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qemu-e2k/tools/virtiofsd/passthrough_ll.c

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/*
* FUSE: Filesystem in Userspace
* Copyright (C) 2001-2007 Miklos Szeredi <miklos@szeredi.hu>
*
* This program can be distributed under the terms of the GNU GPLv2.
* See the file COPYING.
*/
/*
*
* This file system mirrors the existing file system hierarchy of the
* system, starting at the root file system. This is implemented by
* just "passing through" all requests to the corresponding user-space
* libc functions. In contrast to passthrough.c and passthrough_fh.c,
* this implementation uses the low-level API. Its performance should
* be the least bad among the three, but many operations are not
* implemented. In particular, it is not possible to remove files (or
* directories) because the code necessary to defer actual removal
* until the file is not opened anymore would make the example much
* more complicated.
*
* When writeback caching is enabled (-o writeback mount option), it
* is only possible to write to files for which the mounting user has
* read permissions. This is because the writeback cache requires the
* kernel to be able to issue read requests for all files (which the
* passthrough filesystem cannot satisfy if it can't read the file in
* the underlying filesystem).
*
* Compile with:
*
* gcc -Wall passthrough_ll.c `pkg-config fuse3 --cflags --libs` -o
* passthrough_ll
*
* ## Source code ##
* \include passthrough_ll.c
*/
#define _GNU_SOURCE
#define FUSE_USE_VERSION 31
#include "config.h"
#include <assert.h>
#include <dirent.h>
#include <errno.h>
#include <fuse_lowlevel.h>
#include <inttypes.h>
#include <limits.h>
#include <pthread.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/file.h>
#include <sys/xattr.h>
#include <unistd.h>
#include "passthrough_helpers.h"
/*
* We are re-using pointers to our `struct lo_inode` and `struct
* lo_dirp` elements as inodes. This means that we must be able to
* store uintptr_t values in a fuse_ino_t variable. The following
* incantation checks this condition at compile time.
*/
#if defined(__GNUC__) && \
(__GNUC__ > 4 || __GNUC__ == 4 && __GNUC_MINOR__ >= 6) && \
!defined __cplusplus
_Static_assert(sizeof(fuse_ino_t) >= sizeof(uintptr_t),
"fuse_ino_t too small to hold uintptr_t values!");
#else
struct _uintptr_to_must_hold_fuse_ino_t_dummy_struct {
unsigned _uintptr_to_must_hold_fuse_ino_t
: ((sizeof(fuse_ino_t) >= sizeof(uintptr_t)) ? 1 : -1);
};
#endif
struct lo_inode {
struct lo_inode *next; /* protected by lo->mutex */
struct lo_inode *prev; /* protected by lo->mutex */
int fd;
bool is_symlink;
ino_t ino;
dev_t dev;
uint64_t refcount; /* protected by lo->mutex */
};
enum {
CACHE_NEVER,
CACHE_NORMAL,
CACHE_ALWAYS,
};
struct lo_data {
pthread_mutex_t mutex;
int debug;
int writeback;
int flock;
int xattr;
const char *source;
double timeout;
int cache;
int timeout_set;
struct lo_inode root; /* protected by lo->mutex */
};
static const struct fuse_opt lo_opts[] = {
{ "writeback", offsetof(struct lo_data, writeback), 1 },
{ "no_writeback", offsetof(struct lo_data, writeback), 0 },
{ "source=%s", offsetof(struct lo_data, source), 0 },
{ "flock", offsetof(struct lo_data, flock), 1 },
{ "no_flock", offsetof(struct lo_data, flock), 0 },
{ "xattr", offsetof(struct lo_data, xattr), 1 },
{ "no_xattr", offsetof(struct lo_data, xattr), 0 },
{ "timeout=%lf", offsetof(struct lo_data, timeout), 0 },
{ "timeout=", offsetof(struct lo_data, timeout_set), 1 },
{ "cache=never", offsetof(struct lo_data, cache), CACHE_NEVER },
{ "cache=auto", offsetof(struct lo_data, cache), CACHE_NORMAL },
