diff --git a/lib/libc/gen/time.3 b/lib/libc/gen/time.3 --- a/lib/libc/gen/time.3 +++ b/lib/libc/gen/time.3 @@ -32,7 +32,7 @@ .\" @(#)time.3 8.1 (Berkeley) 6/4/93 .\" $FreeBSD$ .\" -.Dd March 4, 2022 +.Dd April 14, 2022 .Dt TIME 3 .Os .Sh NAME @@ -49,7 +49,7 @@ .Fn time function returns the value of time in seconds since 0 hours, 0 minutes, -0 seconds, January 1, 1970, Coordinated Universal Time. +0 seconds, January 1, 1970, Coordinated Universal Time (UTC). If an error occurs, .Fn time returns the value @@ -73,12 +73,54 @@ The .Nm function conforms to -.St -p1003.1-2001 . +.St -p1003.1-2008 . .Sh HISTORY -A +The +.Fn time +system call first appeared in +.At v1 . +Through the +.At v3 , +it returned 60 Hz ticks since an epoch that changed occasionally, because it +was a 32-bit value that overflowed in a little over 2 years. +.Pp +In +.At v4 +the granularity of the return value was reduced to whole seconds, +delaying the aforementioned overflow until 2038. +.Pp +.At v7 +introduced the +.Fn ftime +system call, which returned time at a millisecond level, +though retained the +.Fn gtime +system call (exposed as +.Fn time +in userland). +.Fn time +could have been implemented as a wrapper around +.Fn ftime , +but that wasn't done. +.Pp +.Bx 4.1c +implemented a higher-precision time function +.Fn gettimeofday +to replace +.Fn ftime +and reimplemented +.Fn time +in terms of that. +.Pp +Since +.Fx 9 +the implementation of .Fn time -function appeared in -.At v6 . +uses +.Fn clock_gettime "CLOCK_SECOND" +instead of +.Fn gettimeofday +for performance reasons. .Sh BUGS Neither .St -isoC-99 @@ -92,8 +134,7 @@ the valid time value \-1 (representing the last UTC second of 1969) from the error return value. .Pp -Systems conforming to earlier versions of the C and -.Tn POSIX +Systems conforming to earlier versions of the C and POSIX standards (including older versions of .Fx ) did not set