Convert stream filtering errors to warnings

Jay Berkenbilt
1 parent 40f00122
Showing 13 changed files with 58 additions and 32 deletions
ChangeLog
include/qpdf/QPDF.hh
libqpdf/QPDF_Stream.cc
libqpdf/qpdf-c.cc
libqpdf/qpdf/QPDF_Stream.hh
qpdf/qpdf.testcov
qpdf/qtest/qpdf.test
qpdf/qtest/qpdf/bad30-recover.out
qpdf/qtest/qpdf/bad30.out
qpdf/qtest/qpdf/bad33-recover.out
qpdf/qtest/qpdf/c-write-errors.out
qpdf/qtest/qpdf/c-write-warnings-and-errors.out → qpdf/qtest/qpdf/c-write-warnings.out
qpdf/test_driver.cc
 2017-07-27  Jay Berkenbilt  <ejb@ql.org>
  
+	* Recover gracefully from streams that aren't filterable because
+	the filter parameters are invalid in the stream dictionary or the
+	dictionary itself is invalid.
+
 	* Significantly improve recoverability from invalid qpdf objects.
 	Most conditions in basic object parsing that used to cause qpdf to
 	exit are now warnings. There are still many more opportunities for
@@ -526,6 +526,7 @@ class QPDF
     class Warner
     {
 	friend class QPDFObjectHandle;
+        friend class QPDF_Stream;
       private:
         static void warn(QPDF* qpdf, QPDFExc const& e)
         {
@@ -235,9 +235,10 @@ QPDF_Stream::filterable(std::vector&lt;std::string&gt;&amp; filters,
     if (! filters_okay)
     {
 	QTC::TC("qpdf", "QPDF_Stream invalid filter");
-	throw QPDFExc(qpdf_e_damaged_pdf, qpdf->getFilename(),
-		      "", this->offset,
-		      "stream filter type is not name or array");
+	warn(QPDFExc(qpdf_e_damaged_pdf, qpdf->getFilename(),
+                     "", this->offset,
+                     "stream filter type is not name or array"));
+        return false;
     }
  
     bool filterable = true;
@@ -300,12 +301,16 @@ QPDF_Stream::filterable(std::vector&lt;std::string&gt;&amp; filters,
     // /Filters was empty has been seen in the wild.
     if ((filters.size() != 0) && (decode_parms.size() != filters.size()))
     {
-        // We should just issue a warning and treat this as not
-        // filterable.
-	throw QPDFExc(qpdf_e_damaged_pdf, qpdf->getFilename(),
-		      "", this->offset,
-		      "stream /DecodeParms length is"
-                      " inconsistent with filters");
+        warn(QPDFExc(qpdf_e_damaged_pdf, qpdf->getFilename(),
+                     "", this->offset,
+                     "stream /DecodeParms length is"
+                     " inconsistent with filters"));
+        filterable = false;
+    }
+
+    if (! filterable)
+    {
+        return false;
     }
  
     for (unsigned int i = 0; i < filters.size(); ++i)
@@ -454,7 +459,9 @@ QPDF_Stream::pipeStreamData(Pipeline* pipeline, bool filter,
             else
             {
                 QTC::TC("qpdf", "QPDF_Stream provider length mismatch");
-                throw std::logic_error(
+                // This would be caused by programmer error on the
+                // part of a library user, not by invalid input data.
+                throw std::runtime_error(
                     "stream data provider for " +
                     QUtil::int_to_string(this->objid) + " " +
                     QUtil::int_to_string(this->generation) +
@@ -542,3 +549,9 @@ QPDF_Stream::replaceDict(QPDFObjectHandle new_dict)
         this->length = 0;
     }
 }
+
+void
+QPDF_Stream::warn(QPDFExc const& e)
+{
+    QPDF::Warner::warn(this->qpdf, e);
+}
@@ -646,6 +646,6 @@ QPDF_ERROR_CODE qpdf_write(qpdf_data qpdf)
 {
     QPDF_ERROR_CODE status = QPDF_SUCCESS;
     status = trap_errors(qpdf, &call_write);
-    QTC::TC("qpdf", "qpdf-c called qpdf_write", status);
+    QTC::TC("qpdf", "qpdf-c called qpdf_write", (status == 0) ? 0 : 1);
     return status;
 }
@@ -52,6 +52,7 @@ class QPDF_Stream: public QPDFObject
         int& predictor, int& columns, bool& early_code_change);
     bool filterable(std::vector<std::string>& filters,
 		    int& predictor, int& columns, bool& early_code_change);
+    void warn(QPDFExc const& e);
  
