file: WishIntfc.cxx


/*--
  Description:

  Methods for Class WishIntfc is used to interface to a 'wish' shell
  It has functions that 'spawn' a wish shell and establish
  pipes that communicate with the wish shell

  Last Modified: 18 Jan, 1999 by Prakash Gopalakrishnan (prakashg@ece.cmu.edu)

  --*/
#include <signal.h>
#include <sys/wait.h>
#include <iostream.h>
#include "WishIntfc.hxx"


void
WishIntfc::Initialize(void){
  
  // currently does nothing

}
/*-
  This spawns the wish shell and makes it source the TCL script from tcl_fname
  -*/
int
WishIntfc::Start(char* tcl_fname) 
{

  assert(strlen(path) > 0);

  // file descriptors These will be set by the pipes
  int fdTo[2], fdFrom[2];

  if(pipe(fdTo) == ERROR){
    perror("pipe");    
    return (ERROR);            
  }
  if(pipe(fdFrom) == ERROR){
    perror("pipe");
    return (ERROR);      
  }

  if((childPid = fork()) == ERROR){
    perror("fork");
    return (ERROR);
  }

  if(childPid == 0){ // child process    
    if(dup2(fdFrom[1], STDOUT_FILENO) != STDOUT_FILENO){
      perror("dup2");
      return (ERROR);	  
    }
      
    close(fdFrom[0]);
    close(fdFrom[1]);
    
    if(dup2(fdTo[0], STDIN_FILENO) != STDIN_FILENO){
      perror("dup2");
      return (ERROR);	  
 
    }
      
    close(fdTo[0]);
    close(fdTo[1]);
    
    const char *pathPtr = path;
    execl((char *) pathPtr, "wish", NULL);  
    perror("execl");
    return (ERROR);  
  }

  
   close(fdFrom[1]);
   close(fdTo[0]);

   toWish = fdTo[1];
   fromWish = fdFrom[0];

   // give the child some time to exec
   //   sleep(0.5);

   /*
     source tcl_fname ..gives the basic look and feel of the window
   */

   sprintf(TCLcommand,"source %s \n", tcl_fname);
   SendCommand(TCLcommand);
   
   return (NOERROR);
}

int
WishIntfc::End(void)
{
  return (SendCommand("exit\n"));
}

int
WishIntfc::SendCommand(const char* cmd)
{
  // set SIGPIPE so we can recover if there is no reader
  if(signal(SIGPIPE, wish_catch_sig_pipe) == SIG_ERR){
    return ERROR;
  }
  
  if (writen(toWish,(char*) cmd, strlen(cmd)) == ERROR)
    return(ERROR);
  
  return(NOERROR);
}


int
WishIntfc::Kill(void)
{
   int ReturnValue = kill(childPid, SIGKILL);
   // wait for the child to go away
   waitpid(childPid, NULL, 0);
   close(toWish);
   close(fromWish);
   
   return (ReturnValue);
}




void
wish_catch_sig_alrm(int Signal)
{
   cerr << "SIGALRM Generated.No response from WISH..." 
	<< endl;
}

void
wish_catch_sig_pipe(int Signal)
{
   cerr << "SIGPIPE Generated. No reader on WISH pipe....."
        << endl;
}



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