D-SP-Ch5aa-stat_fstat_lstat

Stats

Headers

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

Function Prototype

int stat(const char *pathname, struct stat *buf);
int fstat(int filedes, struct stat *buf)
int lstat(const char *pathname, struct stat *buf)

Function

These three functions all return a structure which contains the metadata of files stored in i-node table

Detail

stat

Takes file path and fill the metadata in buffer

fstat

Takes file descriptor and fill the metadata in buffer

lstat

Similar to stat(). However, when encountering a symlink, stat() will trace back to the original file and display metadata of the original file. lstat(), on the other hand, will return metadata of the link

This system call is used to implement ls -l

struct stat

struct stat {
    mode_t    st_mode;    /* file type & mode (permissions) */
    ino_t     st_ino;     /* i-node number (serial number) */
    dev_t     st_dev;     /* device number (file system) */
    dev_t     st_rdev;    /* device number for special files */
    nlink_t   st_nlink;   /* number of links */
    uid_t     st_uid;     /* user ID of owner */
    gid_t     st_gid;     /* group ID of owner */
    off_t     st_size;    /* size in bytes, for regular files */
    time_t    st_atime;   /* time of last access */
    time_t    st_mtime;   /* time of last modification */
    time_t    st_ctime;   /* time of last file status change */
    blksize_t st_blksize; /* best I/O block size */
	blkcnt_t  st_blocks; /* number of disk blocks allocated (typically 512-byte units) */
};