{ "cache=always", offsetof(struct lo_data, cache), CACHE_ALWAYS },
FUSE_OPT_END
};
static struct lo_data *lo_data(fuse_req_t req)
{
return (struct lo_data *)fuse_req_userdata(req);
}
static struct lo_inode *lo_inode(fuse_req_t req, fuse_ino_t ino)
{
if (ino == FUSE_ROOT_ID) {
return &lo_data(req)->root;
} else {
return (struct lo_inode *)(uintptr_t)ino;
}
}
static int lo_fd(fuse_req_t req, fuse_ino_t ino)
{
return lo_inode(req, ino)->fd;
}
static bool lo_debug(fuse_req_t req)
{
return lo_data(req)->debug != 0;
}
static void lo_init(void *userdata, struct fuse_conn_info *conn)
{
struct lo_data *lo = (struct lo_data *)userdata;
if (conn->capable & FUSE_CAP_EXPORT_SUPPORT) {
conn->want |= FUSE_CAP_EXPORT_SUPPORT;
}
if (lo->writeback && conn->capable & FUSE_CAP_WRITEBACK_CACHE) {
if (lo->debug) {
fuse_log(FUSE_LOG_DEBUG, "lo_init: activating writeback\n");
}
conn->want |= FUSE_CAP_WRITEBACK_CACHE;
}
if (lo->flock && conn->capable & FUSE_CAP_FLOCK_LOCKS) {
if (lo->debug) {
fuse_log(FUSE_LOG_DEBUG, "lo_init: activating flock locks\n");
}
conn->want |= FUSE_CAP_FLOCK_LOCKS;
}
}
static void lo_getattr(fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi)
{
int res;
struct stat buf;
struct lo_data *lo = lo_data(req);
(void)fi;
res =
fstatat(lo_fd(req, ino), "", &buf, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW);
if (res == -1) {
return (void)fuse_reply_err(req, errno);
}
fuse_reply_attr(req, &buf, lo->timeout);
}
static int utimensat_empty_nofollow(struct lo_inode *inode,
const struct timespec *tv)
{
int res;
char procname[64];
if (inode->is_symlink) {
res = utimensat(inode->fd, "", tv, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW);
if (res == -1 && errno == EINVAL) {
/* Sorry, no race free way to set times on symlink. */
errno = EPERM;
}
return res;
}
sprintf(procname, "/proc/self/fd/%i", inode->fd);
return utimensat(AT_FDCWD, procname, tv, 0);
}
static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
int valid, struct fuse_file_info *fi)
{
int saverr;
char procname[64];
struct lo_inode *inode = lo_inode(req, ino);
int ifd = inode->fd;
int res;
if (valid & FUSE_SET_ATTR_MODE) {
if (fi) {
res = fchmod(fi->fh, attr->st_mode);
} else {
sprintf(procname, "/proc/self/fd/%i", ifd);
res = chmod(procname, attr->st_mode);
}
if (res == -1) {
goto out_err;
}
}
if (valid & (FUSE_SET_ATTR_UID | FUSE_SET_ATTR_GID)) {
uid_t uid = (valid & FUSE_SET_ATTR_UID) ? attr->st_uid : (uid_t)-1;
gid_t gid = (valid & FUSE_SET_ATTR_GID) ? attr->st_gid : (gid_t)-1;
res = fchownat(ifd, "", uid, gid, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW);
if (res == -1) {
goto out_err;
}
}
if (valid & FUSE_SET_ATTR_SIZE) {
if (fi) {
res = ftruncate(fi->fh, attr->st_size);
} else {
sprintf(procname, "/proc/self/fd/%i", ifd);
res = truncate(procname, attr->st_size);
}
if (res == -1) {
goto out_err;
}
}
if (valid & (FUSE_SET_ATTR_ATIME | FUSE_SET_ATTR_MTIME)) {
struct timespec tv[2];
tv[0].tv_sec = 0;
tv[1].tv_sec = 0;
tv[0].tv_nsec = UTIME_OMIT;
tv[1].tv_nsec = UTIME_OMIT;
if (valid & FUSE_SET_ATTR_ATIME_NOW) {
tv[0].tv_nsec = UTIME_NOW;
} else if (valid & FUSE_SET_ATTR_ATIME) {
tv[0] = attr->st_atim;
}
if (valid & FUSE_SET_ATTR_MTIME_NOW) {
tv[1].tv_nsec = UTIME_NOW;
} else if (valid & FUSE_SET_ATTR_MTIME) {
tv[1] = attr->st_mtim;
}
if (fi) {
res = futimens(fi->fh, tv);
} else {
res = utimensat_empty_nofollow(inode, tv);
}
if (res == -1) {
goto out_err;
}
}
return lo_getattr(req, ino, fi);
out_err:
saverr = errno;
fuse_reply_err(req, saverr);
}
static struct lo_inode *lo_find(struct lo_data *lo, struct stat *st)
{
struct lo_inode *p;
struct lo_inode *ret = NULL;
pthread_mutex_lock(&lo->mutex);
for (p = lo->root.next; p != &lo->root; p = p->next) {
