getpwnam(3) - OpenBSD manual pages (original) (raw)

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 structurestruct 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 functionsgetpwnam() andgetpwuid() search the password database for the given login name or user ID, respectively, always returning the first one encountered.

Thegetpwnam_r() andgetpwuid_r() functions both update the passwd structure pointed to bypwstore 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 matchingname or uid. Storage referenced by the passwd structure will be allocated from the memory provided with thebuf parameter, which is bufsiz characters in size. The maximum size needed for this buffer can be determined withsysconf(_SC_GETPW_R_SIZE_MAX).

setpassent() accomplishes two purposes. First, it causesgetpwent(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 toendpwent(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It is dangerous for long-running programs to keep the file descriptors open as the database will become out of date if it is updated while the program is running.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 thegetpwnam_shadow() andgetpwuid_shadow() functions.

YP support

If YP is active, the functions getpwnam() and getpwnam_r() also use themaster.passwd.byname YP map (if available) or thepasswd.byname YP map; and the functionsgetpwuid() 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(),getpwnam_shadow(),getpwuid(), andgetpwuid_shadow() 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. Subsequent calls to getpwent(),getpwnam(),getpwnam_shadow(),getpwuid() orgetpwuid_shadow() may invalidate the returned pointer or overwrite the contents of the passwd structure it points to.

The functions getpwnam_r() andgetpwuid_r() update result to point to pwstore if a match is found or set it toNULL 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

legacy password file

ERRORS

The getpwnam_r() andgetpwuid_r() functions may fail if:

[ERANGE]

The storage supplied via buf andbufsize 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.

STANDARDS

The getpwnam(),getpwnam_r(), getpwuid(), and getpwuid_r() functions are compliant with theIEEE Std 1003.1-2008 (“POSIX.1”) specification.

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

HISTORY

A predecessor to getpwuid(),getpw(), first appeared inVersion 4 AT&T UNIX. Thegetpwnam() and getpwuid() functions appeared in Version 7 AT&T UNIX, setpassent() in4.3BSD-Reno, andgetpwnam_shadow() andgetpwuid_shadow() in OpenBSD 5.9.