DragonFly On-Line Manual Pages
GETPWENT(3) DragonFly Library Functions Manual GETPWENT(3)
NAME
getpwent, getpwent_r, 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);
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 <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.
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 thread-
safe versions of getpwent(), 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 success-
ful, 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 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 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 getpwent_r(), getpwnam_r(), and
getpwuid_r() return 0 if no error occurred, or an error number to indi-
cate 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
/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 specification of
alternate password databases, has been deprecated and is no longer avail-
able.
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() func-
tions 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 and DragonFly 2.1.
BUGS
The functions getpwent(), getpwnam(), and getpwuid(), leave their results
in an internal static object and return a pointer to that object. Subse-
quent calls to the same function will modify the same object.
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() functions make no
attempt to suppress duplicate information if multiple sources are speci-
fied in nsswitch.conf(5).
DragonFly 3.5 April 16, 2003 DragonFly 3.5