time.3: miscellaneous manpage cleanup

- Change "tloc" variable to "now" to reinforce meaning.
- Simplify DESCRIPTION.
- No point in describing how gettimeofday(2) can fail here.
- Add a STANDARDS section.
- Rework the HISTORY section.

With input from jmc@, millert@, and schwarze@.

Thread: https://marc.info/?l=openbsd-tech&m=162766815024823&w=2

"reads fine" jmc@, ok schwarze@

diff --git a/lib/libc/gen/time.3 b/lib/libc/gen/time.3
index cc1bd43..84ad5ef 100644 (file)
--- a/lib/libc/gen/time.3
+++ b/lib/libc/gen/time.3
@@ -1,4 +1,4 @@
-.\"    $OpenBSD: time.3,v 1.16 2015/01/29 01:46:30 schwarze Exp $
+.\"    $OpenBSD: time.3,v 1.17 2021/12/06 00:15:01 cheloha Exp $
 .\"
 .\" Copyright (c) 1989, 1991, 1993
 .\"    The Regents of the University of California.  All rights reserved.
@@ -31,7 +31,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: January 29 2015 $
+.Dd $Mdocdate: December 6 2021 $
 .Dt TIME 3
 .Os
 .Sh NAME
@@ -40,48 +40,45 @@
 .Sh SYNOPSIS
 .In time.h
 .Ft time_t
-.Fn time "time_t *tloc"
+.Fn time "time_t *now"
 .Sh DESCRIPTION
 The
 .Fn time
-function returns the value of time in seconds since 0 hours, 0 minutes,
-0 seconds, January 1, 1970, Coordinated Universal Time (UTC).
-.Pp
-A copy of the time value may be saved to the area indicated by the
-pointer
-.Fa tloc .
-If
-.Fa tloc
-is a null pointer, no value is stored.
+function returns the the number of seconds elapsed since
+Jan 1 1970 00:00:00 UTC.
+This value is also written to
+.Fa now
+unless
+.Fa now
+is
+.Dv NULL .
 .Sh RETURN VALUES
-Upon successful completion,
+The
 .Fn time
-returns the value of time.
-Otherwise a value of
-.Po Fa time_t Pc Ns -1
-is returned and the global variable
-.Va errno
-is set to indicate the error.
-.Sh ERRORS
-The following error codes may be set in
-.Va errno :
-.Bl -tag -width Er
-.It Bq Er EFAULT
-An argument address referenced invalid memory.
-.El
+function is always successful,
+and no return value is reserved to indicate an error.
 .Sh SEE ALSO
 .Xr clock_gettime 2 ,
 .Xr gettimeofday 2 ,
 .Xr ctime 3
+.Sh STANDARDS
+The
+.Fn time
+function conforms to
+.St -p1003.1-2008 .
 .Sh HISTORY
 A
 .Fn time
 system call first appeared in
-.At v1
-and used to return time in sixtieths of a second in 32 bits,
-which was to guarantee a crisis every 2.26 years.
-Since
-.At v6 ,
-.Fn time
-scale was changed to seconds, extending the pre-crisis stagnation
-period up to a total of 68 years.
+.At v1 .
+That version counted time in sixtieths of a second with a 32-bit return value,
+ensuring an integer overflow crisis every 2.26 years.
+In
+.At v6
+the granularity of the return value was reduced to whole seconds,
+delaying the aforementioned crisis until 2038.
+In
+.Bx 4.1c
+the function was moved out of the kernel into the C standard library and
+reimplemented with
+.Xr gettimeofday 2 .