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[RFC][BZ #14627] Make linux close errno to EINPROGRESS when interrupted in signal.
- From: OndÅej BÃlka <neleai at seznam dot cz>
- To: libc-alpha at sourceware dot org
- Date: Thu, 5 Dec 2013 18:10:54 +0100
- Subject: [RFC][BZ #14627] Make linux close errno to EINPROGRESS when interrupted in signal.
- Authentication-results: sourceware.org; auth=none
Hi,
As was recently said
https://www.sourceware.org/ml/libc-alpha/2013-12/msg00086.html
linux when close is interrupted by signal closes file descriptor but
returns EINTR errno which lies application about restartability. As
kernel does not restart close on SA_RESTART only thing needed is to
return EINPROGRESS instead EINTR as specified by POSIX.
I do not have actual implementation ready as close is automatically
generated syscall wrapper.
Second concern is cancelability, there is a close_nocancel macro and
also in libc.so close is implemented as header before close_nocancel but
i couldn't find definition.
Could somebody clarify?
As actual implementation one could use something like this. As in fclose
we use noncancelable version should we also disable cancelability in
close?
diff --git a/sysdeps/unix/sysv/linux/close.c b/sysdeps/unix/sysv/linux/close.c
new file mode 100644
index 0000000..223d6ed
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/close.c
@@ -0,0 +1,44 @@
+/* Copyright (C) 2013 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <sysdep-cancel.h>
+
+int
+__libc_close (int fd)
+{
+ if (SINGLE_THREAD_P)
+ return INLINE_SYSCALL (close, 1, fd);
+
+ int oldtype = LIBC_CANCEL_ASYNC ();
+
+ int result = INLINE_SYSCALL (close, 1, fd);
+
+ if (errno == EINTR)
+ errno = EINPROGRESS;
+
+ LIBC_CANCEL_RESET (oldtype);
+
+ return result;
+}
+
+weak_alias (__libc_close, __close)
+libc_hidden_weak (__close)
+weak_alias (__libc_close, close)