From freefall.cdrom.com!owner-freebsd-hackers Wed Aug 24 07:58:32 1994 Return-Path: Received: from freefall.cdrom.com by tfs.com (smail3.1.28.1) with SMTP id m0qdJmQ-0003xpa; Wed, 24 Aug 94 07:58 PDT Received: (from root@localhost) by freefall.cdrom.com (8.6.8/8.6.6) id HAA12879 for freebsd-hackers-outgoing; Wed, 24 Aug 1994 07:54:14 -0700 Received: from id.slip.bcm.tmc.edu (id.slip.bcm.tmc.edu [128.249.248.67]) by freefall.cdrom.com (8.6.8/8.6.6) with ESMTP id HAA12864 for ; Wed, 24 Aug 1994 07:51:33 -0700 Received: by id.slip.bcm.tmc.edu (8.6.8/1.34) id JAA17760; Wed, 24 Aug 1994 09:48:58 -0501 Date: Wed, 24 Aug 1994 09:48:58 -0501 From: rich@id.slip.bcm.tmc.edu (Rich Murphey) Message-Id: <199408241449.JAA17760@id.slip.bcm.tmc.edu> To: davidg@Root.COM CC: ache@astral.msk.su, batie@agora.rdrop.com, marc@dev.com, freebsd-hackers@freefall.cdrom.com In-reply-to: <199408240955.CAA02488@corbin.Root.COM> (message from David Greenman on Wed, 24 Aug 1994 02:55:06 -0700) Subject: Re: apply this patch file Reply-To: rich@freefall.cdrom.com Sender: freebsd-hackers-owner@freefall.cdrom.com Precedence: bulk Status: RO :From: David Greenman : :>This is against POSIX: POSIX says that you can't do anything :>with carrier lost device until closing it, i.e. clearing :>TS_ZOMBIE is illegal. Proper POSIX way is close()/open() device :>again like kermit/uucp does. Ask Bruce for more detailed info. : : I'm aware of the issues involved. : The problem has to do with a vnode reference that prevents the tty from :being completely closed (caused by the tty being a session leader with a :control tty). Regardless of what POSIX says, this is the only reasonable way :to solve this problem until the code is changed to allow a session leader to :get rid of it's control tty. I tried to find a way to do this and was :unsuccessful. The only solution that the code allows is for the process to :exit. It should not be necessary for the process to exit. If you can come up :with fixes for slattach and pppd so that they work without the patch, then :please do. Bruce Evans suggested doing the fork before reopening the tty and redialing. That fixes slattach and I commited it in the 2.0 tree. I've also sent a copy of the patch for 1.1.5's slattach to Poul. diff -rub slattach.orig/slattach.c src/sbin/slattach/slattach.c --- slattach.orig/slattach.c Mon May 9 14:04:20 1994 +++ src/sbin/slattach/slattach.c Tue Aug 23 00:39:05 1994 @@ -85,8 +85,8 @@ * gjung@gjbsd.franken.de * * sighup_handler changed to set CLOCAL before running redial_cmd. - * added flag exiting, so exit_handler is not run twice. - * + * added flag exiting, so exit_handler is not run twice. Fork + * before reopening tty. */ #ifndef lint @@ -126,13 +126,13 @@ void sigint_handler(); /* SIGINT handler */ void sigterm_handler(); /* SIGTERM handler */ void exit_handler(int ret); /* run exit_cmd iff specified upon exit. */ -void setup_line(); /* configure slip line */ -void attach_line(); /* switch to slip line discipline */ +void setup_line(int cflag); /* configure terminal settings */ +void slip_discipline(); /* switch to slip line discipline */ +void configure_network(); /* configure slip interface */ +void acquire_line(); /* get tty device as controling terminal */ int fd = -1; char *dev = (char *)0; -int slipdisc = SLIPDISC; -int ttydisc = TTYDISC; int flow_control = 0; /* non-zero to enable hardware flow control. */ int modem_control = 0; /* non-zero iff we watch carrier. */ int comstate; /* TIOCMGET