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qemu/hw/virtio-9p-local.c
Sanchit Garg 56d15a5329 [virtio-9p] Use preadv/pwritev instead of readv/writev 
readv & writev, read & write respectively from the current offset
of the file & hence their use has to be preceeded by a call to lseek.
preadv/writev can be used instead, as they take the offset as an argument.
This saves one system call( lseek ).
In case preadv is not supported, it is implemented by an lseek
followed by a readv. Depending upon the configuration of QEMU, the
appropriate read & write methods are selected. This patch also fixes the
zero byte read/write bug & obviates the need to apply a fix for that bug separately.

Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com>
Signed-off-by: Sanchit Garg <sancgarg@linux.vnet.ibm.com>
Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
2010-10-20 12:10:59 -05:00

560 lines
14 KiB
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/*
* Virtio 9p Posix callback
*
* Copyright IBM, Corp. 2010
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
*/
#include "virtio.h"
#include "virtio-9p.h"
#include "virtio-9p-xattr.h"
#include <arpa/inet.h>
#include <pwd.h>
#include <grp.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <attr/xattr.h>
static int local_lstat(FsContext *fs_ctx, const char *path, struct stat *stbuf)
{
int err;
err = lstat(rpath(fs_ctx, path), stbuf);
if (err) {
return err;
}
if (fs_ctx->fs_sm == SM_MAPPED) {
/* Actual credentials are part of extended attrs */
uid_t tmp_uid;
gid_t tmp_gid;
mode_t tmp_mode;
dev_t tmp_dev;
if (getxattr(rpath(fs_ctx, path), "user.virtfs.uid", &tmp_uid,
sizeof(uid_t)) > 0) {
stbuf->st_uid = tmp_uid;
}
if (getxattr(rpath(fs_ctx, path), "user.virtfs.gid", &tmp_gid,
sizeof(gid_t)) > 0) {
stbuf->st_gid = tmp_gid;
}
if (getxattr(rpath(fs_ctx, path), "user.virtfs.mode", &tmp_mode,
sizeof(mode_t)) > 0) {
stbuf->st_mode = tmp_mode;
}
if (getxattr(rpath(fs_ctx, path), "user.virtfs.rdev", &tmp_dev,
sizeof(dev_t)) > 0) {
stbuf->st_rdev = tmp_dev;
}
}
return err;
}
static int local_set_xattr(const char *path, FsCred *credp)
{
int err;
if (credp->fc_uid != -1) {
err = setxattr(path, "user.virtfs.uid", &credp->fc_uid, sizeof(uid_t),
0);
if (err) {
return err;
}
}
if (credp->fc_gid != -1) {
err = setxattr(path, "user.virtfs.gid", &credp->fc_gid, sizeof(gid_t),
0);
if (err) {
return err;
}
}
if (credp->fc_mode != -1) {
err = setxattr(path, "user.virtfs.mode", &credp->fc_mode,
sizeof(mode_t), 0);
if (err) {
return err;
}
}
if (credp->fc_rdev != -1) {
err = setxattr(path, "user.virtfs.rdev", &credp->fc_rdev,
sizeof(dev_t), 0);
if (err) {
return err;
}
}
return 0;
}
static int local_post_create_passthrough(FsContext *fs_ctx, const char *path,
FsCred *credp)
{
if (chmod(rpath(fs_ctx, path), credp->fc_mode & 07777) < 0) {
return -1;
}
if (lchown(rpath(fs_ctx, path), credp->fc_uid, credp->fc_gid) < 0) {
/*
* If we fail to change ownership and if we are
* using security model none. Ignore the error
*/
if (fs_ctx->fs_sm != SM_NONE) {
return -1;
}
}
return 0;
}
static ssize_t local_readlink(FsContext *fs_ctx, const char *path,
char *buf, size_t bufsz)
