Fix mdbook serve unexpected panic

Cargo.toml

@@ -28,6 +28,7 @@ log = "0.4.17"
 memchr = "2.5.0"
 opener = "0.6.1"
 pulldown-cmark = { version = "0.9.3", default-features = false }
+pathdiff = "0.2.1"
 regex = "1.8.1"
 serde = { version = "1.0.163", features = ["derive"] }
 serde_json = "1.0.96"

src/cmd/watch.rs

@@ -4,6 +4,7 @@ use ignore::gitignore::Gitignore;
 use mdbook::errors::Result;
 use mdbook::utils;
 use mdbook::MDBook;
+use pathdiff::diff_paths;
 use std::path::{Path, PathBuf};
 use std::sync::mpsc::channel;
 use std::thread::sleep;
@@ -87,11 +88,18 @@ fn find_gitignore(book_root: &Path) -> Option<PathBuf> {
 }
 
 fn filter_ignored_files(ignore: Gitignore, paths: &[PathBuf]) -> Vec<PathBuf> {
+    let ignore_root = ignore
+        .path()
+        .canonicalize()
+        .expect("ignore root canonicalize error");
+
     paths
         .iter()
         .filter(|path| {
+            let relative_path =
+                diff_paths(&path, &ignore_root).expect("One of the paths should be an absolute");
             !ignore
-                .matched_path_or_any_parents(path, path.is_dir())
+                .matched_path_or_any_parents(&relative_path, relative_path.is_dir())
                 .is_ignore()
         })
         .map(|path| path.to_path_buf())
@@ -179,3 +187,50 @@ where
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use ignore::gitignore::GitignoreBuilder;
+    use std::env;
+
+    fn path_to_buf(root: &str, file_name: &str) -> PathBuf {
+        let mut path = PathBuf::from(root);
+        path.push(file_name);
+        path
+    }
+
+    #[test]
+    fn test_filter_ignored_files() {
+        let current_dir = env::current_dir().unwrap();
+
+        let ignore = GitignoreBuilder::new(&current_dir)
+            .add_line(None, "*.html")
+            .unwrap()
+            .build()
+            .unwrap();
+        let should_remain = path_to_buf(current_dir.to_str().unwrap(), "record.text");
+        let should_filter = path_to_buf(current_dir.to_str().unwrap(), "index.html");
+
+        let remain = filter_ignored_files(ignore, &[should_remain.clone(), should_filter]);
+        assert_eq!(remain, vec![should_remain])
+    }
+
+    #[test]
+    fn filter_ignored_files_should_handle_parent_dir() {
+        let current_dir = env::current_dir().unwrap();
+
+        let ignore = GitignoreBuilder::new(&current_dir)
+            .add_line(None, "*.html")
+            .unwrap()
+            .build()
+            .unwrap();
+
+        let parent_dir = format!("{}/../", current_dir.to_str().unwrap());
+        let should_remain = path_to_buf(&parent_dir, "record.text");
+        let should_filter = path_to_buf(&parent_dir, "index.html");
+
+        let remain = filter_ignored_files(ignore, &[should_remain.clone(), should_filter]);
+        assert_eq!(remain, vec![should_remain])
+    }
+}