Signature support: break out function for obtaining hash bytes

1 files changed, 30 insertions, 0 deletions

diff --git a/source/pdf/pdf-form.c b/source/pdf/pdf-form.c
index 36d07ee1..88737ce4 100644
--- a/source/pdf/pdf-form.c
+++ b/source/pdf/pdf-form.c
@@ -1295,6 +1295,36 @@ int pdf_signature_widget_byte_range(fz_context *ctx, pdf_document *doc, pdf_widg
 	return n;
 }
 
+fz_stream *pdf_signature_widget_hash_bytes(fz_context *ctx, pdf_document *doc, pdf_widget *widget)
+{
+	fz_range *byte_range = NULL;
+	int byte_range_len;
+	fz_stream *bytes = NULL;
+
+	fz_var(byte_range);
+	fz_try(ctx)
+	{
+		byte_range_len = pdf_signature_widget_byte_range(ctx, doc, widget, NULL);
+		if (byte_range_len)
+		{
+			byte_range = fz_calloc(ctx, byte_range_len, sizeof(*byte_range));
+			pdf_signature_widget_byte_range(ctx, doc, widget, byte_range);
+		}
+
+		bytes = fz_open_null_n(ctx, fz_keep_stream(ctx, doc->file), byte_range, byte_range_len);
+	}
+	fz_always(ctx)
+	{
+		fz_free(ctx, byte_range);
+	}
+	fz_catch(ctx)
+	{
+		fz_rethrow(ctx);
+	}
+
+	return bytes;
+}
+
 int pdf_signature_widget_contents(fz_context *ctx, pdf_document *doc, pdf_widget *widget, char **contents)
 {
 	pdf_annot *annot = (pdf_annot *)widget;