openbsd-src / lib / libutil / pw_init.3

.\"	$OpenBSD: pw_init.3,v 1.16 2025/06/06 22:01:40 schwarze Exp $
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.Dd $Mdocdate: June 6 2025 $
.Dt PW_INIT 3
.Os
.Sh NAME
.Nm pw_init ,
.Nm pw_setdir ,
.Nm pw_file ,
.Nm pw_edit ,
.Nm pw_prompt ,
.Nm pw_copy ,
.Nm pw_scan ,
.Nm pw_error
.Nd utility functions for interactive passwd file updates
.Sh SYNOPSIS
.Lb libutil
.In pwd.h
.In util.h
.Ft void
.Fn pw_init void
.Ft void
.Fn pw_setdir "const char *directory"
.Ft char *
.Fn pw_file "const char *filename"
.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" "const struct passwd *pw" "const struct passwd *opw"
.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_setdir
function sets an alternative directory where the rest of the functions look
for password-related files.
Use this if you are writing utilities that should
be able to handle password files outside of
.Pa /etc .
.Pp
The
.Fn pw_file
function transforms filenames so that they end up in the directory specified
to the latest
.Fn pw_setdir
call.
The rule is that all directories are stripped of the given name and
only the filename is appended to the directory.
.Pp
The
.Fn pw_edit
function runs an editor (named by the environment variable EDITOR, or
.Pa /usr/bin/vi
if EDITOR is not set) on the file
.Fa filename
(or
.Pa /etc/ptmp
if
.Fa filename
is 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 they want 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-\*(Gtpw_name
with the information in
.Fa pw .
If
.Fa opw
is not NULL, opw-\*(Gtpw_name will be used for matching instead.
Additionally, if the existing entry does not match
.Fa opw ,
the operation is aborted.
The use of
.Fa opw
allows the caller to change the user name in an entry as well as
guarantee that the entry being replaced has not changed in the
meantime.
.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 is filled in with the following flags:
.Bl -tag -width _PASSWORD_NOGIDxxx
.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 _PASSWD_NOCHG
The change field of
.Fa bp
is empty.
.It Dv _PASSWD_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_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.passwdXXX" -compact
.It Pa /etc/master.passwd
Current password file.
.It Pa /etc/passwd
Legacy password file.
.It Pa /etc/ptmp
Password lock file.
.It Pa /etc/pwd.db
Insecure password database file.
.It Pa /etc/spwd.db
Secure password database file.
.El
.Sh SEE ALSO
.Xr pw_lock 3 ,
.Xr passwd 5