huschi.net

SHADOW(3)                        Library Calls                       SHADOW(3)

NAME
       shadow, getspnam - encrypted password file routines
SYNTAX
       #include <shadow.h>
       struct spwd *getspent();
       struct spwd *getspnam(char*name);
       void setspent();
       void endspent();
       struct spwd *fgetspent(FILE*fp);
       struct spwd *sgetspent(char*cp);
       int putspent(struct spwd*p,FILE*fp);
       int lckpwdf();
       int ulckpwdf();
DESCRIPTION
       shadow manipulates the contents of the shadow password file,
       /etc/shadow. The structure in the #include file is:
           struct spwd {
                 char          *sp_namp; /* user login name */
                 char          *sp_pwdp; /* encrypted password */
                 long int      sp_lstchg; /* last password change */
                 long int      sp_min; /* days until change allowed. */
                 long int      sp_max; /* days before change required */
                 long int      sp_warn; /* days warning for expiration */
                 long int      sp_inact; /* days before account inactive */
                 long int      sp_expire; /* date when account expires */
                 unsigned long int  sp_flag; /* reserved for future use */
           }

       The meanings of each field are:
       o   sp_namp - pointer to null-terminated user name
       o   sp_pwdp - pointer to null-terminated password
       o   sp_lstchg - days since Jan 1, 1970 password was last changed
       o   sp_min - days before which password may not be changed
       o   sp_max - days after which password must be changed
       o   sp_warn - days before password is to expire that user is warned of
           pending password expiration
       o   sp_inact - days after password expires that account is considered
           inactive and disabled
       o   sp_expire - days since Jan 1, 1970 when account will be disabled
       o   sp_flag - reserved for future use
DESCRIPTION
       getspent, getspname, fgetspent, and sgetspent each return a pointer to
       a struct spwd.  getspent returns the next entry from the file, and
       fgetspent returns the next entry from the given stream, which is
       assumed to be a file of the proper format.  sgetspent returns a pointer
       to a struct spwd using the provided string as input.  getspnam searches
       from the current position in the file for an entry matching name.
       setspent and endspent may be used to begin and end, respectively,
       access to the shadow password file.
       The lckpwdf and ulckpwdf routines should be used to insure exclusive
       access to the /etc/shadow file.  lckpwdf attempts to acquire a lock
       using pw_lock for up to 15 seconds. It continues by attempting to
       acquire a second lock using spw_lock for the remainder of the initial
       15 seconds. Should either attempt fail after a total of 15 seconds,
       lckpwdf returns -1. When both locks are acquired 0 is returned.
DIAGNOSTICS
       Routines return NULL if no more entries are available or if an error
       occurs during processing. Routines which have int as the return value
       return 0 for success and -1 for failure.
CAVEATS
       These routines may only be used by the superuser as access to the
       shadow password file is restricted.
FILES
       /etc/shadow
           Secure user account information.
SEE ALSO
       getpwent(3), shadow(5).

shadow-utils 4.6                  08/09/2019                         SHADOW(3)