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| author | Ulrich Drepper <drepper@redhat.com> | 2002-08-26 01:13:25 +0000 |
|---|---|---|
| committer | Ulrich Drepper <drepper@redhat.com> | 2002-08-26 01:13:25 +0000 |
| commit | f51dadcc36ae43517182b44720c7b1a8d10ffe1a (patch) | |
| tree | 011a11991463da97279e120cf03c073a1fbdad9f /manual | |
| parent | b9cbf9d72130f1bd3da48ac94cb1754c97c2bbcd (diff) | |
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(Setting an Alarm): Document that SA_RESTART must not be set when y sycall has to be interrupted.
Diffstat (limited to 'manual')
| -rw-r--r-- | manual/time.texi | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/manual/time.texi b/manual/time.texi index 645c876287..e76dfe74ae 100644 --- a/manual/time.texi +++ b/manual/time.texi @@ -2301,6 +2301,15 @@ could cause the timer to expire before your program establishes the handler. In this case it would be terminated, since termination is the default action for the alarm signals. @xref{Signal Handling}. +To be able to use the alarm function to interrupt a system call which +might block otherwise indefinitely it is important to @emph{not} set the +@code{SA_RESTART} flag when registering the signal handler using +@code{sigaction}. When not using @code{sigaction} things get even +uglier: the @code{signal} function has to fixed semantics with respect +to restarts. The BSD semantics for this function is to set the flag. +Therefore, if @code{sigaction} for whatever reason cannot be used, it is +necessary to use @code{sysv_signal} and not @code{signal}. + The @code{setitimer} function is the primary means for setting an alarm. This facility is declared in the header file @file{sys/time.h}. The @code{alarm} function, declared in @file{unistd.h}, provides a somewhat |