/* * Public domain dup2() lookalike * by Curtis Jackson @ AT&T Technologies, Burlington, NC * electronic address:  burl!rcj * * dup2 performs the following functions: * * Check to make sure that fd1 is a valid open file descriptor. * Check to see if fd2 is already open; if so, close it. * Duplicate fd1 onto fd2; checking to make sure fd2 is a valid fd. * Return fd2 if all went well; return BADEXIT otherwise. */ #include <fcntl.h> #define BADEXIT -1 intdup2(int fd1, int fd2){	if (fd1 != fd2) {		if (fcntl(fd1, F_GETFL) < 0)			return BADEXIT;		if (fcntl(fd2, F_GETFL) >= 0)			close(fd2);		if (fcntl(fd1, F_DUPFD, fd2) < 0)			return BADEXIT;	}	return fd2;}