Hi Zijun, On 2023-06-20 20:21, Zijun Zhao wrote: > Hi Alejandro, > I already created the patch attached below. How to add it to this > page? Do I need to use git push, or just provide the patch? Could you > help put it in .SH VERSIONS? Thank you! > Best, > Zijun Zhao I've applied the patch. (You just need to provide the patch, as you did. I apply and push it.) Thanks! Alex > > On Fri, May 19, 2023 at 3:42 PM Alejandro Colomar > <alx.manpages@xxxxxxxxx> wrote: >> >> On 5/20/23 00:21, enh wrote: >>> On Fri, May 19, 2023 at 1:03 AM Alejandro Colomar >>> <alx.manpages@xxxxxxxxx> wrote: >> [...] >> >>>> You'll also need to add _Nullable to the function prototypes in the >>>> SYNOPSIS. >>> >>> heh, funnily enough, zijunzhao's adding exactly those annotations to >>> the bionic headers, which is how we stumbled across this. >> >> :) >> >>> >>>> BTW, I see that glibc still requires nonnull in gettimeofday(3). It's >>>> only settimeofday(3) that is nullable. >>> >>> yeah, but the _kernel_ allows null in both (see kernel/time/time.c), >>> and this is section 2 of the man page. it's unclear to me whether >>> that's worth calling out up here, or should be down in the >>> Linux-specific section? (this page seems to be written as if it cares >>> about Hurd? "On a non-Linux kernel, with glibc ...".) >> >> Yes, we care about hurd, and non-g libc, in this page and others. >> Normally, I would be cautious, and specify the strictest prototype of >> all implementations about which I care, but in this case, glibc seems >> unnecessarily restrictive, and I'm ready to add _Nullable if the kernel >> and some libc support that. However, as a caution, please add a >> (CAVEATS?) section documenting that glibc doesn't allow NULL there. >> Or maybe keep the SYNOPSIS without _Nullable, and have some VERSIONS >> section specifying that other libcs and the kernel support NULL. >> >>> >>>> See: >>>> >>>> >>>> $ grepc gettimeofday /usr/include/*/sys/time.h >>>> /usr/include/x86_64-linux-gnu/sys/time.h:67: >>>> extern int gettimeofday (struct timeval *__restrict __tv, >>>> void *__restrict __tz) __THROW __nonnull ((1)); >>>> >>>> >>>> /usr/include/x86_64-linux-gnu/sys/time.h:75: >>>> # define gettimeofday __gettimeofday64 >>>> >>>> >>>> $ grepc settimeofday /usr/include/*/sys/time.h >>>> /usr/include/x86_64-linux-gnu/sys/time.h:86: >>>> extern int settimeofday (const struct timeval *__tv, >>>> const struct timezone *__tz) >>>> __THROW; >>>> >>>> >>>> /usr/include/x86_64-linux-gnu/sys/time.h:106: >>>> # define settimeofday __settimeofday64 >>>> >>>> >>>> And while NULL may be non-UB, the manual page is not very clear on why >>>> someone would want to call these functions with NULL. Could you >>>> please also explain why would someone want to call these functions >>>> with NULL? (Let's discuss it in the list, and then we see what >>>> wording we use for the page.) >>> >>> so there are definitely several orders of magnitude more users of a >>> null timezone --- most callers don't want that (not least because >>> glibc seems to not fill it out anyway? musl certainly doesn't, >>> implementing gettimeofday() in terms of clock_gettime() instead). >>> >>> the users for a null time (and non-null timezone; i haven't seen >>> anyone -- not even a test -- pass null for both!) are interesting. >>> Android's init uses settimeofday() with only a timezone, but -- >>> although the timezone to use is settable in device-specific init >>> scripts -- for devices in our tree, that's actually always 0. there's >>> other proprietary (non-Google) code that uses gettimeofday() with only >>> a timezone, and i'm honestly not sure whether it's deliberate that >>> it's asking the _kernel_ for the timezone or not (i'm guessing they >>> want the device timezone rather than the app timezone, but i do not >>> believe there are devices where the _kernel_ timezone matches the >>> device timezone?). certainly both of these use cases seem worth >>> following up on, and i will do. >> >> Please. And thanks for the details! >> >>> >>> but looking at musl (which ignores tz in both cases) it seems like the >>> most impactful change would be to fix "The