fix incorrect yaml positions (#7946)

YAML parsing was fixed in
#7918 and
#7931, but I didn't catch
that node start/end positions were incorrect. This was because in
`ctypes_read()` we were returning a JS int when we should have been
returning `UInt32` instead.

test plan:
- confirmed locally that the playground works properly w/ a yaml pattern
- added unit test to confirm yaml check works and returns correct
positions
- `dune build && make test` succeeded

js/engine/tests/index.test.js

@@ -28,3 +28,34 @@ describe("engine", () => {
     expect(engine.isMissingLanguages()).toBe(false);
   });
 });
+
+describe("yaml parser", () => {
+  test("parses a pattern", async () => {
+    const engine = await enginePromise;
+    const result = JSON.parse(
+      engine.execute(
+        "yaml",
+        `${__dirname}/test-rule-yaml.json`,
+        `${__dirname}/test.yaml`
+      )
+    );
+
+    // it took a lot of work to get libyaml working, so let's confirm start/end locations are correct
+    expect(result.stats.okfiles).toBe(1);
+    expect(result.matches.length).toBe(1);
+    const match = result.matches[0];
+    expect(match.location.start).toEqual(
+      expect.objectContaining({ offset: 0, line: 1, col: 1 })
+    );
+    expect(match.location.end).toEqual(
+      expect.objectContaining({ offset: 8, line: 1, col: 9 })
+    );
+    expect(match.extra.metavars["$X"].start).toEqual(
+      expect.objectContaining({ offset: 5, line: 1, col: 6 })
+    );
+    expect(match.extra.metavars["$X"].end).toEqual(
+      expect.objectContaining({ offset: 8, line: 1, col: 9 })
+    );
+    expect(match.extra.metavars["$X"].abstract_content).toEqual("bar");
+  });
+});

js/engine/tests/test-rule-yaml.json

@@ -0,0 +1,11 @@
+{
+  "rules": [
+    {
+      "id": "test",
+      "languages": ["yaml"],
+      "pattern": "foo: $X",
+      "message": "test",
+      "severity": "ERROR"
+    }
+  ]
+}

js/engine/tests/test.yaml

@@ -0,0 +1 @@
+foo: bar

js/libyaml/runtime.js

@@ -45,7 +45,7 @@ function ctypes_read(primType, buffer) {
     case 5: // Ctypes_Int
       return libyaml.getValue(buffer[2], "i32");
     case 13: // Ctypes_Size_t
-      return libyaml.getValue(buffer[2], "i32");
+      return new UInt32(libyaml.getValue(buffer[2], "i32"));
     case 20: // Ctypes_Uint32_t
       return new UInt32(libyaml.getValue(buffer[2], "i32"));
     default:

src/parsing/yaml_to_generic.ml

@@ -132,8 +132,7 @@ let mk_bracket
         _;
       } ) v env =
   (* The end index needs to be adjusted by one because the token is off *)
-  (* TODO: figure out why we get an off-by-one with jsoo *)
-  let e_index' = if !Common.jsoo then e_index else e_index - 1 in
+  let e_index' = e_index - 1 in
   let e_line, e_column =
     match env.charpos_to_pos with
     | None -> (e_line, e_column)