On Mon, Jul 26, 2021 at 10:37:03AM -0600, Todd C. Miller wrote: > On Mon, 26 Jul 2021 07:55:00 -0500, Scott Cheloha wrote: > > > [...] > > > > Anyway, updated patch. No mention of SIGALRM or alarm(3) except in > > the History section. > > I think this is OK for now. > > > Still wondering whether we need an Errors section to mention that > > sleep(3) can set errno. > > POSIX doesn't define any errors. Of the errors returned by nanosleep, > only EINTR is really possible. I guess we could save & restore > errno in sleep.c but I don't see any implementations that actually > do that. I only checked illumos, glibc and musl though.
We definitely don't want to save/restore. I meant more like a simple acknowledgement for the programmer. Knowing what can set errno is helpful. We do it for other library functions where some part of the functionality is implemented with a system call. In other manpages we say something like: The .Fn foo function may fail and set .Va errno for any of the errors specified for the .Fn bar 2 routine. See, e.g., `man 3 nice` or `man 3 fopen`. Then again, there's really only one error. Maybe we should just duplicate the information in sleep.3. What about this? The .Fn sleep function sets .Va errno to .Dv EINTR if it is interrupted by the delivery of a signal. Index: sleep.3 =================================================================== RCS file: /cvs/src/lib/libc/gen/sleep.3,v retrieving revision 1.16 diff -u -p -r1.16 sleep.3 --- sleep.3 8 Feb 2020 01:09:57 -0000 1.16 +++ sleep.3 27 Jul 2021 22:13:22 -0000 @@ -32,7 +32,7 @@ .Os .Sh NAME .Nm sleep -.Nd suspend process execution for interval measured in seconds +.Nd suspend execution for an interval of seconds .Sh SYNOPSIS .In unistd.h .Ft unsigned int @@ -40,41 +40,46 @@ .Sh DESCRIPTION The .Fn sleep -function suspends execution of the calling process until either +function suspends execution until at least the given number of .Fa seconds -seconds have elapsed or a signal is delivered to the process and its -action is to invoke a signal-catching function or to terminate the -process. -The suspension time may be longer than requested due to the -scheduling of other activity by the system. +have elapsed or an unmasked signal is delivered to the calling thread. .Pp -This function is implemented using -.Xr nanosleep 2 -by pausing for -.Fa seconds -seconds or until a signal occurs. -Consequently, in this implementation, -sleeping has no effect on the state of process timers, -and there is no special handling for -.Dv SIGALRM . +This version of +.Fn sleep +is implemented with +.Xr nanosleep 2 , +so delivery of any unmasked signal will terminate the sleep early, +even if +.Dv SA_RESTART +is set with +.Xr sigaction 2 +for the interrupting signal. .Sh RETURN VALUES -If the +If +.Fn sleep +sleeps for the full count of +.Fa seconds +it returns 0. +Otherwise, +.Fn sleep +returns the number of seconds remaining from the original request. +.Sh ERRORS +The .Fn sleep -function returns because the requested time has elapsed, the value -returned will be zero. -If the -.Fn sleep -function returns due to the delivery of a signal, the value returned -will be the unslept amount (the request time minus the time actually -slept) in seconds. +function sets +.Va errno +to +.Dv EINTR +if it is interrupted by the delivery of a signal. .Sh SEE ALSO .Xr sleep 1 , -.Xr nanosleep 2 +.Xr nanosleep 2 , +.Xr sigaction 2 .Sh STANDARDS The .Fn sleep function conforms to -.St -p1003.1-90 . +.St -p1003.1-2008 . .Sh HISTORY A .Fn sleep
