Setuid wrapper and Makefile

Makefile

# Makefile for the wrapper
# The wrapper target is going to prompt you for your root password 
# so don't run this if you are set to do stuff non-interactively.

THIS_DIR = $(shell pwd)
DEFINES=-DPING_AGENT_PATH="\"$(THIS_DIR)\""

wrapper: wrapper.o
	gcc -o wrapper wrapper.c $(DEFINES)
	sudo chown root wrapper
	sudo chmod u+s wrapper

%.o: %.c
	gcc -c $(DEFINES) $<

clean:
	rm -f wrapper
	rm -f *.o
	

wrapper.c

/*
 * wrapper.c
 * Wrapper around the ping-agent.js.
 * It is stupid dangerous to run setuid so this requires you to 
 * set the explicit path at compile time with a -D flag. 
 */

#ifndef PING_AGENT_PATH
#error you forgot to set the PING_AGENT_PATH
#endif

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>

const char *PATH = PING_AGENT_PATH "/ping-agent.js";
char *ARGS[] = {"ping-agent.js"};

int main(int argc, char *argv) {
	printf("Ping agent wrapper\n");
	printf("Path: %s\n", PATH);

	// Are we running this with setuid?  If not, we probably
	// messed something up.
	uid_t real_uid = getuid();
	uid_t effective_uid = geteuid();
	printf("Real UID: %d\n", real_uid);
	printf("Effective UID: %d\n", effective_uid);
	if (0 != effective_uid) {
		fprintf(stderr, "WARNING: Not running as root\n");
	}

	execv(PATH, ARGS);

	return 0;
}