if (p->ino == st->st_ino && p->dev == st->st_dev) {
assert(p->refcount > 0);
ret = p;
ret->refcount++;
break;
}
}
pthread_mutex_unlock(&lo->mutex);
return ret;
}
static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,
struct fuse_entry_param *e)
{
int newfd;
int res;
int saverr;
struct lo_data *lo = lo_data(req);
struct lo_inode *inode;
memset(e, 0, sizeof(*e));
e->attr_timeout = lo->timeout;
e->entry_timeout = lo->timeout;
newfd = openat(lo_fd(req, parent), name, O_PATH | O_NOFOLLOW);
if (newfd == -1) {
goto out_err;
}
res = fstatat(newfd, "", &e->attr, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW);
if (res == -1) {
goto out_err;
}
inode = lo_find(lo_data(req), &e->attr);
if (inode) {
close(newfd);
newfd = -1;
} else {
struct lo_inode *prev, *next;
saverr = ENOMEM;
inode = calloc(1, sizeof(struct lo_inode));
if (!inode) {
goto out_err;
}
inode->is_symlink = S_ISLNK(e->attr.st_mode);
inode->refcount = 1;
inode->fd = newfd;
inode->ino = e->attr.st_ino;
inode->dev = e->attr.st_dev;
pthread_mutex_lock(&lo->mutex);
prev = &lo->root;
next = prev->next;
next->prev = inode;
inode->next = next;
inode->prev = prev;
prev->next = inode;
pthread_mutex_unlock(&lo->mutex);
}
e->ino = (uintptr_t)inode;
if (lo_debug(req)) {
fuse_log(FUSE_LOG_DEBUG, " %lli/%s -> %lli\n",
(unsigned long long)parent, name, (unsigned long long)e->ino);
}
return 0;
out_err:
saverr = errno;
if (newfd != -1) {
close(newfd);
}
return saverr;
}
static void lo_lookup(fuse_req_t req, fuse_ino_t parent, const char *name)
{
struct fuse_entry_param e;
int err;
if (lo_debug(req)) {
fuse_log(FUSE_LOG_DEBUG, "lo_lookup(parent=%" PRIu64 ", name=%s)\n",
parent, name);
}
err = lo_do_lookup(req, parent, name, &e);
if (err) {
fuse_reply_err(req, err);
} else {
fuse_reply_entry(req, &e);
}
}
static void lo_mknod_symlink(fuse_req_t req, fuse_ino_t parent,
const char *name, mode_t mode, dev_t rdev,
const char *link)
{
int res;
int saverr;
struct lo_inode *dir = lo_inode(req, parent);
struct fuse_entry_param e;
saverr = ENOMEM;
res = mknod_wrapper(dir->fd, name, link, mode, rdev);
saverr = errno;
if (res == -1) {
goto out;
}
saverr = lo_do_lookup(req, parent, name, &e);
if (saverr) {
goto out;
}
if (lo_debug(req)) {
fuse_log(FUSE_LOG_DEBUG, " %lli/%s -> %lli\n",
(unsigned long long)parent, name, (unsigned long long)e.ino);
}
fuse_reply_entry(req, &e);
return;
out:
fuse_reply_err(req, saverr);
}
static void lo_mknod(fuse_req_t req, fuse_ino_t parent, const char *name,
mode_t mode, dev_t rdev)
{
lo_mknod_symlink(req, parent, name, mode, rdev, NULL);
}
static void lo_mkdir(fuse_req_t req, fuse_ino_t parent, const char *name,
mode_t mode)
{
lo_mknod_symlink(req, parent, name, S_IFDIR | mode, 0, NULL);
}
static void lo_symlink(fuse_req_t req, const char *link, fuse_ino_t parent,
const char *name)
{
lo_mknod_symlink(req, parent, name, S_IFLNK, 0, link);
}
static int linkat_empty_nofollow(struct lo_inode *inode, int dfd,
const char *name)
{
int res;
char procname[64];
if (inode->is_symlink) {
res = linkat(inode->fd, "", dfd, name, AT_EMPTY_PATH);
if (res == -1 && (errno == ENOENT || errno == EINVAL)) {
/* Sorry, no race free way to hard-link a symlink. */
errno = EPERM;
}
return res;
}
sprintf(procname, "/proc/self/fd/%i", inode->fd);
return linkat(AT_FDCWD, procname, dfd, name, AT_SYMLINK_FOLLOW);
}
static void lo_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent,
const char *name)
{
int res;
struct lo_data *lo = lo_data(req);
struct lo_inode *inode = lo_inode(req, ino);
struct fuse_entry_param e;
int saverr;
memset(&e, 0, sizeof(struct fuse_entry_param));
e.attr_timeout = lo->timeout;
e.entry_timeout = lo->timeout;
