApplicationCompany;

  // Relative path of ".exe" registry key.
  static const wchar_t* kRegExePath;

  // Registry value name of the open verb.
  static const wchar_t* kRegVerbOpen;

  // Registry value name of the opennewwindow verb.
  static const wchar_t* kRegVerbOpenNewWindow;

  // Registry value name of the run verb.
  static const wchar_t* kRegVerbRun;

  // Registry value name for command entries.
  static const wchar_t* kRegCommand;

  // Registry value name for the DelegateExecute verb handler.
  static const wchar_t* kRegDelegateExecute;

  // Registry value name for the OpenWithProgids entry for file associations.
  static const wchar_t* kRegOpenWithProgids;

  // Returns true if |chrome_exe| is registered in HKLM with |suffix|.
  // Note: This only checks one deterministic key in HKLM for |chrome_exe| and
  // doesn't otherwise validate a full Chrome install in HKLM.
  static bool QuickIsChromeRegisteredInHKLM(const base::FilePath& chrome_exe,
                                            const base::string16& suffix);

  // Returns true if the current Windows version supports the presence of
  // shortcuts at |location|.
  static bool ShortcutLocationIsSupported(ShortcutLocation location);

  // Sets |path| to the path for a shortcut at the |location| desired for the
  // given |level| (CURRENT_USER for per-user path and SYSTEM_LEVEL for
  // all-users path).
  // Returns false on failure.
  static bool GetShortcutPath(ShortcutLocation location,
                              ShellChange level,
                              base::FilePath* path);

  // Populates the uninitialized members of |properties| with default values.
  static void AddDefaultShortcutProperties(const base::FilePath& target_exe,
                                           ShortcutProperties* properties);

  // Move an existing shortcut from |old_location| to |new_location| for the
  // set |shortcut_level|.  If the folder containing |old_location| is then
  // empty, it will be removed.
  static bool MoveExistingShortcut(ShortcutLocation old_location,
                                   ShortcutLocation new_location,
                                   const ShortcutProperties& properties);

  // Updates shortcut in |location| (or creates it if |options| specify
  // SHELL_SHORTCUT_CREATE_ALWAYS).
  // |properties| and |operation| affect this method as described on their
  // invidividual definitions above.
  // |location| may be one of SHORTCUT_LOCATION_DESKTOP,
  // SHORTCUT_LOCATION_QUICK_LAUNCH, SHORTCUT_LOCATION_START_MENU_ROOT,
  // SHORTCUT_LOCATION_START_MENU_CHROME_DIR, or
  // SHORTCUT_LOCATION_START_MENU_CHROME_APPS_DIR.
  static bool CreateOrUpdateShortcut(ShortcutLocation location,
                                     const ShortcutProperties& properties,
                                     ShortcutOperation operation);

  // Returns the string "|icon_path|,|icon_index|" (see, for example,
  // http://msdn.microsoft.com/library/windows/desktop/dd391573.aspx).
  static base::string16 FormatIconLocation(const base::FilePath& icon_path,
                                           int icon_index);

  // This method returns the command to open URLs/files using chrome. Typically
  // this command is written to the registry under shell\open\command key.
  // |chrome_exe|: the full path to chrome.exe
  static base::string16 GetChromeShellOpenCmd(const base::FilePath& chrome_exe);

  // This method returns the command to be called by the DelegateExecute verb
  // handler to launch chrome on Windows 8. Typically this command is written to
  // the registry under the HKCR\Chrome\.exe\shell\(open|run)\command key.
  // |chrome_exe|: the full path to chrome.exe
  static base::string16 GetChromeDelegateCommand(
      const base::FilePath& chrome_exe);

  // Gets a mapping of all registered browser names (excluding the current
  // browser) and their reinstall command (which usually sets browser as
  // default).
  // Given browsers can be registered in HKCU (as of Win7) and/or in HKLM, this
  // method looks in both and gives precedence to values in HKCU as per the msdn
  // standard: http://goo.gl/xjczJ.
  static void GetRegisteredBrowsers(
      std::map<base::string16, base::string16>* browsers);

  // Returns the suffix this user's Chrome install is registered with.
  // Always returns the empty string on system-level installs.
  //
  // This method is meant for external methods which need to know the suffix of
  // the current install at run-time, not for install-time decisions.
  // There are no guarantees that this suffix will not change later:
  // (e.g. if two user-level installs were previously installed in parallel on
  // the same machine, both without admin rights and with no user-level install
  // having claimed the non-suffixed HKLM registrations, they both have no
  // suffix in their progId entries (as per the old suffix rules). If they were
  // to both fully register (i.e. click "Make Chrome Default" and go through
  // UAC; or upgrade to Win8 and get the automatic no UAC full registration)
  // they would then both get a suffixed registration as per the new suffix
  // rules).
  //
  // |chrome_exe| The path to the currently installed (or running) chrome.exe.
  static base::string16 GetCurrentInstallationSuffix(
      const base::FilePath& chrome_exe);

