Change QPDFWriter stream_decode_level default to qpdf_dl_generalized

Also, fix disabling of preserve_encryption to be ignore
stream_decode_level, but disable preserve_encryption if compress_streams is
false.

Fixes #1286

ChangeLog

@@ -3,6 +3,11 @@
 	* Add C API function qpdf_oh_free_buffer to release memory allocated
 	by stream data functions.
 
+2024-09-19  M Holger  <m.holger@qpdf.org>
+
+	* Bug fix: QPDFWriter stream DecodeLevel incorrectly defaulted to
+	none instead of generalied. Fixes #1286.
+
 2024-08-25  M Holger  <m.holger@qpdf.org>
 
 	* Add new command-line arguments --remove-metadata and --remove-info

libqpdf/QPDFWriter.cc

@@ -2126,7 +2126,7 @@ QPDFWriter::doWriteSetup()
     if (m->encrypted) {
         // Encryption has been explicitly set
         m->preserve_encryption = false;
-    } else if (m->normalize_content || m->stream_decode_level || m->pclm || m->qdf_mode) {
+    } else if (m->normalize_content || !m->compress_streams || m->pclm || m->qdf_mode) {
         // Encryption makes looking at contents pretty useless.  If the user explicitly encrypted
         // though, we still obey that.
         m->preserve_encryption = false;

libqpdf/qpdf/QPDFWriter_private.hh

@@ -65,7 +65,7 @@ class QPDFWriter::Members
     bool normalize_content{false};
     bool compress_streams{true};
     bool compress_streams_set{false};
-    qpdf_stream_decode_level_e stream_decode_level{qpdf_dl_none};
+    qpdf_stream_decode_level_e stream_decode_level{qpdf_dl_generalized};
     bool stream_decode_level_set{false};
     bool recompress_flate{false};
     bool qdf_mode{false};

qpdf/qtest/encryption.test

@@ -723,7 +723,7 @@ $td->runtest("check file's validity",
 $td->runtest("handle missing/invalid Length",
              {$td->COMMAND => "qpdf --check bad-encryption-length.pdf"},
              {$td->FILE => "bad-encryption-length.out",
-                  $td->EXIT_STATUS => 0},
+                  $td->EXIT_STATUS => 3},
              $td->NORMALIZE_NEWLINES);
 
 cleanup();

qpdf/qtest/inline-images.test

@@ -56,7 +56,7 @@ $td->runtest("externalize damaged image",
                   "qpdf --externalize-inline-images" .
                   " --compress-streams=n --static-id" .
                   " damaged-inline-image.pdf a.pdf"},
-             {$td->STRING => "", $td->EXIT_STATUS => 0},
+             {$td->FILE => "damaged-inline-image.out", $td->EXIT_STATUS => 3},
              $td->NORMALIZE_NEWLINES);
 $td->runtest("check output",
              {$td->FILE => "a.pdf"},

qpdf/qtest/qpdf/bad-encryption-length.out

@@ -14,5 +14,5 @@ modify annotations: allowed
 modify other: allowed
 modify anything: allowed
 File is not linearized
-No syntax or stream encoding errors found; the file may still contain
-errors that qpdf cannot detect
+WARNING: bad-encryption-length.pdf, object 7 0 at offset 531 -> dictionary key /Length: operation for integer attempted on object of type null: returning 0
+qpdf: operation succeeded with warnings

qpdf/qtest/qpdf/damaged-inline-image.out

@@ -0,0 +1,3 @@
+WARNING: damaged-inline-image.pdf, stream object 8 0: error while getting stream data: stream inflate: inflate: data: invalid distance too far back
+WARNING: damaged-inline-image.pdf, stream object 8 0: qpdf will attempt to write the damaged stream unchanged
+qpdf: operation succeeded with warnings; resulting file may have some problems

qpdf/qtest/qpdf/fuzz-16214.out

@@ -6,6 +6,11 @@ WARNING: fuzz-16214.pdf (xref stream, offset 116): Cross-reference stream data h
 WARNING: fuzz-16214.pdf: reported number of objects (6) is not one plus the highest object number (35)
 WARNING: fuzz-16214.pdf (object 14 0, offset 652): expected dictionary key but found non-name object; inserting key /QPDFFake1
 WARNING: fuzz-16214.pdf (object 14 0, offset 734): expected endobj
+WARNING: fuzz-16214.pdf (object 15 0, offset 869): unknown token while reading object; treating as string
+WARNING: fuzz-16214.pdf (object 15 0, offset 745): expected dictionary key but found non-name object; inserting key /QPDFFake1
+WARNING: fuzz-16214.pdf (object 15 0, offset 894): expected endobj
+WARNING: fuzz-16214.pdf, object 15 0 at offset 745: kid 0 (from 0) MediaBox is undefined; setting to letter / ANSI A
+WARNING: fuzz-16214.pdf, object 15 0 at offset 745: /Type key should be /Page but is not; overriding
 WARNING: fuzz-16214.pdf: file is damaged
 WARNING: fuzz-16214.pdf (object 1 0, offset 7189): expected n n obj
 WARNING: fuzz-16214.pdf: Attempting to reconstruct cross-reference table

qpdf/qtest/qpdf/invalid-id-xref.out

@@ -15,4 +15,6 @@ modify annotations: allowed
 modify other: not allowed
 modify anything: not allowed
 File is not linearized
+WARNING: invalid-id-xref.pdf, trailer at offset 910 -> dictionary key /ID: operation for array attempted on object of type null: returning null
+WARNING: invalid-id-xref.pdf, trailer at offset 910 -> dictionary key /ID -> null returned from invalid array access: operation for string attempted on object of type null: returning empty string
 qpdf: operation succeeded with warnings