Update

libgambatte/libretro-common/include/libretro.h

@@ -967,6 +967,23 @@ enum retro_mod
                                             * core supports VFS before it starts handing out paths.
                                             * It is recomended to do so in retro_set_environment */
 
+/* VFS functionality */
+
+/* File paths:
+ * File paths passed as parameters when using this api shall be well formed unix-style,
+ * using "/" (unquoted forward slash) as directory separator regardless of the platform's native separator.
+ * Paths shall also include at least one forward slash ("game.bin" is an invalid path, use "./game.bin" instead).
+ * Other than the directory separator, cores shall not make assumptions about path format:
+ * "C:/path/game.bin", "http://example.com/game.bin", "#game/game.bin", "./game.bin" (without quotes) are all valid paths.
+ * Cores may replace the basename or remove path components from the end, and/or add new components;
+ * however, cores shall not append "./", "../" or multiple consecutive forward slashes ("//") to paths they request to front end.
+ * The frontend is encouraged to make such paths work as well as it can, but is allowed to give up if the core alters paths too much.
+ * Frontends are encouraged, but not required, to support native file system paths (modulo replacing the directory separator, if applicable).
+ * Cores are allowed to try using them, but must remain functional if the front rejects such requests.
+ * Cores are encouraged to use the libretro-common filestream functions for file I/O,
+ * as they seamlessly integrate with VFS, deal with directory separator replacement as appropriate
+ * and provide platform-specific fallbacks in cases where front ends do not support VFS. */
+
 /* Opaque file handle
  * Introduced in VFS API v1 */
 struct retro_vfs_file_handle;
@@ -985,6 +1002,11 @@ struct retro_vfs_file_handle;
 /* Indicate that the file will be accessed many times. The frontend should aggressively cache everything. */
 #define RETRO_VFS_FILE_ACCESS_HINT_FREQUENT_ACCESS   (1 << 0)
 
+/* Seek positions */
+#define RETRO_VFS_SEEK_POSITION_START    0
+#define RETRO_VFS_SEEK_POSITION_CURRENT  1
+#define RETRO_VFS_SEEK_POSITION_END      2
+
 /* Get path from opaque handle. Returns the exact same path passed to file_open when getting the handle
  * Introduced in VFS API v1 */
 typedef const char *(RETRO_CALLCONV *retro_vfs_get_path_t)(struct retro_vfs_file_handle *stream);
@@ -1009,7 +1031,7 @@ typedef int64_t (RETRO_CALLCONV *retro_vfs_tell_t)(struct retro_vfs_file_handle
 
 /* Set the current read/write position for the file. Returns the new position, -1 for error.
  * Introduced in VFS API v1 */
-typedef int64_t (RETRO_CALLCONV *retro_vfs_seek_t)(struct retro_vfs_file_handle *stream, int64_t offset, int whence);
+typedef int64_t (RETRO_CALLCONV *retro_vfs_seek_t)(struct retro_vfs_file_handle *stream, int64_t offset, int seek_position);
 
 /* Read data from a file. Returns the number of bytes read, or -1 for error.
  * Introduced in VFS API v1 */

libgambatte/libretro-common/include/streams/file_stream.h

@@ -60,7 +60,7 @@ int64_t filestream_get_size(RFILE *stream);
  **/
 RFILE *filestream_open(const char *path, unsigned mode, unsigned hints);
 
-ssize_t filestream_seek(RFILE *stream, ssize_t offset, int whence);
+ssize_t filestream_seek(RFILE *stream, ssize_t offset, int seek_position);
 
 ssize_t filestream_read(RFILE *stream, void *data, int64_t len);
 

libgambatte/libretro-common/include/vfs/vfs_implementation.h

@@ -48,7 +48,7 @@ int64_t retro_vfs_file_size_impl(libretro_vfs_implementation_file *stream);
 
 int64_t retro_vfs_file_tell_impl(libretro_vfs_implementation_file *stream);
 
-int64_t retro_vfs_file_seek_impl(libretro_vfs_implementation_file *stream, int64_t offset, int whence);
+int64_t retro_vfs_file_seek_impl(libretro_vfs_implementation_file *stream, int64_t offset, int seek_position);
 
 int64_t retro_vfs_file_read_impl(libretro_vfs_implementation_file *stream, void *s, uint64_t len);
 

libgambatte/libretro-common/streams/file_stream.c

@@ -188,14 +188,14 @@ int filestream_getc(RFILE *stream)
    return EOF;
 }
 
-ssize_t filestream_seek(RFILE *stream, ssize_t offset, int whence)
+ssize_t filestream_seek(RFILE *stream, ssize_t offset, int seek_position)
 {
    int64_t output;
 
    if (filestream_seek_cb != NULL)
-      output = filestream_seek_cb(stream->hfile, offset, whence);
+      output = filestream_seek_cb(stream->hfile, offset, seek_position);
    else
-      output = retro_vfs_file_seek_impl((libretro_vfs_implementation_file*)stream->hfile, offset, whence);
+      output = retro_vfs_file_seek_impl((libretro_vfs_implementation_file*)stream->hfile, offset, seek_position);
 
    if (output == vfs_error_return_value)
       stream->error_flag = true;
@@ -233,7 +233,7 @@ void filestream_rewind(RFILE *stream)
 {
    if (!stream)
       return;
-   filestream_seek(stream, 0L, SEEK_SET);
+   filestream_seek(stream, 0L, RETRO_VFS_SEEK_POSITION_START);
    stream->error_flag = false;
 }
 

libgambatte/libretro-common/vfs/vfs_implementation.c

@@ -24,6 +24,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <errno.h>
+#include <sys/types.h>
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
@@ -376,9 +377,23 @@ int64_t retro_vfs_file_tell_impl(libretro_vfs_implementation_file *stream)
    return 0;
 }
 
-int64_t retro_vfs_file_seek_impl(libretro_vfs_implementation_file *stream, int64_t offset, int whence)
+int64_t retro_vfs_file_seek_impl(libretro_vfs_implementation_file *stream, int64_t offset, int seek_position)
 {
-	return retro_vfs_file_seek_internal(stream, offset, whence);
+   int whence = -1;
+   switch (seek_position)
+   {
+   case RETRO_VFS_SEEK_POSITION_START:
+      whence = SEEK_SET;
+      break;
+   case RETRO_VFS_SEEK_POSITION_CURRENT:
+      whence = SEEK_CUR;
+      break;
+   case RETRO_VFS_SEEK_POSITION_END:
+      whence = SEEK_END;
+      break;
+   }
+
+   return retro_vfs_file_seek_internal(stream, offset, whence);
 }
 
 int64_t retro_vfs_file_read_impl(libretro_vfs_implementation_file *stream, void *s, uint64_t len)