luet/vendor/github.com/mudler/go-pluggable/plugin.go
2021-05-13 18:13:44 +02:00

78 lines
2.3 KiB
Go

// Copyright © 2020 Ettore Di Giacinto <mudler@mocaccino.org>
//
// 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 2 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 <http://www.gnu.org/licenses/>.
package pluggable
import (
"bytes"
"encoding/json"
"io/ioutil"
"os"
"os/exec"
"github.com/pkg/errors"
)
// Plugin describes binaries to be hooked on events, with common js input, and common js output
type Plugin struct {
Name string
Executable string
}
// A safe threshold to avoid unpleasant exec buffer fill for argv too big. Seems 128K is the limit on Linux.
const maxMessageSize = 1 << 13
// Run runs the Event on the plugin, and returns an EventResponse
func (p Plugin) Run(e Event) (EventResponse, error) {
r := EventResponse{}
eventToprocess := &e
if len(e.Data) > maxMessageSize {
copy := e.Copy()
copy.Data = ""
f, err := ioutil.TempFile(os.TempDir(), "pluggable")
if err != nil {
return r, errors.Wrap(err, "while creating temporary file")
}
if err := ioutil.WriteFile(f.Name(), []byte(e.Data), os.ModePerm); err != nil {
return r, errors.Wrap(err, "while writing to temporary file")
}
copy.File = f.Name()
eventToprocess = copy
defer os.RemoveAll(f.Name())
}
k, err := eventToprocess.JSON()
if err != nil {
return r, errors.Wrap(err, "while marshalling event")
}
cmd := exec.Command(p.Executable, string(e.Name), k)
cmd.Env = os.Environ()
var b bytes.Buffer
cmd.Stderr = &b
out, err := cmd.Output()
if err != nil {
r.Error = "error while executing plugin: " + err.Error() + string(b.String())
return r, errors.Wrap(err, "while executing plugin: "+string(b.String()))
}
if err := json.Unmarshal(out, &r); err != nil {
r.Error = err.Error()
return r, errors.Wrap(err, "while unmarshalling response")
}
return r, nil
}