getpwent(3) BSD Library Functions Manual getpwent(3)
NAME
getpwent, getpwnam, getpwnam_r, getpwuid, getpwuid_r, setpassent,
setpwent, endpwent -- password database operations
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/types.h>
#include <pwd.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);
int
setpassent(int stayopen);
void
setpwent(void);
void
endpwent(void);
DESCRIPTION
These functions obtain information from DirectoryService(8), including
records in /etc/passwd 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.
On Mac 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.
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() and getpwuid_r() are thread-safe versions of
getpwnam() and getpwuid(), respectively. 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 updated 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 of user records
created on Mac OS X 10.3 or later, by returning a structure whose pass-
word field points to the string `********'. Legacy crypt passwords are
still returned for user records created on earlier versions of Mac OS X
whose DirectoryService(8) attribute contains the value `;basic;'.
RETURN VALUES
The functions getpwent(), getpwnam(), and getpwuid() 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() and getpwuid_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.
FILES
The secure password database file
/etc/master.passwd The current password file
/etc/passwd A Version 7 format password file
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), passwd(5), DirectoryService(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() func-
tions 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.
BUGS
The functions getpwent(), getpwnam(), and getpwuid(), 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.
BSD April 16, 2003 BSD
Mac OS X 10.6 - Generated Thu Sep 17 20:20:08 CDT 2009