fix: prevent file descriptor buildup in recursive rm on Linux

Drop the main directory file descriptor early in `safe_remove_dir_recursive_impl` and open fresh parent FDs per entry unlink to avoid accumulating open file descriptors during recursive directory removal. This resolves potential FD exhaustion issues when removing large directory trees.

Author: mattsu2020

src/uu/rm/src/platform/linux.rs

@@ -343,7 +343,7 @@ pub fn safe_remove_dir_recursive_impl(
         }
     };
 
-    // Collect names and stat data
+    // Collect names and stat data, then drop fd to avoid FD buildup
     let mut collected = Vec::with_capacity(entries.len());
     for entry_name in entries {
         match dir_fd.stat_at(&entry_name, false) {
@@ -356,6 +356,7 @@ pub fn safe_remove_dir_recursive_impl(
             }
         }
     }
+    drop(dir_fd);
 
     let mut error = false;
 
@@ -385,15 +386,35 @@ pub fn safe_remove_dir_recursive_impl(
                 if let Some(pb) = progress_bar {
                     pb.inc(1);
                 }
-                error = handle_unlink(&dir_fd, entry_name.as_ref(), &entry_path, true, options)
-                    || error;
+                match DirFd::open(path) {
+                    Ok(parent_fd) => {
+                        error = handle_unlink(
+                            &parent_fd,
+                            entry_name.as_ref(),
+                            &entry_path,
+                            true,
+                            options,
+                        ) || error;
+                    }
+                    Err(e) => {
+                        error = handle_error_with_force(e, &entry_path, options) || error;
+                    }
+                }
             }
         } else if prompt_file_with_stat(&entry_path, &entry_stat, options) {
             if let Some(pb) = progress_bar {
                 pb.inc(1);
             }
-            error =
-                handle_unlink(&dir_fd, entry_name.as_ref(), &entry_path, false, options) || error;
+            match DirFd::open(path) {
+                Ok(parent_fd) => {
+                    error =
+                        handle_unlink(&parent_fd, entry_name.as_ref(), &entry_path, false, options)
+                            || error;
+                }
+                Err(e) => {
+                    error = handle_error_with_force(e, &entry_path, options) || error;
+                }
+            }
         }
     }