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Xref stream progress

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This commit is contained in:
Jeroen Bobbeldijk
2017-09-10 17:26:01 +02:00
parent 1c9a9d60b1
commit d3dbbaa81b
2 changed files with 106 additions and 25 deletions
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5
sign/pdftrailer.go
View File

@@ -6,6 +6,8 @@ import (
)
func (context *SignContext) writeTrailer() error {
if context.PDFReader.XrefInformation.Type == "table" {
trailer_length := context.PDFReader.XrefInformation.IncludingTrailerEndPos - context.PDFReader.XrefInformation.EndPos
// Read the trailer so we can replace the size.
@@ -36,9 +38,10 @@ func (context *SignContext) writeTrailer() error {
if _, err := context.OutputFile.Write([]byte(trailer_string)); err != nil {
return err
}
}
// Write the new xref start position.
if _, err := context.OutputFile.Write([]byte(strconv.FormatInt(context.NewXrefStart, 10) + "\n")); err != nil {
if _, err := context.OutputFile.Write([]byte("\nstartxref\n" + strconv.FormatInt(context.NewXrefStart, 10) + "\n")); err != nil {
return err
}

82
sign/pdfxref.go
View File

@@ -3,16 +3,21 @@ package sign
import (
"errors"
"strconv"
"encoding/hex"
"compress/zlib"
"bytes"
)
func (context *SignContext) writeXref() error {
// @todo: support stream xref.
if context.PDFReader.XrefInformation.Type == "table" {
if err := context.writeXrefTable(); err != nil {
return err
}
} else if context.PDFReader.XrefInformation.Type == "stream" {
if err := context.writeXrefStream(); err != nil {
return err
}
} else {
return errors.New("Unkwn xref type: " + context.PDFReader.XrefInformation.Type)
}
@@ -71,3 +76,76 @@ func (context *SignContext) writeXrefTable() error {
return nil
}
func (context *SignContext) writeXrefStream() error {
// @todo: DO NOT FORGET TO ADD SELF REFERENCE!!!
// @todo: fix format (columns) for stream
// @todo: add PNG-Up support.
var streamBytes bytes.Buffer
w := zlib.NewWriter(&streamBytes)
// Create the new catalog xref line.
visual_signature_object_start_position := strconv.FormatInt(context.Filesize, 10)
visual_signature_xref_line := leftPad(visual_signature_object_start_position, "0", 10-len(visual_signature_object_start_position)) + " 00000 n \n"
// Write the new catalog xref line.
if _, err := w.Write([]byte(visual_signature_xref_line)); err != nil {
return err
}
// Create the new catalog xref line.
catalog_object_start_position := strconv.FormatInt(context.Filesize+context.VisualSignData.Length, 10)
catalog_xref_line := leftPad(catalog_object_start_position, "0", 10-len(catalog_object_start_position)) + " 00000 n \n"
// Write the new catalog xref line.
if _, err := w.Write([]byte(catalog_xref_line)); err != nil {
return err
}
// Create the new signature xref line.
info_object_start_position := strconv.FormatInt(context.Filesize+context.VisualSignData.Length+context.CatalogData.Length, 10)
info_xref_line := leftPad(info_object_start_position, "0", 10-len(info_object_start_position)) + " 00000 n \n"
// Write the new signature xref line.
if _, err := w.Write([]byte(info_xref_line)); err != nil {
return err
}
// Create the new signature xref line.
signature_object_start_position := strconv.FormatInt(context.Filesize+context.VisualSignData.Length+context.CatalogData.Length+context.InfoData.Length, 10)
signature_xref_line := leftPad(signature_object_start_position, "0", 10-len(signature_object_start_position)) + " 00000 n \n"
// Write the new signature xref line.
if _, err := w.Write([]byte(signature_xref_line)); err != nil {
return err
}
w.Close()
new_info := "Info " + strconv.FormatInt(int64(context.InfoData.ObjectId), 10) + " 0 R"
new_root := "Root " + strconv.FormatInt(int64(context.CatalogData.ObjectId), 10) + " 0 R"
id := context.PDFReader.Trailer().Key("ID")
id0 := hex.EncodeToString([]byte(id.Index(0).RawString()))
id1 := hex.EncodeToString([]byte(id.Index(0).RawString()))
new_xref := strconv.Itoa(int(context.SignData.ObjectId + 1)) + " 0 obj\n"
new_xref += "<< /Type /XRef /Length " + strconv.Itoa(len(streamBytes.Bytes())) + " /Filter /FlateDecode /DecodeParms << /Columns 5 /Predictor 12 >> /W [ 1 3 1 ] /Prev " + strconv.FormatInt(context.PDFReader.XrefInformation.StartPos, 10) + " /Size " + strconv.FormatInt(context.PDFReader.XrefInformation.ItemCount+5, 10) + " /Index [ 5 " + strconv.FormatInt(context.PDFReader.XrefInformation.ItemCount, 10) + " ] /" + new_info + " /" + new_root + " /ID [<" + id0 + "><" + id1 + ">] >>\n"
if _, err := context.OutputFile.Write([]byte(new_xref)); err != nil {
return err
}
if _, err := context.OutputFile.Write([]byte("stream\n")); err != nil {
return err
}
if _, err := context.OutputFile.Write(streamBytes.Bytes()); err != nil {
return err
}
if _, err := context.OutputFile.Write([]byte("\nendstream\n")); err != nil {
return err
}
return nil
}