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file-mime.go
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file-mime.go
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/*
* Copyright (c) 2019-2021. Abstrium SAS <team (at) pydio.com>
* This file is part of Pydio Cells.
*
* Pydio Cells is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Pydio Cells 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with Pydio Cells. If not, see <http://www.gnu.org/licenses/>.
*
* The latest code can be found at <https://pydio.com>.
*/
package nodes
import (
"context"
"io"
"math"
"net/http"
"github.com/h2non/filetype"
"github.com/pydio/cells/v4/common"
"github.com/pydio/cells/v4/common/proto/tree"
"github.com/pydio/cells/v4/common/runtime"
"github.com/pydio/cells/v4/common/service/context/metadata"
)
const (
mimeReadLimit = 8192
mimeDefault = "application/octet-stream"
)
type MimeResult struct {
mime string
err error
}
func (m *MimeResult) GetMime() string {
return m.mime
}
func (m *MimeResult) GetError() error {
return m.err
}
// TeeMimeReader dynamically looks up for mimetype while consuming the io.Reader
type TeeMimeReader struct {
r io.Reader
cb func(result *MimeResult)
waiter chan *MimeResult
limit int
data []byte
loadError error
loaded chan bool
done bool
}
// NewTeeMimeReader creates a TeeMimeReader from an existing reader and calls the callbackRoutine once
// the mimetype is guessed
func NewTeeMimeReader(reader io.Reader, callbackRoutine func(result *MimeResult)) *TeeMimeReader {
mr := &TeeMimeReader{
r: reader,
cb: callbackRoutine,
data: make([]byte, 0, 8192),
loaded: make(chan bool, 1),
limit: mimeReadLimit,
}
go func() {
<-mr.loaded
//fmt.Printf("Stored %d bytes in buffer - Error: %v\n", len(mr.data), mr.loadError)
kind, _ := filetype.Match(mr.data)
mime := kind.MIME.Value
if mime == mimeDefault || mime == "" {
mime = http.DetectContentType(mr.data)
}
if callbackRoutine != nil {
callbackRoutine(&MimeResult{mime: mime, err: mr.loadError})
}
if mr.waiter != nil {
mr.waiter <- &MimeResult{mime: mime, err: mr.loadError}
close(mr.waiter)
}
}()
return mr
}
// SetLimit can override default mimeReadLimit (used mainly for testing)
func (m *TeeMimeReader) SetLimit(size int) {
m.limit = size
}
// Wait returns a blocking chan until a *MimeResult is returned
func (m *TeeMimeReader) Wait() chan *MimeResult {
m.waiter = make(chan *MimeResult, 1)
return m.waiter
}
// Read implements io.Reader interface by calling underlying reader Read.
func (m *TeeMimeReader) Read(p []byte) (n int, err error) {
n, err = m.r.Read(p)
if n > 0 && !m.done {
limit := int(math.Min(float64(n), float64(mimeReadLimit-len(m.data))))
if len(m.data) < mimeReadLimit {
//fmt.Println("Appending data", limit)
m.data = append(m.data, p[:limit]...)
}
if len(m.data) == mimeReadLimit {
m.done = true
close(m.loaded)
}
}
if err != nil && !m.done {
if err != io.EOF {
m.loadError = err
}
//fmt.Println("Close now", n, err)
m.done = true
close(m.loaded)
}
return
}
// WrapReaderForMime wraps a reader in a TeeMimeReader with a preset callback that stores detected mime in Metadata.
func WrapReaderForMime(ctx context.Context, clone *tree.Node, reader io.Reader) io.Reader {
if IsUnitTestEnv {
return reader
}
bgCtx := metadata.NewBackgroundWithMetaCopy(ctx)
bgCtx = runtime.ForkContext(bgCtx, ctx)
return NewTeeMimeReader(reader, func(result *MimeResult) {
mime := mimeDefault
if result.GetError() == nil && result.GetMime() != "" {
mime = result.GetMime()
}
// Store in metadata service
MustCoreMetaSet(bgCtx, clone.Uuid, common.MetaNamespaceMime, mime, clone.HasMetaKey(common.MetaNamespaceDatasourceInternal))
})
}
// IsDefaultMime checks if cType is empty or "application/octet-stream".
func IsDefaultMime(cType string) bool {
return cType != "" && cType != mimeDefault
}