msetpriority.cxx File Reference

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sched.h>
#include <sys/resource.h>

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Functions
int	main (int argc, char **argv)

Function Documentation

main()

int main	(	int	argc,
		char **	argv
	)

Definition at line 18 of file msetpriority.cxx.

{
   int status;
 
   // check if we are root
 
   uid_t uid = getuid();
   uid_t euid = geteuid();
 
   //printf("uid %d, euid %d\n", uid, euid);
 
   if (euid != 0) {
      fprintf(stderr, "%s: must be setuid-root, please do: chown root, chmod u+s\n", argv[0]);
      exit(1);
   }
 
#if 1
   struct sched_param sparam; 
   sparam.sched_priority = 50; 
   //status = sched_setscheduler(0, SCHED_RR, &sparam); 
   status = sched_setscheduler(0, SCHED_FIFO, &sparam); 
 
   if (status < 0) {
      fprintf(stderr, "%s: sched_setscheduler() returned %d, errno %d (%s)\n", argv[0], status, errno, strerror(errno));
      exit(1);
   }
#endif
 
#if 0
   status = setpriority(PRIO_PROCESS, 0, -20); 
 
   if (status < 0) {
      fprintf(stderr, "%s: setpriority() returned %d, errno %d (%s)\n", argv[0], status, errno, strerror(errno));
      exit(1);
   }
#endif 
 
   // surrender root privileges
   status = setuid(uid);
 
   if (status < 0) {
      fprintf(stderr, "%s: cannot surrender root priveleges, setuid(%d) returned %d, errno %d (%s)\n", argv[0], uid, status, errno, strerror(errno));
      exit(1);
   }
 
   if (argc < 2) {
      fprintf(stderr, "Usage: %s program [arguments...]\n", argv[0]);
      exit(1);
   }
 
   status = execvp(argv[1], &argv[1]); // does not return unless error.
 
   fprintf(stderr, "%s: execvp(\"%s\") returned %d, errno %d (%s)\n", argv[0], argv[1], status, errno, strerror(errno));
   exit(1);
}

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