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GETPWENT(3) BSD Library Functions Manual GETPWENT(3)
NAME
endpwent, getpwent, getpwnam, getpwnam_r, getpwuid, getpwuid_r,
setpassent, setpwent -- password database operations
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <pwd.h>
void
endpwent(void);
struct passwd *
getpwent(void);
struct passwd *
getpwnam(const char *login);
int
getpwnam_r(const char *login, struct passwd *pwd, char *buffer,
size_t bufsize, struct passwd **result);
struct passwd *
getpwuid(uid_t uid);
int
getuid_r(uid_t uid, struct passwd *pwd, char *buffer, size_t bufsize,
struct passwd **result);
int
setpassent(int stayopen);
void
setpwent(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 <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() and getpwuid() search the password database for
the given login name or user uid, respectively, always returning the
first one encountered.
All of these routines are thread-safe. The getpwent(), getpwnam(), and
getpwuid() routines return a pointer to a result managed by the system
library in a thread-specific data structure. Every thread has space for
a pointer to a struct passwd and allocates its own storage for the
result. Neither previously returned values in memory nor a previously
returned pointer value should be used by a thread after calling any one
of these three routines. Memory allocated by a thread is automatically
released on subsequent calls by the same thread to any of these three
routines, and when the thread exits.
The functions getpwnam_r() and getpwuid_r() take additional arguments
which supply storage space for the returned result. The pwd parameter is
a pointer to a struct passwd, which must be allocated by the caller. The
buffer parameter is a pointer to a block of memory with a size specified
by bufsize. This buffer is used to hold the values which are pointed to
by values filled in the pwd structure. Zero is returned on success. If
insufficient memory is supplied, these routines return ERANGE.
The getpwent() function sequentially reads the password database and is
intended for programs that wish to process the complete list of users.
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 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 identical to setpassent() with an argument of
zero, save that it does not return a status value.
The endpwent() function closes any open files.
As of Mac OS X 10.3, there are now different per-user behaviours of this
function, based on the AuthenticationAuthority value stored for the
queried user in DirectoryServices.
If the queried user is still a legacy crypt password user or now has an
AuthenticationAuthority value containing ``;basic;'', these routines will
behave in their standard BSD fashion. These functions will ``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 `*'.
By default in Mac OS X 10.3 and later all users will have an Authentica-tionAuthority AuthenticationAuthority
tionAuthority with the value ``;ShadowHash;''. These users will have a
visible password value of ``********''. These functions will have no
access to the encrypted password whatsoever. Setting or changing an user
password must be done entirely through the DirectoryService APIs for this
default user.
There also exists an ``Apple Password Server'' user whose password value
is also ``********'' and with an AuthenticationAuthority that contains
the value ";ApplePasswordServer;" among other data. There is no getpwnam
access to the password for this user either and again set/change password
can be done through the DirectoryService API.
Finally in support of local user caching there is a local cached user
whose password is also ``********'' and has an AuthenticationAuthority
value containing ``;LocalCachedUser;'' among other data. These functions
also provide no access to the password for this user and set/change pass-word password
word functionality is through the DirectoryService API.
RETURN VALUES
The functions getpwent(), getpwnam(), and getpwuid() return a valid
pointer to a passwd structure on success and a null pointer if end-of-file end-offile
file is reached or an error occurs. The setpassent() function returns 0
on failure and 1 on success. 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
LEGACY SYNOPSIS
#include <sys/types.h>
#include <pwd.h>
The include file <sys/types.h> is necessary for the getpwent, getpwnam,
and getpwuid functions.
int
setpwent(void);
The setpwent() function returns 0 on failure and 1 on success.
SEE ALSO
getlogin(2), getgrent(3), yp(8), passwd(5), pwd_mkdb(8), vipw(8)
HISTORY
The getpwent(), getpwnam(), getpwuid(), setpwent(), and endpwent() func-tions functions
tions appeared in Version 7 AT&T UNIX. The setpassent() function
appeared in 4.3BSD-Reno.
COMPATIBILITY
The historic function setpwfile(3), which allowed the specification of
alternate password databases, has been deprecated and is no longer avail-able. available.
able.
BUGS
The functions getpwent(), getpwnam(), and getpwuid() leave their results
in internal thread-specific memory and return a pointer to that object.
Subsequent calls to any of these three routines by the same thread will
release the object and return a new pointer value.
BSD September 20, 1994 BSD
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