From c80d3c6b9cde8128a702b13215fd5c1c60d54103 Mon Sep 17 00:00:00 2001
From: "Eric S. Raymond" <esr@thyrsus.com>
Date: Mon, 26 Aug 2002 18:47:09 +0000
Subject: Refactor so we can use idle.c in the cookbook.

svn path=/trunk/; revision=3688
---
 idle.c | 74 ++++++++++++++++++++++++++++++++++--------------------------------
 1 file changed, 38 insertions(+), 36 deletions(-)

(limited to 'idle.c')

diff --git a/idle.c b/idle.c
index b3ecd503..d91e10a2 100644
--- a/idle.c
+++ b/idle.c
@@ -1,23 +1,32 @@
-/*
- * idle.c -- pause code for fetchmail
- *
- * For license terms, see the file COPYING in this directory.
- */
-#include "config.h"
+/*****************************************************************************
+
+NAME:
+   idle.c -- code for interruptible delays without sleep(3).
+
+ENTRY POINTS:
+   interruptible_idle() -- delay for some time, interruptible by signal.
+
+THEORY:
+   Sometimes you need more than one time delay per program, so alarm(3)
+won't cut it.  This code illustrates time delays with select(2).
+
+AUTHOR:
+   Eric S. Raymond <esr@thyrsus.com>, 1997.  This source code example
+is part of fetchmail and the Unix Cookbook, and are released under the
+MIT license.  Compile with -DMAIN to build the demonstrator.
 
+******************************************************************************/
 #include <stdio.h>
-#if defined(STDC_HEADERS)
 #include <stdlib.h>
-#endif
-#if defined(HAVE_UNISTD_H)
 #include <unistd.h>
-#endif
 #include <signal.h>
 #include <errno.h>
 #include <sys/time.h>
 
-#include "fetchmail.h"
-#include "i18n.h"
+#ifndef TRUE
+#define TRUE 1
+#define FALSE 0
+#endif
 
 volatile int lastsig;		/* last signal received */
 
@@ -27,18 +36,13 @@ volatile int lastsig;		/* last signal received */
  * SIGALRM can hose the code (ALARM is triggered *before* pause() is called).
  * This is a bit of a kluge; the real right thing would use sigprocmask(),
  * sigsuspend().  This workaround lets the interval timer trigger the first
- * alarm after the required interval and will then generate alarms all 5
- * seconds, until it is certain, that the critical section (ie., the window)
- * is left.
+ * alarm after the required interval and will then generate alarms
+ * seconds until it is certain that the critical section (ie., the window)
+ * is exited.
  */
-#if defined(STDC_HEADERS)
 static sig_atomic_t	alarm_latch = FALSE;
-#else
-/* assume int can be written in one atomic operation on non ANSI-C systems */
-static int		alarm_latch = FALSE;
-#endif
 
-RETSIGTYPE gotsigalrm(int sig)
+void gotsigalrm(int sig)
 {
     signal(sig, gotsigalrm);
     lastsig = sig;
@@ -63,24 +67,11 @@ void itimerthread(void* dummy)
 }
 #endif
 
-RETSIGTYPE donothing(int sig) {signal(sig, donothing); lastsig = sig;}
-
 int interruptible_idle(int seconds)
 /* time for a pause in the action; return TRUE if awakened by signal */
 {
     int awoken = FALSE;
 
-    /*
-     * With this simple hack, we make it possible for a foreground 
-     * fetchmail to wake up one in daemon mode.  What we want is the
-     * side effect of interrupting any sleep that may be going on,
-     * forcing fetchmail to re-poll its hosts.  The second line is
-     * for people who think all system daemons wake up on SIGHUP.
-     */
-    signal(SIGUSR1, donothing);
-    if (!getuid())
-	signal(SIGHUP, donothing);
-
 #ifndef __EMX__
 #ifdef SLEEP_WITH_ALARM		/* not normally on */
     /*
@@ -123,7 +114,7 @@ int interruptible_idle(int seconds)
     setitimer(ITIMER_REAL,&ntimeout,NULL);	/* then start timer */
     /* there is a very small window between the next two lines */
     /* which could result in a deadlock.  But this will now be  */
-    /* caught by periodical alarms (see it_interval) */
+    /* caught by periodic alarms (see it_interval) */
     if (!alarm_latch)
 	pause();
     /* stop timer */
@@ -146,7 +137,7 @@ int interruptible_idle(int seconds)
     {
     struct timeval timeout;
 
-    timeout.tv_sec = run.poll_interval;
+    timeout.tv_sec = seconds;
     timeout.tv_usec = 0;
     do {
 	lastsig = 0;
@@ -174,4 +165,15 @@ int interruptible_idle(int seconds)
     return(awoken ? lastsig : 0);
 }
 
+#ifdef MAIN
+int main(int argc, **argv)
+{
+    for (;;)
+    {
+	printf("How may I serve you, master?\n");
+	interruptible_idle(5);
+    }
+}
+#endif /* MAIN */
+
 /* idle.c ends here */
-- 
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