mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 08:46:55 +08:00
65 lines
1.8 KiB
Go
65 lines
1.8 KiB
Go
// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package ofdgo
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import (
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"archive/zip"
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"bytes"
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"errors"
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"fmt"
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"io"
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)
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// DetectFormat 按文件内容识别PDF或OFD，不读取压缩内容或关闭输入
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// 识别结果不代表文档完整有效，仍需通过对应阅读器解析
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// 入参: input 输入源
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// 返回: string 格式标识pdf或ofd, error 读取错误或不支持的格式
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func DetectFormat(input *Input) (string, error) {
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if input == nil || input.Size() <= 0 {
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return "", fmt.Errorf("empty document input")
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}
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size := input.Size()
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var header [1024]byte
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data := header[:min(size, int64(len(header)))]
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n, err := input.ReadAt(data, 0)
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if err != nil && err != io.EOF {
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return "", err
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}
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if n != len(data) {
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return "", io.ErrUnexpectedEOF
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}
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if bytes.HasPrefix(data, []byte("%PDF-")) {
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return "pdf", nil
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}
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archive, err := zip.NewReader(input, size)
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if err == nil {
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reader := &Reader{Zip: archive}
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if err := reader.indexPackage(); err != nil {
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return "", err
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}
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if reader.fileNames["OFD.xml"] || reader.fileNames["Encryptions.xml"] {
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return "ofd", nil
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}
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} else {
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if !errors.Is(err, zip.ErrFormat) {
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return "", err
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}
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if bytes.Contains(data, []byte("%PDF-")) {
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return "pdf", nil
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}
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}
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return "", fmt.Errorf("unsupported input format")
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}
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