add pipeline-based stream data replacement function

git-svn-id: svn+q:///qpdf/trunk@990 71b93d88-0707-0410-a8cf-f5a4172ac649

add pipeline-based stream data replacement function
git-svn-id: svn+q:///qpdf/trunk@990 71b93d88-0707-0410-a8cf-f5a4172ac649
Jay Berkenbilt
1 parent 98765c3b
Showing 9 changed files with 167 additions and 29 deletions
TODO
include/qpdf/QPDFObjectHandle.hh
libqpdf/QPDFObjectHandle.cc
libqpdf/QPDF_Stream.cc
libqpdf/qpdf/QPDF_Stream.hh
qpdf/qpdf.testcov
qpdf/qtest/qpdf.test
qpdf/qtest/qpdf/test8.out
qpdf/test_driver.cc
@@ -12,22 +12,6 @@ Next
    Stefan Heinsen <stefan.heinsen@gmx.de> in August, 2009.  He seems
    to like to send encrypted mail.  (key 01FCC336)
-   It appears that the only thing in the code that actually has to
-   change is the QPDF_Stream object.  When replacing stream data, we
-   have to mutate the stream's dictionary to adjust /Filter,
-   /DecodeParms, and /Length.  We should probably just provide a
-   method to replace the stream data, /Filter, and /DecodeParms all at
-   once.  If new values are provided, then pipeStreamData can use the
-   new values, and we essentially then lose the original values.  The
-   code for replacing stream data would be to use getStreamData to get
-   the old data and then to replace it all before any calls that would
-   cause QPDFWriter to write new stream data.  Will have to go through
-   QPDF_Stream.cc carefully line by line to make sure everything is
-   adjusted properly.
-
-   Don't forget to provide a method that provides a pipeline through
-   which the stream data is to be piped.
-
  * Add helper routines for manipulating page content streams.
    Operations should include ability to convert page contents from a
    stream to an array of streams and to append or prepend to the page
@@ -195,8 +195,42 @@ class QPDFObjectHandle
     // decryption filters have been applied, is as presented.
     QPDF_DLL
     void replaceStreamData(PointerHolder<Buffer> data,
-			   QPDFObjectHandle filter,
-			   QPDFObjectHandle decode_parms);
+			   QPDFObjectHandle const& filter,
+			   QPDFObjectHandle const& decode_parms);
+
+    class StreamDataProvider
+    {
+      public:
+	QPDF_DLL
+	virtual ~StreamDataProvider()
+	{
+	}
+	// See replaceStreamData below for details on how to override
+	// this method.
+	virtual void provideStreamData(int objid, int generation,
+				       Pipeline* pipeline) = 0;
+    };
+    // As above, replace this stream's stream data.  Instead of
+    // directly providing a buffer with the stream data, call the
+    // given provider's provideStreamData method.  The method is to
+    // write the unencrypted, raw stream data to the provided
+    // pipeline.  The stream's /Length key will be set to the length
+    // as provided.  This must match the number of bytes written to
+    // the pipeline.  The provider must write exactly the same data to
+    // the pipeline every time it is called.  The method is invoked
+    // with the object ID and generation number, which are just there
+    // to be available to the handler in case it is useful for
+    // indexing purposes.  This makes it easier to reuse the same
+    // StreamDataProvider object for multiple streams.  Although it is
+    // more complex to use this form of replaceStreamData, it makes it
+    // possible to avoid allocating memory for the stream data.
+    // Example programs are provided that use both forms of
+    // replaceStreamData.
