Allow set*EncryptionParameters before filename iset (fixes #336)

ChangeLog

@@ -1,5 +1,8 @@
 2019-06-22  Jay Berkenbilt  <ejb@ql.org>
 
+	* QPDFWriter: allow calling set*EncryptionParameters before
+	calling setFilename. Fixes #336.
+
 	* It now works to run --completion-bash and --completion-zsh when
 	qpdf is started from an AppImage.
 

libqpdf/QPDFWriter.cc

@@ -26,7 +26,7 @@
 
 QPDFWriter::Members::Members(QPDF& pdf) :
     pdf(pdf),
-    filename(0),
+    filename("unspecified"),
     file(0),
     close_file(false),
     buffer_pipeline(0),

manual/qpdf-manual.xml

@@ -4344,6 +4344,15 @@ print "\n";
           when qpdf is invoked as an AppImage.
          </para>
         </listitem>
+        <listitem>
+         <para>
+          Calling
+          <function>QPDFWriter::set*EncryptionParameters</function> on
+          a <classname>QPDFWriter</classname> object whose output
+          filename has not yet been set no longer produces a
+          segmentation fault.
+         </para>
+        </listitem>
        </itemizedlist>
       </listitem>
       <listitem>

qpdf/qtest/qpdf.test

@@ -3522,6 +3522,19 @@ foreach my $d (@enc_key)
              $td->NORMALIZE_NEWLINES);
 }
 
+# Miscellaneous encryption tests
+$n_tests += 2;
+
+$td->runtest("set encryption before set filename",
+             {$td->COMMAND => "test_driver 63 minimal.pdf"},
+             {$td->STRING => "test 63 done\n", $td->EXIT_STATUS => 0},
+             $td->NORMALIZE_NEWLINES);
+$td->runtest("check file's validity",
+             {$td->COMMAND => "qpdf --check --password=u a.pdf"},
+             {$td->FILE => "encrypt-before-filename.out",
+                  $td->EXIT_STATUS => 0},
+             $td->NORMALIZE_NEWLINES);
+
 show_ntests();
 # ----------
 $td->notify("--- Unicode Passwords ---");

qpdf/qtest/qpdf/encrypt-before-filename.out

@@ -0,0 +1,20 @@
+checking a.pdf
+PDF Version: 1.7 extension level 8
+R = 6
+P = -4
+User password = u
+extract for accessibility: allowed
+extract for any purpose: allowed
+print low resolution: allowed
+print high resolution: allowed
+modify document assembly: allowed
+modify forms: allowed
+modify annotations: allowed
+modify other: allowed
+modify anything: allowed
+stream encryption method: AESv3
+string encryption method: AESv3
+file encryption method: AESv3
+File is not linearized
+No syntax or stream encoding errors found; the file may still contain
+errors that qpdf cannot detect

qpdf/test_driver.cc

@@ -2094,6 +2094,19 @@ void runtest(int n, char const* filename1, char const* arg2)
         assert_compare_numbers(INT_MAX, t.getKey("/Q3").getIntValueAsInt());
         assert_compare_numbers(UINT_MAX, t.getKey("/Q3").getUIntValueAsUInt());
     }
+    else if (n == 63)
+    {
+        QPDFWriter w(pdf);
+        // Exercise setting encryption parameters before setting the
+        // output filename. The previous bug does not happen if static
+        // or deterministic ID is used because the filename is not
+        // used as part of the input data for ID generation in those
+        // cases.
+        w.setR6EncryptionParameters(
+            "u", "o", true, true, true, true, true, true, qpdf_r3p_full, true);
+        w.setOutputFilename("a.pdf");
+        w.write();
+    }
     else
     {
 	throw std::runtime_error(std::string("invalid test ") +