mirror of
https://github.com/klzgrad/naiveproxy.git
synced 2024-11-28 08:16:09 +03:00
71 lines
2.8 KiB
C++
71 lines
2.8 KiB
C++
|
// 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 Mac OS X 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.
|
||
|
|
//
|
||
|
|
// Mac OS X 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 name is set by an asm
|
||
|
|
// label on the declaration of the close function, so the definition of that
|
||
|
|
// function receives that name. The function calls the $NOCANCEL variant, which
|
||
|
|
// is resolved from libsyscall. By linking with this version of close prior to
|
||
|
|
// the libsyscall version, close's implementation is overridden.
|
||
|
|
|
||
|
|
#include <sys/cdefs.h>
|
||
|
|
#include <unistd.h>
|
||
|
|
|
||
|
|
// If the non-cancelable variants of all system calls have already been
|
||
|
|
// chosen, do nothing.
|
||
|
|
#if !__DARWIN_NON_CANCELABLE
|
||
|
|
|
||
|
|
extern "C" {
|
||
|
|
|
||
|
|
#if !__DARWIN_ONLY_UNIX_CONFORMANCE
|
||
|
|
|
||
|
|
// When there's a choice between UNIX2003 and pre-UNIX2003. There's no
|
||
|
|
// close$NOCANCEL symbol in this case, so use close$NOCANCEL$UNIX2003 as the
|
||
|
|
// implementation. It does the same thing that close$NOCANCEL would do.
|
||
|
|
#define close_implementation close$NOCANCEL$UNIX2003
|
||
|
|
|
||
|
|
#else // __DARWIN_ONLY_UNIX_CONFORMANCE
|
||
|
|
|
||
|
|
// When only UNIX2003 is supported:
|
||
|
|
#define close_implementation close$NOCANCEL
|
||
|
|
|
||
|
|
#endif
|
||
|
|
|
||
|
|
int close_implementation(int fd);
|
||
|
|
|
||
|
|
int close(int fd) {
|
||
|
|
return close_implementation(fd);
|
||
|
|
}
|
||
|
|
|
||
|
|
#undef close_implementation
|
||
|
|
|
||
|
|
} // extern "C"
|
||
|
|
|
||
|
|
#endif // !__DARWIN_NON_CANCELABLE
|