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/*
* The MIT License
*
* Copyright (C) 2016 Alexander Saprykin <saprykin.spb@gmail.com>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* 'Software'), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
/*
* Copyright 2013 The Chromium Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*
* http://crbug.com/269623
* http://openradar.appspot.com/14999594
*
* When the default version of close used on macOS fails with EINTR, the
* file descriptor is not in a deterministic state. It may have been closed,
* or it may not have been. This makes it impossible to gracefully recover
* from the error. If the close is retried after the FD has been closed, the
* subsequent close can report EBADF, or worse, it can close an unrelated FD
* opened by another thread. If the close is not retried after the FD has been
* left open, the FD is leaked. Neither of these are good options.
*
* macOS provides an alternate version of close, close$NOCANCEL. This
* version will never fail with EINTR before the FD is actually closed. With
* this version, it is thus safe to call close without checking for EINTR (as
* the HANDLE_EINTR macro does) and not risk leaking the FD. In fact, mixing
* this verison of close with HANDLE_EINTR is hazardous.
*
* The $NOCANCEL variants of various system calls are activated by compiling
* with __DARWIN_NON_CANCELABLE, which prevents them from being pthread
* cancellation points. Rather than taking such a heavy-handed approach, this
* file implements an alternative: to use the $NOCANCEL variant of close (thus
* preventing it from being a pthread cancellation point) without affecting
* any other system calls.
*
* This file operates by providing a close function with the non-$NOCANCEL
* symbol name expected for the compilation environment as set by <unistd.h>
* and <sys/cdefs.h> (the DARWIN_ALIAS_C macro). That function calls the
* $NOCANCEL variant, which is resolved from libsyscall. By linking with this
* version of close prior to the libsyscall version, close's implementation is
* overridden.
*/
#include <sys/cdefs.h>
/* If the non-cancelable variants of all system calls have already been chosen,
* do nothing. */
#if !__DARWIN_NON_CANCELABLE
# if __DARWIN_UNIX03 && !__DARWIN_ONLY_UNIX_CONFORMANCE
/* When there's a choice between UNIX2003 and pre-UNIX2003 and UNIX2003 has
* been chosen. */
extern int close$NOCANCEL$UNIX2003 (int fd);
# define PLIBSYS_CLOSE_INTERFACE close$NOCANCEL$UNIX2003
# elif !__DARWIN_UNIX03 && !__DARWIN_ONLY_UNIX_CONFORMANCE
/* When there's a choice between UNIX2003 and pre-UNIX2003 and pre-UNIX2003
* has been chosen. There's no close$NOCANCEL symbol in this case, so use
* close$NOCANCEL$UNIX2003 as the implementation. It does the same thing that
* close$NOCANCEL would do. */
extern int close$NOCANCEL$UNIX2003 (int fd);
# define PLIBSYS_CLOSE_INTERFACE close$NOCANCEL$UNIX2003
# else
/* When only UNIX2003 is supported. */
extern int close$NOCANCEL (int fd);
# define PLIBSYS_CLOSE_INTERFACE close$NOCANCEL
# endif
#endif
#include "psysclose-private.h"
pint
p_sys_close (pint fd)
{
return PLIBSYS_CLOSE_INTERFACE (fd);
}
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