getpwnam



GETPWNAM(3)                Library Functions Manual                GETPWNAM(3)


NAME

     getpwnam, getpwuid, getpwnam_r, getpwuid_r, getpwnam_shadow,
     getpwuid_shadow, setpassent - password database operations


SYNOPSIS

     #include <pwd.h>

     struct passwd *
     getpwnam(const char *login);

     struct passwd *
     getpwuid(uid_t uid);

     int
     getpwnam_r(const char *login, struct passwd *pwstore, char *buf,
         size_t bufsize, struct passwd **result);

     int
     getpwuid_r(uid_t uid, struct passwd *pwstore, char *buf, size_t bufsize,
         struct passwd **result);

     struct passwd *
     getpwnam_shadow(const char *login);

     struct passwd *
     getpwuid_shadow(uid_t uid);

     int
     setpassent(int stayopen);


DESCRIPTION

     These functions operate on the password database file which is described
     in passwd(5).  Each entry in the database is defined by the structure
     struct passwd found in the include file <pwd.h>:

           struct passwd {
                   char    *pw_name;       /* user name */
                   char    *pw_passwd;     /* encrypted password */
                   uid_t   pw_uid;         /* user uid */
                   gid_t   pw_gid;         /* user gid */
                   time_t  pw_change;      /* password change time */
                   char    *pw_class;      /* user access class */
                   char    *pw_gecos;      /* Honeywell login info */
                   char    *pw_dir;        /* home directory */
                   char    *pw_shell;      /* default shell */
                   time_t  pw_expire;      /* account expiration */
           };

     The functions getpwnam() and getpwuid() search the password database for
     the given login name or user ID, respectively, always returning the first
     one encountered.

     The getpwnam_r() and getpwuid_r() functions both update the passwd
     structure pointed to by pwstore and store a pointer to that structure at
     the location pointed to by result.  The structure is filled with an entry
     from the password database with a matching name or uid.  Storage
     referenced by the passwd structure will be allocated from the memory
     provided with the buf parameter, which is bufsiz characters in size.  The
     maximum size needed for this buffer can be determined with
     sysconf(_SC_GETPW_R_SIZE_MAX).

     setpassent() accomplishes two purposes.  First, it causes getpwent(3) to
     ``rewind'' to the beginning of the database.  Additionally, if stayopen
     is non-zero, file descriptors are left open, significantly speeding up
     subsequent accesses for the lookup routines.  These file descriptors can
     be closed by a call to endpwent(3).

     It is dangerous for long-running programs to keep the file descriptors
     open as the database will become out of date if it is updated while the
     program is running.  However the file descriptors are automatically
     closed when execve(2) is called.

     These routines have been written to ``shadow'' the password file, that
     is, allow only certain programs to have access to the encrypted password.
     The default functions will not return the true encrypted password, but
     instead only the string `*'.  If the process which calls them has an
     effective UID of 0 or has the ``_shadow'' group in its group vector, and
     wishes to access the encrypted password, it should use the
     getpwnam_shadow() and getpwuid_shadow() functions.

   YP support
     If YP is active, the functions getpwnam() and getpwnam_r() also use the
     master.passwd.byname YP map (if available) or the passwd.byname YP map;
     and the functions getpwuid() and getpwuid_r() also use the
     master.passwd.byuid YP map (if available) or the passwd.byuid YP map.
     This is in addition to the passwd file, and respects the order of both
     normal and YP entries in the passwd file.


RETURN VALUES

     The functions getpwnam() and getpwuid() return a pointer to a passwd
     structure if a match is found or a NULL pointer if no match is found or
     an error occurs.

     The functions getpwnam_r() and getpwuid_r() update result to point to
     pwstore if a match is found or set it to NULL if no match is found or an
     error occurs.  They return 0 on success, even if no match is found, or an
     error number if an error occurs; see ERRORS.

     The setpassent() function returns 0 on failure or 1 on success.


FILES

     /etc/pwd.db         insecure password database file
     /etc/spwd.db        secure password database file
     /etc/master.passwd  current password file
     /etc/passwd         a Version 7 format password file


ERRORS

     The getpwnam_r() and getpwuid_r() functions may fail if:

     [ERANGE]           The storage supplied via buf and bufsize is too small
                        and cannot contain all the strings to be returned in
                        pwstore.

     The getpwnam(), getpwnam_r(), getpwuid(), and getpwuid_r() functions may
     also fail for any of the errors specified for dbopen(3) and its get()
     routine.

     If YP is active, they may also fail due to errors caused by the YP
     subsystem.


SEE ALSO

     getlogin(2), getgrent(3), getgrouplist(3), getpwent(3), pw_dup(3),
     sysconf(3), passwd(5), Makefile.yp(8), pwd_mkdb(8), vipw(8), yp(8)


STANDARDS

     The getpwnam(), getpwnam_r(), getpwuid(), and getpwuid_r() functions are
     compliant with the IEEE Std 1003.1-2008 (``POSIX.1'') specification.

     YP support and the setpassent() function are extensions to that
     specification.


HISTORY

     A predecessor to getpwuid(), getpw(), first appeared in Version 4 AT&T
     UNIX.  The getpwnam() and getpwuid() functions appeared in Version 7 AT&T
     UNIX.  The setpassent() function appeared in 4.3BSD-Reno.


BUGS

     The getpwnam() and getpwuid() functions store their results in an
     internal static buffer and return a pointer to that buffer.  Subsequent
     calls to getpwent(), getpwnam(), or getpwuid() will overwrite the same
     buffer.

OpenBSD 5.9                    November 18, 2015                   OpenBSD 5.9

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