Add documentation, expand error handling, implement file and buffer io

include/bh/internal/file.h

@@ -0,0 +1,20 @@
+#ifndef BH_INTERNAL_FILE_H
+#define BH_INTERNAL_FILE_H
+
+#include "io.h"
+#include <bh/file.h>
+
+#if defined(BH_PLATFORM_POSIX)
+#include "file_posix.h"
+#elif defined(BH_PLATFORM_WIN)
+#include "file_win.h"
+#else
+#include "file_null.h"
+#endif
+
+int bh_file_init(bh_file_t *file,
+                 const char *path);
+
+void bh_file_destroy(bh_file_t *file);
+
+#endif /* BH_INTERNAL_FILE_H */