Add mj_markStack and mj_freeStack as public API functions.

Also add asan instrumentation to detect stack frame leakages (i.e. `mj_markStack` without a corresponding `mj_freeStack` in the same caller function).

PiperOrigin-RevId: 562625645
Change-Id: I4e3ff66ca0b9d08ed0a95cef45393db8e3053e22

introspect/functions.py

@@ -677,6 +677,34 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
          ),
          doc='Reset data, set fields from specified keyframe.',
      )),
+    ('mj_markStack',
+     FunctionDecl(
+         name='mj_markStack',
+         return_type=ValueType(name='void'),
+         parameters=(
+             FunctionParameterDecl(
+                 name='d',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjData'),
+                 ),
+             ),
+         ),
+         doc='Mark a new frame on the mjData stack.',
+     )),
+    ('mj_freeStack',
+     FunctionDecl(
+         name='mj_freeStack',
+         return_type=ValueType(name='void'),
+         parameters=(
+             FunctionParameterDecl(
+                 name='d',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjData'),
+                 ),
+             ),
+         ),
+         doc='Free the current mjData stack frame. All pointers returned by mj_stackAlloc since the last call to mj_markStack must no longer be used afterwards.',  # pylint: disable=line-too-long
+     )),
     ('mj_stackAlloc',
      FunctionDecl(
          name='mj_stackAlloc',

introspect/structs.py

@@ -3502,6 +3502,11 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  type=ValueType(name='size_t'),
                  doc='first available mjtNum address in stack',
              ),
+             StructFieldDecl(
+                 name='pbase',
+                 type=ValueType(name='size_t'),
+                 doc='value of pstack when mj_markStack was last called',
+             ),
              StructFieldDecl(
                  name='parena',
                  type=ValueType(name='size_t'),