Add mj_containsFileVFS and mj_containsBufferVFS functions.

PiperOrigin-RevId: 903785790
Change-Id: I013b37a177284f8440179c4ae5c6221e0f572b49

doc/APIreference/functions.rst

@@ -1519,6 +1519,24 @@ Add file to VFS from buffer; return 0: success, 2: repeated name, -1: failed to
 
 Delete file from VFS; return 0: success, -1: not found in VFS.
 
+.. _mj_containsBufferVFS:
+
+`mj_containsBufferVFS <#mj_containsBufferVFS>`__
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. mujoco-include:: mj_containsBufferVFS
+
+Check if buffer exists in VFS; return 1: exists, 0: not found.
+
+.. _mj_containsFileVFS:
+
+`mj_containsFileVFS <#mj_containsFileVFS>`__
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. mujoco-include:: mj_containsFileVFS
+
+Check if file exists in VFS; return 1: exists, 0: not found.
+
 .. _mj_deleteVFS:
 
 `mj_deleteVFS <#mj_deleteVFS>`__

doc/changelog.rst

@@ -9,6 +9,7 @@ General
 ^^^^^^^
 - Added new :ref:`mj_maxContact<mj_maxContact>` function to get the maximum number of possible contacts returned by
   two geoms.
+- Added ``mj_containsBufferVFS`` and ``mj_containsFileVFS`` to check for existence of buffers and files in VFS.
 - Added :ref:`multi-cell support<body-flexcomp-cellnum>` for trilinear and quadratic flexes. Note that the implicit
   integrator uses a dense solver for the flex degrees of freedom, which can be slow for multi-cell flexes.
 - Refactored ``flexstrain`` equality constraints to be instantiated per cell instead of per flex object, reducing the

doc/includes/references.h

@@ -3161,6 +3161,8 @@ int mj_unmountVFS(mjVFS* vfs, const char* filename);
 int mj_addFileVFS(mjVFS* vfs, const char* directory, const char* filename);
 int mj_addBufferVFS(mjVFS* vfs, const char* name, const void* buffer, int nbuffer);
 int mj_deleteFileVFS(mjVFS* vfs, const char* filename);
+int mj_containsBufferVFS(mjVFS* vfs, const char* name);
+int mj_containsFileVFS(mjVFS* vfs, const char* directory, const char* filename);
 void mj_deleteVFS(mjVFS* vfs);
 size_t mj_getCacheSize(const mjCache* cache);
 size_t mj_getCacheCapacity(const mjCache* cache);

include/mujoco/mujoco.h

@@ -94,6 +94,12 @@ MJAPI int mj_addBufferVFS(mjVFS* vfs, const char* name, const void* buffer, int
 // Delete file from VFS; return 0: success, -1: not found in VFS.
 MJAPI int mj_deleteFileVFS(mjVFS* vfs, const char* filename);
 
+// Check if buffer exists in VFS; return 1: exists, 0: not found.
+MJAPI int mj_containsBufferVFS(mjVFS* vfs, const char* name);
+
+// Check if file exists in VFS; return 1: exists, 0: not found.
+MJAPI int mj_containsFileVFS(mjVFS* vfs, const char* directory, const char* filename);
+
 // Delete all files from VFS and deallocates VFS internal memory.
 MJAPI void mj_deleteVFS(mjVFS* vfs);
 

python/mujoco/introspect/functions.py

@@ -162,6 +162,52 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
          ),
          doc='Delete file from VFS; return 0: success, -1: not found in VFS.',
      )),
+    ('mj_containsBufferVFS',
+     FunctionDecl(
+         name='mj_containsBufferVFS',
+         return_type=ValueType(name='int'),
+         parameters=(
+             FunctionParameterDecl(
+                 name='vfs',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjVFS'),
+                 ),
+             ),
+             FunctionParameterDecl(
+                 name='name',
+                 type=PointerType(
+                     inner_type=ValueType(name='char', is_const=True),
+                 ),
+             ),
+         ),
+         doc='Check if buffer exists in VFS; return 1: exists, 0: not found.',
+     )),
+    ('mj_containsFileVFS',
+     FunctionDecl(
+         name='mj_containsFileVFS',
+         return_type=ValueType(name='int'),
+         parameters=(
+             FunctionParameterDecl(
+                 name='vfs',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjVFS'),
+                 ),
+             ),
+             FunctionParameterDecl(
+                 name='directory',
+                 type=PointerType(
+                     inner_type=ValueType(name='char', is_const=True),
+                 ),
+             ),
+             FunctionParameterDecl(
+                 name='filename',
+                 type=PointerType(
+                     inner_type=ValueType(name='char', is_const=True),
+                 ),
+             ),
+         ),
+         doc='Check if file exists in VFS; return 1: exists, 0: not found.',
+     )),
     ('mj_deleteVFS',
      FunctionDecl(
          name='mj_deleteVFS',

src/user/user_vfs.cc

@@ -236,6 +236,24 @@ VFS::Status VFS::Unmount(const FilePath& path) {
   return kInvalidResourceProvider;
 }
 
