Add checksums (used as a timestamp) to VFS.

Deprecate mj_makeEmptyFileVFS in favor of mj_addBufferVFS.

PiperOrigin-RevId: 608915388
Change-Id: Id9e9b042799bc1bf547f0795ae6f386447d53cdd

include/mujoco/mjmodel.h

@@ -16,6 +16,7 @@
 #define MUJOCO_MJMODEL_H_
 
 #include <stddef.h>
+#include <stdint.h>
 
 
 #include <mujoco/mjtnum.h>
@@ -390,11 +391,12 @@ typedef struct mjLROpt_ mjLROpt;
 
 //---------------------------------- mjVFS ---------------------------------------------------------
 
-struct mjVFS_ {                             // virtual file system for loading from memory
-  int    nfile;                             // number of files present
-  char   filename[mjMAXVFS][mjMAXVFSNAME];  // file name without path
-  size_t filesize[mjMAXVFS];                // file size in bytes
-  void*  filedata[mjMAXVFS];                // buffer with file data
+struct mjVFS_ {                               // virtual file system for loading from memory
+  int      nfile;                             // number of files present
+  char     filename[mjMAXVFS][mjMAXVFSNAME];  // file name without path
+  size_t   filesize[mjMAXVFS];                // file size in bytes
+  void*    filedata[mjMAXVFS];                // buffer with file data
+  uint64_t filestamp[mjMAXVFS];               // checksum of the file data
 };
 typedef struct mjVFS_ mjVFS;
 

include/mujoco/mjplugin.h

@@ -26,11 +26,12 @@
 struct mjResource_ {
   char* name;                                   // name of resource (filename, etc)
   void* data;                                   // opaque data pointer
+  char timestamp[512];                          // timestamp of the resource
   const struct mjpResourceProvider* provider;   // pointer to the provider
 };
 typedef struct mjResource_ mjResource;
 
-// callback for opeing a resource, returns zero on failure
+// callback for opening a resource, returns zero on failure
 typedef int (*mjfOpenResource)(mjResource* resource);
 
 // callback for reading a resource
@@ -44,10 +45,12 @@ typedef void (*mjfCloseResource)(mjResource* resource);
 // sets dir to directory string with ndir being size of directory string
 typedef void (*mjfGetResourceDir)(mjResource* resource, const char** dir, int* ndir);
 
-// callback for checking if a resource was modified since last read
-// returns > 0 if resource was modified since last open, 0 if resource was not
-// modified, and < 0 if inconclusive
-typedef int (*mjfResourceModified)(const mjResource* resource);
+// callback for checking if the current resource was modified from the time
+// specified by the timestamp
+// returns 0 if the resource's timestamp matches the provided timestamp
+// returns > 0 if the the resource is younger than the given timestamp
+// returns < 0 if the resource is older than the given timestamp
+typedef int (*mjfResourceModified)(const mjResource* resource, const char* timestamp);
 
 // struct describing a single resource provider
 struct mjpResourceProvider {

include/mujoco/mujoco.h

@@ -82,8 +82,8 @@ MJAPI void mj_defaultVFS(mjVFS* vfs);
 // Add file to VFS, return 0: success, 1: full, 2: repeated name, -1: failed to load.
 MJAPI int mj_addFileVFS(mjVFS* vfs, const char* directory, const char* filename);
 
-// Make empty file in VFS, return 0: success, 1: full, 2: repeated name.
-MJAPI int mj_makeEmptyFileVFS(mjVFS* vfs, const char* filename, int filesize);
+// Add file to VFS from buffer, return 0: success, 1: full, 2: repeated name, -1: failed to load.
+MJAPI int mj_addBufferVFS(mjVFS* vfs, const char* name, const void* buffer, int nbuffer);
 
 // Return file index in VFS, or -1 if not found in VFS.
 MJAPI int mj_findFileVFS(const mjVFS* vfs, const char* filename);
@@ -94,6 +94,8 @@ MJAPI int mj_deleteFileVFS(mjVFS* vfs, const char* filename);
 // Delete all files from VFS.
 MJAPI void mj_deleteVFS(mjVFS* vfs);
 
+// deprecated: use mj_copyBufferVFS.
+MJAPI int mj_makeEmptyFileVFS(mjVFS* vfs, const char* filename, int filesize);
 
 //---------------------------------- Parse and compile ---------------------------------------------