res = linkat_empty_nofollow(inode, lo_fd(req, parent), name);
if (res == -1) {
goto out_err;
}
res = fstatat(inode->fd, "", &e.attr, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW);
if (res == -1) {
goto out_err;
}
pthread_mutex_lock(&lo->mutex);
inode->refcount++;
pthread_mutex_unlock(&lo->mutex);
e.ino = (uintptr_t)inode;
if (lo_debug(req)) {
fuse_log(FUSE_LOG_DEBUG, " %lli/%s -> %lli\n",
(unsigned long long)parent, name, (unsigned long long)e.ino);
}
fuse_reply_entry(req, &e);
return;
out_err:
saverr = errno;
fuse_reply_err(req, saverr);
}
static void lo_rmdir(fuse_req_t req, fuse_ino_t parent, const char *name)
{
int res;
res = unlinkat(lo_fd(req, parent), name, AT_REMOVEDIR);
fuse_reply_err(req, res == -1 ? errno : 0);
}
static void lo_rename(fuse_req_t req, fuse_ino_t parent, const char *name,
fuse_ino_t newparent, const char *newname,
unsigned int flags)
{
int res;
if (flags) {
fuse_reply_err(req, EINVAL);
return;
}
res = renameat(lo_fd(req, parent), name, lo_fd(req, newparent), newname);
fuse_reply_err(req, res == -1 ? errno : 0);
}
static void lo_unlink(fuse_req_t req, fuse_ino_t parent, const char *name)
{
int res;
res = unlinkat(lo_fd(req, parent), name, 0);
fuse_reply_err(req, res == -1 ? errno : 0);
}
static void unref_inode(struct lo_data *lo, struct lo_inode *inode, uint64_t n)
{
if (!inode) {
return;
}
pthread_mutex_lock(&lo->mutex);
assert(inode->refcount >= n);
inode->refcount -= n;
if (!inode->refcount) {
struct lo_inode *prev, *next;
prev = inode->prev;
next = inode->next;
next->prev = prev;
prev->next = next;
pthread_mutex_unlock(&lo->mutex);
close(inode->fd);
free(inode);
} else {
pthread_mutex_unlock(&lo->mutex);
}
}
static void lo_forget_one(fuse_req_t req, fuse_ino_t ino, uint64_t nlookup)
{
struct lo_data *lo = lo_data(req);
struct lo_inode *inode = lo_inode(req, ino);
if (lo_debug(req)) {
fuse_log(FUSE_LOG_DEBUG, " forget %lli %lli -%lli\n",
(unsigned long long)ino, (unsigned long long)inode->refcount,
(unsigned long long)nlookup);
}
unref_inode(lo, inode, nlookup);
}
static void lo_forget(fuse_req_t req, fuse_ino_t ino, uint64_t nlookup)
{
lo_forget_one(req, ino, nlookup);
fuse_reply_none(req);
}
static void lo_forget_multi(fuse_req_t req, size_t count,
struct fuse_forget_data *forgets)
{
int i;
for (i = 0; i < count; i++) {
lo_forget_one(req, forgets[i].ino, forgets[i].nlookup);
}
fuse_reply_none(req);
}
static void lo_readlink(fuse_req_t req, fuse_ino_t ino)
{
char buf[PATH_MAX + 1];
int res;
res = readlinkat(lo_fd(req, ino), "", buf, sizeof(buf));
if (res == -1) {
return (void)fuse_reply_err(req, errno);
}
if (res == sizeof(buf)) {
return (void)fuse_reply_err(req, ENAMETOOLONG);
}
buf[res] = '\0';
fuse_reply_readlink(req, buf);
}
struct lo_dirp {
DIR *dp;
struct dirent *entry;
off_t offset;
};
static struct lo_dirp *lo_dirp(struct fuse_file_info *fi)
{
return (struct lo_dirp *)(uintptr_t)fi->fh;
}
static void lo_opendir(fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi)
{
int error = ENOMEM;
struct lo_data *lo = lo_data(req);
struct lo_dirp *d;
int fd;
d = calloc(1, sizeof(struct lo_dirp));
if (d == NULL) {
goto out_err;
}
fd = openat(lo_fd(req, ino), ".", O_RDONLY);
if (fd == -1) {
goto out_errno;
}
d->dp = fdopendir(fd);
if (d->dp == NULL) {
goto out_errno;
}
d->offset = 0;
d->entry = NULL;
fi->fh = (uintptr_t)d;
if (lo->cache == CACHE_ALWAYS) {
fi->keep_cache = 1;
}
fuse_reply_open(req, fi);
return;
out_errno:
error = errno;
out_err:
if (d) {
if (fd != -1) {
close(fd);
}
free(d);
}
fuse_reply_err(req, error);
}
static int is_dot_or_dotdot(const char *name)
{
return name[0] == '.' &&
(name[1] == '\0' || (name[1] == '.' && name[2] == '\0'));
}
