mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 17:27:08 +08:00
65 lines
1.8 KiB
Go
65 lines
1.8 KiB
Go
// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
package ofdgo
|
|
|
|
import (
|
|
"archive/zip"
|
|
"bytes"
|
|
"errors"
|
|
"fmt"
|
|
"io"
|
|
)
|
|
|
|
// DetectFormat 按文件内容识别PDF或OFD，不读取压缩内容或关闭输入
|
|
// 识别结果不代表文档完整有效，仍需通过对应阅读器解析
|
|
// 入参: source 输入源
|
|
// 返回: string 格式标识pdf或ofd, error 读取错误或不支持的格式
|
|
func DetectFormat(source *Source) (string, error) {
|
|
if source == nil || source.Size() <= 0 {
|
|
return "", fmt.Errorf("empty document source")
|
|
}
|
|
size := source.Size()
|
|
var header [1024]byte
|
|
data := header[:min(size, int64(len(header)))]
|
|
n, err := source.ReadAt(data, 0)
|
|
if err != nil && err != io.EOF {
|
|
return "", err
|
|
}
|
|
if n != len(data) {
|
|
return "", io.ErrUnexpectedEOF
|
|
}
|
|
if bytes.HasPrefix(data, []byte("%PDF-")) {
|
|
return "pdf", nil
|
|
}
|
|
archive, err := zip.NewReader(source, size)
|
|
if err == nil {
|
|
reader := &Reader{Zip: archive}
|
|
if err := reader.indexPackage(); err != nil {
|
|
return "", err
|
|
}
|
|
if reader.fileNames["OFD.xml"] || reader.fileNames["Encryptions.xml"] {
|
|
return "ofd", nil
|
|
}
|
|
} else {
|
|
if !errors.Is(err, zip.ErrFormat) {
|
|
return "", err
|
|
}
|
|
if bytes.Contains(data, []byte("%PDF-")) {
|
|
return "pdf", nil
|
|
}
|
|
}
|
|
return "", fmt.Errorf("unsupported input format")
|
|
}
|