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group.go
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group.go
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// Mgmt
// Copyright (C) 2013-2024+ James Shubin and the project contributors
// Written by James Shubin <james@shubin.ca> and the project contributors
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
//
// Additional permission under GNU GPL version 3 section 7
//
// If you modify this program, or any covered work, by linking or combining it
// with embedded mcl code and modules (and that the embedded mcl code and
// modules which link with this program, contain a copy of their source code in
// the authoritative form) containing parts covered by the terms of any other
// license, the licensors of this program grant you additional permission to
// convey the resulting work. Furthermore, the licensors of this program grant
// the original author, James Shubin, additional permission to update this
// additional permission if he deems it necessary to achieve the goals of this
// additional permission.
package resources
import (
"context"
"fmt"
"io"
"os/exec"
"os/user"
"strconv"
"syscall"
"github.com/purpleidea/mgmt/engine"
"github.com/purpleidea/mgmt/engine/traits"
"github.com/purpleidea/mgmt/util/errwrap"
"github.com/purpleidea/mgmt/util/recwatch"
)
func init() {
engine.RegisterResource("group", func() engine.Res { return &GroupRes{} })
}
const groupFile = "/etc/group"
// GroupRes is a user group resource.
type GroupRes struct {
traits.Base // add the base methods without re-implementation
traits.Edgeable
init *engine.Init
// State is `exists` or `absent`.
State string `lang:"state" yaml:"state"`
// GID is the group's gid.
GID *uint32 `lang:"gid" yaml:"gid"`
recWatcher *recwatch.RecWatcher
}
// Default returns some sensible defaults for this resource.
func (obj *GroupRes) Default() engine.Res {
return &GroupRes{}
}
// Validate if the params passed in are valid data.
func (obj *GroupRes) Validate() error {
if obj.State != "exists" && obj.State != "absent" {
return fmt.Errorf("state must be 'exists' or 'absent'")
}
return nil
}
// Init runs some startup code for this resource.
func (obj *GroupRes) Init(init *engine.Init) error {
obj.init = init // save for later
return nil
}
// Cleanup is run by the engine to clean up after the resource is done.
func (obj *GroupRes) Cleanup() error {
return nil
}
// Watch is the primary listener for this resource and it outputs events.
func (obj *GroupRes) Watch(ctx context.Context) error {
var err error
obj.recWatcher, err = recwatch.NewRecWatcher(groupFile, false)
if err != nil {
return err
}
defer obj.recWatcher.Close()
obj.init.Running() // when started, notify engine that we're running
var send = false // send event?
for {
if obj.init.Debug {
obj.init.Logf("Watching: %s", groupFile) // attempting to watch...
}
select {
case event, ok := <-obj.recWatcher.Events():
if !ok { // channel shutdown
return nil
}
if err := event.Error; err != nil {
return errwrap.Wrapf(err, "Unknown %s watcher error", obj)
}
if obj.init.Debug { // don't access event.Body if event.Error isn't nil
obj.init.Logf("Event(%s): %v", event.Body.Name, event.Body.Op)
}
send = true
case <-ctx.Done(): // closed by the engine to signal shutdown
return nil
}
// do all our event sending all together to avoid duplicate msgs
if send {
send = false
obj.init.Event() // notify engine of an event (this can block)
}
}
}
// CheckApply method for Group resource.
