From da3810ce626a1c5dca856a7bac757bf254761f69 Mon Sep 17 00:00:00 2001
From: Ken Sharp <ken.sharp@artifex.com>
Date: Thu, 28 Jun 2018 16:44:41 +0100
Subject: [PATCH] pdfwrite - create GC desscriptors for JPEG Passthrough stream

Bug #699427 " Shrinking PDF is causing SIGSEGV"

Its not absolutely clear that this is the same problem, but I'm
reasonably confident. When passing JPEG data through untouched, we
copied the stream pointer for the uncompressed data into the device
structure (because the image enumerator isn't available at that time)
but if the stream should be relocated after the copy is taken, then the
old stream might not be valid any more.

This commit adds a GC descriptor for the copied stream pointer to the
PDF device structure. For me this solves the problem, but the nature
of these kinds of problems means that *any* change which affects memory
layout will affect the execution, so I'm not 100% certain this is the
problem.
---
 devices/vector/gdevpdf.c  | 2 ++
 devices/vector/gdevpdfx.h | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/devices/vector/gdevpdf.c b/devices/vector/gdevpdf.c
index 5c1079e15..544259fbf 100644
--- a/devices/vector/gdevpdf.c
+++ b/devices/vector/gdevpdf.c
@@ -118,6 +118,7 @@ ENUM_PTRS_WITH(device_pdfwrite_enum_ptrs, gx_device_pdf *pdev)
  ENUM_PTR(39, gx_device_pdf, EmbeddedFiles);
  ENUM_PTR(40, gx_device_pdf, pdf_font_dir);
  ENUM_PTR(41, gx_device_pdf, ExtensionMetadata);
+ ENUM_PTR(42, gx_device_pdf, PassThroughWriter);
 #define e1(i,elt) ENUM_PARAM_STRING_PTR(i + gx_device_pdf_num_ptrs, gx_device_pdf, elt);
 gx_device_pdf_do_param_strings(e1)
 #undef e1
@@ -170,6 +171,7 @@ static RELOC_PTRS_WITH(device_pdfwrite_reloc_ptrs, gx_device_pdf *pdev)
  RELOC_PTR(gx_device_pdf, EmbeddedFiles);
  RELOC_PTR(gx_device_pdf, pdf_font_dir);
  RELOC_PTR(gx_device_pdf, ExtensionMetadata);
+ RELOC_PTR(gx_device_pdf, PassThroughWriter);
 #define r1(i,elt) RELOC_PARAM_STRING_PTR(gx_device_pdf,elt);
         gx_device_pdf_do_param_strings(r1)
 #undef r1
diff --git a/devices/vector/gdevpdfx.h b/devices/vector/gdevpdfx.h
index f06eb16a6..1aa2a9d71 100644
--- a/devices/vector/gdevpdfx.h
+++ b/devices/vector/gdevpdfx.h
@@ -927,7 +927,7 @@ struct gx_device_pdf_s {
  m(39, gx_device_pdf, EmbeddedFiles);
  m(40, gx_device_pdf, pdf_font_dir);
  m(41, gx_device_pdf, Extension_Metadata);*/
-#define gx_device_pdf_num_ptrs 42
+#define gx_device_pdf_num_ptrs 43
 #define gx_device_pdf_do_param_strings(m)\
     m(0, OwnerPassword) m(1, UserPassword) m(2, NoEncrypt)\
     m(3, DocumentUUID) m(4, InstanceUUID)
-- 
2.14.4