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