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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
/**
* We just started (we haven't written anything to disk yet) from
* `Paths.clean`. The backup directory may not exist.
*/
const STATE_CLEAN = "clean";
/**
* We know that `Paths.recovery` is good, either because we just read
* it (we haven't written anything to disk yet) or because have
* already written once to `Paths.recovery` during this session.
* `Paths.clean` is absent or invalid. The backup directory exists.
*/
const STATE_RECOVERY = "recovery";
/**
* We just started from `Paths.upgradeBackup` (we haven't written
* anything to disk yet). Both `Paths.clean`, `Paths.recovery` and
* `Paths.recoveryBackup` are absent or invalid. The backup directory
* exists.
*/
const STATE_UPGRADE_BACKUP = "upgradeBackup";
/**
* We just started without a valid session store file (we haven't
* written anything to disk yet). The backup directory may not exist.
*/
const STATE_EMPTY = "empty";
var sessionFileIOMutex = Promise.resolve();
// Ensure that we don't do concurrent I/O on the same file.
// Example usage:
// const unlock = await lockIOWithMutex();
// try {
// ... (Do I/O work here.)
// } finally { unlock(); }
function lockIOWithMutex() {
// Return a Promise that resolves when the mutex is free.
return new Promise(unlock => {
// Overwrite the mutex variable with a chained-on, new Promise. The Promise
// we returned to the caller can be called to resolve that new Promise
// and unlock the mutex.
sessionFileIOMutex = sessionFileIOMutex.then(() => {
return new Promise(unlock);
});
});
}
/**
* Interface dedicated to handling I/O for Session Store.
*/
export const SessionWriter = {
init(origin, useOldExtension, paths, prefs = {}) {
return SessionWriterInternal.init(origin, useOldExtension, paths, prefs);
},
/**
* Write the contents of the session file.
* @param state - May get changed on shutdown.
*/
async write(state, options = {}) {
const unlock = await lockIOWithMutex();
try {
return await SessionWriterInternal.write(state, options);
} finally {
unlock();
}
},
async wipe() {
const unlock = await lockIOWithMutex();
try {
return await SessionWriterInternal.wipe();
} finally {
unlock();
}
},
};
const SessionWriterInternal = {
// Path to the files used by the SessionWriter
Paths: null,
/**
* The current state of the session file, as one of the following strings:
* - "empty" if we have started without any sessionstore;
* - one of "clean", "recovery", "recoveryBackup", "cleanBackup",
* "upgradeBackup" if we have started by loading the corresponding file.
*/
state: null,
/**
* A flag that indicates we loaded a session file with the deprecated .js extension.
*/
useOldExtension: false,
/**
* Number of old upgrade backups that are being kept
*/
maxUpgradeBackups: null,
/**
* Initialize (or reinitialize) the writer.
*
* @param {string} origin Which of sessionstore.js or its backups
* was used. One of the `STATE_*` constants defined above.
* @param {boolean} a flag indicate whether we loaded a session file with ext .js
* @param {object} paths The paths at which to find the various files.
* @param {object} prefs The preferences the writer needs to know.
*/
init(origin, useOldExtension, paths, prefs) {
if (!(origin in paths || origin == STATE_EMPTY)) {
throw new TypeError("Invalid origin: " + origin);
}
// Check that all required preference values were passed.
for (let pref of [
"maxUpgradeBackups",
"maxSerializeBack",
"maxSerializeForward",
]) {
if (!prefs.hasOwnProperty(pref)) {
throw new TypeError(`Missing preference value for ${pref}`);
}
}
this.useOldExtension = useOldExtension;
this.state = origin;
this.Paths = paths;
this.maxUpgradeBackups = prefs.maxUpgradeBackups;
this.maxSerializeBack = prefs.maxSerializeBack;
this.maxSerializeForward = prefs.maxSerializeForward;
this.upgradeBackupNeeded = paths.nextUpgradeBackup != paths.upgradeBackup;
return { result: true };
},
/**
* Write the session to disk.
* Write the session to disk, performing any necessary backup
* along the way.
*
* @param {object} state The state to write to disk.
* @param {object} options
* - performShutdownCleanup If |true|, we should
* perform shutdown-time cleanup to ensure that private data
* is not left lying around;
* - isFinalWrite If |true|, write to Paths.clean instead of
* Paths.recovery
*/
async write(state, options) {
let exn;
let telemetry = {};
// Cap the number of backward and forward shistory entries on shutdown.
if (options.isFinalWrite) {
for (let window of state.windows) {
for (let tab of window.tabs) {
let lower = 0;
let upper = tab.entries.length;
if (this.maxSerializeBack > -1) {
lower = Math.max(lower, tab.index - this.maxSerializeBack - 1);
}
if (this.maxSerializeForward > -1) {
upper = Math.min(upper, tab.index + this.maxSerializeForward);
}
tab.entries = tab.entries.slice(lower, upper);
tab.index -= lower;
}
}
}
try {
if (this.state == STATE_CLEAN || this.state == STATE_EMPTY) {
// The backups directory may not exist yet. In all other cases,
// we have either already read from or already written to this
// directory, so we are satisfied that it exists.
await IOUtils.makeDirectory(this.Paths.backups);
}
if (this.state == STATE_CLEAN) {
// Move $Path.clean out of the way, to avoid any ambiguity as
// to which file is more recent.
if (!this.useOldExtension) {
await IOUtils.move(this.Paths.clean, this.Paths.cleanBackup);
} else {
// Since we are migrating from .js to .jsonlz4,
// we need to compress the deprecated $Path.clean
// and write it to $Path.cleanBackup.
