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qTox/src/profilelocker.h
tux3 42d7a7bcef
Assert profile locks before writing
This fixes the potential edge case where a frozen then unfrozen qTox instance could have its locks delete by a new qTox instance.

We now check that we still own our locks, restoring them if we can, before saving
2015-04-24 21:05:19 +02:00

47 lines
1.6 KiB
C++

#ifndef PROFILELOCKER_H
#define PROFILELOCKER_H
#include <QLockFile>
#include <memory>
/// Locks a Tox profile so that multiple instances can not use the same profile.
/// Only one lock can be acquired at the same time, which means
/// that there is little need for manually unlocking.
/// The current lock will expire if you exit or acquire a new one.
class ProfileLocker
{
private:
ProfileLocker()=delete;
public:
/// Checks if a profile is currently locked by *another* instance
/// If we own the lock, we consider it lockable
/// There is no guarantee that the result will still be valid by the
/// time it is returned, this is provided on a best effort basis
static bool isLockable(QString profile);
/// Tries to acquire the lock on a profile, will not block
/// Returns true if we already own the lock
static bool lock(QString profile);
/// Releases the lock on the current profile
static void unlock();
/// Releases all locks on all profiles
/// DO NOT call unless all we're the only qTox instance
/// and we don't hold any lock yet.
static void clearAllLocks();
/// Check that we actually own the lock
/// In case the file was deleted on disk, restore it
/// If we can't get a lock, exit qTox immediately
/// If we never had a lock in the firt place, exit immediately
static void assertLock();
private:
static QString lockPathFromName(const QString& name);
static void deathByBrokenLock(); ///< Print an error then exit immediately
private:
static std::unique_ptr<QLockFile> lockfile;
static QString curLockName;
};
#endif // PROFILELOCKER_H