#include <sys/time.h>
#include <sys/wait.h>
#include <unistd.h>
#include <cerrno>
#include <cstdio>
#include <cstdlib>
#include <csignal>

#include <sys/resource.h>
#define SLEEP_NSEC 10000 // 0.01s

int main (int argc, char **argv) {
  char ** cmd = &argv[1];
  // set timer
  struct timeval start, end;
  gettimeofday (&start, 0);
  // fork
  pid_t pid = fork ();
  if (pid < 0)  {
    std::fprintf (stderr, "cannot fork.\n"); std::exit (1);
  } else if (pid == 0) { // child process
    // must not delete this
    execvp (cmd[0], cmd);
    std::fprintf (stderr, "cannot run %s\n", cmd[0]);
    _exit (errno == ENOENT ? 127 : 126);
  }
  // dislable signals
  signal (SIGINT,  SIG_IGN);
  signal (SIGQUIT, SIG_IGN);
  // parent process
  size_t mem = 0;
  int status;
  char statm[32];
  std::sprintf (&statm[0], "/proc/%d/statm", static_cast <int> (pid));
  do {
    FILE *reader = fopen (statm, "r");
    size_t dummy (0), vm (0);
    std::fscanf (reader, "%ld %ld ", &dummy, &vm); // get resident (see procps)
    if (mem < vm) mem = vm;
    std::fclose (reader);
    if (! vm) break;
  } while (! usleep (SLEEP_NSEC));
  mem *= getpagesize ();
  // stop timer
  if (waitpid (pid, &status, 0) == -1)
    std::fprintf (stderr, "error waiting for child process.\n");
  if ((status & 0xff) == 0x7f)
    std::fprintf (stderr, "Command stopped by signal %d\n", (status >> 8) & 0xff);
  else if ((status & 0xff) != 0)
    std::fprintf (stderr, "Command terminated by signal %d\n", status & 0xff);
  else if ((status >> 8) & 0xff)
    std::fprintf (stderr, "Command exited with non-zero status %d\n", (status >> 8) & 0xff);
  gettimeofday (&end, 0);

  std::fprintf (stderr, "elapsed (real): %.3fs; RSS=%.1fM\n",
                end.tv_sec - start.tv_sec + (end.tv_usec - start.tv_usec) * 1e-6,
                static_cast <double> (mem) / (1024.0 * 1024.0));
  // enable signals
  signal (SIGINT,  SIG_DFL);
  signal (SIGQUIT, SIG_DFL);
  return 0;
}