Add method to terminate content stream parsing

ChangeLog

@@ -1,3 +1,9 @@
+2013-03-03  Jay Berkenbilt  <ejb@ql.org>
+
+	* Add protected terminateParsing method to
+	QPDFObjectHandle::ParserCallbacks that implementor can call to
+	terminate parsing of a content stream.
+
 2013-02-28  Jay Berkenbilt  <ejb@ql.org>
 
 	* Favor fopen_s and strerror_s on MSVC to avoid CRT security

include/qpdf/QPDFObjectHandle.hh

@@ -83,6 +83,13 @@ class QPDFObjectHandle
         }
         virtual void handleObject(QPDFObjectHandle) = 0;
         virtual void handleEOF() = 0;
+
+      protected:
+        // Implementors may call this method during parsing to
+        // terminate parsing early.  This method throws an exception
+        // that is caught by parseContentStream, so its effect is
+        // immediate.
+        void terminateParsing();
     };
 
 

libqpdf/QPDFObjectHandle.cc

@@ -23,6 +23,16 @@
 #include <stdlib.h>
 #include <ctype.h>
 
+class TerminateParsing
+{
+};
+
+void
+QPDFObjectHandle::ParserCallbacks::terminateParsing()
+{
+    throw TerminateParsing();
+}
+
 QPDFObjectHandle::QPDFObjectHandle() :
     initialized(false),
     objid(0),
@@ -728,7 +738,14 @@ QPDFObjectHandle::parseContentStream(QPDFObjectHandle stream_or_array,
             throw std::logic_error(
                 "QPDFObjectHandle: parseContentStream called on non-stream");
         }
-        parseContentStream_internal(stream, callbacks);
+        try
+        {
+            parseContentStream_internal(stream, callbacks);
+        }
+        catch (TerminateParsing&)
+        {
+            return;
+        }
     }
     callbacks->handleEOF();
 }

qpdf/qtest/qpdf.test

@@ -199,7 +199,7 @@ $td->runtest("remove page we don't have",
 show_ntests();
 # ----------
 $td->notify("--- Miscellaneous Tests ---");
-$n_tests += 61;
+$n_tests += 62;
 
 $td->runtest("qpdf version",
 	     {$td->COMMAND => "qpdf --version"},
@@ -478,6 +478,11 @@ $td->runtest("tokenize content streams",
              {$td->FILE => "tokenize-content-streams.out",
               $td->EXIT_STATUS => 0},
              $td->NORMALIZE_NEWLINES);
+$td->runtest("terminate parsing",
+             {$td->COMMAND => "test_driver 37 terminate-parsing.pdf"},
+             {$td->FILE => "terminate-parsing.out",
+              $td->EXIT_STATUS => 0},
+             $td->NORMALIZE_NEWLINES);
 $td->runtest("content stream errors",
              {$td->COMMAND => "qpdf --check content-stream-errors.pdf"},
              {$td->FILE => "content-stream-errors.out",

qpdf/qtest/qpdf/terminate-parsing.out

@@ -0,0 +1,86 @@
+name: /potato
+test suite: terminating parsing
+real: 0.1
+integer: 0
+integer: 0
+real: 0.1
+integer: 0
+integer: 0
+operator: cm
+operator: q
+integer: 0
+real: 1.1999
+real: -1.1999
+integer: 0
+real: 121.19
+real: 150.009
+operator: cm
+operator: BI
+name: /CS
+name: /G
+name: /W
+integer: 1
+name: /H
+integer: 1
+name: /BPC
+integer: 8
+name: /F
+name: /Fl
+name: /DP
+dictionary: << /Columns 1 /Predictor 15 >>
+operator: ID
+inline-image: 789c63fc0f0001030101
+operator: EI
+operator: Q
+operator: q
+integer: 0
+real: 35.997
+real: -128.389
+integer: 0
+real: 431.964
+real: 7269.02
+operator: cm
+operator: BI
+name: /CS
+name: /G
+name: /W
+integer: 30
+name: /H
+integer: 107
+name: /BPC
+integer: 8
+name: /F
+name: /Fl
+name: /DP
+dictionary: << /Columns 30 /Predictor 15 >>
+operator: ID
+inline-image: 789cedd1a11100300800b1b2ffd06503148283bc8dfcf8af2a306ee352eff2e06318638c31c63b3801627b620a
+operator: EI
+operator: Q
+operator: q
+integer: 0
+real: 38.3968
+real: -93.5922
+integer: 0
+real: 431.964
+real: 7567.79
+operator: cm
+operator: BI
+name: /CS
+name: /G
+name: /W
+integer: 32
+name: /H
+integer: 78
+name: /BPC
+integer: 8
+name: /F
+name: /Fl
+name: /DP
+dictionary: << /Columns 32 /Predictor 15 >>
+operator: ID
+inline-image: 789c63fccf801f308e2a185530aa60882a20203faa605401890a0643aa1e5530aa6054010d140000bdd03c13
+operator: EI
+operator: Q
+-EOF-
+test 37 done

qpdf/test_driver.cc

@@ -72,6 +72,11 @@ class ParserCallbacks: public QPDFObjectHandle::ParserCallbacks
 void
 ParserCallbacks::handleObject(QPDFObjectHandle obj)
 {
+    if (obj.isName() && (obj.getName() == "/Abort"))
+    {
+        std::cout << "test suite: terminating parsing" << std::endl;
+        terminateParsing();
+    }
     std::cout << obj.getTypeName() << ": ";
     if (obj.isInlineImage())
     {