mirror of
https://github.com/gotenberg/gotenberg.git
synced 2026-08-08 00:22:14 +01:00
feat: add embeds metadata
This commit is contained in:
hubert.lenoir
committed by
Julien Neuhart
Julien Neuhart
parent
eff9444294
commit
3187980ead
@@ -3,12 +3,14 @@ package qpdf
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import (
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"bytes"
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"context"
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"encoding/json"
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"errors"
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"fmt"
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"log/slog"
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"os"
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"os/exec"
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"path/filepath"
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"strings"
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"syscall"
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"go.opentelemetry.io/otel/codes"
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@@ -348,6 +350,291 @@ func (engine *QPdf) EmbedFiles(ctx context.Context, logger *slog.Logger, filePat
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return err
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}
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// EmbedFilesMetadata sets metadata on already-embedded files in a PDF using
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// QPDF's JSON manipulation. It sets /AFRelationship on Filespec objects,
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// /Subtype on EmbeddedFile streams, and ensures the Catalog /AF array
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// references the Filespec objects.
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func (engine *QPdf) EmbedFilesMetadata(ctx context.Context, logger *slog.Logger, metadata map[string]map[string]string, inputPath string) error {
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ctx, span := gotenberg.Tracer().Start(ctx, "qpdf.EmbedFilesMetadata",
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trace.WithSpanKind(trace.SpanKindClient),
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trace.WithAttributes(semconv.ServerAddress(engine.binPath)),
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)
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defer span.End()
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if len(metadata) == 0 {
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span.SetStatus(codes.Ok, "")
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return nil
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}
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logger.DebugContext(ctx, fmt.Sprintf("setting embeds metadata on %s with QPDF", inputPath))
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args := append([]string{inputPath}, engine.globalArgs...)
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args = append(args, "--newline-before-endstream", "--json-output")
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output, err := engine.execCaptureOutput(ctx, args...)
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if err != nil {
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err = fmt.Errorf("get PDF JSON with QPDF: %w", err)
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span.RecordError(err)
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span.SetStatus(codes.Error, err.Error())
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return err
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}
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objects, err := parsePdfObjects(output)
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if err != nil {
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span.RecordError(err)
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span.SetStatus(codes.Error, err.Error())
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return err
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}
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catalogRef, catalogValue, filespecRefs, updateObjects := patchFilespecMetadata(logger, objects, metadata)
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if len(filespecRefs) == 0 {
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span.SetStatus(codes.Ok, "")
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return nil
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}
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patchCatalogAF(catalogRef, catalogValue, filespecRefs, updateObjects)
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err = engine.writeAndApplyUpdate(ctx, logger, inputPath, updateObjects)
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if err != nil {
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span.RecordError(err)
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span.SetStatus(codes.Error, err.Error())
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return err
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}
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span.SetStatus(codes.Ok, "")
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return nil
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}
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// execCaptureOutput runs QPDF and returns its stdout. This uses
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// exec.CommandContext directly because gotenberg.Cmd does not support
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// capturing stdout (it only pipes to debug logs).
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func (engine *QPdf) execCaptureOutput(ctx context.Context, args ...string) ([]byte, error) {
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cmd := exec.CommandContext(ctx, engine.binPath, args...) //nolint:gosec
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cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
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return cmd.Output()
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}
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// parsePdfObjects parses QPDF JSON v2 output and returns the objects map.
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func parsePdfObjects(output []byte) (map[string]json.RawMessage, error) {
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var pdfJSON struct {
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Qpdf []json.RawMessage `json:"qpdf"`
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}
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if err := json.Unmarshal(output, &pdfJSON); err != nil {
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return nil, fmt.Errorf("parse PDF JSON: %w", err)
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}
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if len(pdfJSON.Qpdf) < 2 {
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return nil, fmt.Errorf("unexpected QPDF JSON structure: expected at least 2 elements")
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}
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var objects map[string]json.RawMessage
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if err := json.Unmarshal(pdfJSON.Qpdf[1], &objects); err != nil {
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return nil, fmt.Errorf("parse QPDF objects: %w", err)
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}
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return objects, nil
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}
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// patchFilespecMetadata walks QPDF objects to find Filespecs matching the
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// metadata keys. It sets /AFRelationship and /Subtype on matching objects
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// and returns the catalog reference, catalog value, filespec references,
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// and the update objects map.
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func patchFilespecMetadata(logger *slog.Logger, objects map[string]json.RawMessage, metadata map[string]map[string]string) (string, map[string]any, []string, map[string]any) {
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updateObjects := make(map[string]any)
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var catalogRef string
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var catalogValue map[string]any
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var filespecRefs []string
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for ref, raw := range objects {
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var obj map[string]json.RawMessage
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if err := json.Unmarshal(raw, &obj); err != nil {
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continue
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}
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valueRaw, hasValue := obj["value"]
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if !hasValue {
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continue
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}
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var value map[string]any
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if err := json.Unmarshal(valueRaw, &value); err != nil {
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continue
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}
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typeVal, _ := value["/Type"].(string)
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if typeVal == "/Catalog" {
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catalogRef = ref
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catalogValue = value
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}
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if typeVal == "/Filespec" {
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uf, _ := value["/UF"].(string)
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if uf == "" {
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uf, _ = value["/F"].(string)
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}
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cleanUf := stripQpdfStringPrefix(uf)
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meta, exists := metadata[cleanUf]
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if !exists {
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continue
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}
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if rel, ok := meta["relationship"]; ok {
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value["/AFRelationship"] = "/" + rel
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}
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if mimeType, ok := meta["mimeType"]; ok {
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if ef, ok := value["/EF"].(map[string]any); ok {
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efRef, _ := ef["/F"].(string)
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if efRef != "" {
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setStreamSubtype(logger, objects, updateObjects, efRef, mimeType)
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}
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}
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}
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filespecRefs = append(filespecRefs, ref)
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updateObjects[ref] = map[string]any{"value": value}
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}
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}
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return catalogRef, catalogValue, filespecRefs, updateObjects
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}
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// patchCatalogAF ensures the Catalog /AF array references all filespec objects.
