pipe.c

Gcomm is a serial communications program similar to seyon, but more modern, and easier to use. Works

#ifndef lint
static const char rcsid[] = "$Id: pipe.c,v 1.1.1.1 2001/03/08 00:01:47 efalk Exp $" ;
#endif

/*
 * Copyright (c) 1995 by Edward A. Falk
 */


/**********
 *
 *
 *	@@@@    @@@   @@@@   @@@@@  
 *	@   @    @    @   @  @      
 *	@@@@     @    @@@@   @@@    
 *	@        @    @      @      
 *	@       @@@   @      @@@@@  
 *
 *	PIPE - Open connection to a program.
 *
 *	Routines provided here:
 *
 *
 *	PipeConnect()
 *		open pipe
 *
 *	PipeDisConnect()
 *		close pipe
 *
 *
 *
 *	Edward A. Falk
 *
 *	January, 1995
 *
 *
 *
 **********/




#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <malloc.h>
#include <string.h>
#include <ctype.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/param.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/stat.h>

#include <sys/wait.h>
#include <sys/signal.h>

#include "gcomm.h"
#include "winutils.h"

extern	int	errno ;

static	int	pid ;

void
PipeConnect( char *programArgs )
{
	int	ifds[2], ofds[2] ;
	char	*argv[128] ;
	char	argstr[1024] ;
	char	*optr, *ptr, **vptr ;
	int	i,j ;

	/* parse programArgs into argv */

	programArgs = strdup( programArgs) ;
	ptr = programArgs ;
	optr = argstr ;
	vptr = argv ;

	while( isspace(*ptr) ) ++ptr ;

	*vptr++ = optr ;

	while( *ptr != '\0' )
	{
	  if( isspace(*ptr) )	/* blank */
	  {
	    *optr++ = '\0' ;
	    while( isspace(*ptr) ) ++ptr ;
	    if( *ptr != '\0' )
	      *vptr++ = optr ;
	  }
	  else if( *ptr == '\''  ||	/* ' */
		   *ptr == '"' )	/* " */
	  {
	    char q = *ptr++ ;
	    while( *ptr != q && *ptr != '\0' )
	      *optr++ = *ptr++ ;
	    if( *ptr != '\0' )
	      ++ptr ;
	  }
	  else if( *ptr == '\\' )	/* \ */
	  {
	    if( *++ptr != '\0' )
	      *optr++ = *ptr++ ;
	  }
	  else
	    *optr++ = *ptr++ ;
	}
	*optr = '\0' ;
	*vptr = NULL ;




	if( argv[0] == NULL ) {
	  free( programArgs ) ;
	  WindowStatus("Program name not specified") ;
	  return ;
	}

	if( pipe(ifds) < 0 ) {
	  free( programArgs ) ;
	  WindowStatus("Cannot create pipe: %s", strerror(errno)) ;
	  return ;
	}

	if( pipe(ofds) < 0 ) {
	  close(ifds[0]) ;
	  close(ifds[1]) ;
	  free( programArgs ) ;
	  WindowStatus("Cannot create pipe: %s", strerror(errno)) ;
	  return ;
	}

	pid = vfork() ;
	if( pid == -1 ) {
	  close(ifds[0]) ;
	  close(ifds[1]) ;
	  close(ofds[0]) ;
	  close(ofds[1]) ;
	  free( programArgs ) ;
	  WindowStatus("Cannot fork: %s", strerror(errno)) ;
	  return ;
	}

	if( pid == 0 ) {
	  /* Child, we write to ifds[1], read from ofds[0] */
	  dup2(ofds[0],0) ;	/* stdin */
	  dup2(ifds[1],1) ;	/* stdout */
	  close(ifds[0]) ;
	  close(ifds[1]) ;
	  close(ofds[0]) ;
	  close(ofds[1]) ;
	  execvp(argv[0], argv) ;
	  perror(argv[0]) ;
	  _exit(127) ;
	}

	/* Parent.  We read from ifds[0], write to ofds[1] */
	close(ifds[1]) ;
	close(ofds[0]) ;
	ifd = ifds[0] ;
	ofd = ofds[1] ;

	i = fcntl(ifd, F_GETFL, 0) ;
	j = fcntl(ifd, F_SETFL, i|O_NDELAY) ;
	i = fcntl(ofd, F_GETFL, 0) ;
	j = fcntl(ofd, F_SETFL, i|O_NDELAY) ;

	connectionActive = True ;
	connectTime0 = time(NULL) ;
	free( programArgs ) ;
	WindowStatus("Connected") ;
}






static	int
wait_for_sig(int pid, int wtime)
{
	struct timeval timeout ;
	int	i, status ;

	timeout.tv_sec = wtime ;
	timeout.tv_usec = 0 ;
	if( (i=waitpid(pid, &status, WNOHANG)) > 0 ) 
	  return i ;
#ifdef	COMMENT
	oldmask = sigsetmask(~sigmask(SIGCHLD)) ; /* block all but SIGCHLD */
#endif	/* COMMENT */
	i = select(0,NULL,NULL,NULL, &timeout) ;
	if( i == -1 && errno != EINTR )
	  perror("breakPipeConnection: select") ;

	return waitpid(pid, &status, WNOHANG) ;
}

void
PipeDisConnect()
{
	int	status ;
	int	i ;

	/* first, block SIGCHLD so we don't get confused */

#ifdef	COMMENT
	oldmask = sigblock(sigmask(SIGCHLD)) ;
#endif	/* COMMENT */

	close(ifd) ;
	close(ofd) ;

	/* see if process has already exited */

	i = waitpid(pid, &status, WNOHANG) ;
	if( i <= 0 ) {
	  /* we'll wait 10 seconds for it */
	  WindowStatus("Waiting for child process to exit...") ;
	  i = wait_for_sig(pid, 10) ;
	  if( i <= 0 ) {
	    WindowStatus("Sending SIGTERM to child process...") ;
	    if( kill(pid, SIGTERM) < 0 )
	      perror("breakPipeConnection: select") ;
	    i = wait_for_sig(pid, 10) ;
	    if( i <= 0 ) {
	      WindowStatus("Sending SIGKILL to child process...") ;
	      if( kill(pid, SIGKILL) < 0 )
		perror("breakPipeConnection: select") ;
	      i = wait_for_sig(pid, 10) ;
	      if( i <= 0 )
		WindowStatus( "Warning, process %d wouldn't die", pid) ;
	    }
	  }
	}

#ifdef	COMMENT
	(void) sigsetmask(oldmask) ;
#endif	/* COMMENT */

	ifd = ofd = -1 ;

	ConnectionDone() ;
}