Pass cwd around

src/main.rs

     }
 }
 
-fn read_posts_dir() -> fs::ReadDir {
-    let cwd = env::current_dir()
-        .expect("Couldn't read current directory")
-        .join("posts");
+fn read_posts_dir(cwd: &path::PathBuf) -> fs::ReadDir {
     match fs::read_dir(cwd) {
         Ok(posts) => posts,
         Err(err) => panic!(err),
 }
 
 fn main() {
-    let post_paths = read_posts_dir();
+    let cwd = env::current_dir()
+        .expect("Couldn't read current directory");
+    let post_paths = read_posts_dir(&cwd.join("posts"));
     for path in post_paths {
         match path {
             Ok(p) => {