functions gettimeofday() >>> and settimeofday() can get and set the time as well as a timezone" :-) >> >> :-) >> >> Makes sense; although it would be worth being clear about if that's >> really true, and if libcs do support that as well as the kernel. >> >>> >>> it also seems like an improvement to really call out the libc/kernel >>> differences more clearly though. >> >> Sure. Many pages have a dedicated subsection. Feel free to add it >> to this page. I'd put it in .SH VERSIONS. >> >> $ grep -rn 'C library/kernel differences' man* >> man2/sigprocmask.2:120:.SS C library/kernel differences >> man2/setreuid.2:168:.SS C library/kernel differences >> man2/brk.2:126:.SS C library/kernel differences >> man2/sigwaitinfo.2:114:.SS C library/kernel differences >> man2/gethostname.2:122:.SS C library/kernel differences >> man2/getcpu.2:73:.SS C library/kernel differences >> man2/fork.2:263:.SS C library/kernel differences >> man2/epoll_wait.2:258:.SS C library/kernel differences >> man2/wait4.2:157:.SS C library/kernel differences >> man2/stat.2:355:.SS C library/kernel differences >> man2/sigsuspend.2:74:.SS C library/kernel differences >> man2/access.2:40: /* But see C library/kernel differences, below */ >> man2/access.2:285:.SS C library/kernel differences >> man2/clock_getres.2:354:.SS C library/kernel differences >> man2/getpid.2:57:.SS C library/kernel differences >> man2/setfsgid.2:57:.SS C library/kernel differences >> man2/getgroups.2:142:.SS C library/kernel differences >> man2/sigaction.2:946:.SS C library/kernel differences >> man2/setresuid.2:100:.SS C library/kernel differences >> man2/readv.2:290:.SS C library/kernel differences >> man2/readv.2:342:.SS Historical C library/kernel differences >> man2/open.2:1393:.SS C library/kernel differences >> man2/setgid.2:58:.SS C library/kernel differences >> man2/setfsuid.2:97:.SS C library/kernel differences >> man2/ptrace.2:2814:.SS C library/kernel differences >> man2/poll.2:382:.SS C library/kernel differences >> man2/sigreturn.2:130:.SS C library/kernel differences >> man2/eventfd.2:267:.SS C library/kernel differences >> man2/mmap.2:729:.SS C library/kernel differences >> man2/_exit.2:104:.SS C library/kernel differences >> man2/time.2:86:.SS C library/kernel differences >> man2/pread.2:101:.SS C library/kernel differences >> man2/seccomp.2:975:.IR "C library/kernel differences" . >> man2/setuid.2:104:.SS C library/kernel differences >> man2/sched_setaffinity.2:95:return 0 (but see "C library/kernel differences" below, >> man2/sched_setaffinity.2:220:.SS C library/kernel differences >> man2/select.2:559:.SS C library/kernel differences >> man2/sigpending.2:52:.SS C library/kernel differences >> man2/posix_fadvise.2:135:.SS C library/kernel differences >> man2/gettimeofday.2:173:.SS C library/kernel differences >> man2/uname.2:83:.SS C library/kernel differences >> man2/clone.2:1576:.SS C library/kernel differences >> man2/getpriority.2:185:.SS C library/kernel differences >> man2/signalfd.2:331:.SS C library/kernel differences >> man2/timer_create.2:225:.SS C library/kernel differences >> man2/wait.2:464:.SS C library/kernel differences >> man2/nice.2:80:.SS C library/kernel differences >> man2/chmod.2:303:.SS C library/kernel differences >> man2/seteuid.2:114:.SS C library/kernel differences >> man3/getcwd.3:217:.SS C library/kernel differences >> man3/killpg.3:98:.SS C library/kernel differences >> man3/mq_notify.3:174:.SS C library/kernel differences >> man3/mq_open.3:269:.SS C library/kernel differences >> man3/sigqueue.3:118:.SS C library/kernel differences >> man3type/epoll_event.3type:37:.SS C library/kernel differences >> man7/man-pages.7:402:.I "C library/kernel differences" >> >> Cheers, >> Alex >> >>> >>>> Thanks! >>>> Alex >>>> >>>> -- >>>> <http://www.alejandro-colomar.es/> >>>> GPG key fingerprint: A9348594CE31283A826FBDD8D57633D441E25BB5 >>>> >> >> -- >> <http://www.alejandro-colomar.es/> >> GPG key fingerprint: A9348594CE31283A826FBDD8D57633D441E25BB5 -- <http://www.alejandro-colomar.es/> GPG key fingerprint: A9348594CE31283A826FBDD8D57633D441E25BB5
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