Rework immutability and overlays

overlayfs-tools/sh.h

@@ -0,0 +1,20 @@
+#ifndef OVERLAYFS_TOOLS_SH_H
+#define OVERLAYFS_TOOLS_SH_H
+
+enum {
+    LOWERDIR,
+    UPPERDIR,
+    MOUNTDIR,
+    LOWERNEW,
+    UPPERNEW,
+    NUM_VARS
+};
+
+extern const char *var_names[NUM_VARS];
+extern char *vars[NUM_VARS];
+
+FILE* create_shell_script(char *tmp_path_buffer);
+
+int command(FILE *output, const char *command_format, ...);
+
+#endif //OVERLAYFS_TOOLS_SH_H