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c741c45512
linux/fs/hostfs/hostfs_user.c
Al Viro f8ad850f11 try to get rid of races in hostfs open() 
In case of mode mismatch, do *not* blindly close the descriptor
another openers might be using right now.  Open the underlying
file with currently sufficient mode, then
	* if current mode has grown so that it's sufficient for
us now, just close our new fd
	* if current mode has grown and our fd is *not* enough
to cover it, close and repeat.
	* otherwise, install our fd if the file hadn't been
opened at all or dup2() our fd over the current one (and close
our fd).
Critical section is protected by mutex; yes, system-wide.  All
we do under it is a bunch of comparison and maybe an overwriting
dup2() on host.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-09 16:48:15 -04:00

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/*
* Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
* Licensed under the GPL
*/
#include <stdio.h>
#include <stddef.h>
#include <unistd.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/vfs.h>
#include "hostfs.h"
#include "os.h"
#include "user.h"
#include <utime.h>
static void stat64_to_hostfs(const struct stat64 *buf, struct hostfs_stat *p)
{
p->ino = buf->st_ino;
p->mode = buf->st_mode;
p->nlink = buf->st_nlink;
p->uid = buf->st_uid;
p->gid = buf->st_gid;
p->size = buf->st_size;
p->atime.tv_sec = buf->st_atime;
p->atime.tv_nsec = 0;
p->ctime.tv_sec = buf->st_ctime;
p->ctime.tv_nsec = 0;
p->mtime.tv_sec = buf->st_mtime;
p->mtime.tv_nsec = 0;
p->blksize = buf->st_blksize;
p->blocks = buf->st_blocks;
p->maj = os_major(buf->st_rdev);
p->min = os_minor(buf->st_rdev);
}
int stat_file(const char *path, struct hostfs_stat *p, int fd)
{
struct stat64 buf;
if (fd >= 0) {
if (fstat64(fd, &buf) < 0)
return -errno;
} else if (lstat64(path, &buf) < 0) {
return -errno;
}
stat64_to_hostfs(&buf, p);
return 0;
}
int access_file(char *path, int r, int w, int x)
{
int mode = 0;
if (r)
mode = R_OK;
if (w)
mode |= W_OK;
if (x)
mode |= X_OK;
if (access(path, mode) != 0)
return -errno;
else return 0;
}
int open_file(char *path, int r, int w, int append)
{
int mode = 0, fd;
if (r && !w)
mode = O_RDONLY;
else if (!r && w)
mode = O_WRONLY;
else if (r && w)
mode = O_RDWR;
else panic("Impossible mode in open_file");
if (append)
mode |= O_APPEND;
fd = open64(path, mode);
if (fd < 0)
return -errno;
else return fd;
}
void *open_dir(char *path, int *err_out)
{
DIR *dir;
dir = opendir(path);
*err_out = errno;
if (dir == NULL)
return NULL;
return dir;
}
char *read_dir(void *stream, unsigned long long *pos,
unsigned long long *ino_out, int *len_out)
{
DIR *dir = stream;
struct dirent *ent;
seekdir(dir, *pos);
ent = readdir(dir);
if (ent == NULL)
return NULL;
*len_out = strlen(ent->d_name);
*ino_out = ent->d_ino;
*pos = telldir(dir);
return ent->d_name;
}
int read_file(int fd, unsigned long long *offset, char *buf, int len)
{
int n;
n = pread64(fd, buf, len, *offset);
if (n < 0)
return -errno;
*offset += n;
return n;
}
int write_file(int fd, unsigned long long *offset, const char *buf, int len)
{
int n;
n = pwrite64(fd, buf, len, *offset);
if (n < 0)
return -errno;
*offset += n;
return n;
}
int lseek_file(int fd, long long offset, int whence)
{
int ret;
ret = lseek64(fd, offset, whence);
if (ret < 0)
return -errno;
return 0;
}
int fsync_file(int fd, int datasync)
{
int ret;
if (datasync)
ret = fdatasync(fd);
else
ret = fsync(fd);
if (ret < 0)
return -errno;
return 0;
}
int replace_file(int oldfd, int fd)
{
return dup2(oldfd, fd);
}
void close_file(void *stream)
{
close(*((int *) stream));
}
void close_dir(void *stream)
{
closedir(stream);
}
int file_create(char *name, int ur, int uw, int ux, int gr,
int gw, int gx, int or, int ow, int ox)
{
int mode, fd;
mode = 0;
mode |= ur ? S_IRUSR : 0;
mode |= uw ? S_IWUSR : 0;
mode |= ux ? S_IXUSR : 0;
mode |= gr ? S_IRGRP : 0;
mode |= gw ? S_IWGRP : 0;
mode |= gx ? S_IXGRP : 0;
mode |= or ? S_IROTH : 0;
mode |= ow ? S_IWOTH : 0;
mode |= ox ? S_IXOTH : 0;
fd = open64(name, O_CREAT | O_RDWR, mode);
if (fd < 0)
return -errno;
return fd;
}
int set_attr(const char *file, struct hostfs_iattr *attrs, int fd)
{
struct hostfs_stat st;
struct timeval times[2];
int err, ma;
if (attrs->ia_valid & HOSTFS_ATTR_MODE) {
if (fd >= 0) {
if (fchmod(fd, attrs->ia_mode) != 0)
return (-errno);
} else if (chmod(file, attrs->ia_mode) != 0) {
return -errno;
}
}
if (attrs->ia_valid & HOSTFS_ATTR_UID) {
if (fd >= 0) {
if (fchown(fd, attrs->ia_uid, -1))
return -errno;
} else if (chown(file, attrs->ia_uid, -1)) {
return -errno;
}
}
if (attrs->ia_valid & HOSTFS_ATTR_GID) {
if (fd >= 0) {
if (fchown(fd, -1, attrs->ia_gid))
return -errno;
} else if (chown(file, -1, attrs->ia_gid)) {
return -errno;
}
}
if (attrs->ia_valid & HOSTFS_ATTR_SIZE) {
if (fd >= 0) {
if (ftruncate(fd, attrs->ia_size))
return -errno;
} else if (truncate(file, attrs->ia_size)) {
return -errno;
}
}
/*
* Update accessed and/or modified time, in two parts: first set
* times according to the changes to perform, and then call futimes()
* or utimes() to apply them.
