GETPWENT(3) | Library Functions Manual | GETPWENT(3) |
getpwent
, getpwent_r
,
getpwnam
, getpwnam_r
,
getpwuid
, getpwuid_r
,
setpassent
, setpwent
,
endpwent
—
#include <pwd.h>
struct passwd *
getpwent
(void);
int
getpwent_r
(struct passwd *pw,
char *buffer, size_t buflen,
struct passwd **result);
struct passwd *
getpwnam
(const
char *name);
int
getpwnam_r
(const char *name,
struct passwd *pw, char *buffer,
size_t buflen, struct passwd
**result);
struct passwd *
getpwuid
(uid_t
uid);
int
getpwuid_r
(uid_t uid,
struct passwd *pw, char *buffer,
size_t buflen, struct passwd
**result);
int
setpassent
(int
stayopen);
void
setpwent
(void);
void
endpwent
(void);
<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 login class */ char *pw_gecos; /* general information */ 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 user name pointed to by name or user id pointed
to by uid respectively, always returning the first one
encountered. Identical user names or user ids may result in undefined
behavior.
The getpwent
() function sequentially reads
the password database and is intended for programs that wish to process the
complete list of users.
The functions getpwnam_r
(),
getpwuid_r
(), and
getpwent_r
() act like their non re-entrant
counterparts, updating the contents of pw and storing
a pointer to that in result, and returning
0
. Storage used by pw is
allocated from buffer, which is
buflen bytes in size. If the requested entry cannot be
found, result will point to
NULL
and 0
will be returned.
If an error occurs, a non-zero error number will be returned and
result will point to NULL
.
Calling getpwent_r
() from multiple threads will
result in each thread reading a disjoint portion of the password
database.
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 functions.
(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.
The setpwent
() function is equivalent to
setpassent
() with an argument of zero.
The endpwent
() function closes any open
files.
These functions 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
‘*
’.
getpwent
(),
getpwnam
(), and getpwuid
(),
return a valid pointer to a passwd structure on success and a
NULL
pointer if the entry was not found or an error
occurred. If an error occurred, the global variable
errno
is set to indicate the nature of the failure.
The setpassent
() function returns 0 on failure,
setting the global variable errno
to indicate the
nature of the failure, and 1 on success. The
endpwent
() and setpwent
()
functions have no return value. The functions
getpwnam_r
(), getpwuid_r
(),
and getpwent_r
() return 0
on
success or entry not found, and non-zero on failure, setting the global
variable errno
to indicate the nature of the failure.
setpwfile
() which allowed the
specification of alternative password databases, has been deprecated and is no
longer available.
getpwent
, getpwent_r
,
getpwnam
, getpwnam_r
,
getpwuid
, getpwuid_r
, and
setpassent
:
EINTR
]EIO
]EMFILE
]ENFILE
]The following error code may be set in errno
for getpwent_r
, getpwnam_r
,
and getpwuid_r
:
ERANGE
]buffer
and
buflen
.Other errno
values may be set depending on
the specific database backends.
getpwnam
() and getpwuid
(),
functions conform to IEEE Std 1003.1-1990
(“POSIX.1”). The getpwnam_r
() and
getpwuid_r
() functions conform to
IEEE Std 1003.1c-1995 (“POSIX.1c”). The
endpwent
(), getpwent
(), and
setpwent
() functions conform to
X/Open Portability Guide Issue 4, Version 2
(“XPG4.2”) and IEEE Std 1003.1-2004
(“POSIX.1”) (XSI extension).
getpwent
, getpwnam
,
getpwuid
, setpwent
, and
endpwent
functions appeared in
Version 7 AT&T UNIX. The
setpassent
function appeared in
4.3BSD-Reno. The functions
getpwnam_r
() and getpwuid_r
()
appeared in NetBSD 3.0.
getpwent
(),
getpwnam
(), and getpwuid
(),
leave their results in an internal static object and return a pointer to that
object. Subsequent calls to any of these functions will modify the same
object.
The functions getpwent
(),
endpwent
(), setpassent
(),
and setpwent
() are fairly useless in a networked
environment and should be avoided, if possible.
getpwent
() makes no attempt to suppress duplicate
information if multiple sources are specified in
nsswitch.conf(5).
February 7, 2018 | NetBSD 9.2 |