pxar: avoid taking ownership of xattrs, fcaps and quota_projid on corresponding restore functions.

By borrowing these objects we preserve the functionality but make sure
that ownership doesn't change, avoiding problems when contained within other
structs such as e.g. a buffer storing these attributes.

Signed-off-by: Christian Ebner <c.ebner@proxmox.com>

src/pxar/sequential_decoder.rs

@@ -270,7 +270,7 @@ impl <'a, R: Read, F: Fn(&Path) -> Result<(), Error>> SequentialDecoder<'a, R, F
         // If fd is None, this indicates that we just want to skip over these entries (no restore).
         // If on the other hand there is Some(fd), restore the attributes on it.
         if let Some(fd) = fd {
-            self.restore_xattrs_fcaps_fd(fd, xattrs, fcaps)?;
+            self.restore_xattrs_fcaps_fd(fd, &xattrs, &fcaps)?;
 
             let mut acl = acl::ACL::init(5)?;
             acl.add_entry_full(acl::ACL_USER_OBJ, None, mode_user_to_acl_permissions(entry.mode))?;
@@ -315,7 +315,7 @@ impl <'a, R: Read, F: Fn(&Path) -> Result<(), Error>> SequentialDecoder<'a, R, F
                 }
                 acl.set_file(&proc_path, acl::ACL_TYPE_DEFAULT)?;
             }
-            self.restore_quota_projid(fd, quota_projid)?;
+            self.restore_quota_projid(fd, &quota_projid)?;
         }
 
         Ok(head)
@@ -325,16 +325,16 @@ impl <'a, R: Read, F: Fn(&Path) -> Result<(), Error>> SequentialDecoder<'a, R, F
     fn restore_xattrs_fcaps_fd(
         &mut self,
         fd: RawFd,
-        xattrs: Vec<CaFormatXAttr>,
+        xattrs: &Vec<CaFormatXAttr>,
-        fcaps: Option<CaFormatFCaps>
+        fcaps: &Option<CaFormatFCaps>
     ) -> Result<(), Error> {
         for xattr in xattrs {
-            if let Err(err) = xattr::fsetxattr(fd, xattr) {
+            if let Err(err) = xattr::fsetxattr(fd, &xattr) {
                 bail!("fsetxattr failed with error: {}", err);
             }
         }
         if let Some(fcaps) = fcaps {
-            if let Err(err) = xattr::fsetxattr_fcaps(fd, fcaps) {
+            if let Err(err) = xattr::fsetxattr_fcaps(fd, &fcaps) {
                 bail!("fsetxattr_fcaps failed with error: {}", err);
             }
         }
@@ -345,7 +345,7 @@ impl <'a, R: Read, F: Fn(&Path) -> Result<(), Error>> SequentialDecoder<'a, R, F
     fn restore_quota_projid(
         &mut self,
         fd: RawFd,
-        projid: Option<CaFormatQuotaProjID>
+        projid: &Option<CaFormatQuotaProjID>
     ) -> Result<(), Error> {
         if let Some(projid) = projid {
             let mut fsxattr = fs::FSXAttr::default();

src/tools/xattr.rs

@@ -64,7 +64,7 @@ pub fn fgetxattr(fd: RawFd, name: &[u8]) -> Result<Vec<u8>, nix::errno::Errno> {
     Ok(buffer)
 }
 
-pub fn fsetxattr(fd: RawFd, xattr: CaFormatXAttr) -> Result<(), nix::errno::Errno> {
+pub fn fsetxattr(fd: RawFd, xattr: &CaFormatXAttr) -> Result<(), nix::errno::Errno> {
     let mut name = xattr.name.clone();
     name.push('\0' as u8);
     let flags = 0 as libc::c_int;
@@ -79,7 +79,7 @@ pub fn fsetxattr(fd: RawFd, xattr: CaFormatXAttr) -> Result<(), nix::errno::Errn
     Ok(())
 }
 
-pub fn fsetxattr_fcaps(fd: RawFd, fcaps: CaFormatFCaps) -> Result<(), nix::errno::Errno> {
+pub fn fsetxattr_fcaps(fd: RawFd, fcaps: &CaFormatFCaps) -> Result<(), nix::errno::Errno> {
     // TODO casync checks and removes capabilities if they are set
     let name = b"security.capability\0";
     let flags = 0 as libc::c_int;
@@ -159,15 +159,15 @@ mod tests {
             value: b"err".to_vec(),
         };
 
-        assert!(fsetxattr(fd, valid_user).is_ok());
+        assert!(fsetxattr(fd, &valid_user).is_ok());
-        assert!(fsetxattr(fd, valid_empty_value).is_ok());
+        assert!(fsetxattr(fd, &valid_empty_value).is_ok());
 
         if nix::unistd::Uid::current() != nix::unistd::ROOT {
-            assert_eq!(fsetxattr(fd, invalid_trusted), Err(Errno::EPERM));
+            assert_eq!(fsetxattr(fd, &invalid_trusted), Err(Errno::EPERM));
         }
 
-        assert_eq!(fsetxattr(fd, invalid_name_prefix), Err(Errno::EOPNOTSUPP));
+        assert_eq!(fsetxattr(fd, &invalid_name_prefix), Err(Errno::EOPNOTSUPP));
-        assert_eq!(fsetxattr(fd, invalid_name_length), Err(Errno::ERANGE));
+        assert_eq!(fsetxattr(fd, &invalid_name_length), Err(Errno::ERANGE));
 
         let v0 = fgetxattr(fd, b"user.attribute0\0".as_ref()).unwrap();
         let v1 = fgetxattr(fd, b"user.empty\0".as_ref()).unwrap();