move warn_if_readable_by_others to files module

1 files changed, 21 insertions, 0 deletions

diff --git a/src/files.rs b/src/files.rs
index e27bde6..cd2f38c 100644
--- a/src/files.rs
+++ b/src/files.rs
@@ -167,6 +167,27 @@ fn sync_parent(path: &Path) {
     }
 }
 
+/// A key is a secret: a file others may read is worth a warning (not an error: a
+/// group may be deliberate, e.g. shared with a deployment tool). `what`: which key.
+pub(crate) fn warn_if_readable_by_others(path: &Path, what: &str) {
+    #[cfg(unix)]
+    {
+        use std::os::unix::fs::PermissionsExt;
+        if let Ok(metadata) = std::fs::metadata(path) {
+            let mode = metadata.permissions().mode();
+            if mode & 0o077 != 0 {
+                tracing::warn!(
+                    path = %path.display(),
+                    mode = format!("{:o}", mode & 0o777),
+                    "The {what} file is readable by others than its owner; chmod 600 it"
+                );
+            }
+        }
+    }
+    #[cfg(not(unix))]
+    let _ = (path, what);
+}
+
 fn with_suffix(path: &Path, suffix: &str) -> PathBuf {
     let mut name = path.as_os_str().to_owned();
     name.push(suffix);