*/
ma = (HOSTFS_ATTR_ATIME_SET | HOSTFS_ATTR_MTIME_SET);
if (attrs->ia_valid & ma) {
err = stat_file(file, &st, fd);
if (err != 0)
return err;
times[0].tv_sec = st.atime.tv_sec;
times[0].tv_usec = st.atime.tv_nsec / 1000;
times[1].tv_sec = st.mtime.tv_sec;
times[1].tv_usec = st.mtime.tv_nsec / 1000;
if (attrs->ia_valid & HOSTFS_ATTR_ATIME_SET) {
times[0].tv_sec = attrs->ia_atime.tv_sec;
times[0].tv_usec = attrs->ia_atime.tv_nsec / 1000;
}
if (attrs->ia_valid & HOSTFS_ATTR_MTIME_SET) {
times[1].tv_sec = attrs->ia_mtime.tv_sec;
times[1].tv_usec = attrs->ia_mtime.tv_nsec / 1000;
}
if (fd >= 0) {
if (futimes(fd, times) != 0)
return -errno;
} else if (utimes(file, times) != 0) {
return -errno;
}
}
/* Note: ctime is not handled */
if (attrs->ia_valid & (HOSTFS_ATTR_ATIME | HOSTFS_ATTR_MTIME)) {
err = stat_file(file, &st, fd);
attrs->ia_atime = st.atime;
attrs->ia_mtime = st.mtime;
if (err != 0)
return err;
}
return 0;
}
int make_symlink(const char *from, const char *to)
{
int err;
err = symlink(to, from);
if (err)
return -errno;
return 0;
}
int unlink_file(const char *file)
{
int err;
err = unlink(file);
if (err)
return -errno;
return 0;
}
int do_mkdir(const char *file, int mode)
{
int err;
err = mkdir(file, mode);
if (err)
return -errno;
return 0;
}
int do_rmdir(const char *file)
{
int err;
err = rmdir(file);
if (err)
return -errno;
return 0;
}
int do_mknod(const char *file, int mode, unsigned int major, unsigned int minor)
{
int err;
err = mknod(file, mode, os_makedev(major, minor));
if (err)
return -errno;
return 0;
}
int link_file(const char *to, const char *from)
{
int err;
err = link(to, from);
if (err)
return -errno;
return 0;
}
int hostfs_do_readlink(char *file, char *buf, int size)
{
int n;
n = readlink(file, buf, size);
if (n < 0)
return -errno;
if (n < size)
buf[n] = '\0';
return n;
}
int rename_file(char *from, char *to)
{
int err;
err = rename(from, to);
if (err < 0)
return -errno;
return 0;
}
int do_statfs(char *root, long *bsize_out, long long *blocks_out,
long long *bfree_out, long long *bavail_out,
long long *files_out, long long *ffree_out,
void *fsid_out, int fsid_size, long *namelen_out,
long *spare_out)
{
struct statfs64 buf;
int err;
err = statfs64(root, &buf);
if (err < 0)
return -errno;
*bsize_out = buf.f_bsize;
*blocks_out = buf.f_blocks;
*bfree_out = buf.f_bfree;
*bavail_out = buf.f_bavail;
*files_out = buf.f_files;
*ffree_out = buf.f_ffree;
memcpy(fsid_out, &buf.f_fsid,
sizeof(buf.f_fsid) > fsid_size ? fsid_size :
sizeof(buf.f_fsid));
*namelen_out = buf.f_namelen;
spare_out[0] = buf.f_spare[0];
spare_out[1] = buf.f_spare[1];
spare_out[2] = buf.f_spare[2];
spare_out[3] = buf.f_spare[3];
spare_out[4] = buf.f_spare[4];
return 0;
}
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