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/*
* Copyright (C) 2015 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <errno.h>
#include <unistd.h>
extern "C" int ___close(int);
int close(int fd) {
int rc = ___close(fd);
if (rc == -1 && errno == EINTR) {
// POSIX says that if close returns with EINTR, the fd must not be closed.
// Linus disagrees: http://lkml.indiana.edu/hypermail/linux/kernel/0509.1/0877.html
// The future POSIX solution is posix_close (http://austingroupbugs.net/view.php?id=529),
// with the state after EINTR being undefined, and EINPROGRESS for the case where close
// was interrupted by a signal but the file descriptor was actually closed.
// My concern with that future behavior is that it breaks existing code that assumes
// that close only returns -1 if it failed. Unlike other system calls, I have real
// difficulty even imagining a caller that would need to know that close was interrupted
// but succeeded. So returning EINTR is wrong (because Linux always closes) and EINPROGRESS
// is harmful because callers need to be rewritten to understand that EINPROGRESS isn't
// actually a failure, but will be reported as one.
// We don't restore errno because that would incur a cost (the TLS read) for every caller.
// Since callers don't know ahead of time whether close will legitimately fail, they need
// to have stashed the old errno value anyway if they plan on using it afterwards, so
// us clobbering errno here doesn't change anything in that respect.
return 0;
}
return rc;
}
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