current state of serial driver */ @@ -145,7 +145,6 @@ FILE *console; struct termios tty; -struct termios tty_orig; /* For saving original tty state */ char devname[32]; char hostname[MAXHOSTNAMELEN]; @@ -171,7 +170,6 @@ int main(int argc, char **argv) { int option; - char name[32]; extern char *optarg; extern int optind; @@ -244,22 +242,13 @@ if (!foreground) daemon(0,0); /* fork, setsid, chdir /, and close std*. */ + /* daemon() closed stderr, so log errors from here on. */ + openlog("slattach",LOG_CONS|LOG_PID,LOG_DAEMON); - /* Note: daemon() closes stderr, so log errors from here on. */ - (void)sprintf(name,"slattach[%d]", getpid()); - openlog(name,LOG_CONS,LOG_DAEMON); + acquire_line(); /* get tty device as controling terminal */ + setup_line(0); /* configure for slip line discipline */ + slip_discipline(); /* switch to slip line discipline */ - if ((fd = open(dev, O_RDWR | O_NONBLOCK)) < 0) { - syslog(LOG_ERR, "open(%s): %m", dev); - exit_handler(1); - } - /* acquire the serial line as a controling terminal. */ - if (ioctl(fd, TIOCSCTTY, 0) < 0) - syslog(LOG_NOTICE,"ioctl(TIOCSCTTY) failed: %s: %m"); - /* Make us the foreground process group associated with the - slip line which is our controlling terminal. */ - if (tcsetpgrp(fd, getpid()) < 0) - syslog(LOG_NOTICE,"tcsetpgrp failed: %s: %m"); /* upon INT log a timestamp and exit. */ if ((int)signal(SIGINT,sigint_handler) < 0) syslog(LOG_NOTICE,"cannot install SIGINT handler: %s: %m"); @@ -269,36 +258,76 @@ /* upon HUP redial and reconnect. */ if ((int)signal(SIGHUP,sighup_handler) < 0) syslog(LOG_NOTICE,"cannot install SIGHUP handler: %s: %m"); - /* Keep track of our original terminal values for redialing */ - if (tcgetattr(fd, &tty_orig) < 0) { - syslog(LOG_ERR, "tcgetattr: %m"); - exit_handler(1); - } - - - setup_line(); if (redial_on_startup) sighup_handler(); - else - attach_line(); - if (!(modem_control & CLOCAL)) { + else if (!(modem_control & CLOCAL)) { ioctl(fd, TIOCMGET, &comstate); if (!(comstate & TIOCM_CD)) { /* check for carrier */ /* force a redial if no carrier */ kill (getpid(), SIGHUP); } } + else + configure_network(); /* configure the network if needed. */ + for (;;) { - sigset_t mask = 0; + sigset_t mask; + sigemptyset(&mask); sigsuspend(&mask); } } -void setup_line() +/* Close all FDs, fork, reopen tty port as 0-2, and make it the + controlling terminal for our process group. */ +void acquire_line() +{ + int ttydisc = TTYDISC; + int pgrp; + + ioctl(fd, TIOCSETD, &ttydisc); /* reset to tty discipline */ + + (void)close(STDIN_FILENO); /* close FDs before forking. */ + (void)close(STDOUT_FILENO); + (void)close(STDERR_FILENO); + if (fd > 2) + (void)close(fd); + + signal(SIGHUP, SIG_IGN); /* ignore HUP signal when parent dies. */ + daemon(0,0); /* fork, setsid, chdir /, and close std*. */ + + while (getppid () != 1) + sleep (1); /* Wait for parent to die. */ + + if ((int)signal(SIGHUP,sighup_handler) < 0) /* Re-enable HUP signal */ + syslog(LOG_NOTICE,"cannot install SIGHUP handler: %s: %m"); + + if ((fd = open(dev, O_RDWR | O_NONBLOCK, 0)) < 0) { + syslog(LOG_ERR, "open(%s) fd=%d: %m", dev, fd); + exit_handler(1); + } + (void)dup2(fd, STDIN_FILENO); + (void)dup2(fd, STDOUT_FILENO); + (void)dup2(fd, STDERR_FILENO); + if (fd > 2) + (void)close (fd); + fd = STDIN_FILENO; + + /* acquire the serial line as a controling terminal. */ + if (ioctl(fd, TIOCSCTTY, 0) < 0) + syslog(LOG_NOTICE,"ioctl(TIOCSCTTY) failed: %s: %m"); + /* Make us the foreground