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/*
* Set or clear file descriptor flags.
*
* Simple functions (wrappers around fcntl) to set or clear file descriptor
* flags like close-on-exec or nonblocking I/O.
*
* The canonical version of this file is maintained in the rra-c-util package,
* which can be found at <https://www.eyrie.org/~eagle/software/rra-c-util/>.
*
* Written by Russ Allbery <eagle@eyrie.org>
* Copyright 2008, 2011, 2013
* The Board of Trustees of the Leland Stanford Junior University
* Copyright 2004-2006 Internet Systems Consortium, Inc. ("ISC")
* Copyright 1991, 1994-2003 The Internet Software Consortium and Rich Salz
*
* This code is derived from software contributed to the Internet Software
* Consortium by Rich Salz.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
* OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*
* SPDX-License-Identifier: ISC
*/
#include <config.h>
#include <portable/system.h>
#ifdef _WIN32
# include <winsock2.h>
#else
# include <fcntl.h>
# ifndef O_NONBLOCK
# include <sys/ioctl.h>
# if HAVE_SYS_FILIO_H
# include <sys/filio.h>
# endif
# endif
#endif
#include <util/fdflag.h>
#include <util/macros.h>
/*
* Set a file to close-on-exec (or clear that setting if the flag is false),
* returning true on success and false on failure.
*
* One is supposed to retrieve the flags, add FD_CLOEXEC, and then set them,
* although I've never seen a system with any flags other than close-on-exec.
* Do it right anyway; it's not that expensive.
*
* Stub this out on Windows, where it's not supported (at least currently by
* this utility library). Do not use socket_type for the first parameter,
* since it's meaningful to set file descriptors for regular files to
* close-on-exec (even though this is currently irrelevant since the function
* isn't supported on Windows).
*/
#ifdef _WIN32
bool
fdflag_close_exec(int fd UNUSED, bool flag UNUSED)
{
return false;
}
#else
bool
fdflag_close_exec(int fd, bool flag)
{
int oflag, mode;
oflag = fcntl(fd, F_GETFD, 0);
if (oflag < 0)
return false;
mode = flag ? (oflag | FD_CLOEXEC) : (oflag & ~FD_CLOEXEC);
return (fcntl(fd, F_SETFD, mode) == 0);
}
#endif
/*
* Set a file descriptor to nonblocking (or clear the nonblocking flag if flag
* is false), returning true on success and false on failure.
*
* For Windows, be aware that this will only work for sockets. For UNIX, you
* can pass a non-socket in and it will do the right thing, since UNIX doesn't
* distinguish, but Windows will not allow that. Thankfully, there's rarely
* any need to set non-sockets non-blocking.
*
* For UNIX, always use O_NONBLOCK; O_NDELAY is not the same thing
* historically. The semantics of O_NDELAY are that if the read would block,
* it returns 0 instead. This is indistinguishable from an end of file
* condition. POSIX added O_NONBLOCK, which requires read to return -1 and
* set errno to EAGAIN, which is what we want.
*
* FNDELAY (4.3BSD) originally did the correct thing, although it has a
* different incompatibility (affecting all users of a socket rather than just
* a file descriptor and returning EWOULDBLOCK instead of EAGAIN) that we
* probably don't care about. Using it is probably safe, but BSD should also
* have the ioctl, and at least on Solaris FNDELAY does the same thing as
* O_NDELAY, not O_NONBLOCK. So if we don't have O_NONBLOCK, fall back to the
* ioctl instead.
*
* Reference: Stevens, Advanced Unix Programming, pg. 364.
*
* Note that O_NONBLOCK is known not to work on earlier versions of ULTRIX,
* SunOS, and AIX, possibly not setting the socket nonblocking at all, despite
* the fact that they do define it. It works in later SunOS and, current AIX,
* however, and a 1999-10-25 survey of current operating systems failed to
* turn up any that didn't handle it correctly (as required by POSIX), while
* HP-UX 11.00 did use the broken return-zero semantics of O_NDELAY (most
* other operating systems surveyed treated O_NDELAY as synonymous with
* O_NONBLOCK). Accordingly, we currently unconditionally use O_NONBLOCK. If
* this causes too many problems, an autoconf test may be required.
*/
#if defined(_WIN32)
bool
fdflag_nonblocking(socket_type fd, bool flag)
{
u_long mode;
mode = flag ? 1 : 0;
return (ioctlsocket(fd, FIONBIO, &mode) == 0);
}
#elif defined(O_NONBLOCK)
bool
fdflag_nonblocking(socket_type fd, bool flag)
{
int mode;
mode = fcntl(fd, F_GETFL, 0);
if (mode < 0)
return false;
mode = (flag ? (mode | O_NONBLOCK) : (mode & ~O_NONBLOCK));
return (fcntl(fd, F_SETFL, mode) == 0);
}
#else /* !O_NONBLOCK */
bool
fdflag_nonblocking(socket_type fd, bool flag)
{
int state;
state = flag ? 1 : 0;
return (ioctl(fd, FIONBIO, &state) == 0);
}
#endif /* !O_NONBLOCK */
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