/*
 * Sample program for setuid systme call  - No.23
 *
 * setuid(2) - set user identity
 *
 * Synopsis
 *     #include <sys/types.h>
 *     #include <unistd.h>
 *
 *     int setuid(uid_t uid);
 */

#include <stdio.h>
#include <errno.h>
#include <error.h>

main(int argc, char *argv[])
{
	FILE *fp;
	int c;

	if (argc == 2 && argv[1][0] == 's')
		setuid(500);		/* need to replace 500 with real uid */

	if ((fp = fopen("/etc/shadow", "r")) != NULL) {
		while((c = getc(fp)) != EOF)
			putchar(c);
		fclose(fp);
	} else {
		error(0, errno, "%s", "can't open file");
	}

	exit(0);
}