37 lines
899 B
C
37 lines
899 B
C
/*
|
|
dup2 -- 7th Edition UNIX system call emulation for UNIX System V
|
|
|
|
last edit: 11-Feb-1987 D A Gwyn
|
|
*/
|
|
|
|
#include <errno.h>
|
|
#include <fcntl.h>
|
|
|
|
extern int close(), fcntl();
|
|
|
|
int
|
|
dup2( oldfd, newfd )
|
|
int oldfd; /* already-open file descriptor */
|
|
int newfd; /* desired duplicate descriptor */
|
|
{
|
|
register int ret; /* for fcntl() return value */
|
|
register int save; /* for saving entry errno */
|
|
|
|
if ( oldfd == newfd )
|
|
return oldfd; /* be careful not to close() */
|
|
|
|
save = errno; /* save entry errno */
|
|
(void) close( newfd ); /* in case newfd is open */
|
|
/* (may have just clobbered the original errno value) */
|
|
|
|
ret = fcntl( oldfd, F_DUPFD, newfd ); /* dupe it */
|
|
|
|
if ( ret >= 0 )
|
|
errno = save; /* restore entry errno */
|
|
else /* fcntl() returned error */
|
|
if ( errno == EINVAL )
|
|
errno = EBADF; /* we think of everything */
|
|
|
|
return ret; /* return file descriptor */
|
|
}
|