static void lo_do_readdir(fuse_req_t req, fuse_ino_t ino, size_t size,
off_t offset, struct fuse_file_info *fi, int plus)
{
struct lo_dirp *d = lo_dirp(fi);
char *buf;
char *p;
size_t rem = size;
int err;
(void)ino;
buf = calloc(1, size);
if (!buf) {
err = ENOMEM;
goto error;
}
p = buf;
if (offset != d->offset) {
seekdir(d->dp, offset);
d->entry = NULL;
d->offset = offset;
}
while (1) {
size_t entsize;
off_t nextoff;
const char *name;
if (!d->entry) {
errno = 0;
d->entry = readdir(d->dp);
if (!d->entry) {
if (errno) { /* Error */
err = errno;
goto error;
} else { /* End of stream */
break;
}
}
}
nextoff = d->entry->d_off;
name = d->entry->d_name;
fuse_ino_t entry_ino = 0;
if (plus) {
struct fuse_entry_param e;
if (is_dot_or_dotdot(name)) {
e = (struct fuse_entry_param){
.attr.st_ino = d->entry->d_ino,
.attr.st_mode = d->entry->d_type << 12,
};
} else {
err = lo_do_lookup(req, ino, name, &e);
if (err) {
goto error;
}
entry_ino = e.ino;
}
entsize = fuse_add_direntry_plus(req, p, rem, name, &e, nextoff);
} else {
struct stat st = {
.st_ino = d->entry->d_ino,
.st_mode = d->entry->d_type << 12,
};
entsize = fuse_add_direntry(req, p, rem, name, &st, nextoff);
}
if (entsize > rem) {
if (entry_ino != 0) {
lo_forget_one(req, entry_ino, 1);
}
break;
}
p += entsize;
rem -= entsize;
d->entry = NULL;
d->offset = nextoff;
}
err = 0;
error:
/*
* If there's an error, we can only signal it if we haven't stored
* any entries yet - otherwise we'd end up with wrong lookup
* counts for the entries that are already in the buffer. So we
* return what we've collected until that point.
*/
if (err && rem == size) {
fuse_reply_err(req, err);
} else {
fuse_reply_buf(req, buf, size - rem);
}
free(buf);
}
static void lo_readdir(fuse_req_t req, fuse_ino_t ino, size_t size,
off_t offset, struct fuse_file_info *fi)
{
lo_do_readdir(req, ino, size, offset, fi, 0);
}
static void lo_readdirplus(fuse_req_t req, fuse_ino_t ino, size_t size,
off_t offset, struct fuse_file_info *fi)
{
lo_do_readdir(req, ino, size, offset, fi, 1);
}
static void lo_releasedir(fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi)
{
struct lo_dirp *d = lo_dirp(fi);
(void)ino;
closedir(d->dp);
free(d);
fuse_reply_err(req, 0);
}
static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
mode_t mode, struct fuse_file_info *fi)
{
int fd;
struct lo_data *lo = lo_data(req);
struct fuse_entry_param e;
int err;
if (lo_debug(req)) {
fuse_log(FUSE_LOG_DEBUG, "lo_create(parent=%" PRIu64 ", name=%s)\n",
parent, name);
}
fd = openat(lo_fd(req, parent), name, (fi->flags | O_CREAT) & ~O_NOFOLLOW,
mode);
if (fd == -1) {
return (void)fuse_reply_err(req, errno);
}
fi->fh = fd;
if (lo->cache == CACHE_NEVER) {
fi->direct_io = 1;
} else if (lo->cache == CACHE_ALWAYS) {
fi->keep_cache = 1;
}
err = lo_do_lookup(req, parent, name, &e);
if (err) {
fuse_reply_err(req, err);
} else {
fuse_reply_create(req, &e, fi);
}
}
static void lo_fsyncdir(fuse_req_t req, fuse_ino_t ino, int datasync,
struct fuse_file_info *fi)
{
int res;
int fd = dirfd(lo_dirp(fi)->dp);
(void)ino;
if (datasync) {
res = fdatasync(fd);
} else {
res = fsync(fd);
}
fuse_reply_err(req, res == -1 ? errno : 0);
}
static void lo_open(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi)
{
int fd;
char buf[64];
struct lo_data *lo = lo_data(req);
if (lo_debug(req)) {
fuse_log(FUSE_LOG_DEBUG, "lo_open(ino=%" PRIu64 ", flags=%d)\n", ino,
fi->flags);
}
/*
* With writeback cache, kernel may send read requests even
* when userspace opened write-only
*/
if (lo->writeback && (fi->flags & O_ACCMODE) == O_WRONLY) {
fi->flags &= ~O_ACCMODE;
fi->flags |= O_RDWR;
}
/*
* With writeback cache, O_APPEND is handled by the kernel.