let oldCleanPath = this.Paths.clean.replace("jsonlz4", "js");
let d = await IOUtils.read(oldCleanPath);
await IOUtils.write(this.Paths.cleanBackup, d, { compress: true });
}
}
let startWriteMs = Date.now();
let fileStat;
if (options.isFinalWrite) {
// We are shutting down. At this stage, we know that
// $Paths.clean is either absent or corrupted. If it was
// originally present and valid, it has been moved to
// $Paths.cleanBackup a long time ago. We can therefore write
// with the guarantees that we erase no important data.
await IOUtils.writeJSON(this.Paths.clean, state, {
tmpPath: this.Paths.clean + ".tmp",
compress: true,
});
fileStat = await IOUtils.stat(this.Paths.clean);
} else if (this.state == STATE_RECOVERY) {
// At this stage, either $Paths.recovery was written >= 15
// seconds ago during this session or we have just started
// from $Paths.recovery left from the previous session. Either
// way, $Paths.recovery is good. We can move $Path.backup to
// $Path.recoveryBackup without erasing a good file with a bad
// file.
await IOUtils.writeJSON(this.Paths.recovery, state, {
tmpPath: this.Paths.recovery + ".tmp",
backupFile: this.Paths.recoveryBackup,
compress: true,
});
fileStat = await IOUtils.stat(this.Paths.recovery);
} else {
// In other cases, either $Path.recovery is not necessary, or
// it doesn't exist or it has been corrupted. Regardless,
// don't backup $Path.recovery.
await IOUtils.writeJSON(this.Paths.recovery, state, {
tmpPath: this.Paths.recovery + ".tmp",
compress: true,
});
fileStat = await IOUtils.stat(this.Paths.recovery);
}
telemetry.FX_SESSION_RESTORE_WRITE_FILE_MS = Date.now() - startWriteMs;
telemetry.FX_SESSION_RESTORE_FILE_SIZE_BYTES = fileStat.size;
} catch (ex) {
// Don't throw immediately
exn = exn || ex;
}
// If necessary, perform an upgrade backup
let upgradeBackupComplete = false;
if (
this.upgradeBackupNeeded &&
(this.state == STATE_CLEAN || this.state == STATE_UPGRADE_BACKUP)
) {
try {
// If we loaded from `clean`, the file has since then been renamed to `cleanBackup`.
let path =
this.state == STATE_CLEAN
? this.Paths.cleanBackup
: this.Paths.upgradeBackup;
await IOUtils.copy(path, this.Paths.nextUpgradeBackup);
this.upgradeBackupNeeded = false;
upgradeBackupComplete = true;
} catch (ex) {
// Don't throw immediately
exn = exn || ex;
}
// Find all backups
let backups = [];
try {
let children = await IOUtils.getChildren(this.Paths.backups);
backups = children.filter(path =>
path.startsWith(this.Paths.upgradeBackupPrefix)
);
} catch (ex) {
// Don't throw immediately
exn = exn || ex;
}
// If too many backups exist, delete them
if (backups.length > this.maxUpgradeBackups) {
// Use alphanumerical sort since dates are in YYYYMMDDHHMMSS format
backups.sort();
// remove backup file if it is among the first (n-maxUpgradeBackups) files
for (let i = 0; i < backups.length - this.maxUpgradeBackups; i++) {
try {
await IOUtils.remove(backups[i]);
} catch (ex) {
exn = exn || ex;
}
}
}
}
if (options.performShutdownCleanup && !exn) {
// During shutdown, if auto-restore is disabled, we need to
// remove possibly sensitive data that has been stored purely
// for crash recovery. Note that this slightly decreases our
// ability to recover from OS-level/hardware-level issue.
// If an exception was raised, we assume that we still need
// these files.
await IOUtils.remove(this.Paths.recoveryBackup);
await IOUtils.remove(this.Paths.recovery);
}
this.state = STATE_RECOVERY;
if (exn) {
throw exn;
}
return {
result: {
upgradeBackup: upgradeBackupComplete,
},
telemetry,
};
},
/**
* Wipes all files holding session data from disk.
*/
async wipe() {
// Don't stop immediately in case of error.
let exn = null;
// Erase main session state file
try {
await IOUtils.remove(this.Paths.clean);
// Remove old extension ones.
let oldCleanPath = this.Paths.clean.replace("jsonlz4", "js");
await IOUtils.remove(oldCleanPath, {
ignoreAbsent: true,
});
} catch (ex) {
// Don't stop immediately.
exn = exn || ex;
}
// Wipe the Session Restore directory
try {
await IOUtils.remove(this.Paths.backups, { recursive: true });
} catch (ex) {
exn = exn || ex;
}
// Wipe legacy Session Restore files from the profile directory
try {
await this._wipeFromDir(PathUtils.profileDir, "sessionstore.bak");
} catch (ex) {
exn = exn || ex;
}
this.state = STATE_EMPTY;
if (exn) {
throw exn;
}
return { result: true };
},
/**
* Wipe a number of files from a directory.
*
* @param {string} path The directory.
* @param {string} prefix Remove files whose
* name starts with the prefix.
*/
async _wipeFromDir(path, prefix) {
// Sanity check
if (!prefix) {
throw new TypeError("Must supply prefix");
}
let exn = null;
let children = await IOUtils.getChildren(path, {
ignoreAbsent: true,
});
for (let entryPath of children) {
if (!PathUtils.filename(entryPath).startsWith(prefix)) {
continue;
}
try {
let { type } = await IOUtils.stat(entryPath);
if (type == "directory") {
continue;
}
await IOUtils.remove(entryPath);
} catch (ex) {
// Don't stop immediately
exn = exn || ex;
}
}
if (exn) {
throw exn;
}
},
};