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 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
