#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>

void create_load(int iters);
void cleanup();

int   high_rate = 0;
int   num_iters = 100000;
int   fd1;
char  file1[50];
char  file2[50];
char  dir1[50];
char  symlink1[50];

/* Purpose: To create system load by invoking system calls used by templates.
 *
 * Note: The unlink(2) of a file can be an expensive operation (i.e., event 
 *       rate goes way down).
 */

main(int argc, char **argv) {

  int              num_children=1;
  int              iters;
  int              i;
  char             c;

  while ((c = getopt(argc, argv, "hi:")) != -1) {
    switch (c) {
    case 'h':
      /*
       * Desire "high" event rate
       */
      high_rate = 1;
      argc--;
      break;
    case 'i':
      /*
       * Desire a specified number of iterations
       */
      num_iters = atoi(optarg);
      argc--;
      break;
    default:
      fprintf(stderr,"Unknown option: %c\n",optarg);
      exit(1);
    }
  }


  /*if(argv[optind] != NULL) {
    num_children = atoi(argv[optind]);
  } else {
    num_children = 0;
  }
  Register cleanup routine */
  fprintf(stderr,"Registering cleanup routine...\n");
  if (atexit(cleanup) == -1) {
    fprintf(stderr,"Error calling atexit(), errno=%d(%s)\n",
	    errno,strerror(errno));
    exit(1);
  }
    

  /* fork child processes, if any requested */
  for(i=1; i < num_children; i++) {
    if(fork() == 0) {

      printf("child pid: %d\n",getpid());

      /* Setup file names based on child's pid */
      sprintf(file1,"./file1_%d",getpid());
      sprintf(file2,"./file2_%d",getpid());
      sprintf(dir1,"./dir1_%d",getpid());
      sprintf(symlink1,"./file1symlink_%d",getpid());

      /* each child creates load */	
      iters=0;
      if (num_iters == -1) {
	while(1) {
	  create_load(iters);
	  iters++;
	  if( (iters % 1000) == 0) {
	    printf("pid %d iteration %d\n",getpid(),iters);
	  }
	}
      } else {
	while(iters < num_iters) {
	  create_load(iters);
	  iters++;
	  if( (iters % 1000) == 0) {
	    printf("pid %d iteration %d\n",getpid(),iters);
	  }
	}
      }
    }
  }

  /* Parent creates load also */
  printf("parent pid: %d\n",getpid());

  /* Setup file names based on parent's pid */
  sprintf(file1,"./file1_%d",getpid());
  sprintf(file2,"./file2_%d",getpid());
  sprintf(dir1,"./dir1_%d",getpid());
  sprintf(symlink1,"./file1symlink_%d",getpid());

  iters=0;
  if (num_iters == -1) {
    while(1) {
      create_load(iters);
      iters++;
      if( (iters % 1000) == 0) {
	printf("pid %d iteration %d\n",getpid(),iters);
      }
    }
  } else {
    while(iters < num_iters) {
      create_load(iters);
      iters++;
      if( (iters % 1000) == 0) {
	printf("pid %d iteration %d\n",getpid(),iters);
      }
    }
  }

} /* main */


void create_load(int iters) {

  int pid;
  char *args[2];
  struct stat stat_buf;

  fd1 = creat(file1,0x644);
  if (fd1 == -1) {
    fprintf(stderr,"pid %d: creat() returned error for file %s, errno=%d(%s)\n",
	    getpid(),file1,errno,strerror(errno));
    exit(1);
  }
  if (close(fd1) == -1) {
    fprintf(stderr,"pid %d: close() returned error, errno=%d(%s)\n",
	    getpid(),errno,strerror(errno));
    exit(1);
  }
  fd1 = open(file1, O_RDWR, 0777);
  if (fd1 == -1) {
    fprintf(stderr,"pid %d: open() returned error, errno=%d(%s)\n",
	    getpid(),errno,strerror(errno));
    exit(1);
  }

  /* Chown this file to root instead of user ids so that we don't generate a 
   * non-owned alert when the file is truncated when invoking creat() again
   * as root on an existing file owned by another user.
   */
  if (chown(file1,0,0) == -1) {
    fprintf(stderr,"pid %d: chown(%d,%d) returned error, errno=%d(%s)\n",
	    getpid(),0,0,errno,strerror(errno));
    exit(1);
  }    
 
  if (fchown(fd1,0,0) == -1) {
    fprintf(stderr,"pid %d: fchown(%d,%d) returned error, errno=%d(%s)\n",
	    getpid(),0,0,errno,strerror(errno));
    exit(1);
  }   
   
  if (chmod(file1, S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH) == -1) {
    fprintf(stderr,"pid %d: chmod(S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH) returned error, errno=%d(%s)\n",
	    getpid(),errno,strerror(errno));
    exit(1);
  }    
  if (fchmod(fd1,   S_IXUSR|S_IXGRP|S_IXOTH) == -1) {
    fprintf(stderr,"pid %d: fchmod(S_IXUSR|S_IXGRP|S_IXOTH) returned error, errno=%d(%s)\n",
	    getpid(),errno,strerror(errno));
    exit(1);
  }


