diff options
| -rw-r--r-- | fetchmail.c | 17 | ||||
| -rw-r--r-- | idle.c | 74 |
2 files changed, 55 insertions, 36 deletions
diff --git a/fetchmail.c b/fetchmail.c index ade69cc2..93f4754a 100644 --- a/fetchmail.c +++ b/fetchmail.c @@ -116,6 +116,12 @@ static char *timestamp (void) #define timestamp rfc822timestamp #endif +static RETSIGTYPE donothing(int sig) +{ + extern volatile int lastsig; /* declared in idle.c */ + signal(sig, donothing); lastsig = sig; +} + int main(int argc, char **argv) { int bkgd = FALSE; @@ -719,6 +725,17 @@ int main(int argc, char **argv) GT_("sleeping at %s\n"), timestamp()); /* + * 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); + + /* * OK, now pause until it's time for the next poll cycle. * A nonzero return indicates we received a wakeup signal; * unwedge all servers in case the problem has been @@ -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 */ |