help with supplying credentials from a program.

[Nagesh Pabbisetty]

Folks,


I am currently developing a tool that transfers files between file servers
and workstations. The tool reads commands from a file. Provision is made to
specify the time at which this tool is to start tranfering files. However,
sybntax-checking of the command-file should be done at the current time,

It is possible that the user of this tool has different login names and
passwords on different file servers. I want the program to accept the
various login names and passwords at the current time. Then, when the
actual file transfer is to take place, I want the program to login to the 2
file servers involved in the transfer (validate credentials using
"servlogin") and continue with the transfer operation. 

In order to test if fork-exec-pipe combination would help me in the
process, I developed a prototype, excerpts of which are given below:

----------------------------------  
# include <stdio.h>

# define R 0
# define W 1

main()

{
	int	fork(), p[2], q[2] ;
	FILE	*writeptr, *readptr;
	char	buffer[200];

	if (pipe(p) == -1)
		perror("pipe(p) failed\n");
	 if (pipe(q) == -1)
		perror("pipe(q) failed\n");
	
	switch(fork()) {
		case 0: /* child process */
			close(p[W]); 
			close(R);
			dup(p[R]);
			close(p[R]);
			close(q[R]);
			close(W);
			dup(q[W]);
			close(q[W]); 
			execlp("/export/swap/opt/sun3/servlogin","servlogin",0);
			perror("exec failed\n");
			exit (1);
			
	       	case -1: /* unsuccesful fork */
			perror("fork failed\n");
			exit (1);
			
		default: /* parent process */
			 close(p[R]);
			 close(q[W]);
			 writeptr = fdopen(p[W],"w");
			 readptr = fdopen(q[R],"r");
			 
			/* this obviously doesn't work! */
			fprintf(writeptr,"Pabbisetty\n");
			fflush(writeptr);
			fprintf(writeptr,"hastalavista\n");
			fflush(writeptr);
			
				.
				.
				.
			fclose(writeptr);
			}
}

			
----------------------------------  

As is obvious from this simple program, I have set up bi-directional pipes
between the parent and the child process. From the parent, I am trying to
pipe the user-name and password to the login process. However, this doesn't
work. I get the login prompt to the terminal!! 

How can I get the login process to accept login-name and password from the
parent process and not expect it from the terminal?

Could anyone out there suggest a correct way to do this? 

Any help in this regard is appreciated!!! 


Thanks....

Nagesh
716-427-1827 / 5458