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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);
+}