On Fri, Jul 30, 2021 at 05:01:30PM +0200, Max Reitz wrote: > Strictly speaking, this is not necessary, because lo_inode_open() will > always return a new FD owned by the caller, so TempFd.owned will always > be true. > > However, auto-cleanup is nice, and in some cases this plays nicely with > an lo_inode_fd() call in another conditional branch (see lo_setattr()). > > Signed-off-by: Max Reitz <mre...@redhat.com> > --- > tools/virtiofsd/passthrough_ll.c | 138 +++++++++++++------------------ > 1 file changed, 59 insertions(+), 79 deletions(-) > > diff --git a/tools/virtiofsd/passthrough_ll.c > b/tools/virtiofsd/passthrough_ll.c > index 9e1bc37af8..292b7f7e27 100644 > --- a/tools/virtiofsd/passthrough_ll.c > +++ b/tools/virtiofsd/passthrough_ll.c > @@ -291,10 +291,8 @@ static void temp_fd_clear(TempFd *temp_fd) > /** > * Return an owned fd from *temp_fd that will not be closed when > * *temp_fd goes out of scope. > - * > - * (TODO: Remove __attribute__ once this is used.) > */ > -static __attribute__((unused)) int temp_fd_steal(TempFd *temp_fd) > +static int temp_fd_steal(TempFd *temp_fd) > { > if (temp_fd->owned) { > temp_fd->owned = false; > @@ -673,9 +671,12 @@ static int lo_fd(fuse_req_t req, fuse_ino_t ino, TempFd > *tfd) > * when a malicious client opens special files such as block device nodes. > * Symlink inodes are also rejected since symlinks must already have been > * traversed on the client side. > + * > + * The fd is returned in tfd->fd. The return value is 0 on success and > -errno > + * otherwise. > */ > -static int lo_inode_open(struct lo_data *lo, struct lo_inode *inode, > - int open_flags) > +static int lo_inode_open(const struct lo_data *lo, const struct lo_inode > *inode, > + int open_flags, TempFd *tfd) > { > g_autofree char *fd_str = g_strdup_printf("%d", inode->fd); > int fd; > @@ -694,7 +695,13 @@ static int lo_inode_open(struct lo_data *lo, struct > lo_inode *inode, > if (fd < 0) { > return -errno; > } > - return fd; > + > + *tfd = (TempFd) { > + .fd = fd, > + .owned = true, > + }; > + > + return 0; > } > > static void lo_init(void *userdata, struct fuse_conn_info *conn) > @@ -852,7 +859,12 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, > struct stat *attr, > return; > } > > - res = lo_inode_fd(inode, &inode_fd); > + if (!fi && (valid & FUSE_SET_ATTR_SIZE)) { > + /* We need an O_RDWR FD for ftruncate() */ > + res = lo_inode_open(lo, inode, O_RDWR, &inode_fd); > + } else { > + res = lo_inode_fd(inode, &inode_fd); > + }
A minor nit. So inode_fd could hold either an O_PATH fd returned by lo_inode_fd() or a O_RDWR fd returned by lo_inode_open(). Previous code held these fds in two different variables, inode_fd and truncfd respectively. I kind of found that easier to read because looking at variable name, I knew whether I am dealing with O_PATH fd or an O_RDWR fd I just opened. So a minor nit. We could continue to have two variables, say inode_fd and trunc_fd. Just that type of trunc_fd will now be TempFd. Also I liked previous style easier to read where I always got hold of O_PATH fd first. And later opened a O_RDWR fd if operation is FUSE_ATTR_SIZE. So "valid & FUSE_SET_ATTR_SIZE" check was not at two places. Anyway, this is a minor nit. If you don't like the idea of using two separate variables to hold O_PATH fd and O_RDWR fd, that's ok. > if (res < 0) { > saverr = -res; > goto out_err; > @@ -900,18 +912,11 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, > struct stat *attr, > if (fi) { > truncfd = fd; > } else { > - truncfd = lo_inode_open(lo, inode, O_RDWR); > - if (truncfd < 0) { > - saverr = -truncfd; > - goto out_err; > - } > + truncfd = inode_fd.fd; > } > > saverr = drop_security_capability(lo, truncfd); > if (saverr) { > - if (!fi) { > - close(truncfd); > - } > goto out_err; > } > > @@ -919,9 +924,6 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, > struct stat *attr, > res = drop_effective_cap("FSETID", &cap_fsetid_dropped); > if (res != 0) { > saverr = res; > - if (!fi) { > - close(truncfd); > - } > goto out_err; > } > } > @@ -934,9 +936,6 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, > struct stat *attr, > fuse_log(FUSE_LOG_ERR, "Failed to gain CAP_FSETID\n"); > } > } > - if (!fi) { > - close(truncfd); > - } > if (res == -1) { > goto out_err; > } > @@ -1822,11 +1821,12 @@ static struct lo_dirp *lo_dirp(fuse_req_t req, struct > fuse_file_info *fi) > static void lo_opendir(fuse_req_t req, fuse_ino_t ino, > struct fuse_file_info *fi) > { > + g_auto(TempFd) inode_fd = TEMP_FD_INIT; > int error = ENOMEM; > struct lo_data *lo = lo_data(req); > struct lo_inode *inode; > struct lo_dirp *d = NULL; > - int fd; > + int res; > ssize_t fh; > > inode = lo_inode(req, ino); > @@ -1840,13 +1840,13 @@ static void lo_opendir(fuse_req_t req, fuse_ino_t ino, > goto out_err; > } > > - fd = lo_inode_open(lo, inode, O_RDONLY); > - if (fd < 0) { > - error = -fd; > + res = lo_inode_open(lo, inode, O_RDONLY, &inode_fd); > + if (res < 0) { > + error = -res; > goto out_err; > } > > - d->dp = fdopendir(fd); > + d->dp = fdopendir(temp_fd_steal(&inode_fd)); So we are using temp_fd_steal(), because if fdopendir() is succesful, we don't want to close fd instead it will be closed during closedir() call. inode_fd will be closed once lo_opendir(), so we get fd ownership which will need to close explicitly, when appropriate. Who closes the stolen fd returned by temp_fd_steal() if fdopendir() fails? > if (d->dp == NULL) { > goto out_errno; > } > @@ -1876,8 +1876,6 @@ out_err: > if (d) { > if (d->dp) { > closedir(d->dp); > - } else if (fd != -1) { > - close(fd); > } > free(d); > } > @@ -2077,6 +2075,7 @@ static void update_open_flags(int writeback, int > allow_direct_io, > static int lo_do_open(struct lo_data *lo, struct lo_inode *inode, > int existing_fd, struct fuse_file_info *fi) > { > + g_auto(TempFd) inode_fd = TEMP_FD_INIT; It bothers me that we are using variable inode_fd both to hold O_PATH fd as well as regular fd. Will be nice if just by looking at variable name I could figure out which type of fd it is. Will it make sense to use path_fd, or ipath_fd, or inode_path_fd to represent where we are using O_PATH fd. Thanks Vivek