func (obj *GroupRes) CheckApply(ctx context.Context, apply bool) (bool, error) {
obj.init.Logf("CheckApply(%t)", apply)
// check if the group exists
exists := true
group, err := user.LookupGroup(obj.Name())
if err != nil {
if _, ok := err.(user.UnknownGroupError); !ok {
return false, errwrap.Wrapf(err, "error looking up group")
}
exists = false
}
// if the group doesn't exist and should be absent, we are done
if obj.State == "absent" && !exists {
return true, nil
}
// if the group exists and no GID is specified, we are done
if obj.State == "exists" && exists && obj.GID == nil {
return true, nil
}
if exists && obj.GID != nil {
// check if GID is taken
lookupGID, err := user.LookupGroupId(strconv.Itoa(int(*obj.GID)))
if err != nil {
if _, ok := err.(user.UnknownGroupIdError); !ok {
return false, errwrap.Wrapf(err, "error looking up GID")
}
}
if lookupGID != nil && lookupGID.Name != obj.Name() {
return false, fmt.Errorf("the requested GID belongs to another group")
}
// get the existing group's GID
existingGID, err := strconv.ParseUint(group.Gid, 10, 32)
if err != nil {
return false, errwrap.Wrapf(err, "error casting existing GID")
}
// check if existing group has the wrong GID
// if it is wrong groupmod will change it to the desired value
if *obj.GID != uint32(existingGID) {
obj.init.Logf("Inconsistent GID: %s", obj.Name())
}
// if the group exists and has the correct GID, we are done
if obj.State == "exists" && *obj.GID == uint32(existingGID) {
return true, nil
}
}
if !apply {
return false, nil
}
var cmdName string
args := []string{obj.Name()}
if obj.State == "exists" {
if exists {
obj.init.Logf("Modifying group: %s", obj.Name())
cmdName = "groupmod"
} else {
obj.init.Logf("Adding group: %s", obj.Name())
cmdName = "groupadd"
}
if obj.GID != nil {
args = append(args, "-g", fmt.Sprintf("%d", *obj.GID))
}
}
if obj.State == "absent" && exists {
obj.init.Logf("Deleting group: %s", obj.Name())
cmdName = "groupdel"
}
cmd := exec.Command(cmdName, args...)
cmd.SysProcAttr = &syscall.SysProcAttr{
Setpgid: true,
Pgid: 0,
}
// open a pipe to get error messages from os/exec
stderr, err := cmd.StderrPipe()
if err != nil {
return false, errwrap.Wrapf(err, "failed to initialize stderr pipe")
}
// start the command
if err := cmd.Start(); err != nil {
return false, errwrap.Wrapf(err, "cmd failed to start")
}
// capture any error messages
slurp, err := io.ReadAll(stderr)
if err != nil {
return false, errwrap.Wrapf(err, "error slurping error message")
}
// wait until cmd exits and return error message if any
if err := cmd.Wait(); err != nil {
return false, errwrap.Wrapf(err, "%s", slurp)
}
return false, nil
}
// Cmp compares two resources and returns an error if they are not equivalent.
func (obj *GroupRes) Cmp(r engine.Res) error {
// we can only compare GroupRes to others of the same resource kind
res, ok := r.(*GroupRes)
if !ok {
return fmt.Errorf("not a %s", obj.Kind())
}
if obj.State != res.State {
return fmt.Errorf("the State differs")
}
if (obj.GID == nil) != (res.GID == nil) {
return fmt.Errorf("the GID differs")
}
if obj.GID != nil && res.GID != nil {
if *obj.GID != *res.GID {
return fmt.Errorf("the GID differs")
}
}
return nil
}
// GroupUID is the UID struct for GroupRes.
type GroupUID struct {
engine.BaseUID
name string
gid *uint32
}
// AutoEdges returns the AutoEdge interface.
func (obj *GroupRes) AutoEdges() (engine.AutoEdge, error) {
return nil, nil
}
// IFF aka if and only if they are equivalent, return true. If not, false.
func (obj *GroupUID) IFF(uid engine.ResUID) bool {
res, ok := uid.(*GroupUID)
if !ok {
return false
}
if obj.gid != nil && res.gid != nil {
if *obj.gid != *res.gid {
return false
}
}
if obj.name != "" && res.name != "" {
if obj.name != res.name {
return false
}
}
return true
}
// UIDs includes all params to make a unique identification of this object. Most
// resources only return one, although some resources can return multiple.
func (obj *GroupRes) UIDs() []engine.ResUID {
x := &GroupUID{
BaseUID: engine.BaseUID{Name: obj.Name(), Kind: obj.Kind()},
name: obj.Name(),
gid: obj.GID,
}
return []engine.ResUID{x}
}
// UnmarshalYAML is the custom unmarshal handler for this struct. It is
// primarily useful for setting the defaults.
func (obj *GroupRes) UnmarshalYAML(unmarshal func(interface{}) error) error {
type rawRes GroupRes // indirection to avoid infinite recursion
def := obj.Default() // get the default
res, ok := def.(*GroupRes) // put in the right format
if !ok {
return fmt.Errorf("could not convert to GroupRes")
}
raw := rawRes(*res) // convert; the defaults go here
if err := unmarshal(&raw); err != nil {
return err
}
*obj = GroupRes(raw) // restore from indirection with type conversion!
return nil
}