[dkarl]

> why the file API so hard to use that even experts make mistakes?

Sounds like Worse Is Better™: operating systems that tried to present safer abstractions were at a disadvantage compared to operating systems that shipped whatever was easiest to implement.

(I'm not an expert in the history, just observing the surface similarity and hoping someone with more knowledge can substantiate it.)

[ncruces]

POSIX file locking is clearly modeled around whatever was simplest to implement, although it makes no sense at all.

[tjalfi]

Jeremy Allison tracked down why POSIX standardized this behavior[0].

The reason is historical and reflects a flaw in the POSIX standards process, in my opinion, one that hopefully won't be repeated in the future. I finally tracked down why this insane behavior was standardized by the POSIX committee by talking to long-time BSD hacker and POSIX standards committee member Kirk McKusick (he of the BSD daemon artwork). As he recalls, AT&T brought the current behavior to the standards committee as a proposal for byte-range locking, as this was how their current code implementation worked. The committee asked other ISVs if this was how locking should be done. The ISVs who cared about byte range locking were the large database vendors such as Oracle, Sybase and Informix (at the time). All of these companies did their own byte range locking within their own applications, none of them depended on or needed the underlying operating system to provide locking services for them. So their unanimous answer was "we don't care". In the absence of any strong negative feedback on a proposal, the committee added it "as-is", and took as the desired behavior the specifics of the first implementation, the brain-dead one from AT&T.

[0] https://www.samba.org/samba/news/articles/low_point/tale_two...

[ncruces]

The most egregious part of it for me is that if I open and close a file I might be canceling some other library's lock that I'm completely unaware of.

I resisted using them in my SQLite VFS, until I partially relented for WAL locks.

I wish more platforms embraced OFD locks. macOS has them, but hidden. illumos fakes them with BSD locks (which is worse, actually). The BSDs don't add them. So it's just Linux, and Windows with sane locking. In some ways Windows is actually better (supports timeouts).

[trinix912]

> Sounds like Worse Is Better™: operating systems that tried to present safer abstractions were at a disadvantage compared to operating systems that shipped whatever was easiest to implement.

What about the Windows API? Windows is a pretty successful OS with a less leaky FS abstraction. I know it's a totally different deal than POSIX (files can't be devices etc), the FS function calls require a seemingly absurd number of arguments, but it does seem safer and clearer what's going to happen.

[thfuran]

Why does that seem more likely than file system API simply not having been a major factor in the success of failure of OSes?