Encode stackframe names

src/collapsed_stack.rs

@@ -7,6 +7,8 @@ pub struct CollapsedStack {
 /// Contains the data collected by the profiler in collapsed stacks format.
 /// The main use case is to call `write_to_file` on a `CollapsedStacks` instance.
 /// The resulting file can be opened in a variety of profiling tools.
+/// Frame names percent-encode `%`, `;`, carriage returns, and newlines so they
+/// cannot be confused with frame or sample delimiters.
 /// The format is explained here: https://github.com/jlfwong/speedscope/wiki/Importing-from-custom-sources#brendan-greggs-collapsed-stack-format
 pub struct CollapsedStacks(Vec<CollapsedStack>);
 
@@ -42,7 +44,15 @@ impl fmt::Display for CollapsedStack {
             } else {
                 write!(f, ";")?;
             }
-            write!(f, "{}", frame)?;
+            for character in frame.chars() {
+                match character {
+                    '%' => write!(f, "%25")?,
+                    ';' => write!(f, "%3B")?,
+                    '\r' => write!(f, "%0D")?,
+                    '\n' => write!(f, "%0A")?,
+                    other => write!(f, "{other}")?,
+                }
+            }
         }
         write!(f, " {}", self.weight)
     }
@@ -56,3 +66,28 @@ impl fmt::Display for CollapsedStacks {
         Ok(())
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::CollapsedStacks;
+
+    #[test]
+    fn escapes_frame_delimiters_and_literal_percent_signs() {
+        let stacks = CollapsedStacks::new(
+            vec!["leaf;frame\nnext\r%3B".into(), "root".into()],
+            vec![vec![0, 1]],
+            Some(vec![7]),
+        );
+        assert_eq!(stacks.to_string(), "root;leaf%3Bframe%0Anext%0D%253B 7\n");
+    }
+
+    #[test]
+    fn preserves_ordinary_frame_names() {
+        let stacks = CollapsedStacks::new(
+            vec!["space::foo(int, β)".into(), "root".into()],
+            vec![vec![0, 1]],
+            Some(vec![7]),
+        );
+        assert_eq!(stacks.to_string(), "root;space::foo(int, β) 7\n");
+    }
+}