  // Returns the AppUserModelId. This identifier is unconditionally suffixed
  // with a unique id for this user on user-level installs (in contrast to other
  // registration entries which are suffixed as described in
  // GetCurrentInstallationSuffix() above).
  static base::string16 GetBrowserModelId(bool is_per_user_install);

  // Returns an AppUserModelId composed of each member of |components| separated
  // by dots.
  // The returned appid is guaranteed to be no longer than
  // chrome::kMaxAppModelIdLength (some of the components might have been
  // shortened to enforce this).
  static base::string16 BuildAppUserModelId(
      const std::vector<base::string16>& components);

  // Returns true if Chrome can make itself the default browser without relying
  // on the Windows shell to prompt the user. This is the case for versions of
  // Windows prior to Windows 8.
  static bool CanMakeChromeDefaultUnattended();

  enum InteractiveSetDefaultMode {
    // The intent picker is opened with the different choices available to the
    // user.
    INTENT_PICKER,
    // The Windows default apps settings page is opened with the current default
    // app focused.
    SYSTEM_SETTINGS,
  };

  // Returns the interactive mode that should be used to set the default browser
  // or default protocol client on Windows 8+.
  static InteractiveSetDefaultMode GetInteractiveSetDefaultMode();

  // Returns the DefaultState of Chrome for HTTP and HTTPS and updates the
  // default browser beacons as appropriate.
  static DefaultState GetChromeDefaultState();

  // Returns the DefaultState of the Chrome instance with the specified path for
  // HTTP and HTTPs and updates the default browser beacons as appropriate.
  static DefaultState GetChromeDefaultStateFromPath(
      const base::FilePath& chrome_exe);

  // Returns the DefaultState of Chrome for |protocol|.
  static DefaultState GetChromeDefaultProtocolClientState(
      const base::string16& protocol);

  // Make Chrome the default browser. This function works by going through
  // the url protocols and file associations that are related to general
  // browsing, e.g. http, https, .html etc., and requesting to become the
  // default handler for each. If any of these fails the operation will return
  // false to indicate failure, which is consistent with the return value of
  // shell_integration::GetDefaultBrowser.
  //
  // In the case of failure any successful changes will be left, however no
  // more changes will be attempted.
  // TODO(benwells): Attempt to undo any changes that were successfully made.
  // http://crbug.com/83970
  //
  // shell_change: Defined whether to register as default browser at system
  //               level or user level. If value has ShellChange::SYSTEM_LEVEL
  //               we should be running as admin user.
  // chrome_exe: The chrome.exe path to register as default browser.
  // elevate_if_not_admin: On Vista if user is not admin, try to elevate for
  //                       Chrome registration.
  static bool MakeChromeDefault(int shell_change,
                                const base::FilePath& chrome_exe,
                                bool elevate_if_not_admin);

  // Opens the Apps & Features page in the Windows settings in branded builds.
  //
  // This function DCHECKS that it is only called on Windows 10 or higher.
  static bool LaunchUninstallAppsSettings();

  // Windows 8: Shows and waits for the "How do you want to open webpages?"
  // dialog if Chrome is not already the default HTTP/HTTPS handler. Also does
  // XP-era registrations if Chrome is chosen or was already the default. Do
  // not use on pre-Win8 OSes.
  //
  // Windows 10: The associations dialog cannot be launched so the settings
  // dialog focused on default apps is launched. The function does not wait
  // in this case.
  //
  // |chrome_exe| The chrome.exe path to register as default browser.
  static bool ShowMakeChromeDefaultSystemUI(const base::FilePath& chrome_exe);

  // Make Chrome the default application for a protocol.
  // chrome_exe: The chrome.exe path to register as default browser.
  // protocol: The protocol to register as the default handler for.
  static bool MakeChromeDefaultProtocolClient(const base::FilePath& chrome_exe,
                                              const base::string16& protocol);

  // Shows and waits for the Windows 8 "How do you want to open links of this
  // type?" dialog if Chrome is not already the default |protocol|
  // handler. Also does XP-era registrations if Chrome is chosen or was already
  // the default for |protocol|. Do not use on pre-Win8 OSes.
  //
  // |chrome_exe| The chrome.exe path to register as default browser.
  // |protocol| is the protocol being registered.
  static bool ShowMakeChromeDefaultProtocolClientSystemUI(
      const base::FilePath& chrome_exe,
      const base::string16& protocol);

