/* Simple backwards compat code to exec old version */#ifndef CONFIG_NO_BACKWARDS_COMPAT#include <sys/types.h>#include <sys/stat.h>#include <unistd.h>#include <stdlib.h>#include <errno.h>#include <stdio.h>#include <string.h>#include <asm/unistd.h>extern long create_module(const char *, size_t);#include "testing.h"static void exec_old(const char *progname, char *argv[]){	char *sep;	pid_t pid;	char ascii_pid[32];	char pathname[strlen(argv[0])+1];	char oldname[strlen(progname) + strlen(argv[0]) + sizeof(".old")];	memset(pathname, 0, strlen(argv[0])+1);	sep = strrchr(argv[0], '/');	if (sep)		memcpy(pathname, argv[0], sep - argv[0]+1);	sprintf(oldname, "%s%s.old", pathname, progname);	/* Recursion detection: we need an env var since we can't	   change argv[0] (as older modutils uses it to determine	   behavior).  We *can* recurse in the case of old-style	   pre-install etc. commands, so make sure pid is exactly the	   same. */	pid = getpid();	snprintf(ascii_pid, sizeof(ascii_pid), "%lu", (unsigned long)pid);	if (strcmp(getenv("MODULE_RECURSE") ?: "", ascii_pid) == 0) {		fprintf(stderr, "WARNING: %s: I am not the old version!\n",			oldname);		return;	}	setenv("MODULE_RECURSE", ascii_pid, 1);	execvp(oldname, argv);	fprintf(stderr,		"Kernel requires old %s, but couldn't run %s: %s\n",		progname, oldname, strerror(errno));	exit(2);}static void try_old_version(const char *progname, char *argv[]){	errno = 0;	if (create_module(NULL, 0) >= 0 /* Uh oh, what have I just done? */	    || errno != ENOSYS)		exec_old(progname, argv);}#else /* CONFIG_NO_BACKWARDS_COMPAT */static inline void try_old_version(const char *progname, char *argv[]){}#endif /* !CONFIG_NO_BACKWARDS_COMPAT */