#define _GNU_SOURCE
#include <sys/types.h>
#include <sys/mount.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/xattr.h>

#include <dirent.h>
#include <errno.h>
#include <error.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <linux/falloc.h>
#include <linux/loop.h>

// derived from https://github.com/oracle/kernel-fuzzing/blob/master/include/mount.hh
static void activity(char *mpoint) {

  char *foo_bar_baz;
  char *foo_baz;
  char *xattr;
  char *hln;
  char *sln;
  int err;

  static int buf[8192];
  memset(buf, 0, sizeof(buf));

  err = asprintf(&foo_bar_baz, "%s/foo/bar/baz", mpoint);
  err = asprintf(&foo_baz, "%s/foo/baz", mpoint);
  err = asprintf(&xattr, "%s/foo/bar/xattr", mpoint);
  err = asprintf(&hln, "%s/foo/bar/hln", mpoint);
  err = asprintf(&sln, "%s/foo/bar/sln", mpoint);

  // opendir / readdir
  DIR *dir = (DIR *)opendir(mpoint);
  if (dir) {
    readdir(dir);
    closedir(dir);
  }

  // open / mmap / read
  // mmap MAP_SHARED?
  int fd = open(foo_bar_baz, O_RDONLY, 0);
  if (fd >= 0) {
    void *mem = mmap(NULL, 4096, PROT_READ, MAP_PRIVATE | MAP_POPULATE, fd, 0);

    if (mem != MAP_FAILED)
      munmap(mem, 4096);

    read(fd, (char *)buf, 11);
    read(fd, (char *)buf, 11);
    close(fd);
  }

  // open / write / read
  fd = open(foo_bar_baz, O_RDWR | O_TRUNC, 0777);
  if (fd >= 0) { 
    write(fd, (char *)buf, 517); 
    write(fd, (char *)buf, sizeof(buf)); 
    fdatasync(fd);
    fsync(fd);

    lseek(fd, 0, SEEK_SET); 
    read(fd, (char *)buf, sizeof(buf)); 
    lseek(fd, 1234, SEEK_SET);
    read(fd, (char *)buf, 517); 
    close(fd); 
  }  

  // open / lseek / write / fallocate
  fd = open(foo_bar_baz, O_RDWR | O_TRUNC, 0777);
  if (fd >= 0) {
    lseek(fd, 1024 - 33, SEEK_SET);
    write(fd, (char *)buf, sizeof(buf));
    lseek(fd, 1024 * 1024 + 67, SEEK_SET);
    write(fd, (char *)buf, sizeof(buf));
    lseek(fd, 1024 * 1024 * 1024 - 113, SEEK_SET);
    write(fd, (char *)buf, sizeof(buf));

    lseek(fd, 0, SEEK_SET);
    write(fd, (char *)buf, sizeof(buf));

    fallocate(fd, 0, 0, 123871237);
    fallocate(fd, 0, -13123, 123);
    fallocate(fd, 0, 234234, -45897);
    fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, 0, 4243261);
    fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, -95713, 38447);
    fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, 18237, -9173);

    close(fd);
  }

  // rename
  rename(foo_bar_baz, foo_baz);
  
  // stat
  struct stat st;
  memset(&st, 0, sizeof(st));
  stat(foo_baz, &st);

  // chmod / chown
  chmod(foo_baz, 0000);
  chmod(foo_baz, 1777);
  chmod(foo_baz, 3777);
  chmod(foo_baz, 7777);
  chown(foo_baz, 0, 0);
  chown(foo_baz, 1, 1);

  // unlink
  unlink(foo_bar_baz);
  unlink(foo_baz);

  // mknod
  mknod(foo_baz, 0777, makedev(0, 0));

  // xattr
  char buf2[113];
  memset(buf2, 0, sizeof(buf2));
  listxattr(xattr, buf2, sizeof(buf2));
  removexattr(xattr, "user.mime_type");
  setxattr(xattr, "user.md5", buf2, sizeof(buf2), XATTR_CREATE);
  setxattr(xattr, "user.md5", buf2, sizeof(buf2), XATTR_REPLACE);

  // link
  readlink(sln, buf2, sizeof(buf2));
  
}

int main(int argc, char *argv[]) {
  activity(argv[1]);
  return 0;
}