1 /*
2 * Copyright (C) 2015 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <errno.h>
30 #include <unistd.h>
31
32 extern "C" int ___close(int);
33
close(int fd)34 int close(int fd) {
35 int rc = ___close(fd);
36 if (rc == -1 && errno == EINTR) {
37 // POSIX says that if close returns with EINTR, the fd must not be closed.
38 // Linus disagrees: http://lkml.indiana.edu/hypermail/linux/kernel/0509.1/0877.html
39 // The future POSIX solution is posix_close (http://austingroupbugs.net/view.php?id=529),
40 // with the state after EINTR being undefined, and EINPROGRESS for the case where close
41 // was interrupted by a signal but the file descriptor was actually closed.
42 // My concern with that future behavior is that it breaks existing code that assumes
43 // that close only returns -1 if it failed. Unlike other system calls, I have real
44 // difficulty even imagining a caller that would need to know that close was interrupted
45 // but succeeded. So returning EINTR is wrong (because Linux always closes) and EINPROGRESS
46 // is harmful because callers need to be rewritten to understand that EINPROGRESS isn't
47 // actually a failure, but will be reported as one.
48
49 // We don't restore errno because that would incur a cost (the TLS read) for every caller.
50 // Since callers don't know ahead of time whether close will legitimately fail, they need
51 // to have stashed the old errno value anyway if they plan on using it afterwards, so
52 // us clobbering errno here doesn't change anything in that respect.
53 return 0;
54 }
55 return rc;
56 }
57