GETPWENT(3) | Library Functions Manual | GETPWENT(3) |
getpwent
,
getpwnam
, getpwnam_r
,
getpwuid
, getpwuid_r
,
getpwuuid
, getpwuuid_r
,
setpassent
, setpwent
,
endpwent
— password database
operations
Standard C Library (libc, -lc)
#include
<sys/types.h>
#include <pwd.h>
#include <uuid/uuid.h>
struct passwd *
getpwent
(void);
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);
struct passwd *
getpwuuid
(uuid_t
uuid);
int
getpwuuid_r
(uuid_t
uuid, struct passwd
*pwd, char *buffer,
size_t bufsize,
struct passwd
**result);
int
setpassent
(int
stayopen);
void
setpwent
(void);
void
endpwent
(void);
These functions obtain information from
opendirectoryd(8), including
records in /etc/master.passwd which is described in
master.passwd(5). Each entry in
the database is defined by the structure 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 */ int pw_fields; /* internal: fields filled in */ };
The functions
getpwnam
(),
getpwuid
(),
and
getpwuuid
()
search the password database for the given login name, user uid, or user
uuid respectively, always returning the first one encountered.
Note that the password file
/etc/master.passwd does not contain user UUIDs. The
UUID for a user may be found using
mbr_uid_to_uuid
().
On OS X, these routines are thread-safe and return a pointer to a thread-specific data structure. The contents of this data structure are automatically released by subsequent calls to any of these routines on the same thread, or when the thread exits. These routines are therefore unsuitable for use in libraries or frameworks, from where they may overwrite the per-thread data that the calling application expects to find as a result of its own calls to these routines. Library and framework code should use the alternative reentrant variants detailed below.
The
getpwent
()
function searches all available directory services on its first invocation.
It caches the returned entries in a list and returns user account entries
one at a time.
NOTE
that
getpwent
()
may cause a very lengthy search for user account records by
opendirectoryd
and may result in a large number of
user account records being cached by the calling process. Use of this
function is not advised.
The functions
getpwnam_r
(),
getpwuid_r
(),
and
getpwuuid_r
()
are alternative versions of getpwnam
(),
getpwuid
(), and getpwuuid
()
respectively. They store the results of their search in the caller-provided
pwd structure, which additionally contains pointers to
strings that are stored in the caller-provided buffer
of size bufsize. (The maximum required
bufsize can be obtained by passing the
_SC_GETPW_R_SIZE_MAX constant to the
sysconf(3) call. See example code
below.) When these functions are successful, the pwd
argument will be filled in, and a pointer to that argument will be stored in
the caller-provided result. If an entry is not found
or an error occurs, result will be set to
NULL
.
The
setpassent
()
function causes getpwent
() to ``rewind'' to the
beginning of the list of entries cached by a previous
getpwent
() call. The cache is not cleared. The
stayopen parameter value is unused on OS X.
The
setpwent
()
and
endpwent
()
functions clear the cached results from a previous
getpwent
() call.
These routines have been written to
‘shadow
’ the password of user records
created on Mac OS X 10.3 or later, by returning a structure whose password
field points to the string ‘********
’.
Legacy crypt passwords are still returned for user records created on
earlier versions of Mac OS X whose
opendirectoryd(8) attribute
contains the value ‘;basic;
’.
Note that opendirectoryd(8) allows user records from some sources which may not include all the component fields present in a passwd structure. Only the name, uid, and gid of a user record are required. Default values will be supplied as follows:
pw_passwd = "*" pw_change = 0 pw_class = "" pw_gecos = "" pw_dir = "/var/empty" pw_shell = "/usr/bin/false" pw_expire = 0
The functions getpwent
(),
getpwnam
(), getpwuid
(), and
getpwuuid
() return a valid pointer to a passwd
structure on success or NULL
if the entry 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 getpwnam_r
(),
getpwuid_r
(), and
getpwuuid_r
() return 0 if no error occurred, or an
error number 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 success. The endpwent
() and
setpwent
() functions have no return value.
To print the current user's home directory without depending on per-thread storage:
#include <sys/types.h> #include <unistd.h> #include <stdlib.h> #include <stdio.h> #include <pwd.h> int bufsize; if ((bufsize = sysconf(_SC_GETPW_R_SIZE_MAX)) == -1) abort(); char buffer[bufsize]; struct passwd pwd, *result = NULL; if (getpwuid_r(getuid(), &pwd, buffer, bufsize, &result) != 0 || !result) abort(); printf("%s\n", pwd.pw_dir);
The secure password database file
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
]getlogin(2), getgrent(3), passwd(5), mbr_uid_to_uuid(3,) opendirectoryd(8), yp(8)
The getpwent
(),
getpwnam
(), getpwnam_r
(),
getpwuid
(), getpwuid_r
(),
setpwent
(), and endpwent
()
functions conform to ISO/IEC 9945-1:1996
(“POSIX.1”).
The getpwent
(),
getpwnam
(), getpwuid
(),
setpwent
(), and endpwent
()
functions appeared in Version 7 AT&T
UNIX. The setpassent
() function appeared in
4.3BSD-Reno. The
getpwnam_r
() and
getpwuid_r
() functions appeared in
FreeBSD 5.1. The functions
getpwuuid
() and
getpwuuid_r
() appeared in Mac OS X 10.8.
The functions getpwent
(),
getpwnam
(), getpwuid
(), and
getpwuuid
(), leave their results in an internal
thread-specific memory and return a pointer to that object. Subsequent calls
to the same function will modify the same object.
October 26, 2011 | macOS 14.6 |