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| -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 |