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/*
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 */
}
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