* Copyright (c) 1990 The Regents of the University of California.
* This code is derived from software contributed to Berkeley by
* %sccs.include.redist.c%
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid
[] = "@(#)freopen.c 5.4 (Berkeley) %G%";
#endif /* LIBC_SCCS and not lint */
* Re-direct an existing, open (probably) file to some other file.
* ANSI is written such that the original file gets closed if at
* all possible, no matter what.
int flags
, isopen
, oflags
, sverrno
, wantfd
;
if ((flags
= __sflags(mode
, &oflags
)) == 0) {
* There are actually programs that depend on being able to "freopen"
* descriptors that weren't originally open. Keep this from breaking.
* Remember whether the stream was open to begin with, and which file
* descriptor (if any) was associated with it. If it was attached to
* a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin)
* should work. This is unnecessary if it was not a Unix file.
fp
->_flags
= __SEOF
; /* hold on to it */
/* flush the stream; ANSI doesn't require this. */
/* if close is NULL, closing is a no-op, hence pointless */
isopen
= fp
->_close
!= NULL
;
if ((wantfd
= fp
->_file
) < 0 && isopen
) {
(void) (*fp
->_close
)(fp
->_cookie
);
/* Get a new descriptor to refer to the new file. */
f
= open(file
, oflags
, DEFFILEMODE
);
/* If out of fd's close the old one and try again. */
if (errno
== ENFILE
|| errno
== EMFILE
) {
(void) (*fp
->_close
)(fp
->_cookie
);
f
= open(file
, oflags
, DEFFILEMODE
);
* Finish closing fp. Even if the open succeeded above, we cannot
* keep fp->_base: it may be the wrong size. This loses the effect
* of any setbuffer calls, but stdio has always done this before.
(void) (*fp
->_close
)(fp
->_cookie
);
free((char *)fp
->_bf
._base
);
if (f
< 0) { /* did not get it after all */
fp
->_flags
= 0; /* set it free */
errno
= sverrno
; /* restore in case _close clobbered */
* If reopening something that was open before on a real file, try
* to maintain the descriptor. Various C library routines (perror)
* assume stderr is always fd STDERR_FILENO, even if being freopen'd.
if (wantfd
>= 0 && f
!= wantfd
) {
if (dup2(f
, wantfd
) >= 0) {