hurd: Make write and pwrite64 cancellation points

and add _nocancel variants.

* sysdeps/mach/hurd/write.c (__libc_write): Call __write_nocancel
surrounded by enabling async cancel, to replace implementation moved
to...
* sysdeps/mach/hurd/write_nocancel.c (__write_nocancel): ... here.
* sysdeps/mach/hurd/pwrite64.c (__libc_pwrite64): Call
__pwrite64_nocancel surrounded by enabling async cancel, to replace
implementation moved to...
* sysdeps/mach/hurd/pwrite64_nocancel.c (__pwrite64_nocancel): ... here.
* sysdeps/mach/hurd/Makefile (sysdep_routines): Add write_nocancel and
pwrite64_nocancel.
* sysdeps/mach/hurd/not-cancel.h (__write_nocancel,
__pwrite64_nocancel): Replace macros with prototypes with a hidden proto on
libc.

* sysdeps/mach/hurd/dl-sysdep.c (__write_nocancel): New alias, check
that it is not hidden.
* sysdeps/mach/hurd/Versions (libc.GLIBC_PRIVATE): Add __write_nocancel.
(ld.GLIBC_PRIVATE): Add __write_nocancel.
* sysdeps/mach/hurd/i386/localplt.data (__write_nocancel): Add
reference.

1 files changed, 30 insertions, 0 deletions

diff --git a/sysdeps/mach/hurd/write_nocancel.c b/sysdeps/mach/hurd/write_nocancel.c
new file mode 100644
index 0000000000..ab11c9cdd1
--- /dev/null
+++ b/sysdeps/mach/hurd/write_nocancel.c
@@ -0,0 +1,30 @@
+/* Copyright (C) 1991-2020 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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <unistd.h>
+#include <hurd/fd.h>
+#include <not-cancel.h>
+
+ssize_t
+__write_nocancel (int fd, const void *buf, size_t nbytes)
+{
+  error_t err = HURD_FD_USE (fd, _hurd_fd_write (descriptor,
+						 buf, &nbytes, -1));
+  return err ? __hurd_dfail (fd, err) : nbytes;
+}
+libc_hidden_weak (__write_nocancel)