Convert remaining public classes to use Members pattern

Have classes contain only a single private member of type PointerHolder<Members>. This makes it safe to change the structure of the Members class without breaking binary compatibility. Many of the classes already follow this pattern quite successfully. This brings in the rest of the class that are part of the public API.

Convert remaining public classes to use Members pattern
Have classes contain only a single private member of type PointerHolder<Members>. This makes it safe to change the structure of the Members class without breaking binary compatibility. Many of the classes already follow this pattern quite successfully. This brings in the rest of the class that are part of the public API.
Jay Berkenbilt
1 parent 864a546a
Showing 34 changed files with 623 additions and 321 deletions
README-maintainer
TODO
include/qpdf/Buffer.hh
include/qpdf/BufferInputSource.hh
include/qpdf/FileInputSource.hh
include/qpdf/InputSource.hh
include/qpdf/Pipeline.hh
include/qpdf/Pl_Buffer.hh
include/qpdf/Pl_Concatenate.hh
include/qpdf/Pl_Count.hh
include/qpdf/Pl_DCT.hh
include/qpdf/Pl_Discard.hh
include/qpdf/Pl_Flate.hh
include/qpdf/Pl_RunLength.hh
include/qpdf/Pl_StdioFile.hh
include/qpdf/QPDFExc.hh
include/qpdf/QPDFObjGen.hh
include/qpdf/QPDFSystemError.hh
include/qpdf/QPDFXRefEntry.hh
libqpdf/Buffer.cc
@@ -70,6 +70,9 @@ CODING RULES
   it seems also for classes that are intended to be subclassed across
   the shared library boundary.
  
+* Put private member variables in PointerHolder<Members> for all
+  public classes. Remember to use QPDF_DLL on ~Members().
+
 RELEASE PREPARATION
  
 * Each year, update copyright notices. Just do a case-insensitive
 Next ABI
 ========
  
- * Check all classes that don't use the Members pattern and see if
-   they should be converted. Most of the pipeline classes should be
-   converted.
-
-   Buffer.hh
-   BufferInputSource.hh
-   FileInputSource.hh
-   InputSource.hh
-   Pl_Buffer.hh
-   Pl_Concatenate.hh
-   Pl_Count.hh
-   Pl_DCT.hh
-   Pl_Discard.hh
-   Pl_Flate.hh
-   Pl_RunLength.hh
-   Pl_StdioFile.hh
-   QPDFExc.hh
-   QPDFObjGen.hh
-   QPDFSystemError.hh
-   QPDFXRefEntry.hh
-
- * Pl_Buffer's internal structure is not right for what it does. It
-   was modified for greater efficiency, but it was done in a way that
-   preserved binary compatibility, so the implementation is a bit
-   convoluted.
-
  * Check all overloaded methods to see if any can be eliminated by
    using defaulted arguments. See ../misc/find-overloaded-functions.pl
    (not in source repo)
@@ -23,7 +23,8 @@
 #define BUFFER_HH
  
 #include <qpdf/DLL.h>
-#include <cstring>              // for size_t
+#include <qpdf/PointerHolder.hh>
+#include <stddef.h>
  
 class Buffer
 {
@@ -46,8 +47,6 @@ class Buffer
     QPDF_DLL
     Buffer& operator=(Buffer const&);
     QPDF_DLL
-    ~Buffer();
-    QPDF_DLL
     size_t getSize() const;
     QPDF_DLL
     unsigned char const* getBuffer() const;
@@ -55,13 +54,26 @@ class Buffer
     unsigned char* getBuffer();
  
   private:
-    void init(size_t size, unsigned char* buf, bool own_memory);
+    class Members
+    {
+        friend class Buffer;
+
+      public:
+        QPDF_DLL
+        ~Members();
+
+      private:
+        Members(size_t size, unsigned char* buf, bool own_memory);
+        Members(Members const&);
+
+        bool own_memory;
+        size_t size;
+        unsigned char* buf;
+    };
+
     void copy(Buffer const&);
-    void destroy();
  
-    bool own_memory;
-    size_t size;
-    unsigned char* buf;
+    PointerHolder<Members> m;
 };
  
 #endif // BUFFER_HH
@@ -56,10 +56,25 @@ class BufferInputSource: public InputSource
   private:
     qpdf_offset_t const bufSizeAsOffset() const;
  
