NetBSD/lib/libutil/pw_init.3

.\"	$NetBSD: pw_init.3,v 1.17 2022/12/04 11:16:39 uwe Exp $
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.Dd August 1, 2004
.Dt PW_INIT 3
.Os
.Sh NAME
.Nm pw_init ,
.Nm pw_edit ,
.Nm pw_prompt ,
.Nm pw_copy ,
.Nm pw_copyx ,
.Nm pw_scan ,
.Nm pw_error
.Nd utility functions for interactive passwd file updates
.Sh LIBRARY
.Lb libutil
.Sh SYNOPSIS
.In pwd.h
.In util.h
.Ft void
.Fn pw_init "void"
.Ft void
.Fn pw_edit "int notsetuid" "const char *filename"
.Ft void
.Fn pw_prompt "void"
.Ft void
.Fn pw_copy "int ffd" "int tfd" "struct passwd *pw" "struct passwd *old_pw"
.Ft int
.Fn pw_copyx "int ffd" "int tfd" "struct passwd *pw" "struct passwd *old_pw" \
    "char *errbuf" "size_t errbufsz"
.Ft int
.Fn pw_scan "char *bp" "struct passwd *pw" "int *flags"
.Ft void
.Fn pw_error "const char *name" "int err" "int eval"
.Sh DESCRIPTION
These functions are designed as conveniences for interactive programs
which update the passwd file and do nothing else.
They generally handle errors by printing out a message to the standard error
stream and possibly aborting the process.
.Pp
The
.Fn pw_init
function prepares for a passwd update by unlimiting all resource
constraints, disabling core dumps (thus preventing dumping the
contents of the passwd database into a world-readable file), and
disabling most signals.
.Pp
The
.Fn pw_edit
function runs an editor (named by the environment variable
.Ev EDITOR ,
or
.Pa /usr/bin/vi
if
.Ev EDITOR
is not set) on the file
.Fa filename
(or
.Pa /etc/ptmp
if
.Fa filename
is
.Dv NULL ) .
If
.Fa notsetuid
is nonzero,
.Fn pw_edit
will set the effective user and group ID to the real user and group ID
before running the editor.
.Pp
The
.Fn pw_prompt
function asks the user whether he or she wants to re-edit the password
file; if the answer is no,
.Fn pw_prompt
deletes the lock file and exits the process.
.Pp
The
.Fn pw_copy
function reads a passwd file from
.Fa ffd
and writes it to
.Fa tfd ,
updating the entry corresponding to pw->pw_name with the information
in
.Fa pw .
If
.Fa old_pw
is not
.Dv NULL ,
it checks to make sure the old entry is the same as
the one described in
.Fa old_pw
or the process is aborted.
If an entry is not found to match
.Fa pw ,
a new entry is appended to the passwd file only if the real user
ID is 0.
If an error occurs,
.Fn pw_copy
will display a message on
.Dv stderr
and call
.Fn pw_error .
.Pp
The
.Fn pw_copyx
function performs the same operation as
.Fn pw_copy
with the exception of error handling.
Upon an error,
.Fn pw_copyx
will write an error message into the buffer pointed to by
.Fa errbuf
which has the size
.Fa errbufsz .
.Pp
The
.Fn pw_scan
function accepts in
.Fa bp
a passwd entry as it would be represented in
.Pa /etc/master.passwd
and fills in
.Fa pw
with corresponding values; string fields in
.Fa pw
will be pointers into
.Fa bp .
Some characters in
.Fa bp
will be overwritten with 0s in order to terminate the strings pointed
to by
.Fa pw .
If
.Fa flags
is non-null, it should be cleared and the following options
enabled if required:
.Bl -tag -offset indent -width _PASSWORD_OLDFMT
.It Dv _PASSWORD_NOWARN
Don't print warnings.
.It Dv _PASSWORD_OLDFMT
Parse
.Fa bp
as an old format entry as found in
.Pa /etc/passwd .
.El
.Pp
Upon return it is cleared, and filled in with the following flags:
.Bl -tag -offset indent -width _PASSWORD_NOGID
.It Dv _PASSWORD_NOUID
The uid field of
.Fa bp
is empty.
.It Dv _PASSWORD_NOGID
The gid field of
.Fa bp
is empty.
.It Dv _PASSWORD_NOCHG
The change field of
.Fa bp
is empty.
.It Dv _PASSWORD_NOEXP
The expire field of
.Fa bp
is empty.
.El
.Pp
The
.Fn pw_error
function displays an error message, aborts the current passwd update,
and exits the current process.
If
.Fa err
is non-zero, a warning message beginning with
.Fa name
is printed for the current value of
.Va errno .
The process exits with status
.Fa eval .
.Sh RETURN VALUES
The
.Fn pw_copyx
function returns 1 if the new password entry was successfully written
to the destination file, and 0 otherwise.
.Pp
The
.Fn pw_scan
function prints a warning message and returns 0 if the string in the
.Fa bp
argument is not a valid passwd string.
Otherwise,
.Fn pw_scan
returns 1.
.Sh FILES
.Bl -tag -width /etc/master.passwd -compact
.It Pa /etc/master.passwd
.It Pa /etc/ptmp
.El
.Sh SEE ALSO
.Xr pw_lock 3 ,
.Xr passwd 5