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package filter
import (
"bytes"
"code.laria.me/petrific/objects"
"code.laria.me/petrific/storage"
"errors"
"os/exec"
)
type Filter interface {
Transform([]byte) ([]byte, error)
}
type PipeFilter []string
var emptyCommand = errors.New("Need at least one argument for pipeFilter")
func (pf PipeFilter) Transform(b []byte) ([]byte, error) {
if len(pf) == 0 {
return []byte{}, emptyCommand
}
cmd := exec.Command(pf[0], pf[1:]...)
buf := new(bytes.Buffer)
cmd.Stdout = buf
cmd.Stdin = bytes.NewReader(b)
if err := cmd.Run(); err != nil {
return []byte{}, err
}
return buf.Bytes(), nil
}
// FilterSorage is a storage implementation wrapping around another storage, sending each raw object through an extrenal
// binary for custom de/encoding (think encryption, compression, ...).
//
// It is used in a configuration by using the method "filter". It needs the config key "base" referencing the name of
// another configured storage. Also needed are the string lists "decode" and "encode", describing which binary to call
// with which parameters.
//
// For example, here is a configuration for a filter storage wrapping a storage "foo",
// encrypting the content with gpg for the key "foobar"
//
// [storage.foo_encrypted]
// method="filter"
// base="foo"
// encode=["gpg", "--encrypt", "--recipient", "foobar"]
// decode=["gpg", "--decrypt"]
type FilterStorage struct {
Base storage.Storage
Decode, Encode Filter
}
func (filt FilterStorage) Get(id objects.ObjectId) ([]byte, error) {
data, err := filt.Base.Get(id)
if err != nil {
return data, err
}
if filt.Decode == nil {
return data, nil
}
return filt.Decode.Transform(data)
}
func (filt FilterStorage) Has(id objects.ObjectId) (bool, error) {
return filt.Base.Has(id)
}
func (filt FilterStorage) Set(id objects.ObjectId, typ objects.ObjectType, raw []byte) error {
if filt.Encode != nil {
var err error
raw, err = filt.Encode.Transform(raw)
if err != nil {
return err
}
}
return filt.Base.Set(id, typ, raw)
}
func (filt FilterStorage) List(typ objects.ObjectType) ([]objects.ObjectId, error) {
return filt.Base.List(typ)
}
func (filt FilterStorage) Close() error {
return filt.Base.Close()
}
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