GhostPDF + GS - improve error handling

Arising from Bug #705784, if we hadn't built the PDF interpreter we
would get typecheck errors which were somewhat misleading as to the
source of the problem.

This commit tidies up the error handling in the area of .PDFInit so
that we not only detect the problem there but give a warning that it
occurred.

In addition, add a means to detect if the PDF interpreter is built in
before we stat trying to process a PDF file and, if it is not, give
a sensible error message.

Tested with BUILD_PDF 0 and with NEWPDF true and false.

2 files changed, 59 insertions, 16 deletions

diff --git a/Resource/Init/pdf_main.ps b/Resource/Init/pdf_main.ps
index 0399efffb..f5fcdd62f 100644
--- a/Resource/Init/pdf_main.ps
+++ b/Resource/Init/pdf_main.ps
@@ -258,6 +258,9 @@ systemdict /NEWPDF known not {/NEWPDF //true def} if
 %     Uses currentdict as an argument to pdfclose, which closes /PDFfile. Also
 %     executes restore and various cleanup activities.
 %
+% pdfavailable     - pdfavailable <bool>
+%     Determines if there is a PDF interpreter available
+%
 % Also Used by gsview 5
 % =====================
 % pdfopen            <file> pdfopen <dict>
@@ -878,22 +881,27 @@ currentdict /PDFSwitches undef
 /newpdf_runpdf
 {
   runpdfbegin                       % <file> runpdfbegin -
-  PDFInfo /Collection known
+  PDFInfo type /dicttype eq
   {
-    PDFInfo /Collection get
-    pdfclose
-    dup length 1 sub 0 2 3 -1 roll
+    PDFInfo /Collection known
     {
-      1 index exch get (r) file runpdf
-    } for
-    pop
-  }
-  {
-    process_trailer_attrs             % - process_trailer_attrs -
-    runpdfpagerange                   % - runpdfpagerange <int> <int>
-    dopdfpages                        % <int> <int> dopdfpages -
-    runpdfend                         % - runpdfend -
-  } ifelse
+      PDFInfo /Collection get
+      pdfclose
+      dup length 1 sub 0 2 3 -1 roll
+      {
+        1 index exch get (r) file runpdf
+      } for
+      pop
+    }
+    {
+      process_trailer_attrs             % - process_trailer_attrs -
+      runpdfpagerange                   % - runpdfpagerange <int> <int>
+      dopdfpages                        % <int> <int> dopdfpages -
+      runpdfend                         % - runpdfend -
+    } ifelse
+  } {
+    pop pop
+  }ifelse
 } bind def
 
 /newpdf_runpdfbegin
@@ -939,6 +947,7 @@ currentdict /PDFSwitches undef
   {
     {.PDFInit} stopped
     {
+      (   **** Error: Failed to initialise PDF interpreter.\n) newpdf_pdfformaterror
       /PDFFile //null def
       /PDFInfo //null def
     }
@@ -1094,6 +1103,11 @@ currentdict /PDFSwitches undef
   }ifelse
 } bind def
 
+/pdfavailable
+{
+  .PDFAvailable NEWPDF not or
+} bind def
+
 % <int> <int> dopdfpages -
 % First Page and then LastPage
 % If PDFPageList array exists, the parameters are 1 pdfpagecount and are ignored.
@@ -1199,10 +1213,20 @@ currentdict /PDFSwitches undef
             % stack: tempname tempfile
             dup 0 setfileposition
             dup
-              runpdf
+              pdfavailable {
+                runpdf
+              }{
+                closefile
+                (%stderr) (w) file (   **** ERROR: No PDF interpreter available, unable to process PDF files as input.\n)writestring
+              } ifelse
             closefile deletefile
           } {
-              runpdf
+              pdfavailable {
+                runpdf
+              }{
+                closefile
+                (%stderr) (w) file (   **** ERROR: No PDF interpreter available, unable to process PDF files as input.\n)writestring
+              } ifelse
           } ifelse
         } {
           pop pop pop pop cvx .runps % (%!PS) found first
diff --git a/psi/zpdfops.c b/psi/zpdfops.c
index c20921d3f..e55267729 100644
--- a/psi/zpdfops.c
+++ b/psi/zpdfops.c
@@ -1601,6 +1601,11 @@ static int zPDFpageinfo(i_ctx_t *i_ctx_p)
     return_error(gs_error_undefined);
 }
 
+static int zPDFpageinfoExt(i_ctx_t *i_ctx_p)
+{
+    return_error(gs_error_undefined);
+}
+
 static int zPDFmetadata(i_ctx_t *i_ctx_p)
 {
     return_error(gs_error_undefined);
@@ -1627,6 +1632,19 @@ static int zPDFparsePageList(i_ctx_t *i_ctx_p)
 }
 #endif
 
+static int zPDFAvailable(i_ctx_t *i_ctx_p)
+{
+    os_ptr op = osp;
+
+    push(1);
+#if defined(BUILD_PDF) && BUILD_PDF == 1
+    make_bool(op, true);
+#else
+    make_bool(op, false);
+#endif
+    return 0;
+}
+
 /* ------ Initialization procedure ------ */
 
 const op_def zpdfops_op_defs[] =
@@ -1645,6 +1663,7 @@ const op_def zpdfops_op_defs[] =
     {"1.PDFDrawAnnots", zPDFdrawannots},
     {"1.PDFInit", zPDFInit},
     {"1.PDFparsePageList", zPDFparsePageList},
+    {"0.PDFAvailable", zPDFAvailable},
 #ifdef HAVE_LIBIDN
     {"1.saslprep", zsaslprep},
 #endif