mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-26 23:10:06 +00:00
c79a72aa5c
Currently all architectures but microblaze use wire-up syscall for
p{readv,write}v. Microblaze still uses the syscall emulation using
sysdep/posix/p{readv,writev}.c and it was reported in some ocasions
[1] [2] that it might have some issues with some linux specific
usage (mainly with O_DIRECT and the alignment requirement).
Although it is not an issue for virtually all the system, this
patch refactors the sysdeps/posix p{read,write}v syscall to avoid
such issue (by using posix_memalign on the buffer used on
p{read,write} call) and by refactoring it common files to avoid
the need check on defines to correct set the alias and internal
symbols.
Checked on microblaze-linux-gnu check with run-built-tests=no and
by using the sysdeps/posix implementation on x86_64-linux-gnu (just
for sanity test where it shown no regression).
* sysdeps/posix/preadv.c: Use sysdeps/posix/preadv_common.c.
* sysdeps/posix/preadv64.c: Likewise.
* sysdeps/unix/sysv/linux/preadv.c: Likewise.
* sysdeps/unix/sysv/linux/preadv64.c: Likewise.
* sysdeps/posix/pwritev.c: Use sysdeps/posix/pwritev_common.c.
* sysdeps/posix/pwritev64.c: Likewise.
* sysdeps/unix/sysv/linux/pwritev.c: Likewise.
* sysdeps/unix/sysv/linux/pwritev64.c: Likewise.
* sysdeps/posix/preadv_common.c: New file.
* sysdeps/posix/pwritev_common.c: Likewise.
[1] http://www.mail-archive.com/qemu-devel@nongnu.org/msg25282.html
[2] https://bugzilla.redhat.com/show_bug.cgi?id=563103#c8
73 lines
2.6 KiB
C
73 lines
2.6 KiB
C
/* Write data into multiple buffers. Base implementation for pwritev
|
|
and pwritev64.
|
|
Copyright (C) 2017 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 <unistd.h>
|
|
#include <sys/uio.h>
|
|
#include <sys/param.h>
|
|
#include <errno.h>
|
|
#include <malloc.h>
|
|
|
|
#include <ldsodefs.h>
|
|
|
|
/* 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 'write' (see
|
|
<unistd.h>) except that the data are taken from IOVEC instead of a
|
|
contiguous buffer. */
|
|
ssize_t
|
|
PWRITEV (int fd, const struct iovec *vector, int count, OFF_T offset)
|
|
{
|
|
/* Find the total number of bytes to be read. */
|
|
size_t bytes = 0;
|
|
for (int i = 0; i < count; ++i)
|
|
{
|
|
/* Check for ssize_t overflow. */
|
|
if (SSIZE_MAX - bytes < vector[i].iov_len)
|
|
{
|
|
__set_errno (EINVAL);
|
|
return -1;
|
|
}
|
|
bytes += vector[i].iov_len;
|
|
}
|
|
|
|
/* Allocate a temporary buffer to hold the data. It could be done with a
|
|
stack allocation, but due limitations on some system (Linux with
|
|
O_DIRECT) it aligns the buffer to pagesize. A possible optimization
|
|
would be querying if the syscall would impose any alignment constraint,
|
|
but 1. it is system specific (not meant in generic implementation), and
|
|
2. it would make the implementation more complex, and 3. it will require
|
|
another syscall (fcntl). */
|
|
void *buffer = NULL;
|
|
if (__posix_memalign (&buffer, GLRO(dl_pagesize), bytes) != 0)
|
|
return -1;
|
|
|
|
/* Copy the data from BUFFER into the memory specified by VECTOR. */
|
|
char *ptr = buffer;
|
|
for (int i = 0; i < count; ++i)
|
|
ptr = __mempcpy ((void *) ptr, (void *) vector[i].iov_base,
|
|
vector[i].iov_len);
|
|
|
|
ssize_t ret = PWRITE (fd, buffer, bytes, offset);
|
|
|
|
free (buffer);
|
|
|
|
return ret;
|
|
}
|