add wrappers for preadv/pwritev

include/sys/uio.h

@@ -48,6 +48,32 @@ extern ssize_t readv (int __fd, const struct iovec *__iovec, int __count);
    __THROW.  */
 extern ssize_t writev (int __fd, const struct iovec *__iovec, int __count);
 
+#ifdef __USE_MISC
+/* Read data from file descriptor FD at the given position OFFSET
+   without change the file pointer, and put the result in the buffers
+   described by IOVEC, which is a vector of COUNT 'struct iovec's.
+   The buffers are filled in the order specified.  Operates just like
+   'pread' (see <unistd.h>) except that data are put in IOVEC instead
+   of a contiguous buffer.
+
+   This function is a cancellation point and therefore not marked with
+   __THROW.  */
+extern ssize_t preadv (int __fd, const struct iovec *__iovec, int __count,
+		       __off_t __offset) __wur;
+
+/* Write data pointed by the buffers described by IOVEC, which is a
+   vector of COUNT 'struct iovec's, to file descriptor FD at the given
+   position OFFSET without change the file pointer.  The data is
+   written in the order specified.  Operates just like 'pwrite' (see
+   <unistd.h>) except that the data are taken from IOVEC instead of a
+   contiguous buffer.
+
+   This function is a cancellation point and therefore not marked with
+   __THROW.  */
+extern ssize_t pwritev (int __fd, const struct iovec *__iovec, int __count,
+			__off_t __offset) __wur;
+#endif	/* Use misc.  */
+
 __END_DECLS
 
 #endif /* sys/uio.h */

libc/sysdeps/linux/common/preadv.c

@@ -0,0 +1,26 @@
+/* Copyright (C) 2009-2016 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 <sys/uio.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+ssize_t
+preadv (int fd, const struct iovec *vector, int count, off_t offset)
+{
+  return INLINE_SYSCALL (preadv, 4, fd, vector, count, offset);
+}

libc/sysdeps/linux/common/pwritev.c

@@ -0,0 +1,26 @@
+/* Copyright (C) 2009-2016 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 <sys/uio.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+ssize_t
+pwritev (int fd, const struct iovec *vector, int count, off_t offset)
+{
+  return INLINE_SYSCALL (pwritev, 4, fd, vector, count, offset);
+}