+    QPDF_DLL
+    void replaceStreamData(PointerHolder<StreamDataProvider> provider,
+			   QPDFObjectHandle const& filter,
+			   QPDFObjectHandle const& decode_parms,
+			   size_t length);
     // return 0 for direct objects
     QPDF_DLL
@@ -354,14 +354,25 @@ QPDFObjectHandle::pipeStreamData(Pipeline* p, bool filter,
 void
 QPDFObjectHandle::replaceStreamData(PointerHolder<Buffer> data,
-				    QPDFObjectHandle filter,
-				    QPDFObjectHandle decode_parms)
+				    QPDFObjectHandle const& filter,
+				    QPDFObjectHandle const& decode_parms)
 {
     assertType("Stream", isStream());
     dynamic_cast<QPDF_Stream*>(obj.getPointer())->replaceStreamData(
 	data, filter, decode_parms);
 }
+void
+QPDFObjectHandle::replaceStreamData(PointerHolder<StreamDataProvider> provider,
+				    QPDFObjectHandle const& filter,
+				    QPDFObjectHandle const& decode_parms,
+				    size_t length)
+{
+    assertType("Stream", isStream());
+    dynamic_cast<QPDF_Stream*>(obj.getPointer())->replaceStreamData(
+	provider, filter, decode_parms, length);
+}
+
 int
 QPDFObjectHandle::getObjectID() const
 {
@@ -9,6 +9,7 @@
 #include <qpdf/Pl_ASCII85Decoder.hh>
 #include <qpdf/Pl_ASCIIHexDecoder.hh>
 #include <qpdf/Pl_LZWDecoder.hh>
+#include <qpdf/Pl_Count.hh>
 #include <qpdf/QTC.hh>
 #include <qpdf/QPDF.hh>
@@ -326,6 +327,32 @@ QPDF_Stream::pipeStreamData(Pipeline* pipeline, bool filter,
 	pipeline->write(b.getBuffer(), b.getSize());
 	pipeline->finish();
     }
+    else if (this->stream_provider.getPointer())
+    {
+	QPDFObjectHandle::StreamDataProvider& p =
+	    (*this->stream_provider.getPointer());
+	Pl_Count count("stream provider count", pipeline);
+	p.provideStreamData(this->objid, this->generation, &count);
+	size_t actual_length = count.getCount();
+	size_t desired_length =
+	    this->stream_dict.getKey("/Length").getIntValue();
+	if (actual_length == desired_length)
+	{
+	    QTC::TC("qpdf", "QPDF_Stream pipe use stream provider");
+	}
+	else
+	{
+	    QTC::TC("qpdf", "QPDF_Stream provider length mismatch");
+	    throw std::logic_error(
+		"stream data provider for " +
+		QUtil::int_to_string(this->objid) + " " +
+		QUtil::int_to_string(this->generation) +
+		" provided " +
+		QUtil::int_to_string(actual_length) +
+		" bytes instead of expected " +
+		QUtil::int_to_string(desired_length) + " bytes");
+	}
+    }
     else
     {
 	QTC::TC("qpdf", "QPDF_Stream pipe original stream data");
@@ -339,13 +366,33 @@ QPDF_Stream::pipeStreamData(Pipeline* pipeline, bool filter,
 void
 QPDF_Stream::replaceStreamData(PointerHolder<Buffer> data,
-			       QPDFObjectHandle filter,
-			       QPDFObjectHandle decode_parms)
+			       QPDFObjectHandle const& filter,
+			       QPDFObjectHandle const& decode_parms)
 {
     this->stream_data = data;
+    this->stream_provider = 0;
+    replaceFilterData(filter, decode_parms, data.getPointer()->getSize());
+}
+
+void
+QPDF_Stream::replaceStreamData(
+    PointerHolder<QPDFObjectHandle::StreamDataProvider> provider,
+    QPDFObjectHandle const& filter,
+    QPDFObjectHandle const& decode_parms,
+    size_t length)
+{
+    this->stream_provider = provider;
+    this->stream_data = 0;
+    replaceFilterData(filter, decode_parms, length);
+}
+
+void
+QPDF_Stream::replaceFilterData(QPDFObjectHandle const& filter,
+			       QPDFObjectHandle const& decode_parms,
+			       size_t length)
+{
     this->stream_dict.replaceOrRemoveKey("/Filter", filter);
     this->stream_dict.replaceOrRemoveKey("/DecodeParms", decode_parms);
     this->stream_dict.replaceKey("/Length",
-				 QPDFObjectHandle::newInteger(
