minix3/lib/libc/sys/dup2.c

31 lines
540 B
C

#include <sys/cdefs.h>
#include "namespace.h"
#include <lib.h>
#include <fcntl.h>
#include <unistd.h>
int dup2(fd, fd2)
int fd, fd2;
{
/* The behavior of dup2 is defined by POSIX in 6.2.1.2 as almost, but not
* quite the same as fcntl.
*/
if (fd2 < 0 || fd2 > OPEN_MAX) {
errno = EBADF;
return(-1);
}
/* Check to see if fildes is valid. */
if (fcntl(fd, F_GETFL) < 0) {
/* 'fd' is not valid. */
return(-1);
} else {
/* 'fd' is valid. */
if (fd == fd2) return(fd2);
close(fd2);
return(fcntl(fd, F_DUPFD, fd2));
}
}