to get offset of structure for assembly code

offset.c

#include <sys/types.h>
#include <sys/stat.h>
#include <stddef.h>
#include <time.h>

// the following are reported by :  man 2 stat
struct the_stat {
    dev_t     st_dev;         /* ID of device containing file */
    ino_t     st_ino;         /* inode number */
    mode_t    st_mode;        /* protection */
    nlink_t   st_nlink;       /* number of hard links */
    uid_t     st_uid;         /* user ID of owner */
    gid_t     st_gid;         /* group ID of owner */
    dev_t     st_rdev;        /* device ID (if special file) */
    off_t     st_size;        /* total size, in bytes */
    blksize_t st_blksize;     /* blocksize for filesystem I/O */
    blkcnt_t  st_blocks;      /* number of 512B blocks allocated */

    /* Since Linux 2.6, the kernel supports nanosecond
       precision for the following timestamp fields.
       For the details before Linux 2.6, see NOTES. */

    struct timespec st_atim;  /* time of last access */
    struct timespec st_mtim;  /* time of last modification */
    struct timespec st_ctim;  /* time of last status change */

#define st_atime st_atim.tv_sec      /* Backward compatibility */
#define st_mtime st_mtim.tv_sec
#define st_ctime st_ctim.tv_sec
};



int
main(int argc, char *argv[])
{
  printf("\n");
  printf("\n(%d) (%u)     dev_t     st_dev;             ", sizeof(dev_t), offsetof(struct stat, st_dev));
  printf("\n(%d) (%u)     ino_t     st_ino;             ", sizeof(ino_t), offsetof(struct stat, st_ino));
  printf("\n(%d) (%u)     mode_t    st_mode;            ", sizeof(mode_t), offsetof(struct stat, st_mode));
  printf("\n(%d) (%u)     nlink_t   st_nlink;           ", sizeof(nlink_t), offsetof(struct stat, st_nlink));
  printf("\n(%d) (%u)     uid_t     st_uid;             ", sizeof(uid_t), offsetof(struct stat, st_uid));
  printf("\n(%d) (%u)     gid_t     st_gid;             ", sizeof(gid_t), offsetof(struct stat, st_gid));
  printf("\n(%d) (%u)     dev_t     st_rdev;            ", sizeof(dev_t), offsetof(struct stat, st_rdev));
  printf("\n(%d) (%u)     off_t     st_size;            ", sizeof(off_t), offsetof(struct stat, st_size));
  printf("\n(%d) (%u)     blksize_t st_blksize;         ", sizeof(blksize_t), offsetof(struct stat, st_blksize));
  printf("\n(%d) (%u)     blkcnt_t  st_blocks;          ", sizeof(blkcnt_t), offsetof(struct stat, st_blocks));
  printf("\n");                                       
  printf("\n(%d) (%u)     __time_t tv_sec;              ", sizeof(__time_t), offsetof(struct timespec, tv_sec));
  printf("\n(%d) (%u)     __syscall_slong_t tv_nsec;    ", sizeof(__syscall_slong_t), offsetof(struct timespec, tv_nsec));
  printf("\n");
}

// the following is example result :

/*
(8) (0)     dev_t     st_dev;             
(8) (8)     ino_t     st_ino;             
(4) (24)     mode_t    st_mode;            
(8) (16)     nlink_t   st_nlink;           
(4) (28)     uid_t     st_uid;             
(4) (32)     gid_t     st_gid;             
(8) (40)     dev_t     st_rdev;            
(8) (48)     off_t     st_size;            
(8) (56)     blksize_t st_blksize;         
(8) (64)     blkcnt_t  st_blocks;          

(8) (0)     __time_t tv_sec;              
(8) (8)     __syscall_slong_t tv_nsec;
*/

@xieyuheng maybe you need __attribute__ ((packed)) for you structure fields for avoiding padding.
https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-g_t_0040code_007bpacked_007d-variable-attribute-3331