  // Registers Chrome as a potential default browser and handler for filetypes
  // and protocols.
  // If Chrome is already registered, this method is a no-op.
  // This method requires write access to HKLM (prior to Win8) so is just a
  // best effort deal.
  // If write to HKLM is required, but fails, and:
  // - |elevate_if_not_admin| is true (and OS is Vista or above):
  //   tries to launch setup.exe with admin privileges (by prompting the user
  //   with a UAC) to do these tasks.
  // - |elevate_if_not_admin| is false (or OS is XP):
  //   adds the ProgId entries to HKCU. These entries will not make Chrome show
  //   in Default Programs but they are still useful because Chrome can be
  //   registered to run when the user clicks on an http link or an html file.
  //
  // |chrome_exe| full path to chrome.exe.
  // |unique_suffix| Optional input. If given, this function appends the value
  // to default browser entries names that it creates in the registry.
  // Currently, this is only used to continue an install with the same suffix
  // when elevating and calling setup.exe with admin privileges as described
  // above.
  // |elevate_if_not_admin| if true will make this method try alternate methods
  // as described above. This should only be true when following a user action
  // (e.g. "Make Chrome Default") as it allows this method to UAC.
  //
  // Returns true if Chrome is successfully registered (or already registered).
  static bool RegisterChromeBrowser(const base::FilePath& chrome_exe,
                                    const base::string16& unique_suffix,
                                    bool elevate_if_not_admin);

  // Same as RegisterChromeBrowser above, except that we don't stop early if
  // there is an error adding registry entries and we disable rollback.
  // |elevate_if_not_admin| is false and unique_suffix is empty.
  static void RegisterChromeBrowserBestEffort(const base::FilePath& chrome_exe);

  // This method declares to Windows that Chrome is capable of handling the
  // given protocol. This function will call the RegisterChromeBrowser function
  // to register with Windows as capable of handling the protocol, if it isn't
  // currently registered as capable.
  // Declaring the capability of handling a protocol is necessary to register
  // as the default handler for the protocol in Vista and later versions of
  // Windows.
  //
  // If called by the browser and elevation is required, it will elevate by
  // calling setup.exe which will again call this function with elevate false.
  //
  // |chrome_exe| full path to chrome.exe.
  // |unique_suffix| Optional input. If given, this function appends the value
  // to default browser entries names that it creates in the registry.
  // |protocol| The protocol to register as being capable of handling.s
  // |elevate_if_not_admin| if true will make this method try alternate methods
  // as described above.
  static bool RegisterChromeForProtocol(const base::FilePath& chrome_exe,
                                        const base::string16& unique_suffix,
                                        const base::string16& protocol,
                                        bool elevate_if_not_admin);

  // Removes installed shortcut(s) at |location|.
  // |level|: CURRENT_USER to remove per-user shortcuts, or SYSTEM_LEVEL to
  // remove all-users shortcuts.
  // |target_exe|: Shortcut target exe; shortcuts will only be deleted when
  // their target is |target_exe|.
  // If |location| is a Chrome-specific folder, it will be deleted as well.
  // Returns true if all shortcuts pointing to |target_exe| are successfully
  // deleted, including the case where no such shortcuts are found.
  static bool RemoveShortcuts(ShortcutLocation location,
                              ShellChange level,
                              const base::FilePath& target_exe);

  // Updates the target of all shortcuts in |location| that satisfy the
  // following:
  // - the shortcut's original target is |old_target_exe|,
  // - the original arguments are non-empty.
  // If the shortcut's icon points to |old_target_exe|, then it also gets
  // redirected to |new_target_exe|.
  // Returns true if all updates to matching shortcuts are successful, including
  // the vacuous case where no matching shortcuts are found.
  static bool RetargetShortcutsWithArgs(ShortcutLocation location,
                                        ShellChange level,
                                        const base::FilePath& old_target_exe,
                                        const base::FilePath& new_target_exe);

  typedef base::RefCountedData<base::AtomicFlag> SharedCancellationFlag;

  // Appends Chrome shortcuts with disallowed arguments to |shortcuts| if
  // not nullptr. If |do_removal|, also removes disallowed arguments from
  // those shortcuts. This method will abort and return false if |cancel| is
  // non-nullptr and gets set at any point during this call.
  static bool ShortcutListMaybeRemoveUnknownArgs(
      ShortcutLocation location,
      ShellChange level,
      const base::FilePath& chrome_exe,
      bool do_removal,
      const scoped_refptr<SharedCancellationFlag>& cancel,
      std::vector<std::pair<base::FilePath, base::string16>>* shortcuts);

  // Resets file attributes on shortcuts to a known good default value.
  // Ensures that Chrome shortcuts are not hidden from the user.
  // Returns true if all updates to matching shortcuts are successful or if no
  // matching shortcuts were found.
  static bool ResetShortcutFileAttributes(ShortcutLocation location,
                                          ShellChange level,
                                          const base::FilePath& chrome_exe);

