From a26ba2012e5715103e81b3872129dbb3a7e5aa4f Mon Sep 17 00:00:00 2001
From: Alessio Quaglino <quaglino@google.com>
Date: Wed, 9 Oct 2024 11:08:38 -0700
Subject: [PATCH] Return 0 on success from mjs_activatePlugin instead of using
 mju_error.

PiperOrigin-RevId: 684102823
Change-Id: I86b7702094ae886539e1dfb6294381952d507bc1
---
 doc/APIreference/functions.rst | 2 +-
 doc/includes/references.h      | 2 +-
 include/mujoco/mujoco.h        | 4 ++--
 introspect/functions.py        | 4 ++--
 src/user/user_api.cc           | 5 +++--
 src/user/user_api.h            | 4 ++--
 src/xml/xml_native_reader.cc   | 4 +++-
 7 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/doc/APIreference/functions.rst b/doc/APIreference/functions.rst
index 43d4f84b..56bc272e 100644
--- a/doc/APIreference/functions.rst
+++ b/doc/APIreference/functions.rst
@@ -1516,7 +1516,7 @@ mjs_activatePlugin
 
 .. mujoco-include:: mjs_activatePlugin
 
-Activate plugin.
+Activate plugin. Returns 0 on success.
 
 .. _Errorandmemory:
 
diff --git a/doc/includes/references.h b/doc/includes/references.h
index 8b4ad04e..6e193719 100644
--- a/doc/includes/references.h
+++ b/doc/includes/references.h
@@ -3178,7 +3178,7 @@ int mj_setLengthRange(mjModel* m, mjData* d, int index,
 mjSpec* mj_makeSpec(void);
 mjSpec* mj_copySpec(const mjSpec* s);
 void mj_deleteSpec(mjSpec* s);
-void mjs_activatePlugin(mjSpec* s, const char* name);
+int mjs_activatePlugin(mjSpec* s, const char* name);
 void mj_printFormattedModel(const mjModel* m, const char* filename, const char* float_format);
 void mj_printModel(const mjModel* m, const char* filename);
 void mj_printFormattedData(const mjModel* m, mjData* d, const char* filename,
diff --git a/include/mujoco/mujoco.h b/include/mujoco/mujoco.h
index 879ae85a..c146054c 100644
--- a/include/mujoco/mujoco.h
+++ b/include/mujoco/mujoco.h
@@ -241,8 +241,8 @@ MJAPI mjSpec* mj_copySpec(const mjSpec* s);
 // Free memory allocation in mjSpec.
 MJAPI void mj_deleteSpec(mjSpec* s);
 
-// Activate plugin.
-MJAPI void mjs_activatePlugin(mjSpec* s, const char* name);
+// Activate plugin. Returns 0 on success.
+MJAPI int mjs_activatePlugin(mjSpec* s, const char* name);
 
 
 //---------------------------------- Printing ------------------------------------------------------
diff --git a/introspect/functions.py b/introspect/functions.py
index 0d576b8e..447b2e55 100644
--- a/introspect/functions.py
+++ b/introspect/functions.py
@@ -1048,7 +1048,7 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
     ('mjs_activatePlugin',
      FunctionDecl(
          name='mjs_activatePlugin',
-         return_type=ValueType(name='void'),
+         return_type=ValueType(name='int'),
          parameters=(
              FunctionParameterDecl(
                  name='s',
@@ -1063,7 +1063,7 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
                  ),
              ),
          ),
-         doc='Activate plugin.',
+         doc='Activate plugin. Returns 0 on success.',
      )),
     ('mj_printFormattedModel',
      FunctionDecl(
diff --git a/src/user/user_api.cc b/src/user/user_api.cc
index 9dba3c81..12b7a1d2 100644
--- a/src/user/user_api.cc
+++ b/src/user/user_api.cc
@@ -206,14 +206,15 @@ void mjs_addSpec(mjSpec* s, mjSpec* child) {
 
 
 // activate plugin
-void mjs_activatePlugin(mjSpec* s, const char* name) {
+int mjs_activatePlugin(mjSpec* s, const char* name) {
   int plugin_slot = -1;
   const mjpPlugin* plugin = mjp_getPlugin(name, &plugin_slot);
   if (!plugin) {
-    mju_error("unknown plugin '%s'", name);
+    return -1;
   }
   mjCModel* model = static_cast<mjCModel*>(s->element);
   model->ActivatePlugin(plugin, plugin_slot);
+  return 0;
 }
 
 
diff --git a/src/user/user_api.h b/src/user/user_api.h
index f3f25ebc..853c9363 100644
--- a/src/user/user_api.h
+++ b/src/user/user_api.h
@@ -63,8 +63,8 @@ MJAPI void mj_deleteSpec(mjSpec* s);
 // Add spec (model asset) to spec.
 MJAPI void mjs_addSpec(mjSpec* s, mjSpec* child);
 
-// Activate plugin.
-MJAPI void mjs_activatePlugin(mjSpec* s, const char* name);
+// Activate plugin, return 0 on success.
+MJAPI int mjs_activatePlugin(mjSpec* s, const char* name);
 
 
 //---------------------------------- Attachment ----------------------------------------------------
diff --git a/src/xml/xml_native_reader.cc b/src/xml/xml_native_reader.cc
index 4bcd7cd1..404420cc 100644
--- a/src/xml/xml_native_reader.cc
+++ b/src/xml/xml_native_reader.cc
@@ -2890,7 +2890,9 @@ void mjXReader::Extension(XMLElement* section) {
     if (name == "plugin") {
       string plugin_name;
       ReadAttrTxt(elem, "plugin", plugin_name, /* required = */ true);
-      mjs_activatePlugin(spec, plugin_name.c_str());
+      if (mjs_activatePlugin(spec, plugin_name.c_str())) {
+        throw mjXError(elem, "plugin %s not found", plugin_name.c_str());
+      }
 
       XMLElement* child = FirstChildElement(elem);
       while (child) {