#include <unistd.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>
#include <time.h>
#include <stdarg.h>

#define errExit(msg)    do { perror(msg); exit(EXIT_FAILURE); \
} while (0)

#define LOGFILE "/opt/vasystem/valog/memfd.log"

/*****************************************************************************
 函 数 名  : mydebug
 功能描述  : 日志记录函数，记录到文件
 输入参数  : const char *fmt  
             ...              
 输出参数  : 无
 返 回 值  : 无
 调用函数  : 
 被调函数  : 
 
 修改历史      :
  1.日    期   : 2018年1月15日
    作    者   : cheliequan
    修改内容   : 新生成函数

*****************************************************************************/
void mydebug(const char *fmt, ...)
{
	char debugbuff[2048];
	int outlen;
	FILE *fp;
	va_list ap;
	time_t nowtime = time(NULL);
	struct tm *pNowtime=NULL;
	pNowtime = localtime(&nowtime);

	fp=fopen(LOGFILE,"a+");
	if(fp==NULL)
	{
		return;
	}
	va_start(ap, fmt);
	outlen=vsprintf(debugbuff,fmt,ap);
	va_end(ap);
	*(debugbuff+outlen) = 0;
	fprintf(fp,"%d-%02d-%02d %02d:%02d:%02d====",pNowtime->tm_year+1900,pNowtime->tm_mon+1,pNowtime->tm_mday,pNowtime->tm_hour,pNowtime->tm_min,pNowtime->tm_sec);
	fprintf(fp,"%s",debugbuff);
	fclose(fp);
}

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

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

  /* Create an anonymous file in tmpfs; */

  fd = sys_memfd_create(name, MFD_CLOEXEC);

  if (fd == -1)
  {
    errExit("memfd_create");
  }

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

  mydebug("length: %zu\n", len);
  if (ftruncate(fd, len) == -1)
  {
      errExit("truncate");
  }

  if (fstat (fd, &st))
  {
    errExit ("fstat");
  }

  mydebug("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_path_open(int memfd, pid_t pid)
{
  ssize_t  len;
  int fd;
  struct stat st;
  if ((pid != 0) && (memfd != 0))
  {
    char fd_path[512] = {0};
    snprintf(fd_path, sizeof(fd_path), "/proc/%d/fd/%d", pid, memfd);

    fd = open(fd_path, O_RDWR|O_CLOEXEC);
    if (fd == -1)
    {
      errExit("open");
    }
  }

  if (fstat (fd, &st))
  {
    errExit ("fstat");
  }
  len = st.st_size;

  mydebug("length: %zu, atime: %lu.%lu\n", len, st.st_atim.tv_sec, st.st_atim.tv_nsec);

  return fd;
}

int basic_shm_open(int fd, pid_t pid, int flags)
{
    if(0 >= flags)
    {
        basic_shm_path_open(fd, getpid());
    }
    else
    {
        basic_shm_path_open(fd, pid);
    }
}

int basic_shm_mmap(int fd, unsigned char** ppaddr)
{
  struct stat st;
  ssize_t len;  
  if (fstat (fd, &st))
  {
      errExit ("fstat");
  }
  len = st.st_size;
  
  *ppaddr = (unsigned char*) mmap (NULL, len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
  if (*ppaddr == MAP_FAILED)
  {
    errExit("mmap");
  }

  mydebug("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))
    {
        errExit ("fstat");
    }
    len = st.st_size;

    ret = munmap(*ppaddr, len);
    if (ret == -1)
    {
        errExit("munmap()");
    }

    mydebug("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)
{
  if (fd >= 0) 
  {
    close(fd);
  }
}

static void mfd_assert_size(int fd, size_t size)
{
	struct stat st;
	int r;

	r = fstat(fd, &st);
	if (r < 0) {
		mydebug("fstat(%d) failed: %m\n", fd);
	} else if (st.st_size != size) {
		mydebug("wrong file size %lld, but expected %lld\n",
		       (long long)st.st_size, (long long)size);
	}
}

static int mfd_assert_open(int fd, int flags, mode_t mode)
{
	char buf[512];
	int r;

	sprintf(buf, "/proc/self/fd/%d", fd);
	r = open(buf, flags, mode);
	if (r < 0)
  {
		mydebug("open(%s) failed: %m\n", buf);
	}

	return r;
}

int basic_shm_shrink(int fd, ssize_t len)
{
	int r, fd2;

	r = ftruncate(fd, len);
	if (r < 0) {
		mydebug("ftruncate(SHRINK) failed\n");
    return r;
	}

	mfd_assert_size(fd, len);

	fd2 = mfd_assert_open(fd,
			      O_RDWR | O_CREAT | O_TRUNC,
			      S_IRUSR | S_IWUSR);
	if (fd2 < 0) {
		mydebug("basic_shm_shrink failed\n");
    return fd2;
	}
  
  return fd2;
}

int basic_shm_grow(int fd, ssize_t len)
{
	int r;

	r = ftruncate(fd, len);
	if (r < 0) {
		mydebug("ftruncate(GROW) failed: %m\n");
		return r;
	}

	mfd_assert_size(fd, len);

  return r;
}