69 lines
2.4 KiB
Go
69 lines
2.4 KiB
Go
package sign
|
|
|
|
import (
|
|
"strconv"
|
|
"strings"
|
|
)
|
|
|
|
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.
|
|
if _, err := context.InputFile.Seek(context.PDFReader.XrefInformation.EndPos+1, 0); err != nil {
|
|
return err
|
|
}
|
|
trailer_buf := make([]byte, trailer_length)
|
|
if _, err := context.InputFile.Read(trailer_buf); err != nil {
|
|
return err
|
|
}
|
|
|
|
root_string := "Root " + context.CatalogData.RootString
|
|
new_root := "Root " + strconv.FormatInt(int64(context.CatalogData.ObjectId), 10) + " 0 R"
|
|
|
|
size_string := "Size " + strconv.FormatInt(context.PDFReader.XrefInformation.ItemCount, 10)
|
|
new_size := "Size " + strconv.FormatInt(context.PDFReader.XrefInformation.ItemCount+int64(len(context.newXrefEntries)+1), 10)
|
|
|
|
prev_string := "Prev " + context.PDFReader.Trailer().Key("Prev").String()
|
|
new_prev := "Prev " + strconv.FormatInt(context.PDFReader.XrefInformation.StartPos, 10)
|
|
|
|
trailer_string := string(trailer_buf)
|
|
trailer_string = strings.Replace(trailer_string, root_string, new_root, -1)
|
|
trailer_string = strings.Replace(trailer_string, size_string, new_size, -1)
|
|
if strings.Contains(trailer_string, prev_string) {
|
|
trailer_string = strings.Replace(trailer_string, prev_string, new_prev, -1)
|
|
} else {
|
|
trailer_string = strings.Replace(trailer_string, new_root, new_root+"\n /"+new_prev, -1)
|
|
}
|
|
|
|
// Ensure the same amount of padding (two spaces) for each line, except when the line does not start with a whitespace already.
|
|
lines := strings.Split(trailer_string, "\n")
|
|
for i, line := range lines {
|
|
if strings.HasPrefix(line, " ") {
|
|
lines[i] = " " + strings.TrimSpace(line)
|
|
}
|
|
}
|
|
trailer_string = strings.Join(lines, "\n") + "\n"
|
|
|
|
// Write the new trailer.
|
|
if _, err := context.OutputBuffer.Write([]byte(trailer_string)); err != nil {
|
|
return err
|
|
}
|
|
} else if context.PDFReader.XrefInformation.Type == "stream" {
|
|
if _, err := context.OutputBuffer.Write([]byte("startxref\n")); err != nil {
|
|
return err
|
|
}
|
|
}
|
|
// Write the new xref start position.
|
|
if _, err := context.OutputBuffer.Write([]byte(strconv.FormatInt(context.NewXrefStart, 10) + "\n")); err != nil {
|
|
return err
|
|
}
|
|
|
|
// Write PDF ending.
|
|
if _, err := context.OutputBuffer.Write([]byte("%%EOF\n")); err != nil {
|
|
return err
|
|
}
|
|
|
|
return nil
|
|
}
|