fsync, rename, O_ATOMIC/O_PONIES

[Olaf van der Spek]

On 2-3-2012 14:12, Christoph Hellwig wrote:
>> I'd like to ask:
>> - Is there a tool to log all unsafe operations?
>
> What is an unsafe operation?  Anything that's dumb and might lose data?

For example

> The possibilities are sheer endless.

And?

>> - What is the *right* way to update a file?
>
>   fd = open(tmpfile, ...);
>   write(fd, ...);  // or any other update
>   fdatasync(fd);
>   rename(tmpfile, realfile);

Argh, come on.
That's not real and it's not complete. tmpfile is undefined, errors 
aren't handled and you have lots of unlisted assumptions or regressions.

Olaf