process group associated with the + slip line which is our controlling terminal. */ + if (tcsetpgrp(fd, getpid()) < 0) + syslog(LOG_NOTICE,"tcsetpgrp failed: %s: %m"); +} + +/* Set the tty flags and set DTR. */ +/* Call as setup_line(CLOCAL) to force clocal assertion. */ +void setup_line(int cflag) { tty.c_lflag = tty.c_iflag = tty.c_oflag = 0; - tty.c_cflag = CREAD | CS8 | flow_control | modem_control; + tty.c_cflag = CREAD | CS8 | flow_control | modem_control | cflag; tty.c_ispeed = tty.c_ospeed = speed; /* set the line speed and flow control */ if (tcsetattr(fd, TCSAFLUSH, &tty) < 0) { @@ -310,6 +339,13 @@ syslog(LOG_ERR, "ioctl(TIOCSDTR): %m"); exit_handler(1); } +} + +/* Put the line in slip discipline. */ +void slip_discipline() +{ + int slipdisc = SLIPDISC; + /* Switch to slip line discipline. */ if (ioctl(fd, TIOCSETD, &slipdisc) < 0) { syslog(LOG_ERR, "ioctl(TIOCSETD): %m"); @@ -322,8 +358,8 @@ } } -/* switch to slip line discipline and configure the network. */ -void attach_line() +/* configure the interface, eg. by passing the unit number to a script. */ +void configure_network() { int new_unit; @@ -354,27 +390,17 @@ } } -/* Signal handler for SIGHUP when carrier is dropped. */ +/* signup_handler() is invoked when carrier drops, eg. before redial. */ void sighup_handler() { if(exiting) return; again: - /* reset discipline */ - if (ioctl(fd, TIOCSETD, &ttydisc) < 0) { - syslog(LOG_ERR, "ioctl(TIOCSETD): %m"); - exit_handler(1); - } /* invoke a shell for redial_cmd or punt. */ if (redial_cmd) { + acquire_line(); + setup_line(CLOCAL); syslog(LOG_NOTICE,"SIGHUP on %s (sl%d); running %s", dev,unit,redial_cmd); - if (!(modem_control & CLOCAL)) { - tty_orig.c_cflag |= CLOCAL; - if (tcsetattr(fd, TCSAFLUSH, &tty_orig) < 0) { - syslog(LOG_ERR, "tcsetattr(TCSAFLUSH): %m"); - exit_handler(1); - } - } system(redial_cmd); /* Now check again for carrier (dial command is done): */ if (!(modem_control & CLOCAL)) { @@ -390,50 +416,33 @@ } } } else { - /* - * No redial command. - * - * If modem control, just wait for carrier before - * falling through to setup_line() and attach_line(). - * If no modem control, just fall through immediately. - */ + /* If modem control, just wait for carrier before attaching. + If no modem control, just fall through immediately. */ if (!(modem_control & CLOCAL)) { int carrier = 0; - syslog(LOG_NOTICE, "Waiting for carrier on %s (sl%d)", dev, unit); - - /* Now wait for carrier before attaching line: */ + /* Now wait for carrier before attaching line. */ + /* We must poll since CLOCAL prevents signal. */ while (! carrier) { - /* - * Don't burn the CPU checking for carrier; - * carrier must be polled since there is no - * way to have a signal sent when carrier - * goes high (SIGHUP can only be sent when - * carrier is dropped); so add space between - * checks for carrier: - */ sleep(2); - - /* Check for carrier present on tty port: */ ioctl(fd, TIOCMGET, &comstate); - if (comstate & TIOCM_CD) { + if (comstate & TIOCM_CD) carrier = 1; } - } - syslog(LOG_NOTICE, "Carrier now present on %s (sl%d)", dev, unit); } } - setup_line(); - attach_line(); + setup_line(0); + slip_discipline(); + configure_network(); } /* Signal handler for SIGINT. We just log and exit. */ void sigint_handler() { if(exiting) return; - syslog(LOG_NOTICE,"sl%d on %s caught SIGINT, exiting.",unit,dev); + syslog(LOG_NOTICE,"SIGINT on %s (sl%d); exiting",dev,unit); exit_handler(0); } /* Signal handler for SIGTERM. We just log and exit. */