Re: flock

> Hi there,
> 
> a while ago, I implemented advisory locking support to the VFS. 
> However, I didn't add the non-POSIX flock() function; this locking 
> functionality is only available using the POSIX defined fcntl(..., 
> F_SETLK, ...) method.
> Should we add flock() as well even though it's not part of POSIX?
> 

Beware, though fcntl(F_SETLK) uses a struct flock, this one has nothing 
to do and is not compatible with it, and has a different semantic (for 
ex one removes the lock on exec or a close, the other doesn't). I 
scratched my head several days on them.
This one is a BSDism, but I think several apps wants it (samba ?).

IIRC Linux implements both via a single call with a flag to indicate 
the semantics used, and forbids using both on the same file.

You can also add lockf() but this one is just a simple call to fcntl(), 
and might actually be already don't in glibc.

François.

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