{
ssize_t tsize = -1;
if (fs_ctx->fs_sm == SM_MAPPED) {
int fd;
fd = open(rpath(fs_ctx, path), O_RDONLY);
if (fd == -1) {
return -1;
}
do {
tsize = read(fd, (void *)buf, bufsz);
} while (tsize == -1 && errno == EINTR);
close(fd);
return tsize;
} else if ((fs_ctx->fs_sm == SM_PASSTHROUGH) ||
(fs_ctx->fs_sm == SM_NONE)) {
tsize = readlink(rpath(fs_ctx, path), buf, bufsz);
}
return tsize;
}
static int local_close(FsContext *ctx, int fd)
{
return close(fd);
}
static int local_closedir(FsContext *ctx, DIR *dir)
{
return closedir(dir);
}
static int local_open(FsContext *ctx, const char *path, int flags)
{
return open(rpath(ctx, path), flags);
}
static DIR *local_opendir(FsContext *ctx, const char *path)
{
return opendir(rpath(ctx, path));
}
static void local_rewinddir(FsContext *ctx, DIR *dir)
{
return rewinddir(dir);
}
static off_t local_telldir(FsContext *ctx, DIR *dir)
{
return telldir(dir);
}
static struct dirent *local_readdir(FsContext *ctx, DIR *dir)
{
return readdir(dir);
}
static void local_seekdir(FsContext *ctx, DIR *dir, off_t off)
{
return seekdir(dir, off);
}
static ssize_t local_preadv(FsContext *ctx, int fd, const struct iovec *iov,
int iovcnt, off_t offset)
{
#ifdef CONFIG_PREADV
return preadv(fd, iov, iovcnt, offset);
#else
int err = lseek(fd, offset, SEEK_SET);
if (err == -1) {
return err;
} else {
return readv(fd, iov, iovcnt);
}
#endif
}
static ssize_t local_pwritev(FsContext *ctx, int fd, const struct iovec *iov,
int iovcnt, off_t offset)
{
#ifdef CONFIG_PREADV
return pwritev(fd, iov, iovcnt, offset);
#else
int err = lseek(fd, offset, SEEK_SET);
if (err == -1) {
return err;
} else {
return writev(fd, iov, iovcnt);
}
#endif
}
static int local_chmod(FsContext *fs_ctx, const char *path, FsCred *credp)
{
if (fs_ctx->fs_sm == SM_MAPPED) {
return local_set_xattr(rpath(fs_ctx, path), credp);
} else if ((fs_ctx->fs_sm == SM_PASSTHROUGH) ||
(fs_ctx->fs_sm == SM_NONE)) {
return chmod(rpath(fs_ctx, path), credp->fc_mode);
}
return -1;
}
static int local_mknod(FsContext *fs_ctx, const char *path, FsCred *credp)
{
int err = -1;
int serrno = 0;
/* Determine the security model */
if (fs_ctx->fs_sm == SM_MAPPED) {
err = mknod(rpath(fs_ctx, path), SM_LOCAL_MODE_BITS|S_IFREG, 0);
if (err == -1) {
return err;
}
local_set_xattr(rpath(fs_ctx, path), credp);
if (err == -1) {
serrno = errno;
goto err_end;
}
} else if ((fs_ctx->fs_sm == SM_PASSTHROUGH) ||
(fs_ctx->fs_sm == SM_NONE)) {
err = mknod(rpath(fs_ctx, path), credp->fc_mode, credp->fc_rdev);
if (err == -1) {
return err;
}
err = local_post_create_passthrough(fs_ctx, path, credp);
if (err == -1) {
serrno = errno;
goto err_end;
}
}
return err;
err_end:
remove(rpath(fs_ctx, path));
errno = serrno;
return err;
}
static int local_mkdir(FsContext *fs_ctx, const char *path, FsCred *credp)
{
int err = -1;
int serrno = 0;
/* Determine the security model */
if (fs_ctx->fs_sm == SM_MAPPED) {
err = mkdir(rpath(fs_ctx, path), SM_LOCAL_DIR_MODE_BITS);
if (err == -1) {
return err;
}
credp->fc_mode = credp->fc_mode|S_IFDIR;
err = local_set_xattr(rpath(fs_ctx, path), credp);
if (err == -1) {
serrno = errno;
goto err_end;
}
} else if ((fs_ctx->fs_sm == SM_PASSTHROUGH) ||
