Add tempdir support

crates/lb/src/fs.rs

@@ -98,6 +98,14 @@ impl lb_fslib {
             prefix,
         })
     }
+
+    pub extern "Lua-C" fn temp_dir(&self) -> Result<lb_temp_dir> {
+        Ok(tempfile::tempdir()?.into())
+    }
+
+    pub extern "Lua-C" fn temp_dir_in(&self, path: &str) -> Result<lb_temp_dir> {
+        Ok(tempfile::tempdir_in(path)?.into())
+    }
 }
 
 /// Iterator over the entries in a directory.
@@ -401,3 +409,20 @@ impl lb_glob_dir {
         Ok(None)
     }
 }
+
+/// Directory in the filesystem that is automatically deleted when it is garbage-collected.
+#[derive(Debug, From)]
+#[cdef]
+pub struct lb_temp_dir(#[opaque] tempfile::TempDir);
+
+#[metatype]
+impl lb_temp_dir {
+    pub extern "Lua-C" fn path(&self) -> String {
+        self.0.path().to_string_lossy().into()
+    }
+
+    #[tostring]
+    pub extern "Lua" fn tostring(&self) -> String {
+        self.path()
+    }
+}