+bool VFS::ContainsBuffer(const char* name) {
+  if (name == nullptr) {
+    return false;
+  }
+  std::lock_guard<std::mutex> lock(mutex_);
+  return mounts_.contains(name);
+}
+
+bool VFS::ContainsFile(const char* directory, const char* filename) {
+  if (filename == nullptr) {
+    return false;
+  }
+  mujoco::user::FilePath path(directory ? directory : "", filename);
+  std::string key = path.StripPath().Lower().Str();
+  std::lock_guard<std::mutex> lock(mutex_);
+  return mounts_.contains(key);
+}
+
 int VFS::Read(mjResource* resource, const void** buffer) {
   if (resource && resource->provider && resource->provider->read) {
     return resource->provider->read(resource, buffer);
@@ -498,3 +516,22 @@ int mj_deleteFileVFS(mjVFS* vfs, const char* filename) {
   }
   return mujoco::user::VFS::kSuccess;
 }
+
+int mj_containsBufferVFS(mjVFS* vfs, const char* name) {
+  mujoco::user::VFS* impl = mujoco::user::VFS::Upcast(vfs);
+  if (impl == nullptr) {
+    mju_error("mjVFS is null.");
+    return -1;
+  }
+  return impl->ContainsBuffer(name);
+}
+
+int mj_containsFileVFS(mjVFS* vfs, const char* directory, const char* filename) {
+  mujoco::user::VFS* impl = mujoco::user::VFS::Upcast(vfs);
+  if (impl == nullptr) {
+    mju_error("mjVFS is null.");
+    return -1;
+  }
+  return impl->ContainsFile(directory, filename);
+}
+

src/user/user_vfs.h

@@ -90,6 +90,12 @@ class VFS {
   // Unmounts the ResourceProvider from the given path.
   Status Unmount(const FilePath& path);
 
+  // Returns true if the VFS contains a buffer with the given name.
+  bool ContainsBuffer(const char* name);
+
+  // Returns true if the VFS contains a file with the given name.
+  bool ContainsFile(const char* directory, const char* filename);
+
   // Sets a destructor to be called when the VFS has no more open resources.
   // Assumes that `destructor` will delete `this`.
   //

test/user/user_vfs_test.cc

@@ -224,6 +224,38 @@ TEST_F(UserVfsTest, DeleteFileRepeat) {
   mj_deleteVFS(&vfs);
 }
 
+TEST_F(UserVfsTest, ContainsBuffer) {
+  mjVFS vfs;
+  mj_defaultVFS(&vfs);
+  std::string buffer = "<mujoco/>";
+  const void* ptr = static_cast<const void*>(buffer.c_str());
+  mj_addBufferVFS(&vfs, "model", ptr, buffer.size());
+
+  EXPECT_TRUE(mj_containsBufferVFS(&vfs, "model"));
+  EXPECT_FALSE(mj_containsBufferVFS(&vfs, "nonexistent"));
+  EXPECT_FALSE(mj_containsBufferVFS(&vfs, "Model"));
+
+  mj_deleteVFS(&vfs);
+}
+
+TEST_F(UserVfsTest, ContainsFile) {
+  mjVFS vfs;
+  mj_defaultVFS(&vfs);
+
+  constexpr char path[] = "engine/testdata/actuation/";
+  const std::string dir = GetTestDataFilePath(path);
+  std::string file = "activation.xml";
+  mj_addFileVFS(&vfs, dir.c_str(), file.c_str());
+
+  EXPECT_TRUE(mj_containsFileVFS(&vfs, dir.c_str(), file.c_str()));
+  EXPECT_TRUE(mj_containsFileVFS(&vfs, nullptr, (dir + file).c_str()));
+  EXPECT_TRUE(mj_containsFileVFS(&vfs, nullptr, "Activation.xml"));
+  EXPECT_TRUE(mj_containsFileVFS(&vfs, "some/dir/", "activation.xml"));
+  EXPECT_FALSE(mj_containsFileVFS(&vfs, nullptr, "nonexistent.xml"));
+
+  mj_deleteVFS(&vfs);
+}
+
 
 TEST_F(UserVfsTest, AddBuffer) {
   mjVFS vfs;

unity/Runtime/Bindings/MjBindings.cs

@@ -6684,6 +6684,12 @@ public static unsafe extern int mj_addBufferVFS(void* vfs, [MarshalAs(UnmanagedT
 [DllImport("mujoco", CallingConvention = CallingConvention.Cdecl)]
 public static unsafe extern int mj_deleteFileVFS(void* vfs, [MarshalAs(UnmanagedType.LPStr)]string filename);
 
+[DllImport("mujoco", CallingConvention = CallingConvention.Cdecl)]
+public static unsafe extern int mj_containsBufferVFS(void* vfs, [MarshalAs(UnmanagedType.LPStr)]string name);
+
+[DllImport("mujoco", CallingConvention = CallingConvention.Cdecl)]
+public static unsafe extern int mj_containsFileVFS(void* vfs, [MarshalAs(UnmanagedType.LPStr)]string directory, [MarshalAs(UnmanagedType.LPStr)]string filename);
+
 [DllImport("mujoco", CallingConvention = CallingConvention.Cdecl)]
 public static unsafe extern void mj_deleteVFS(void* vfs);
 

wasm/codegen/generators/constants.py

@@ -124,6 +124,8 @@ _SKIPPED_ASSET_CACHE_FUNCTIONS: tuple[str, ...] = (
 _SKIPPED_VFS_FUNCTIONS: tuple[str, ...] = (
     # go/keep-sorted start
     "mj_addFileVFS",
+    "mj_containsBufferVFS",
+    "mj_containsFileVFS",
     "mj_mountVFS",
     "mj_unmountVFS",
     # go/keep-sorted end