     QPDF* qpdf;
     int objid;
@@ -139,7 +139,7 @@ qpdf-c called qpdf_set_preserve_encryption 0
 qpdf-c called qpdf_set_r2_encryption_parameters 0
 qpdf-c called qpdf_set_r3_encryption_parameters 0
 qpdf-c called qpdf_set_linearization 0
-qpdf-c called qpdf_write 3
+qpdf-c called qpdf_write 1
 qpdf-c called qpdf_allow_accessibility 0
 qpdf-c called qpdf_allow_extract_all 0
 qpdf-c called qpdf_allow_print_low_res 0
@@ -787,7 +787,7 @@ my @badfiles = (&quot;not a PDF file&quot;, 			# 1
                 "bad dictionary key",                   # 36
 		);
  
-$n_tests += @badfiles + 4;
+$n_tests += @badfiles + 3;
  
 # Test 6 contains errors in the free table consistency, but we no
 # longer have any consistency check for this since it is not important
@@ -796,7 +796,7 @@ $n_tests += @badfiles + 4;
 # non-fatal.
 my %badtest_overrides = (6 => 0, 12 => 0, 13 => 0,
                          14 => 0, 15 => 0, 17 => 0,
-                         28 => 0, 31 => 0, 36 => 0);
+                         28 => 0, 30 => 0, 31 => 0, 36 => 0);
 for (my $i = 1; $i <= scalar(@badfiles); ++$i)
 {
     my $status = $badtest_overrides{$i};
@@ -813,14 +813,9 @@ $td-&gt;runtest(&quot;C API: errors&quot;,
 	     {$td->FILE => "c-read-errors.out",
 	      $td->EXIT_STATUS => 0},
 	     $td->NORMALIZE_NEWLINES);
-$td->runtest("C API: errors writing",
-	     {$td->COMMAND => "qpdf-ctest 2 bad30.pdf '' a.pdf"},
-	     {$td->FILE => "c-write-errors.out",
-	      $td->EXIT_STATUS => 0},
-	     $td->NORMALIZE_NEWLINES);
-$td->runtest("C API: errors and warnings writing",
+$td->runtest("C API: warnings writing",
 	     {$td->COMMAND => "qpdf-ctest 2 bad33.pdf '' a.pdf"},
-	     {$td->FILE => "c-write-warnings-and-errors.out",
+	     {$td->FILE => "c-write-warnings.out",
 	      $td->EXIT_STATUS => 0},
 	     $td->NORMALIZE_NEWLINES);
 $td->runtest("C API: no recovery",
@@ -840,7 +835,7 @@ $n_tests += @badfiles + 8;
 # though in some cases it may.  Acrobat Reader would not be able to
 # recover any of these files any better.
 my %recover_failures = ();
-for (1, 7, 16, 18..21, 24, 29..30, 33, 35)
+for (1, 7, 16, 18..21, 24, 29, 35)
 {
     $recover_failures{$_} = 1;
 }
-error: bad30.pdf (file position 629): stream filter type is not name or array
-  code: 5
-  file: bad30.pdf
-  pos : 629
-  text: stream filter type is not name or array
@@ -13,7 +13,12 @@ warning: bad33.pdf: Attempting to reconstruct cross-reference table
   file: bad33.pdf
   pos : 0
   text: Attempting to reconstruct cross-reference table
-error: bad33.pdf (file position 629): stream filter type is not name or array
+warning: bad33.pdf (file position 629): stream filter type is not name or array
+  code: 5
+  file: bad33.pdf
+  pos : 629
+  text: stream filter type is not name or array
+warning: bad33.pdf (file position 629): stream filter type is not name or array
   code: 5
   file: bad33.pdf
   pos : 629
@@ -567,7 +567,7 @@ void runtest(int n, char const* filename1, char const* arg2)
 	    qstream.getStreamData();
 	    std::cout << "oops -- getStreamData didn't throw" << std::endl;
 	}
-	catch (std::logic_error const& e)
+        catch (std::exception const& e)
 	{
 	    std::cout << "exception: " << e.what() << std::endl;
 	}