[gs-code-review] Impossible to rewrite pdf files with named action "LastPage" , bug 688311)

[Heiko Oberdiek]

Hello,

the description on http://www.ghostscript.com/ or
http://bugs.ghostscript.com/bugwritinghelp.html was not clear
for me, how to attach files or send patches.
  Thus I have attachted a test file test.pdf and a fix
pdf_main.ps.diff for bug report 688311. I hope, this list
is the right place for this.

Walter Schmidt send me a problem with pdf files that use the named
action "LastPage". The following fails:

gs -sDEVICE=pdfwrite -dBATCH -dNOPAUSE -sOutputFile=t.pdf test.pdf

Processing pages 1 through 1.
Page 1
Error: /rangecheck in --pdfmark--
Operand stack:
   --dict:6/6(L)--   --nostringval--   --nostringval--   Rect
--nostringval--   --dict:4/4(L)--   Page   1   LNK
Execution stack:
   %interp_exit   .runexec2   --nostringval--   --nostringval--
--nostringval--   2   %stopped_push   --nostringval--   --nostringval--
--nostringval--   false   1   %stopped_push 
  1   3   %oparray_pop   1   3   %oparray_pop   1   3   %oparray_pop
--nostringval--   --nostringval--   2   1   1   --nostringval--
%for_pos_int_continue   --nostringval--   --nos
tringval--   1   1   0   --nostringval--   %for_pos_int_continue   9   7
%oparray_pop   --nostringval--
Dictionary stack:
   --dict:1118/1686(ro)(G)--   --dict:0/20(G)--   --dict:75/200(L)--
--dict:75/200(L)--   --dict:105/127(ro)(G)--   --dict:247/347(ro)(G)--
--dict:21/24(L)--
Current allocation mode is local
Last OS error: 2
AFPL Ghostscript 8.50: Unrecoverable error, exit code 1

(gs version doesn't matter, HEAD contains the same bug.)

I could identify it as bug in pdf_main.ps:

% <pagedict> mark ... -proc- -
/namedactions 8 dict dup begin
  /FirstPage {
    /Page 1 3 -1 roll
  } def
  /LastPage {
    counttomark 2 add index pdfpagecount /Page exch 3 -1 roll
  } def
  /NextPage {
    counttomark 2 add index pdfpagenumber 1 add /Page exch 3 -1 roll
  } def
  /PrevPage {
    counttomark 2 add index pdfpagenumber 1 sub /Page exch 3 -1 roll
  } def
end readonly def

The "counttomark 2 add indx" get the dict for "pdfpagenumber".
However "pdfpagecount" doesn't use an argument, thus the dict
remains on the stack and will later break the "/LNK pdfmark",
because the pdfmark expects key value pairs and raises an error
messages if a lonely dict comes in between.

The syntax for /pdfpagecount and /pdfpagenumber (pdf_main.ps):
/pdfpagecount           % - pdfpagecount <int>
/pdfpagenumber          % <pagedict> pdfpagenumber <int>

Thus the fix is easy:
*** pdf_main.ps.org     2005-09-22 17:26:10.000000000 +0200
--- pdf_main.ps 2005-09-22 17:26:45.000000000 +0200
***************
*** 912,918 ****
      /Page 1 3 -1 roll
    } def
    /LastPage {
!     counttomark 2 add index pdfpagecount /Page exch 3 -1 roll
    } def
    /NextPage {
      counttomark 2 add index pdfpagenumber 1 add /Page exch 3 -1 roll
--- 912,918 ----
      /Page 1 3 -1 roll
    } def
    /LastPage {
!     /Page pdfpagecount 3 -1 roll
    } def
    /NextPage {
      counttomark 2 add index pdfpagenumber 1 add /Page exch 3 -1 roll

Yours sincerely
  Heiko <oberdiek at uni-freiburg.de>
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*** pdf_main.ps.org	2005-09-22 17:26:10.000000000 +0200
--- pdf_main.ps	2005-09-22 17:26:45.000000000 +0200
***************
*** 912,918 ****
      /Page 1 3 -1 roll
    } def
    /LastPage {
!     counttomark 2 add index pdfpagecount /Page exch 3 -1 roll
    } def
    /NextPage {
      counttomark 2 add index pdfpagenumber 1 add /Page exch 3 -1 roll
--- 912,918 ----
      /Page 1 3 -1 roll
    } def
    /LastPage {
!     /Page pdfpagecount 3 -1 roll
    } def
    /NextPage {
      counttomark 2 add index pdfpagenumber 1 add /Page exch 3 -1 roll