-				     data.getPointer()->getSize()));
+				 QPDFObjectHandle::newInteger(length));
 }
@@ -23,10 +23,18 @@ class QPDF_Stream: public QPDFObject
 			bool normalize, bool compress);
     PointerHolder<Buffer> getStreamData();
     void replaceStreamData(PointerHolder<Buffer> data,
-			   QPDFObjectHandle filter,
-			   QPDFObjectHandle decode_parms);
+			   QPDFObjectHandle const& filter,
+			   QPDFObjectHandle const& decode_parms);
+    void replaceStreamData(
+	PointerHolder<QPDFObjectHandle::StreamDataProvider> provider,
+	QPDFObjectHandle const& filter,
+	QPDFObjectHandle const& decode_parms,
+	size_t length);
   private:
+    void replaceFilterData(QPDFObjectHandle const& filter,
+			   QPDFObjectHandle const& decode_parms,
+			   size_t length);
     bool filterable(std::vector<std::string>& filters,
 		    int& predictor, int& columns, bool& early_code_change);
@@ -37,6 +45,7 @@ class QPDF_Stream: public QPDFObject
     off_t offset;
     int length;
     PointerHolder<Buffer> stream_data;
+    PointerHolder<QPDFObjectHandle::StreamDataProvider> stream_provider;
 };
 #endif // __QPDF_STREAM_HH__
@@ -176,3 +176,5 @@ qpdf-c called qpdf_has_error 0
 qpdf-c called qpdf_get_qpdf_version 0
 QPDF_Stream pipe original stream data 0
 QPDF_Stream pipe replaced stream data 0
+QPDF_Stream pipe use stream provider 0
+QPDF_Stream provider length mismatch 0
@@ -107,7 +107,7 @@ $td-&gt;runtest(&quot;check output&quot;,
 $td->runtest("replace stream data compressed",
 	     {$td->COMMAND => "test_driver 8 qstream.pdf"},
-	     {$td->STRING => "test 8 done\n", $td->EXIT_STATUS => 0},
+	     {$td->FILE => "test8.out", $td->EXIT_STATUS => 0},
 	     $td->NORMALIZE_NEWLINES);
 $td->runtest("check output",
 	     {$td->FILE => "a.pdf"},
+exception: stream data provider for 7 0 provided 29 bytes instead of expected 28 bytes
+test 8 done
@@ -23,6 +23,39 @@ void usage()
     exit(2);
 }
+class Provider: public QPDFObjectHandle::StreamDataProvider
+{
+  public:
+    Provider(PointerHolder<Buffer> b) :
+	b(b),
+	bad_length(false)
+    {
+    }
+    virtual ~Provider()
+    {
+    }
+    virtual void provideStreamData(int objid, int generation,
+				   Pipeline* p)
+    {
+	p->write(b.getPointer()->getBuffer(),
+		 b.getPointer()->getSize());
+	if (this->bad_length)
+	{
+	    unsigned char ch = ' ';
+	    p->write(&ch, 1);
+	}
+	p->finish();
+    }
+    void badLength(bool v)
+    {
+	this->bad_length = v;
+    }
+
+  private:
+    PointerHolder<Buffer> b;
+    bool bad_length;
+};
+
 void runtest(int n, char const* filename)
 {
     QPDF pdf;
@@ -341,9 +374,25 @@ void runtest(int n, char const* filename)
 	p2.write((unsigned char*)"new data for stream\n", 20); // no null!
 	p2.finish();
 	PointerHolder<Buffer> b = p1.getBuffer();
+	// This is a bogus way to use StreamDataProvider, but it does
+	// adequately test its functionality.
+	Provider* provider = new Provider(b);
+	PointerHolder<QPDFObjectHandle::StreamDataProvider> p = provider;
 	qstream.replaceStreamData(
-	    b, QPDFObjectHandle::newName("/FlateDecode"),
-	    QPDFObjectHandle::newNull());
+	    p, QPDFObjectHandle::newName("/FlateDecode"),
+	    QPDFObjectHandle::newNull(),
+	    b.getPointer()->getSize());
+	provider->badLength(true);
+	try
+	{
+	    qstream.getStreamData();
+	    std::cout << "oops -- getStreamData didn't throw" << std::endl;
+	}
+	catch (std::logic_error const& e)
+	{
+	    std::cout << "exception: " << e.what() << std::endl;
+	}
+	provider->badLength(false);
 	QPDFWriter w(pdf, "a.pdf");
 	w.setStaticID(true);
 	w.setStreamDataMode(qpdf_s_preserve);