  // Sets |suffix| to the base 32 encoding of the md5 hash of this user's sid
  // preceded by a dot.
  // This is guaranteed to be unique on the machine and 27 characters long
  // (including the '.').
  // This suffix is then meant to be added to all registration that may conflict
  // with another user-level Chrome install.
  // Note that prior to Chrome 21, the suffix registered used to be the user's
  // username (see GetOldUserSpecificRegistrySuffix() below). We still honor old
  // installs registered that way, but it was wrong because some of the
  // characters allowed in a username are not allowed in a ProgId.
  // Returns true unless the OS call to retrieve the username fails.
  // NOTE: Only the installer should use this suffix directly. Other callers
  // should call GetCurrentInstallationSuffix().
  static bool GetUserSpecificRegistrySuffix(base::string16* suffix);

  // Sets |suffix| to this user's username preceded by a dot. This suffix should
  // only be used to support legacy installs that used this suffixing
  // style.
  // Returns true unless the OS call to retrieve the username fails.
  // NOTE: Only the installer should use this suffix directly. Other callers
  // should call GetCurrentInstallationSuffix().
  static bool GetOldUserSpecificRegistrySuffix(base::string16* suffix);

  // Associates a set of file extensions with a particular application in the
  // Windows registry, for the current user only. If an extension has no
  // existing default association, the given application becomes the default.
  // Otherwise, the application is added to the Open With menu for this type,
  // but does not become the default.
  //
  // |prog_id| is the ProgId used by Windows for file associations with this
  // application. Must not be empty or start with a '.'.
  // |command_line| is the command to execute when opening a file via this
  // association. It must not contain the Windows filename placeholder "%1";
  // this function will register |command_line| plus the filename placeholder.
  // |application_name| is the friendly name displayed for this application in
  // the Open With menu.
  // |file_type_name| is the friendly name for files of these types when
  // associated with this application by default.
  // |icon_path| is the path of the icon displayed for this application in the
  // Open With menu, and used for files of these types when associated with this
  // application by default.
  // |file_extensions| is the set of extensions to associate. They must not be
  // empty or start with a '.'.
  // Returns true on success, false on failure.
  static bool AddFileAssociations(
      const base::string16& prog_id,
      const base::CommandLine& command_line,
      const base::string16& application_name,
      const base::string16& file_type_name,
      const base::FilePath& icon_path,
      const std::set<base::string16>& file_extensions);

  // Deletes all associations with a particular application in the Windows
  // registry, for the current user only.
  // |prog_id| is the ProgId used by Windows for file associations with this
  // application, as given to AddFileAssociations. All information associated
  // with this name will be deleted.
  static bool DeleteFileAssociations(const base::string16& prog_id);

  // Adds an application entry and metadata sub-entries to
  // HKCU\SOFTWARE\classes\<prog_id> capable of handling file type /
  // protocol associations.
  //
  // |prog_id| is the ProgId used by Windows to uniquely identity this
  // application. Must not be empty or start with a '.'.
  // |shell_open_command_line| is the command to execute when opening the app
  // via association.
  // |application_name| is the friendly name displayed for this application in
  // the Open With menu.
  // |application_description| is the description for this application to be
  // displayed by certain Windows settings dialogs.
  // |icon_path| is the path of the icon displayed for this application in the
  // Open With menu, and used for default files / protocols associated with this
  // application.
  static bool AddApplicationClass(
      const base::string16& prog_id,
      const base::CommandLine& shell_open_command_line,
      const base::string16& application_name,
      const base::string16& application_description,
      const base::FilePath& icon_path);

  // Removes all entries of an application at HKCU\SOFTWARE\classes\<prog_id>.
  static bool DeleteApplicationClass(const base::string16& prog_id);

  // Returns the app name and file associations registered for a particular
  // application in the Windows registry. If there is no entry in the registry
  // for |prog_id|, nothing will be returned.
  static FileAssociationsAndAppName GetFileAssociationsAndAppName(
      const base::string16& prog_id);

  // Retrieves the file path of the application registered as the
  // shell->open->command for |prog_id|. This only queries the user's
  // registered applications in HKCU. If |prog_id| is for an app that is
  // unrelated to the user's browser, it will still return the application
  // registered for |prog_id|.
  static base::FilePath GetApplicationPathForProgId(
      const base::string16& prog_id);

  // This method converts all the RegistryEntries from the given list to
  // Set/CreateRegWorkItems and runs them using WorkItemList.
  // |best_effort_no_rollback| is used to set WorkItemList::set_rollback_enabled
  // and WorkItemList::set_best_effort.
  static bool AddRegistryEntries(
      HKEY root,
      const std::vector<std::unique_ptr<RegistryEntry>>& entries,
      bool best_effort_no_rollback = false);

 private:
  DISALLOW_COPY_AND_ASSIGN(ShellUtil);
};

#endif  // CHROME_INSTALLER_UTIL_SHELL_UTIL_H_