(fs_ctx->fs_sm == SM_NONE)) {
err = mkdir(rpath(fs_ctx, path), credp->fc_mode);
if (err == -1) {
return err;
}
err = local_post_create_passthrough(fs_ctx, path, credp);
if (err == -1) {
serrno = errno;
goto err_end;
}
}
return err;
err_end:
remove(rpath(fs_ctx, path));
errno = serrno;
return err;
}
static int local_fstat(FsContext *fs_ctx, int fd, struct stat *stbuf)
{
int err;
err = fstat(fd, stbuf);
if (err) {
return err;
}
if (fs_ctx->fs_sm == SM_MAPPED) {
/* Actual credentials are part of extended attrs */
uid_t tmp_uid;
gid_t tmp_gid;
mode_t tmp_mode;
dev_t tmp_dev;
if (fgetxattr(fd, "user.virtfs.uid", &tmp_uid, sizeof(uid_t)) > 0) {
stbuf->st_uid = tmp_uid;
}
if (fgetxattr(fd, "user.virtfs.gid", &tmp_gid, sizeof(gid_t)) > 0) {
stbuf->st_gid = tmp_gid;
}
if (fgetxattr(fd, "user.virtfs.mode", &tmp_mode, sizeof(mode_t)) > 0) {
stbuf->st_mode = tmp_mode;
}
if (fgetxattr(fd, "user.virtfs.rdev", &tmp_dev, sizeof(dev_t)) > 0) {
stbuf->st_rdev = tmp_dev;
}
}
return err;
}
static int local_open2(FsContext *fs_ctx, const char *path, int flags,
FsCred *credp)
{
int fd = -1;
int err = -1;
int serrno = 0;
/* Determine the security model */
if (fs_ctx->fs_sm == SM_MAPPED) {
fd = open(rpath(fs_ctx, path), flags, SM_LOCAL_MODE_BITS);
if (fd == -1) {
return fd;
}
credp->fc_mode = credp->fc_mode|S_IFREG;
/* Set cleint credentials in xattr */
err = local_set_xattr(rpath(fs_ctx, path), credp);
if (err == -1) {
serrno = errno;
goto err_end;
}
} else if ((fs_ctx->fs_sm == SM_PASSTHROUGH) ||
(fs_ctx->fs_sm == SM_NONE)) {
fd = open(rpath(fs_ctx, path), flags, credp->fc_mode);
if (fd == -1) {
return fd;
}
err = local_post_create_passthrough(fs_ctx, path, credp);
if (err == -1) {
serrno = errno;
goto err_end;
}
}
return fd;
err_end:
close(fd);
remove(rpath(fs_ctx, path));
errno = serrno;
return err;
}
static int local_symlink(FsContext *fs_ctx, const char *oldpath,
const char *newpath, FsCred *credp)
{
int err = -1;
int serrno = 0;
/* Determine the security model */
if (fs_ctx->fs_sm == SM_MAPPED) {
int fd;
ssize_t oldpath_size, write_size;
fd = open(rpath(fs_ctx, newpath), O_CREAT|O_EXCL|O_RDWR,
SM_LOCAL_MODE_BITS);
if (fd == -1) {
return fd;
}
/* Write the oldpath (target) to the file. */
oldpath_size = strlen(oldpath) + 1;
do {
write_size = write(fd, (void *)oldpath, oldpath_size);
} while (write_size == -1 && errno == EINTR);
if (write_size != oldpath_size) {
serrno = errno;
close(fd);
err = -1;
goto err_end;
}
close(fd);
/* Set cleint credentials in symlink's xattr */
credp->fc_mode = credp->fc_mode|S_IFLNK;
err = local_set_xattr(rpath(fs_ctx, newpath), credp);
if (err == -1) {
serrno = errno;
goto err_end;
}
} else if ((fs_ctx->fs_sm == SM_PASSTHROUGH) ||
(fs_ctx->fs_sm == SM_NONE)) {
err = symlink(oldpath, rpath(fs_ctx, newpath));
if (err) {
return err;
}
err = lchown(rpath(fs_ctx, newpath), credp->fc_uid, credp->fc_gid);
if (err == -1) {
/*
* If we fail to change ownership and if we are
* using security model none. Ignore the error
*/
if (fs_ctx->fs_sm != SM_NONE) {
serrno = errno;
goto err_end;
} else
err = 0;
}
}
return err;
err_end:
remove(rpath(fs_ctx, newpath));
errno = serrno;