  if (write(fd1,"Some stuff",strlen("Some stuff")) == -1) {
    fprintf(stderr,"pid %d: write() returned error, errno=%d(%s)\n",
	    getpid(),errno,strerror(errno));
    exit(1);
  }
  if (ftruncate(fd1,7) == -1) {
    fprintf(stderr,"pid %d: ftruncate() returned error, errno=%d(%s)\n",
	    getpid(),errno,strerror(errno));
    exit(1);
  }
  if (close(fd1) == -1) {
    fprintf(stderr,"pid %d: close() returned error, errno=%d(%s)\n",
	    getpid(),errno,strerror(errno));
    exit(1);
  }

  if (truncate(file1,3) == -1) {
    fprintf(stderr,"pid %d: truncate() returned error, errno=%d(%s)\n",
	    getpid(),errno,strerror(errno));
    exit(1);
  }
  if (rename(file1,file2) == -1) {
    fprintf(stderr,"pid %d: rename(%s,%s) returned error, errno=%d(%s)\n",
	    getpid(),file1,file2,errno,strerror(errno));
    exit(1);
  }
  if (rename(file2,file1) == -1) {
    fprintf(stderr,"pid %d: rename(%s,%s) returned error, errno=%d(%s)\n",
	    getpid(),file2,file1,errno,strerror(errno));
    exit(1);
  }
  if (link(file1,file2) == -1) {
    fprintf(stderr,"pid %d: link(%s,%s) returned error, errno=%d(%s)\n",
	    getpid(),file1,file2,errno,strerror(errno));
    exit(1);
  }
  if (symlink(file1,symlink1) == -1) {
    fprintf(stderr,"pid %d: symlink(%s,%s) returned error, errno=%d(%s)\n",
	    getpid(),file1,symlink1,errno,strerror(errno));
    exit(1);
  }
  if (lchown(symlink1,0,0) == -1) {
    fprintf(stderr,"pid %d: lchown(%s,%d,%d) returned error, errno=%d(%s)\n",
	    getpid(),symlink1,0,0,errno,strerror(errno));
    exit(1);
  }
  
  if (lstat(symlink1,&stat_buf) == -1) {
    fprintf(stderr,"pid %d: lstat(%s) returned error, errno=%d(%s)\n",
	    getpid(),symlink1,errno,strerror(errno));
    exit(1);
  }
  if (stat(file1,&stat_buf) == -1) {
    fprintf(stderr,"pid %d: stat(%s) returned error, errno=%d(%s)\n",
	    getpid(),file1,errno,strerror(errno));
    exit(1);
  }
  if (unlink(file1) == -1) {
    fprintf(stderr,"pid %d: unlink(%s) returned error, errno=%d(%s)\n",
	    getpid(),file1,errno,strerror(errno));
    exit(1);
  }
  if (unlink(file2) == -1) {
    fprintf(stderr,"pid %d: unlink(%s) returned error, errno=%d(%s)\n",
	    getpid(),file2,errno,strerror(errno));
    exit(1);
  }
  if (unlink(symlink1) == -1) {
    fprintf(stderr,"pid %d: unlink(%s) returned error, errno=%d(%s)\n",
	    getpid(),symlink1,errno,strerror(errno));
    exit(1);
  }
  if (mkdir(dir1,S_IRUSR|S_IWUSR|S_IXUSR|S_IRGRP|S_IXGRP) == -1) {
    fprintf(stderr,"pid %d: mkdir() returned error, errno=%d(%s)\n",
	    getpid(),errno,strerror(errno));
    exit(1);
  }
  if (rmdir(dir1) == -1) {
    fprintf(stderr,"pid %d: rmdir() returned error, errno=%d(%s)\n",
	    getpid(),errno,strerror(errno));
    exit(1);
  }

  /* Fork every 10000 iterations to not use up process resources too quickly */
  if ( (iters % 10000) == 0) {
    pid = fork();
    if(pid == 0) {
      fprintf(stderr,"child pid %d: fork!\n",getpid());
      // child
      args[0] = "/bin/ls";
      args[1] = NULL;
      close(1);
      close(2);    
      execve(args[0], args, NULL);
      fprintf(stderr,"pid %d: execve(%s) returned error, errno=%d(%s)\n",
	      getpid(),args[0],errno,strerror(errno));
      _exit(1);
    } else if (pid < 0) { 
      fprintf(stderr,"pid %d: fork() returned error, errno=%d(%s)\n",
	      getpid(),errno,strerror(errno));
      exit(1);
    } else {
      fprintf(stderr,"parent pid %d, child pid: %d: fork!\n",getpid(),pid);
    }

    pid = vfork();
    if(pid == 0) {
      args[0] = "/bin/pwd";
      args[1] = NULL;
      close(1);
      close(2);    
      execv(args[0], args);
      fprintf(stderr,"pid %d: execve(%s) returned error, errno=%d(%s)\n",
	      getpid(),args[0],errno,strerror(errno));
      _exit(1);
    } else if (pid < 0) { 
      fprintf(stderr,"pid %d: vfork() returned error, errno=%d(%s)\n",
	      getpid(),errno,strerror(errno));
      exit(1);
    }
  }

  /* Make sure everything is cleaned up and deleted before returning */
  cleanup();

} /* create_load() */

void cleanup() {
  close(fd1);
  unlink(file1);
  unlink(file2);
  unlink(symlink1);
  unlink(dir1);
  return;
}