Change to reflect -current sleep implementation reality

1 files changed, 13 insertions, 28 deletions

diff --git a/lib/libc/gen/sleep.3 b/lib/libc/gen/sleep.3
index f488a0b..ab7e6f0 100644
--- a/lib/libc/gen/sleep.3
+++ b/lib/libc/gen/sleep.3
@@ -52,25 +52,23 @@ of time.
 System activity or time spent in processing the
 call may lengthen the sleep by a second.
 .Pp
-If a timer is already running on the process its state is saved.
+If a timer is already running on the process its state is unaltered by
+this sleep implementation.
 If the value
 .Fa seconds
-is more than or equal to the remaining clock time for the saved timer,
+is more than or equal to the remaining clock time for the running timer,
 the sleep time is set to
 the remaining clock time.
-The state of the previous timer
-is restored after
-.Fa seconds
-has passed.
 .Pp
 This function is implemented using
-.Xr setitimer 2 ;
-it requires eight system calls each time it is invoked.
-A similar but less compatible function can be obtained with a single
-.Xr select 2 ;
-such a function would not restart after signals, but would not interfere
-with other uses of
-.Xr setitimer 2 .
+.Xr signanosleep 2
+by pausing for
+.Fa seconds
+of time or until any signal occurse.
+For compatibility reasons during
+.Fn sleep
+call SIGALRM handler is temporary set to the
+function which does nothing but returns.
 .Sh RETURN VALUES
 The
 .Fn sleep
@@ -81,22 +79,9 @@ needed to be passed to a subsequent sleep to complete the necessary delay.
 repeatedly until it returns zero may busy-wait until a timer
 is available.
 .Sh SEE ALSO
-.Xr setitimer 2 ,
-.Xr sigpause 2 ,
+.Xr signal 3 ,
+.Xr signanosleep 2 ,
 .Xr usleep 3
-.Sh CAVEAT
-In practice the
-.Tn FreeBSD
-implementation will not be interrupted: it will
-always return the original argument or zero. Code that depends on
-sleep being interrupted (using it as a timed pause, for example) needs
-to be recoded to use
-.Xr select 2
-or some other delay mechanism. Code that
-calls
-.Fn sleep
-repeatedly until it returns zero may busy-wait until a timer
-is available.
 .Sh HISTORY
 A
 .Fn sleep