return err;
}
static int local_link(FsContext *ctx, const char *oldpath, const char *newpath)
{
char *tmp = qemu_strdup(rpath(ctx, oldpath));
int err, serrno = 0;
if (tmp == NULL) {
return -ENOMEM;
}
err = link(tmp, rpath(ctx, newpath));
if (err == -1) {
serrno = errno;
}
qemu_free(tmp);
if (err == -1) {
errno = serrno;
}
return err;
}
static int local_truncate(FsContext *ctx, const char *path, off_t size)
{
return truncate(rpath(ctx, path), size);
}
static int local_rename(FsContext *ctx, const char *oldpath,
const char *newpath)
{
char *tmp;
int err;
tmp = qemu_strdup(rpath(ctx, oldpath));
err = rename(tmp, rpath(ctx, newpath));
if (err == -1) {
int serrno = errno;
qemu_free(tmp);
errno = serrno;
} else {
qemu_free(tmp);
}
return err;
}
static int local_chown(FsContext *fs_ctx, const char *path, FsCred *credp)
{
if ((credp->fc_uid == -1 && credp->fc_gid == -1) ||
(fs_ctx->fs_sm == SM_PASSTHROUGH)) {
return lchown(rpath(fs_ctx, path), credp->fc_uid, credp->fc_gid);
} else if (fs_ctx->fs_sm == SM_MAPPED) {
return local_set_xattr(rpath(fs_ctx, path), credp);
} else if ((fs_ctx->fs_sm == SM_PASSTHROUGH) ||
(fs_ctx->fs_sm == SM_NONE)) {
return lchown(rpath(fs_ctx, path), credp->fc_uid, credp->fc_gid);
}
return -1;
}
static int local_utimensat(FsContext *s, const char *path,
const struct timespec *buf)
{
return utimensat(AT_FDCWD, rpath(s, path), buf, AT_SYMLINK_NOFOLLOW);
}
static int local_remove(FsContext *ctx, const char *path)
{
return remove(rpath(ctx, path));
}
static int local_fsync(FsContext *ctx, int fd)
{
return fsync(fd);
}
static int local_statfs(FsContext *s, const char *path, struct statfs *stbuf)
{
return statfs(rpath(s, path), stbuf);
}
static ssize_t local_lgetxattr(FsContext *ctx, const char *path,
const char *name, void *value, size_t size)
{
return v9fs_get_xattr(ctx, path, name, value, size);
}
static ssize_t local_llistxattr(FsContext *ctx, const char *path,
void *value, size_t size)
{
return v9fs_list_xattr(ctx, path, value, size);
}
static int local_lsetxattr(FsContext *ctx, const char *path, const char *name,
void *value, size_t size, int flags)
{
return v9fs_set_xattr(ctx, path, name, value, size, flags);
}
static int local_lremovexattr(FsContext *ctx,
const char *path, const char *name)
{
return v9fs_remove_xattr(ctx, path, name);
}
FileOperations local_ops = {
.lstat = local_lstat,
.readlink = local_readlink,
.close = local_close,
.closedir = local_closedir,
.open = local_open,
.opendir = local_opendir,
.rewinddir = local_rewinddir,
.telldir = local_telldir,
.readdir = local_readdir,
.seekdir = local_seekdir,
.preadv = local_preadv,
.pwritev = local_pwritev,
.chmod = local_chmod,
.mknod = local_mknod,
.mkdir = local_mkdir,
.fstat = local_fstat,
.open2 = local_open2,
.symlink = local_symlink,
.link = local_link,
.truncate = local_truncate,
.rename = local_rename,
.chown = local_chown,
.utimensat = local_utimensat,
.remove = local_remove,
.fsync = local_fsync,
.statfs = local_statfs,
.lgetxattr = local_lgetxattr,
.llistxattr = local_llistxattr,
.lsetxattr = local_lsetxattr,
.lremovexattr = local_lremovexattr,
};
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