* This breaks atomicity (since the file may change in the
* underlying filesystem, so that the kernel's idea of the
* end of the file isn't accurate anymore). In this example,
* we just accept that. A more rigorous filesystem may want
* to return an error here
*/
if (lo->writeback && (fi->flags & O_APPEND)) {
fi->flags &= ~O_APPEND;
}
sprintf(buf, "/proc/self/fd/%i", lo_fd(req, ino));
fd = open(buf, fi->flags & ~O_NOFOLLOW);
if (fd == -1) {
return (void)fuse_reply_err(req, errno);
}
fi->fh = fd;
if (lo->cache == CACHE_NEVER) {
fi->direct_io = 1;
} else if (lo->cache == CACHE_ALWAYS) {
fi->keep_cache = 1;
}
fuse_reply_open(req, fi);
}
static void lo_release(fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi)
{
(void)ino;
close(fi->fh);
fuse_reply_err(req, 0);
}
static void lo_flush(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi)
{
int res;
(void)ino;
res = close(dup(fi->fh));
fuse_reply_err(req, res == -1 ? errno : 0);
}
static void lo_fsync(fuse_req_t req, fuse_ino_t ino, int datasync,
struct fuse_file_info *fi)
{
int res;
(void)ino;
if (datasync) {
res = fdatasync(fi->fh);
} else {
res = fsync(fi->fh);
}
fuse_reply_err(req, res == -1 ? errno : 0);
}
static void lo_read(fuse_req_t req, fuse_ino_t ino, size_t size, off_t offset,
struct fuse_file_info *fi)
{
struct fuse_bufvec buf = FUSE_BUFVEC_INIT(size);
if (lo_debug(req)) {
fuse_log(FUSE_LOG_DEBUG,
"lo_read(ino=%" PRIu64 ", size=%zd, "
"off=%lu)\n",
ino, size, (unsigned long)offset);
}
buf.buf[0].flags = FUSE_BUF_IS_FD | FUSE_BUF_FD_SEEK;
buf.buf[0].fd = fi->fh;
buf.buf[0].pos = offset;
fuse_reply_data(req, &buf, FUSE_BUF_SPLICE_MOVE);
}
static void lo_write_buf(fuse_req_t req, fuse_ino_t ino,
struct fuse_bufvec *in_buf, off_t off,
struct fuse_file_info *fi)
{
(void)ino;
ssize_t res;
struct fuse_bufvec out_buf = FUSE_BUFVEC_INIT(fuse_buf_size(in_buf));
out_buf.buf[0].flags = FUSE_BUF_IS_FD | FUSE_BUF_FD_SEEK;
out_buf.buf[0].fd = fi->fh;
out_buf.buf[0].pos = off;
if (lo_debug(req)) {
fuse_log(FUSE_LOG_DEBUG,
"lo_write(ino=%" PRIu64 ", size=%zd, off=%lu)\n", ino,
out_buf.buf[0].size, (unsigned long)off);
}
res = fuse_buf_copy(&out_buf, in_buf, 0);
if (res < 0) {
fuse_reply_err(req, -res);
} else {
fuse_reply_write(req, (size_t)res);
}
}
static void lo_statfs(fuse_req_t req, fuse_ino_t ino)
{
int res;
struct statvfs stbuf;
res = fstatvfs(lo_fd(req, ino), &stbuf);
if (res == -1) {
fuse_reply_err(req, errno);
} else {
fuse_reply_statfs(req, &stbuf);
}
}
static void lo_fallocate(fuse_req_t req, fuse_ino_t ino, int mode, off_t offset,
off_t length, struct fuse_file_info *fi)
{
int err = EOPNOTSUPP;
(void)ino;
#ifdef HAVE_FALLOCATE
err = fallocate(fi->fh, mode, offset, length);
if (err < 0) {
err = errno;
}
#elif defined(HAVE_POSIX_FALLOCATE)
if (mode) {
fuse_reply_err(req, EOPNOTSUPP);
return;
}
err = posix_fallocate(fi->fh, offset, length);
#endif
fuse_reply_err(req, err);
}
static void lo_flock(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi,
int op)
{
int res;
(void)ino;
res = flock(fi->fh, op);
fuse_reply_err(req, res == -1 ? errno : 0);
}
static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
size_t size)
{
char *value = NULL;
char procname[64];
struct lo_inode *inode = lo_inode(req, ino);
ssize_t ret;
int saverr;
saverr = ENOSYS;
if (!lo_data(req)->xattr) {
goto out;
}
if (lo_debug(req)) {
fuse_log(FUSE_LOG_DEBUG,
"lo_getxattr(ino=%" PRIu64 ", name=%s size=%zd)\n", ino, name,
size);
}
if (inode->is_symlink) {
