#include "memfd_shm.h"

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/syscall.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/memfd.h>
#include <stdlib.h>

static inline int sys_memfd_create(const char *name,
                unsigned int flags)
{
    return syscall(__NR_memfd_create, name, flags);
}

int basic_shm_create(const char *name, int len){
  int fd;
  struct stat st;

  /* Create an anonymous file in tmpfs; */
  if(0 >= len)
  {
      return -1;
  }

  fd = sys_memfd_create(name, MFD_CLOEXEC);

  if (fd == -1)
  {
      return -1;
  }

  /* Size the file as specified on the command line */

  if (ftruncate(fd, len) == -1)
  {
    close(fd);
    return -1;
  }

  if (fstat (fd, &st))
  {
    close(fd);
    return -1;
  }

  // printf("PID: %ld; fd: %d; /proc/%ld/fd/%d, atime: %lu.%lu\n",
  //     (long) getpid(), fd, (long) getpid(), fd, st.st_atim.tv_sec, st.st_atim.tv_nsec);

  return fd;
}

int basic_shm_mmap(int fd, unsigned char** ppaddr){
  struct stat st;
  ssize_t len;
  if (fstat (fd, &st))
  {
      return -1;
  }
  len = st.st_size;

  *ppaddr = (unsigned char*) mmap (NULL, len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
  if (*ppaddr == MAP_FAILED)
  {
    return -1;
  }

  // printf("length: %zu, atime: %lu.%lu\n", len, st.st_atim.tv_sec, st.st_atim.tv_nsec);
  return len;
}

int basic_shm_unmmap(int fd, unsigned char** ppaddr){
    struct stat st;
    ssize_t len;
    int ret = 0;
    if (fstat (fd, &st))
    {
        return -1;
    }
    len = st.st_size;

    ret = munmap((void *)*ppaddr, len);
    if (ret == -1)
    {
        return -1;
    }
    *ppaddr = NULL;
    // printf("length: %zu, atime: %lu.%lu\n", len, st.st_atim.tv_sec, st.st_atim.tv_nsec);
    return len;
}

int basic_shm_close(int fd){
  int ret = -1;
  if (fd >= 0)
  {
    ret = close(fd);
  }
  return ret;
}