Add definition of utmp structure.

man3/getutent.3

@@ -71,6 +71,50 @@ code is done accessing the file with the other functions.
 reads a line from the current file position in the utmp file.
 It returns a pointer to a structure containing the fields of
 the line.
+This structure has the following form:
+.in +4n
+.nf
+
+struct exit_status {
+    short e_termination;          /* Process termination status */
+    short e_exit;                 /* Process exit status */
+};
+
+struct utmp {
+    short   ut_type;              /* Type of record */
+    pid_t   ut_pid;               /* PID of login process */
+    char    ut_line[UT_LINESIZE]; /* Terminal device name */
+    char    ut_id[4];             /* Terminal name suffix,
+                                     or inittab(5) ID */
+    char    ut_user[UT_NAMESIZE]; /* Username */
+    char    ut_host[UT_HOSTSIZE]; /* Hostname for remote login, or
+                                     kernel version for run-level
+                                     messages */
+    struct exit_status ut_exit;   /* Exit status of a process
+                                     marked as DEAD_PROCESS; not
+				     used by Linux init(8) */
+    /* The ut_session and ut_tv fields must be the same size when
+       compiled 32- and 64-bit.  This allows data files and shared
+       memory to be shared between 32- and 64-bit applications. */
+#if __WORDSIZE == 64 && defined __WORDSIZE_COMPAT32
+    int32_t ut_session;           /* Session ID */
+    struct {
+        int32_t tv_sec;           /* Seconds */
+        int32_t tv_usec;          /* Microseconds */
+    } ut_tv;                      /* Time entry was made */
+#else
+    long    ut_session;           /* Session ID */
+    struct timeval ut_tv;         /* Time entry was made */
+#endif
+
+    int32_t ut_addr_v6[4];        /* Internet address of remote
+                                     host; IPv4 address uses
+                                     just ut_addr_v6[0] */
+    char __unused[20];            /* Reserved for future use */
+};
+.fi
+.in
+
 .PP
 .BR getutid ()
 searches forward from the current file position in the utmp