Re: [pbs-devel] [PATCH proxmox-backup 2/2] partially fix #2915: 'stat' in case ReadDirEntry does not contain type

[Wolfgang Bumiller <w.bumiller@proxmox.com>]

On Tue, Jun 28, 2022 at 01:13:18PM +0200, Dominik Csapak wrote:
> readdir/getdents may return 'DT_UNKNOWN' for the file type
> (which corresponds to 'None' in nix::dir::Entry), so stat the file and
> check the type
> 
> Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
> ---
>  pbs-datastore/src/chunk_store.rs | 23 ++++++-------
>  pbs-datastore/src/hierarchy.rs   | 56 ++++++++++++++++++++++++++++++++
>  2 files changed, 66 insertions(+), 13 deletions(-)
> 
> diff --git a/pbs-datastore/src/chunk_store.rs b/pbs-datastore/src/chunk_store.rs
> index c9714c1e..2c281b0c 100644
> --- a/pbs-datastore/src/chunk_store.rs
> +++ b/pbs-datastore/src/chunk_store.rs
> @@ -375,24 +375,21 @@ impl ChunkStore {
>                  ),
>              };
>  
> -            let file_type = match entry.file_type() {
> -                Some(file_type) => file_type,
> -                None => bail!(
> -                    "unsupported file system type on chunk store '{}'",
> -                    self.name
> -                ),
> -            };
> -            if file_type != nix::dir::Type::File {
> -                continue;
> -            }
> -
> -            chunk_count += 1;
> -
>              let filename = entry.file_name();
>  
>              let lock = self.mutex.lock();
>  
>              if let Ok(stat) = fstatat(dirfd, filename, nix::fcntl::AtFlags::AT_SYMLINK_NOFOLLOW) {
> +                if match entry.file_type() {
> +                    Some(file_type) => file_type != nix::dir::Type::File,
> +                    None => stat.st_mode & libc::S_IFREG == 0,

Should be `(stat.st_mode & libc::S_IFMT) != libc::S_IFREG`.

> +                } {
> +                    drop(lock);
> +                    continue;
> +                }
> +
> +                chunk_count += 1;
> +
>                  if stat.st_atime < min_atime {
>                      //let age = now - stat.st_atime;
>                      //println!("UNLINK {}  {:?}", age/(3600*24), filename);
> diff --git a/pbs-datastore/src/hierarchy.rs b/pbs-datastore/src/hierarchy.rs
> index d5007b07..a97a1d2a 100644
> --- a/pbs-datastore/src/hierarchy.rs
> +++ b/pbs-datastore/src/hierarchy.rs
> @@ -9,6 +9,16 @@ use pbs_api_types::{BackupNamespace, BackupType, BACKUP_DATE_REGEX, BACKUP_ID_RE
>  use crate::backup_info::{BackupDir, BackupGroup};
>  use crate::DataStore;
>  
> +fn dir_entry_is_path(entry: &proxmox_sys::fs::ReadDirEntry) -> Result<bool, Error> {
> +    let stat = nix::sys::stat::fstatat(
> +        entry.parent_fd(),
> +        entry.file_name(),
> +        nix::fcntl::AtFlags::AT_SYMLINK_NOFOLLOW,
> +    )?;
> +    let is_dir = stat.st_mode & libc::S_IFDIR > 0;

Should be `(stat.st_mode & libc::S_IFMT) != libc::S_IFDIR`.