pxar: split assert_relative_path

the check for a single component is only required in the dir
stack atm

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

src/pxar/create.rs

@@ -21,7 +21,7 @@ use proxmox::tools::fd::RawFdNum;
 
 use crate::pxar::catalog::BackupCatalogWriter;
 use crate::pxar::flags;
-use crate::pxar::tools::assert_relative_path;
+use crate::pxar::tools::assert_single_path_component;
 use crate::tools::{acl, fs, xattr, Fd};
 
 fn detect_fs_type(fd: RawFd) -> Result<i64, Error> {
@@ -230,7 +230,7 @@ impl<'a, 'b> Archiver<'a, 'b> {
             }
 
             let os_file_name = OsStr::from_bytes(file_name_bytes);
-            assert_relative_path(os_file_name)?;
+            assert_single_path_component(os_file_name)?;
             let full_path = self.path.join(os_file_name);
 
             let stat = match nix::sys::stat::fstatat(

src/pxar/dir_stack.rs

@@ -10,7 +10,7 @@ use nix::sys::stat::{mkdirat, Mode};
 use proxmox::sys::error::SysError;
 use pxar::Metadata;
 
-use crate::pxar::tools::{assert_relative_path, perms_from_metadata};
+use crate::pxar::tools::{assert_single_path_component, perms_from_metadata};
 
 pub struct PxarDir {
     file_name: OsString,
@@ -95,7 +95,7 @@ impl PxarDirStack {
     }
 
     pub fn push(&mut self, file_name: OsString, metadata: Metadata) -> Result<(), Error> {
-        assert_relative_path(&file_name)?;
+        assert_single_path_component(&file_name)?;
         self.path.push(&file_name);
         self.dirs.push(PxarDir::new(file_name, metadata));
         Ok(())

src/pxar/tools.rs

@@ -24,11 +24,22 @@ pub fn assert_relative_path<S: AsRef<OsStr> + ?Sized>(path: &S) -> Result<(), Er
     assert_relative_path_do(Path::new(path))
 }
 
+/// Make sure path is a single component and not '.' or '..'.
+pub fn assert_single_path_component<S: AsRef<OsStr> + ?Sized>(path: &S) -> Result<(), Error> {
+    assert_single_path_component_do(Path::new(path))
+}
+
 fn assert_relative_path_do(path: &Path) -> Result<(), Error> {
     if !path.is_relative() {
         bail!("bad absolute file name in archive: {:?}", path);
     }
 
+    Ok(())
+}
+
+fn assert_single_path_component_do(path: &Path) -> Result<(), Error> {
+    assert_relative_path_do(path)?;
+
     let mut components = path.components();
     match components.next() {
         Some(std::path::Component::Normal(_)) => (),