GETPWNAM(3) OpenBSD Programmer's Manual GETPWNAM(3)NAME
getpwnam, getpwuid, getpwnam_r, getpwuid_r, setpassent - password
database operations
SYNOPSIS
#include <sys/types.h>
#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
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);
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 versions, getpwnam_r() and getpwuid_r(), behave similarly
but the various strings associated with the result are stored in buf, and
pwstore is updated to reference those strings.
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open as the database will become out of date if it is updated while the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. Furthermore, programs that run child processes
should be careful to call endpwent(3) to close these descriptors before
calling execve(2) or system(3).
These routines have been written to ``shadow'' the password file, that
is, 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
returned, otherwise, the password field of the returned structure will
point to the string `*'.
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 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.
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 ALSOgetlogin(2), getgrent(3), getgrouplist(3), getpwent(3), pw_dup(3),
passwd(5), Makefile.yp(8), pwd_mkdb(8), vipw(8), yp(8)HISTORY
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 4.9 June 2, 2009 OpenBSD 4.9