getpwent(3)

NAME

getpwent, getpwent_r, getpwnam, getpwnam_r, getpwuid,

getpwuid_r,
setpassent, setpwent, endpwent - password database opera

tions

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <sys/types.h>
#include <pwd.h>
struct passwd *
getpwent(void);
int
getpwent_r(struct passwd *pwd, char *buffer, size_t bufsize,
        struct passwd **result);
struct passwd *
getpwnam(const char *login);
int
getpwnam_r(const   char  *name,  struct  passwd  *pwd,  char
*buffer,
        size_t bufsize, struct passwd **result);
struct passwd *
getpwuid(uid_t uid);
int
getpwuid_r(uid_t uid,  struct  passwd  *pwd,  char  *buffer,
size_t bufsize,
        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
passwd found in the include file

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 in

fo */
char *pw_dir; /* home directory */
char *pw_shell; /* default shell */
time_t pw_expire; /* account expiration

*/
int pw_fields; /* internal: fields

filled in */

};

The functions getpwnam() and getpwuid() search the password

database for
the given login name or user uid, respectively, always re

turning the
first one encountered.

The getpwent() function sequentially reads the password

database and is
intended for programs that wish to process the complete list

of users.

The functions getpwent_r(), getpwnam_r(), and getpwuid_r()

are threadsafe versions of getpwent(), getpwnam(), and getpwuid(), re

spectively.
The caller must provide storage for the results of the

search in the pwd,
buffer, bufsize, and result arguments. When these functions

are successful, the pwd argument will be filled-in, and a pointer to

that argument
will be stored in result. If an entry is not found or an

error occurs,
result will be set to NULL.

The setpassent() function 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 does not

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 updat

ed while the
program is running.

The setpwent() function is identical to setpassent() with an

argument of
zero.

The endpwent() function closes any open files.

These routines have been written to ``shadow'' the password

file, e.g.
allow only certain programs to have access to the encrypted

password. If
the process which calls them has an effective uid of 0, the

encrypted
password will be returned, 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 NULL if the en

try is not
found or if an error occurs. If an error does occur, errno

will be set.
Note that programs must explicitly set errno to zero before

calling any
of these functions if they need to distinguish between a

non-existent
entry and an error. The functions getpwent_r(),

getpwnam_r(), and
getpwuid_r() return 0 if no error occurred, or an error num

ber to indicate failure. It is not an error if a matching entry is not

found.
(Thus, if result is NULL and the return value is 0, no

matching entry
exists.)

The setpassent() function returns 0 on failure and 1 on suc

cess. The
endpwent() and setpwent() functions have no return value.

FILES

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

COMPATIBILITY

The historic function setpwfile(3), which allowed the speci

fication of
alternate password databases, has been deprecated and is no

longer available.

ERRORS

These routines may fail for any of the errors specified in

open(2),
dbopen(3), socket(2), and connect(2), in addition to the

following:

[ERANGE] The buffer specified by the buffer and

bufsize argu

ments was insufficiently sized to store

the result.
The caller should retry with a larger

buffer.

SEE ALSO

getlogin(2), getgrent(3), nsswitch.conf(5), passwd(5),

pwd_mkdb(8),
vipw(8), yp(8)

STANDARDS

The getpwent(), getpwnam(), getpwnam_r(), getpwuid(),

getpwuid_r(),
setpwent(), and endpwent() functions conform to ISO/IEC

9945-1:1996
(``POSIX.1'').

HISTORY

The getpwent(), getpwnam(), getpwuid(), setpwent(), and

endpwent() functions appeared in Version 7 AT&T UNIX. The setpassent()

function
appeared in 4.3BSD-Reno. The getpwent_r(), getpwnam_r(),

and
getpwuid_r() functions appeared in FreeBSD 5.1.

BUGS

The functions getpwent(), getpwnam(), and getpwuid(), leave

their results
in an internal static object and return a pointer to that

object. Subsequent calls to the same function will modify the same ob

ject.

The functions getpwent(), getpwent_r(), endpwent(),

setpassent(), and
setpwent() are fairly useless in a networked environment and

should be
avoided, if possible. The getpwent() and getpwent_r() func

tions make no
attempt to suppress duplicate information if multiple

sources are specified in nsswitch.conf(5).

BSD April 16, 2003

BSD