/*********************************************************************
* connectPipeLine connects the process to a pipeline by redirecting
* standard input to frontfd[0] and standard output to backfd[1].
* If frontfd[0] = -1, the process is at the front of the pipeline and
* standard input may be redirected to a file.  If backfd[1] = -1,
* the process is at the back of the pipeline and standard output may
* be redirected to a file.  Otherwise redirection to a file is
* an error.  If explicit redirection occurs in cmd, it is removed
* in processing.   A 0 is returned if connectPipeLine is successful
* and a -1 is returned otherwise.
*********************************************************************/

#include "ush.h"

/********************************************************************
* Function checks redirect and calls function redirect
*/
int checkRedirect(char* cmd, int frontfd[], int backfd[])
{
    int result = -1;
    char* inFileName;
    char* outFileName;

    if (parseFile(cmd, IN_REDIRECT_SYMBOL , &inFileName) == -1)
	return result;
    else 
	if (inFileName != NULL && frontfd[0] != -1)
	    /* no redirection allowed at front of pipeline */
	    return result;    
	else 
	    if (parseFile(cmd, OUT_REDIRECT_SYMBOL, &outFileName) == -1)
		return result;
	    else 
		if (outFileName != NULL && backfd[1] != -1)
		    /* no redirection allowed at back of pipeline */
		    return result;    
		else 
		    if (redirect(inFileName, outFileName) == -1)
			return result;
    return 0;
}

int connectPipeLine(char* cmd, int frontfd[], int backfd[])
{
    int result = 0;
    
    if (checkRedirect(cmd, frontfd, backfd) == -1)
	result = -1;
    else 
    {
	/* now connect up appropriate pipes */
	if (frontfd[0] != -1) 
	{
	    if (dup2(frontfd[0], STDIN_FILENO) == -1)
		result = -1;
	}
	
	if (backfd[1] != -1) 
	{
	    if (dup2(backfd[1], STDOUT_FILENO) == -1)
		result = -1;
        } 
    }
		    
    /* close unneeded file descriptors */
    close (frontfd[0]);
    close (frontfd[1]);
    close (backfd[0]);
    close (backfd[1]);
   
    return result;
}