Fix form field validation.

hhrutter · hhrutter · commit ce09a835d525 · 2025-03-08T19:54:00.000+01:00
diff --git a/pkg/pdfcpu/validate/form.go b/pkg/pdfcpu/validate/form.go
@@ -675,10 +675,13 @@ func pageAnnotIndRefForAcroField(xRefTable *model.XRefTable, indRef types.Indire
 
 	var apObjNr int
 	indRef1 := d.IndirectRefEntry("AP")
-	if indRef1 != nil {
-		apObjNr = indRef1.ObjectNumber.Value()
+	if indRef1 == nil && (r.Width() == 0 && r.Height() == 0) {
+		// Probably a signature field.
+		return &indRef, nil
 	}
 
+	apObjNr = indRef1.ObjectNumber.Value()
+
 	for _, m := range xRefTable.PageAnnots {
 		annots, ok := m[model.AnnWidget]
 		if ok {
@@ -690,7 +693,7 @@ func pageAnnotIndRefForAcroField(xRefTable *model.XRefTable, indRef types.Indire
 		}
 	}
 
-	return nil, nil
+	return nil, errors.New("pdfcpu: can't repair form fields")
 }
 
 func validateFormFieldsAgainstPageAnnotations(xRefTable *model.XRefTable) error {
@@ -704,9 +707,6 @@ func validateFormFieldsAgainstPageAnnotations(xRefTable *model.XRefTable) error
 		if err != nil {
 			return err
 		}
-		if indRef == nil {
-			return errors.New("pdfcpu: can't repair form fields")
-		}
 		arr1 = append(arr1, *indRef)
 	}
 

Original file line number	Diff line number	Diff line change
`@@ -675,10 +675,13 @@ func pageAnnotIndRefForAcroField(xRefTable *model.XRefTable, indRef types.Indire`
`675`	`675`
`676`	`676`	`var apObjNr int`
`677`	`677`	`indRef1 := d.IndirectRefEntry("AP")`
`678`		`- if indRef1 != nil {`
`679`		`- apObjNr = indRef1.ObjectNumber.Value()`
	`678`	`+ if indRef1 == nil && (r.Width() == 0 && r.Height() == 0) {`
	`679`	`+ // Probably a signature field.`
	`680`	`+ return &indRef, nil`
`680`	`681`	`}`
`681`	`682`
	`683`	`+ apObjNr = indRef1.ObjectNumber.Value()`
	`684`	`+`
`682`	`685`	`for _, m := range xRefTable.PageAnnots {`
`683`	`686`	`annots, ok := m[model.AnnWidget]`
`684`	`687`	`if ok {`
`@@ -690,7 +693,7 @@ func pageAnnotIndRefForAcroField(xRefTable *model.XRefTable, indRef types.Indire`
`690`	`693`	`}`
`691`	`694`	`}`
`692`	`695`
`693`		`- return nil, nil`
	`696`	`+ return nil, errors.New("pdfcpu: can't repair form fields")`
`694`	`697`	`}`
`695`	`698`
`696`	`699`	`func validateFormFieldsAgainstPageAnnotations(xRefTable *model.XRefTable) error {`
`@@ -704,9 +707,6 @@ func validateFormFieldsAgainstPageAnnotations(xRefTable *model.XRefTable) error`
`704`	`707`	`if err != nil {`
`705`	`708`	`return err`
`706`	`709`	`}`
`707`		`- if indRef == nil {`
`708`		`- return errors.New("pdfcpu: can't repair form fields")`
`709`		`- }`
`710`	`710`	`arr1 = append(arr1, *indRef)`
`711`	`711`	`}`
`712`	`712`