/* Sorry, no race free way to getxattr on symlink. */
saverr = EPERM;
goto out;
}
sprintf(procname, "/proc/self/fd/%i", inode->fd);
if (size) {
value = malloc(size);
if (!value) {
goto out_err;
}
ret = getxattr(procname, name, value, size);
if (ret == -1) {
goto out_err;
}
saverr = 0;
if (ret == 0) {
goto out;
}
fuse_reply_buf(req, value, ret);
} else {
ret = getxattr(procname, name, NULL, 0);
if (ret == -1) {
goto out_err;
}
fuse_reply_xattr(req, ret);
}
out_free:
free(value);
return;
out_err:
saverr = errno;
out:
fuse_reply_err(req, saverr);
goto out_free;
}
static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size)
{
char *value = NULL;
char procname[64];
struct lo_inode *inode = lo_inode(req, ino);
ssize_t ret;
int saverr;
saverr = ENOSYS;
if (!lo_data(req)->xattr) {
goto out;
}
if (lo_debug(req)) {
fuse_log(FUSE_LOG_DEBUG, "lo_listxattr(ino=%" PRIu64 ", size=%zd)\n",
ino, size);
}
if (inode->is_symlink) {
/* Sorry, no race free way to listxattr on symlink. */
saverr = EPERM;
goto out;
}
sprintf(procname, "/proc/self/fd/%i", inode->fd);
if (size) {
value = malloc(size);
if (!value) {
goto out_err;
}
ret = listxattr(procname, value, size);
if (ret == -1) {
goto out_err;
}
saverr = 0;
if (ret == 0) {
goto out;
}
fuse_reply_buf(req, value, ret);
} else {
ret = listxattr(procname, NULL, 0);
if (ret == -1) {
goto out_err;
}
fuse_reply_xattr(req, ret);
}
out_free:
free(value);
return;
out_err:
saverr = errno;
out:
fuse_reply_err(req, saverr);
goto out_free;
}
static void lo_setxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
const char *value, size_t size, int flags)
{
char procname[64];
struct lo_inode *inode = lo_inode(req, ino);
ssize_t ret;
int saverr;
saverr = ENOSYS;
if (!lo_data(req)->xattr) {
goto out;
}
if (lo_debug(req)) {
fuse_log(FUSE_LOG_DEBUG,
"lo_setxattr(ino=%" PRIu64 ", name=%s value=%s size=%zd)\n",
ino, name, value, size);
}
if (inode->is_symlink) {
/* Sorry, no race free way to setxattr on symlink. */
saverr = EPERM;
goto out;
}
sprintf(procname, "/proc/self/fd/%i", inode->fd);
ret = setxattr(procname, name, value, size, flags);
saverr = ret == -1 ? errno : 0;
out:
fuse_reply_err(req, saverr);
}
static void lo_removexattr(fuse_req_t req, fuse_ino_t ino, const char *name)
{
char procname[64];
struct lo_inode *inode = lo_inode(req, ino);
ssize_t ret;
int saverr;
saverr = ENOSYS;
if (!lo_data(req)->xattr) {
goto out;
}
if (lo_debug(req)) {
fuse_log(FUSE_LOG_DEBUG, "lo_removexattr(ino=%" PRIu64 ", name=%s)\n",
ino, name);
}
if (inode->is_symlink) {
/* Sorry, no race free way to setxattr on symlink. */
saverr = EPERM;
goto out;
}
sprintf(procname, "/proc/self/fd/%i", inode->fd);
ret = removexattr(procname, name);
saverr = ret == -1 ? errno : 0;
out:
fuse_reply_err(req, saverr);
}
#ifdef HAVE_COPY_FILE_RANGE
static void lo_copy_file_range(fuse_req_t req, fuse_ino_t ino_in, off_t off_in,
struct fuse_file_info *fi_in, fuse_ino_t ino_out,
off_t off_out, struct fuse_file_info *fi_out,
size_t len, int flags)
{
ssize_t res;
if (lo_debug(req))
fuse_log(FUSE_LOG_DEBUG,
"lo_copy_file_range(ino=%" PRIu64 "/fd=%lu, "
"off=%lu, ino=%" PRIu64 "/fd=%lu, "
"off=%lu, size=%zd, flags=0x%x)\n",
ino_in, fi_in->fh, off_in, ino_out, fi_out->fh, off_out, len,
flags);
res = copy_file_range(fi_in->fh, &off_in, fi_out->fh, &off_out, len, flags);
if (res < 0) {
fuse_reply_err(req, -errno);
} else {
fuse_reply_write(req, res);
}
}
#endif
static void lo_lseek(fuse_req_t req, fuse_ino_t ino, off_t off, int whence,