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func patchCatalogAF(catalogRef string, catalogValue map[string]any, filespecRefs []string, updateObjects map[string]any) {
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if catalogRef == "" || catalogValue == nil {
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return
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}
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afSet := make(map[string]bool)
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existingAF, _ := catalogValue["/AF"].([]any)
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for _, r := range existingAF {
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if s, ok := r.(string); ok {
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afSet[s] = true
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}
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}
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for _, ref := range filespecRefs {
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// Object references in values use "9 0 R" format,
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// not the "obj:9 0 R" key format.
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valRef := strings.TrimPrefix(ref, "obj:")
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if !afSet[valRef] {
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existingAF = append(existingAF, valRef)
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}
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}
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catalogValue["/AF"] = existingAF
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updateObjects[catalogRef] = map[string]any{"value": catalogValue}
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}
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// writeAndApplyUpdate marshals the update objects as QPDF JSON v2, writes
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// them to a temp file, and applies the update via --update-from-json.
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func (engine *QPdf) writeAndApplyUpdate(ctx context.Context, logger *slog.Logger, inputPath string, updateObjects map[string]any) error {
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updateJSON := map[string]any{
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"qpdf": []any{
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map[string]any{
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"jsonversion": 2,
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"pushedinheritedpageresources": false,
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"calledgetallpages": false,
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"maxobjectid": 0,
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},
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updateObjects,
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},
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}
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jsonBytes, err := json.Marshal(updateJSON)
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if err != nil {
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return fmt.Errorf("marshal update JSON: %w", err)
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}
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tmpFile, err := os.CreateTemp(filepath.Dir(inputPath), "qpdf-embeds-metadata-*.json")
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if err != nil {
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return fmt.Errorf("create temp file for update JSON: %w", err)
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}
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defer os.Remove(tmpFile.Name())
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if _, err := tmpFile.Write(jsonBytes); err != nil {
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tmpFile.Close()
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return fmt.Errorf("write update JSON: %w", err)
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}
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if err := tmpFile.Close(); err != nil {
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return fmt.Errorf("close temp file: %w", err)
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}
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updateArgs := make([]string, 0, 5+len(engine.globalArgs))
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updateArgs = append(updateArgs, inputPath)
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updateArgs = append(updateArgs, engine.globalArgs...)
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updateArgs = append(updateArgs, "--newline-before-endstream")
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updateArgs = append(updateArgs, "--update-from-json="+tmpFile.Name())
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updateArgs = append(updateArgs, "--replace-input")
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cmd, err := gotenberg.CommandContext(ctx, logger, engine.binPath, updateArgs...)
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if err != nil {
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return fmt.Errorf("create command for JSON update: %w", err)
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}
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_, err = cmd.Exec()
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if err != nil {
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return fmt.Errorf("update embeds metadata with QPDF: %w", err)
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}
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return nil
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}
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// setStreamSubtype finds a stream object by reference and sets the /Subtype
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// key in its dict.
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func setStreamSubtype(logger *slog.Logger, objects map[string]json.RawMessage, updateObjects map[string]any, ref, mimeType string) {
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objKey := ref
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if !strings.HasPrefix(objKey, "obj:") {
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objKey = "obj:" + objKey
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}
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raw, ok := objects[objKey]
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if !ok {
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logger.Warn(fmt.Sprintf("set stream subtype on %s: object not found", ref))
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return
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}
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var obj map[string]json.RawMessage
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if err := json.Unmarshal(raw, &obj); err != nil {
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logger.Warn(fmt.Sprintf("set stream subtype on %s: unmarshal object: %s", ref, err))
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return
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}
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streamRaw, ok := obj["stream"]
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if !ok {
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logger.Warn(fmt.Sprintf("set stream subtype on %s: no stream key", ref))
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return
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}
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var stream map[string]any
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if err := json.Unmarshal(streamRaw, &stream); err != nil {
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logger.Warn(fmt.Sprintf("set stream subtype on %s: unmarshal stream: %s", ref, err))
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return
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}
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dict, ok := stream["dict"].(map[string]any)
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if !ok {
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logger.Warn(fmt.Sprintf("set stream subtype on %s: stream dict is not a map", ref))
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return
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}
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// QPDF JSON uses literal name syntax; it handles PDF name
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// encoding internally when writing the binary PDF.
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dict["/Subtype"] = "/" + mimeType
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stream["dict"] = dict
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updateObjects[objKey] = map[string]any{"stream": stream}
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}
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// stripQpdfStringPrefix removes the type prefix that QPDF adds to JSON
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// string values. Known prefixes: "u:" (Unicode), "b:" (binary), "e:" (encoded).
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func stripQpdfStringPrefix(s string) string {
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for _, prefix := range []string{"u:", "b:", "e:"} {
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if strings.HasPrefix(s, prefix) {
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return s[len(prefix):]
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}
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}
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return s
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}
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// Watermark is not available in this implementation.
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func (engine *QPdf) Watermark(ctx context.Context, logger *slog.Logger, inputPath string, stamp gotenberg.Stamp) error {
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_, span := gotenberg.Tracer().Start(ctx, "qpdf.Watermark",
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