Merge pull request #260 from joshuawarner32/master

Fix section ordering when adding a Start section

src/elements/module.rs

@@ -244,14 +244,18 @@ impl Module {
 	}
 
 	/// Changes the module's start section.
-	pub fn set_start_section(&mut self, new_start : u32) {
-		for section in self.sections_mut() {
+	pub fn set_start_section(&mut self, new_start: u32) {
+		for section in self.sections_mut().iter_mut() {
 			if let &mut Section::Start(_sect) = section {
 				*section = Section::Start(new_start);
 				return
 			}
 		}
-		self.sections_mut().push(Section::Start(new_start));
+		let insert_before = self.sections().iter().enumerate()
+			.filter_map(|(i, s)| if s.id() > 0x8 { Some(i) } else { None })
+			.next()
+			.unwrap_or(0);
+		self.sections_mut().insert(insert_before, Section::Start(new_start));
 	}
 
 	/// Removes the module's start section.
@@ -755,4 +759,30 @@ mod integration_tests {
         module.clear_start_section();
         assert_eq!(None, module.start_section());
     }
+
+    #[test]
+    fn add_start() {
+        let mut module = deserialize_file("./res/cases/v1/start_add.wasm").expect("failed to deserialize");
+        assert!(module.start_section().is_none());
+        module.set_start_section(0);
+        assert_eq!(module.start_section().expect("Did not find any start section"), 0);
+
+        let sections = module.sections().iter().map(|s| s.id()).collect::<Vec<_>>();
+        assert_eq!(sections, vec![1, 2, 3, 6, 7, 8, 9, 10, 11]);
+    }
+
+    #[test]
+    fn add_start_custom() {
+        let mut module = deserialize_file("./res/cases/v1/start_add_custom.wasm").expect("failed to deserialize");
+
+        let sections = module.sections().iter().map(|s| s.id()).collect::<Vec<_>>();
+        assert_eq!(sections, vec![1, 2, 3, 6, 7, 9, 10, 11, 0]);
+
+        assert!(module.start_section().is_none());
+        module.set_start_section(0);
+        assert_eq!(module.start_section().expect("Did not find any start section"), 0);
+
+        let sections = module.sections().iter().map(|s| s.id()).collect::<Vec<_>>();
+        assert_eq!(sections, vec![1, 2, 3, 6, 7, 8, 9, 10, 11, 0]);
+    }
 }