struct fuse_file_info *fi)
{
off_t res;
(void)ino;
res = lseek(fi->fh, off, whence);
if (res != -1) {
fuse_reply_lseek(req, res);
} else {
fuse_reply_err(req, errno);
}
}
static struct fuse_lowlevel_ops lo_oper = {
.init = lo_init,
.lookup = lo_lookup,
.mkdir = lo_mkdir,
.mknod = lo_mknod,
.symlink = lo_symlink,
.link = lo_link,
.unlink = lo_unlink,
.rmdir = lo_rmdir,
.rename = lo_rename,
.forget = lo_forget,
.forget_multi = lo_forget_multi,
.getattr = lo_getattr,
.setattr = lo_setattr,
.readlink = lo_readlink,
.opendir = lo_opendir,
.readdir = lo_readdir,
.readdirplus = lo_readdirplus,
.releasedir = lo_releasedir,
.fsyncdir = lo_fsyncdir,
.create = lo_create,
.open = lo_open,
.release = lo_release,
.flush = lo_flush,
.fsync = lo_fsync,
.read = lo_read,
.write_buf = lo_write_buf,
.statfs = lo_statfs,
.fallocate = lo_fallocate,
.flock = lo_flock,
.getxattr = lo_getxattr,
.listxattr = lo_listxattr,
.setxattr = lo_setxattr,
.removexattr = lo_removexattr,
#ifdef HAVE_COPY_FILE_RANGE
.copy_file_range = lo_copy_file_range,
#endif
.lseek = lo_lseek,
};
int main(int argc, char *argv[])
{
struct fuse_args args = FUSE_ARGS_INIT(argc, argv);
struct fuse_session *se;
struct fuse_cmdline_opts opts;
struct lo_data lo = { .debug = 0, .writeback = 0 };
int ret = -1;
/* Don't mask creation mode, kernel already did that */
umask(0);
pthread_mutex_init(&lo.mutex, NULL);
lo.root.next = lo.root.prev = &lo.root;
lo.root.fd = -1;
lo.cache = CACHE_NORMAL;
if (fuse_parse_cmdline(&args, &opts) != 0) {
return 1;
}
if (opts.show_help) {
printf("usage: %s [options] <mountpoint>\n\n", argv[0]);
fuse_cmdline_help();
fuse_lowlevel_help();
ret = 0;
goto err_out1;
} else if (opts.show_version) {
fuse_lowlevel_version();
ret = 0;
goto err_out1;
}
if (opts.mountpoint == NULL) {
printf("usage: %s [options] <mountpoint>\n", argv[0]);
printf(" %s --help\n", argv[0]);
ret = 1;
goto err_out1;
}
if (fuse_opt_parse(&args, &lo, lo_opts, NULL) == -1) {
return 1;
}
lo.debug = opts.debug;
lo.root.refcount = 2;
if (lo.source) {
struct stat stat;
int res;
res = lstat(lo.source, &stat);
if (res == -1) {
fuse_log(FUSE_LOG_ERR, "failed to stat source (\"%s\"): %m\n",
lo.source);
exit(1);
}
if (!S_ISDIR(stat.st_mode)) {
fuse_log(FUSE_LOG_ERR, "source is not a directory\n");
exit(1);
}
} else {
lo.source = "/";
}
lo.root.is_symlink = false;
if (!lo.timeout_set) {
switch (lo.cache) {
case CACHE_NEVER:
lo.timeout = 0.0;
break;
case CACHE_NORMAL:
lo.timeout = 1.0;
break;
case CACHE_ALWAYS:
lo.timeout = 86400.0;
break;
}
} else if (lo.timeout < 0) {
fuse_log(FUSE_LOG_ERR, "timeout is negative (%lf)\n", lo.timeout);
exit(1);
}
lo.root.fd = open(lo.source, O_PATH);
if (lo.root.fd == -1) {
fuse_log(FUSE_LOG_ERR, "open(\"%s\", O_PATH): %m\n", lo.source);
exit(1);
}
se = fuse_session_new(&args, &lo_oper, sizeof(lo_oper), &lo);
if (se == NULL) {
goto err_out1;
}
if (fuse_set_signal_handlers(se) != 0) {
goto err_out2;
}
if (fuse_session_mount(se, opts.mountpoint) != 0) {
goto err_out3;
}
fuse_daemonize(opts.foreground);
/* Block until ctrl+c or fusermount -u */
if (opts.singlethread) {
ret = fuse_session_loop(se);
} else {
ret = fuse_session_loop_mt(se, opts.clone_fd);
}
fuse_session_unmount(se);
err_out3:
fuse_remove_signal_handlers(se);
err_out2:
fuse_session_destroy(se);
err_out1:
free(opts.mountpoint);
fuse_opt_free_args(&args);
if (lo.root.fd >= 0) {
close(lo.root.fd);
}
return ret ? 1 : 0;
}
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