cp: Fix broken symlinks to parent-dir

src/uu/cp/src/cp.rs

@@ -7,6 +7,7 @@
 use quick_error::quick_error;
 use std::cmp::Ordering;
 use std::collections::{HashMap, HashSet};
+use std::env;
 #[cfg(not(windows))]
 use std::ffi::CString;
 use std::fs::{self, File, Metadata, OpenOptions, Permissions};
@@ -1868,6 +1869,22 @@ fn handle_copy_mode(
             if dest.exists() && options.overwrite == OverwriteMode::Clobber(ClobberMode::Force) {
                 fs::remove_file(dest)?;
             }
+            if source.is_relative() {
+                let current_dir = env::current_dir()?;
+                let abs_dest =
+                    canonicalize(dest, MissingHandling::Missing, ResolveMode::Physical).unwrap();
+                if let Some(parent) = abs_dest.parent() {
+                    if parent != current_dir {
+                        {
+                            return Err(format!(
+                                "{}: can make relative symbolic links only in current directory",
+                                dest.maybe_quote()
+                            )
+                            .into());
+                        }
+                    }
+                }
+            }
             symlink_file(source, dest, symlinked_files)?;
         }
         CopyMode::Update => {

tests/by-util/test_cp.rs

@@ -5574,6 +5574,34 @@ fn test_preserve_attrs_overriding_2() {
     }
 }
 
+#[test]
+fn test_symlink_to_subdir() {
+    let (at, mut ucmd) = at_and_ucmd!();
+
+    at.touch("file");
+    at.mkdir("dir");
+
+    ucmd.args(&["--symbolic", "file", "dir"])
+        .fails()
+        .no_stdout()
+        .stderr_is("cp: dir/file: can make relative symbolic links only in current directory\n");
+
+    assert!(at.dir_exists("dir"));
+    assert!(!at.file_exists("dir/file"));
+}
+
+#[test]
+fn test_symlink_from_subdir() {
+    let (at, mut ucmd) = at_and_ucmd!();
+
+    at.mkdir("dir");
+    at.touch("dir/file");
+
+    ucmd.args(&["--symbolic", "dir/file", "."]).succeeds();
+
+    assert!(at.symlink_exists("file"));
+}
+
 /// Test the behavior of preserving permissions when copying through a symlink
 #[test]
 #[cfg(unix)]