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Date: Thu, 11 Dec 2014 21:33:45 -0500 From: Morten Welinder <mwelinder@...il.com> To: musl@...ts.openwall.com Subject: Re: stdio [de]merits discussion [Re: possible getopt stderr output changes] It sounds a bit like the main beef you have with printf is that it pulls in floating point stuff. Absent that, it really isn't a lot of code and it really doesn't eat much stack space. So maybe what you are looking for is a way to compile away all floating point support. M. On Thu, Dec 11, 2014 at 6:05 PM, Laurent Bercot <ska-dietlibc@...rnet.org> wrote: > On 11/12/2014 18:51, Rich Felker wrote: >> >> I like it because in all but the tiniest programs, you end up needing >> this kind of functionality, and whenever somebody rolls their own, >> it's inevitably 10x to 100x larger and uglier than musl's printf core. > > > You haven't tried skalibs. ;) > (Sure, calling format functions individually is far from being as > convenient, but the resulting code path is much shorter and there's > no bloat.) > I agree we need standards. I just wish the existing standards were > better, and I don't want to be forced to use them. > > >> Of all that, the only thing contributing non-trivial size is floating >> point support. > > > Yes, that's the main thing, but it's an important one: in system > programming, floating point operations are uncommon - someone who > cares about code size is probably not using floating points. > > >> For seekable files, ftello can tell you. > > > Same thing: system programming is more about pipes and sockets than > seekable files. In applications that write files, the interesting > logic is probably not in the I/O, and they don't care. > > >> But it's perfectly usable for producing new output in >> cases where all write errors will simply result in failing the whole >> "make a file" operation. > > > I agree. > > >> This is solved by fflush before fclose. > > > I'm surprised that you of all people say this. What if another thread > writes to the FILE between the fflush and the fclose ? Granted, if the > situation arises, it's probably a programming error, but still, since > atomicity is a big thing for FILE, needing 2 operations instead of 1 > doesn't scream good design. > > >> GNU software (gnulib in particular) likes to ignore this problem by poking >> at internals; we gave them an alternate solution with musl a couple >> years back just to avoid this. :( > > > Jesus. And you still argue that it's a usable interface, if people have > to hack internal implementation details to get a simple readability > notification working ? > > >> For event-driven models, yes. For threaded models, it's quite usable >> and IMO it simplifies code by a a larger factor than the size it adds, >> in cases where it's sufficient. > > > "If you can't write asynchronous code, use threads and write synchronous > code." :-Þ > I agree that threads are a good paradigm to have, but the choice of > which model to use should not be dictated by the indigence of available > interfaces. > > >> The big thing it provides here is a standard point of synchronization >> for error messages in multithreaded programs. Otherwise there would be >> no lock for different library components to agree on to prevent >> interleaved error output. > > > write() guarantees atomicity up to PIPE_BUF bytes. I have never seen > an stderr error message that was bigger than that. > > >> Yes and no. There are some things that could have been done better, >> and some backwards-compatible additions that could be made to make it >> a lot more useful, but I think stdio still largely succeeds in freeing >> the programmer from having to spend lots of effort on IO code, for a >> large class of useful programs (certainly not all, though!). > > > I agree it's good enough for Hello World and applications that just > need very basic I/O. What irks me is that stdio sets a potential barrier > to designing better I/O interfaces, and people who need reliable I/O > management often still contort themselves to use stdio, and the results > are ugly. See the aforementioned gnulib case. > > -- > Laurent >
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