GETPWENT(3) OpenBSD Programmer's Manual GETPWENT(3)
NAME
getpwent, getpwnam, getpwuid, getpwnam_r, getpwuid_r, setpassent,
setpwent, endpwent - password database operations
SYNOPSIS
#include <sys/types.h>
#include <pwd.h>
struct passwd *
getpwent(void);
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 buflen, struct passwd **result);
int
getpwuid_r(uid_t uid, struct passwd *pwstore, char *buf, size_t buflen,
struct passwd **result);
int
setpassent(int stayopen);
void
setpwent(void);
void
endpwent(void);
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 re-entrant functions getpwnam_r() and getpwuid_r() search the pass-
word database for the given login name or user ID, respectively, always
returning the first one encountered. The various strings associated with
the result are stored in buf, and pwstore is updated to point at those
strings.
getpwent() sequentially reads the password database and is intended for
programs that wish to process the complete list of users.
setpassent() accomplishes two purposes. First, it causes getpwent() 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 all of the routines. (This latter functionality
is unnecessary for getpwent() as it doesn't close its file descriptors by
default.)
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open as the database will become out of date if it is updated while the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.
setpwent() is equivalent to setpassent() with an argument of zero.
The endpwent() function closes any open files.
These routines have been written to ``shadow'' the password file, i.e.,
allow only certain programs to have access to the encrypted password. If
the process which calls them has an effective UID of 0 or has the
``_shadow'' group in its group vector, the encrypted password will be re-
turned, otherwise, the password field of the returned structure will
point to the string `*'.
RETURN VALUES
The functions getpwent(), getpwnam(), and getpwuid() return a valid
pointer to a passwd structure on success or a null pointer if end-of-file
is reached or an error occurs.
The functions getpwnam_r() and getpwuid_r() update result to point to
pwstore and then return 0 on success.
The setpassent() function returns 0 on failure or 1 on success. The
endpwent() and setpwent() functions have no return value.
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
SEE ALSO
getlogin(2), getgrent(3), getgrouplist(3), pw_dup(3), passwd(5),
pwd_mkdb(8), vipw(8)
HISTORY
The getpwent(), getpwnam(), getpwuid(), setpwent(), and endpwent() func-
tions appeared in Version 7 AT&T UNIX. The setpassent() function ap-
peared in 4.3BSD-Reno.
The historic function setpwfile(3), which allowed the specification of
alternate password databases, has been deprecated and is no longer avail-
able.
BUGS
The functions getpwent(), getpwnam(), and getpwuid() leave their results
in an internal static object and return a pointer to that object. Subse-
quent calls to any of these functions will modify the same object.
The routines getpwent(), endpwent(), setpassent(), and setpwent() are
fairly useless in a networked environment and should be avoided, if pos-
sible.
OpenBSD 4.4 June 24, 2008 2