Add a file locking API to std::io::fs

[Dretch]

Some sort of portable advisory file locking API would be useful to me.

Perhaps like http://www.php.net/manual/en/function.flock.php.

I can look into sending a pull request if there are no objections.

[alexcrichton]

It doesn't look like libuv currently has support for this, so this would probably involve adding support for a locking API to libuv as well. Sounds like a good idea though!

[thestinger]

File locking is a disaster, and doesn't really work properly:

• http://0pointer.de/blog/projects/locking.html
• http://www.samba.org/samba/news/articles/low_point/tale_two_stds_os2.html

The semantics aren't going to be portable across operating systems, because POSIX locks are unusable. The BSD locking API is somewhat sane, but I don't think you're going to find a 1:1 equivalent on Windows.

[brson]

I also think that locking is too unportable to put in std.

[gereeter]

If this is too unportable to be implemented, should this be closed?

[alexcrichton]

Yes, it sounds like this shouldn't be added to libstd at this time.