fix: Allow jailer to continue with partial CPU cache info

If CPU caching information is missing, this change allows the jailer to
still continue, and fall through to the validation logic in firecracker.

Signed-off-by: Gudmundur Bjarni Olafsson <[email protected]>

Author: gudmundur

src/jailer/src/env.rs

@@ -574,17 +574,20 @@ impl Env {
                 let host_cache_file = host_path.join(entry);
                 let jailer_cache_file = jailer_path.join(entry);
 
-                let line = readln_special(&host_cache_file)?;
-                writeln_special(&jailer_cache_file, line)?;
-
-                // We now change the permissions.
-                let dest_path_cstr = to_cstring(&jailer_cache_file)?;
-                // SAFETY: Safe because dest_path_cstr is null-terminated.
-                SyscallReturnCode(unsafe {
-                    libc::chown(dest_path_cstr.as_ptr(), self.uid(), self.gid())
-                })
-                .into_empty_result()
-                .map_err(|err| JailerError::ChangeFileOwner(jailer_cache_file.to_owned(), err))?;
+                if let Ok(line) = readln_special(&host_cache_file) {
+                    writeln_special(&jailer_cache_file, line)?;
+
+                    // We now change the permissions.
+                    let dest_path_cstr = to_cstring(&jailer_cache_file)?;
+                    // SAFETY: Safe because dest_path_cstr is null-terminated.
+                    SyscallReturnCode(unsafe {
+                        libc::chown(dest_path_cstr.as_ptr(), self.uid(), self.gid())
+                    })
+                    .into_empty_result()
+                    .map_err(|err| {
+                        JailerError::ChangeFileOwner(jailer_cache_file.to_owned(), err)
+                    })?;
+                }
             }
         }
         Ok(())