autoupdate_overview.md

AutoUpdate Overview

Dolphin's autoupdate procedure is spread through a number of files; this overview describes the update flow.

General notes:

• The updater is only supported on Windows and MacOS.
• There are four update frequency tracks: Dev (updated every commit), Beta (a few times a year), Stable (very rarely), and Disabled.
• Applications can't overwrite themselves so a separate application is responsible for actually updating the Dolphin executable and other files.
• The updater application needs to be able to also update itself, so it creates a copy which updates both Dolphin and the original updater. Every time Dolphin launches it deletes the updater copy (if it exists).

Class and file responsibilities:

• AutoUpdateChecker (UICommon/AutoUpdate.h): Checks if an update is available.
  • Verifies the updater is supported on the user's platform and hasn't been disabled.
  • Retrieves new version information from the update server.
  • Copies the updater application and launches the copy.
• Updater (DolphinQt/Updater.h): Serves as the interface between AutoUpdateChecker and Qt.
  • Spawns a background thread when Dolphin launches that calls AutoUpdateChecker.
  • Creates the update prompt window when an update is available.
  • If the user wants to update now, closes Dolphin.
• MacUpdater/main.m and MacUpdater/AppDelegate.mm: Entry point to MacOS updater.
  • Converts command line arguments to vector<string> and passes them to UpdaterCommon::RunUpdate().
• WinUpdater/main.cpp: Entry point to Windows updater.
  • Converts command line arguments to vector<string>.
  • Checks if updater has write access to the Dolphin executable directory. If not, attempts to relaunch itself with admin privileges (creating a User Account Control prompt).
  • Passes argument vector to UpdaterCommon::RunUpdate().
• UpdaterCommon/UpdaterCommon.cpp: Performs the actual update process.
  • Manages updater UI.
  • Fetches file manifests from update server for current and new versions.
  • Calculates file diff between versions.
  • Downloads and adds/replaces changed files and deletes removed files.
  • Verifies file hashes.
  • If the user updated immediately (rather than waiting for Dolphin to close before starting the update), starts Dolphin again when the update is complete.

Update flow:

• An update check is started in one of two ways:
  • When Dolphin is launched (unless in NoGUI or batch mode):
    • In main.cpp an instance of Updater is created and invokes start(), which is inherited from QThread and creates a new thread which performs the check off the main thread.
    • QThread::start() calls run() which is overridden in Updater and calls AutoUpdateChecker::CheckForUpdate().
  • When the user selects Help -> "Check for Updates..." in the main menu:
    • The menu option runs a callback to MenuBar::InstallUpdateManually().
    • The Config value for the update track is backed up to a temporary variable, then overwritten with "dev" to force a check for the latest version. After the check completes the original Config value is restored.
    • Updater::CheckForUpdate() is called, which calls AutoUpdateChecker::CheckForUpdate().
• AutoUpdateChecker::CheckForUpdate() checks if the selected track has a new version available.
  • If not the check ends. If the user started it, returns to Updater::CheckForUpdate() which tells the user they're up to date.
• Information about the update is passed to OnUpdateAvailable(), which is overridden by Updater.
• OnUpdateAvailable() creates a window displaying the update changelog and asks the user if they want to update now, update after Dolphin closes, not update, or never auto-update.
• If the user wants to update AutoUpdateChecker::TriggerUpdate() is called.
• TriggerUpdate() builds the command line arguments for the updater process, creates a copy of the updater executable, then runs the copy in a new process.
• TriggerUpdate() returns to OnUpdateAvailable(). If the user chose to update now, Dolphin's main window is closed which results in the Dolphin process ending.
• The updater process begins.
  • On MacOS (starts main() in MacUpdater/main.m):
    • Checks that the process received command line arguments. If not it tells the user the updater can't be launched directly and quits.
    • Calls NSApplicationMain(), which passes control to the AppDelegate defined in MacUpdater/AppDelegate.mm.
    • The command line arguments are converted to a vector<string> and passed to RunUpdater() in UpdaterCommon.h.
  • On Windows (starts wWinMain() in WinUpdater/Main.cpp):
    • Checks that the process received command line arguments. If not it tells the user the updater can't be launched directly and quits.
    • Attempts to open Updater.log in the same directory as Dolphin.exe. If this fails, checks to see if the process has admin privileges.
      • If not, attempts to relaunch the updater as admin. This will spawn a User Account Control prompt.
      • If the user declines the UAC prompt, or if the updater already has admin status, the update aborts.
    • Converts the command line arguments to a vector<string> and passes them to RunUpdater() in UpdaterCommon.h.
• RunUpdater() parses and validates the command line arguments, hides the updater UI, then waits for the Dolphin process to quit.
• RunUpdater() begins the actual update.
  • Fetches file manifests from update server for current and new versions.
  • Decompresses manifests and verifies their signatures.
  • Downloads and adds/replaces changed files and deletes removed files.
  • Verifies downloaded files match manifest hashes.
• If the user updated immediately (rather than waiting for Dolphin to close before starting the update), Dolphin restarts.
• As part of Dolphin's normal startup process, the Updater copy is deleted.