xtask: no symlink walks, exclusive test dir; Paste Special picture files must be regular files

crates/ui-egui/src/paste_picture.rs

@@ -147,8 +147,14 @@ pub(crate) fn paste(app: &mut WordApp) -> Option<Result<Value, String>> {
             }
             let mut r = Err(String::new());
             for path in files {
-                let size = std::fs::metadata(&path).map(|m| m.len()).unwrap_or(0);
-                r = if size > MAX_FILE_BYTES {
+                // A clipboard path can name a pipe or device that reports no length and never ends.
+                let md = std::fs::metadata(&path).ok();
+                let size = md.as_ref().map_or(0, |m| m.len());
+                r = if md.as_ref().is_some_and(|m| !m.is_file()) {
+                    let e = format!("{} is not a regular file", path.display());
+                    app.status(e.clone());
+                    Err(e)
+                } else if size > MAX_FILE_BYTES {
                     let e = format!("{} is larger than 200 MB", path.display());
                     app.status(e.clone());
                     Err(e)

xtask/src/assets.rs

@@ -73,8 +73,10 @@ mod tests {
     fn a_failed_file_listing_fails_the_check() {
         // #1364: outside a git checkout `git ls-files` fails, and its empty output read as "no
         // files" passed the check.
-        let dir = std::env::temp_dir().join(format!("wordcraft-xtask-assets-{}", std::process::id()));
-        std::fs::create_dir_all(&dir).unwrap();
+        // Created exclusively under a name no one can predict: an existing folder or link there would be someone else's.
+        let nanos = std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH).map_or(0, |d| d.subsec_nanos());
+        let dir = std::env::temp_dir().join(format!("wordcraft-xtask-assets-{}-{nanos}", std::process::id()));
+        std::fs::create_dir(&dir).unwrap();
         std::fs::write(dir.join("ATTRIBUTION.md"), "").unwrap();
         let inside_git = Command::new("git").current_dir(&dir).args(["rev-parse", "--git-dir"]).output().is_ok_and(|o| o.status.success());
         let result = run(&dir);

xtask/src/stats.rs

@@ -18,12 +18,14 @@ fn walk(dir: &Path, c: &mut Counts) {
         let p = e.path();
         let name = e.file_name();
         let name = name.to_string_lossy();
-        if p.is_dir() {
+        // A symlink is never followed: several links to an ancestor would multiply the walk.
+        if e.file_type().is_ok_and(|t| t.is_dir()) {
             // Nested fuzz workspaces and build output are not part of the crate.
             if name != "target" && name != "fuzz" && !name.starts_with('.') {
                 walk(&p, c);
             }
         } else if name.ends_with(".rs")
+            && e.file_type().is_ok_and(|t| t.is_file())
             && let Ok(s) = std::fs::read_to_string(&p)
         {
             c.files += 1;
@@ -108,11 +110,25 @@ pub fn run(_root: &Path, exact: bool) -> Result<(), String> {
 
 #[cfg(test)]
 mod tests {
-    use super::count_tests;
+    use super::{Counts, count_tests, walk};
 
     #[test]
     fn counts_attributes_and_proptest_blocks() {
         let src = "#[test]\nfn a() {}\n// #[test] commented\n    #[test]\nfn b() {}\nproptest! {\n}\n";
         assert_eq!(count_tests(src), (2, 1));
     }
+
+    #[cfg(unix)]
+    #[test]
+    fn a_walk_does_not_follow_directory_links() {
+        let nanos = std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH).map_or(0, |d| d.subsec_nanos());
+        let dir = std::env::temp_dir().join(format!("wordcraft-xtask-stats-{}-{nanos}", std::process::id()));
+        std::fs::create_dir(&dir).unwrap();
+        std::fs::write(dir.join("a.rs"), "#[test]\n").unwrap();
+        std::os::unix::fs::symlink(&dir, dir.join("loop")).unwrap();
+        let mut c = Counts::default();
+        walk(&dir, &mut c);
+        let _ = std::fs::remove_dir_all(&dir);
+        assert_eq!((c.files, c.tests), (1, 1));
+    }
 }