-    bool own_memory;
-    std::string description;
-    Buffer* buf;
-    qpdf_offset_t cur_offset;
+    class Members
+    {
+        friend class BufferInputSource;
+
+      public:
+        QPDF_DLL
+        ~Members();
+
+      private:
+        Members(bool own_memory, std::string const& description, Buffer* buf);
+        Members(Members const&);
+
+        bool own_memory;
+        std::string description;
+        Buffer* buf;
+        qpdf_offset_t cur_offset;
+    };
+
+    PointerHolder<Members> m;
 };
  
 #endif // QPDF_BUFFERINPUTSOURCE_HH
@@ -54,11 +54,24 @@ class FileInputSource: public InputSource
     FileInputSource(FileInputSource const&);
     FileInputSource& operator=(FileInputSource const&);
  
-    void destroy();
+    class Members
+    {
+        friend class FileInputSource;
  
-    bool close_file;
-    std::string filename;
-    FILE* file;
+      public:
+        QPDF_DLL
+        ~Members();
+
+      private:
+        Members(bool close_file);
+        Members(Members const&);
+
+        bool close_file;
+        std::string filename;
+        FILE* file;
+    };
+
+    PointerHolder<Members> m;
 };
  
 #endif // QPDF_FILEINPUTSOURCE_HH
@@ -24,6 +24,7 @@
  
 #include <qpdf/DLL.h>
 #include <qpdf/Types.h>
+#include <qpdf/PointerHolder.hh>
 #include <stdio.h>
 #include <string>
  
@@ -86,6 +87,22 @@ class QPDF_DLL_CLASS InputSource
  
   protected:
     qpdf_offset_t last_offset;
+
+  private:
+    class Members
+    {
+        friend class InputSource;
+
+      public:
+        QPDF_DLL
+        ~Members();
+
+      private:
+        Members();
+        Members(Members const&);
+    };
+
+    PointerHolder<Members> m;
 };
  
 #endif // QPDF_INPUTSOURCE_HH
@@ -45,6 +45,7 @@
 #define PIPELINE_HH
  
 #include <qpdf/DLL.h>
+#include <qpdf/PointerHolder.hh>
 #include <string>
  
 class QPDF_DLL_CLASS Pipeline
@@ -79,7 +80,22 @@ class QPDF_DLL_CLASS Pipeline
     Pipeline(Pipeline const&);
     Pipeline& operator=(Pipeline const&);
  
-    Pipeline* next;
+    class Members
+    {
+        friend class Pipeline;
+
+      public:
+        QPDF_DLL
+        ~Members();
+
+      private:
+        Members(Pipeline* next);
+        Members(Members const&);
+
+        Pipeline* next;
+    };
+
+    PointerHolder<Members> m;
 };
  
 #endif // PIPELINE_HH
@@ -36,7 +36,6 @@
 #include <qpdf/Pipeline.hh>
 #include <qpdf/PointerHolder.hh>
 #include <qpdf/Buffer.hh>
-#include <list>
  
 class Pl_Buffer: public Pipeline
 {
@@ -57,9 +56,24 @@ class Pl_Buffer: public Pipeline
     Buffer* getBuffer();
  
   private:
-    bool ready;
-    std::list<PointerHolder<Buffer> > data;
-    size_t total_size;
+    class Members
+    {
+        friend class Pl_Buffer;
+
+      public:
+        QPDF_DLL
+        ~Members();
+
+      private:
+        Members();
+        Members(Members const&);
+
+        bool ready;
+        PointerHolder<Buffer> data;
+        size_t total_size;
+    };
+
+    PointerHolder<Members> m;
 };
  
 #endif // PL_BUFFER_HH
@@ -48,6 +48,22 @@ class Pl_Concatenate: public Pipeline
     // the pipeline.
     QPDF_DLL
     void manualFinish();
+
+  private:
+    class Members
+    {
+        friend class Pl_Concatenate;
+
+      public:
+        QPDF_DLL
+        ~Members();
+
+      private:
+        Members();
+        Members(Members const&);
+    };
+
+    PointerHolder<Members> m;
 };
  
 #endif // PL_CONCATENATE_HH
@@ -48,10 +48,25 @@ class Pl_Count: public Pipeline
     unsigned char getLastChar() const;
  
   private:
-    // Must be qpdf_offset_t, not size_t, to handle writing more than
-    // size_t can handle.
-    qpdf_offset_t count;
-    unsigned char last_char;
+    class Members
+    {
+        friend class Pl_Count;
+
+      public:
+        QPDF_DLL
+        ~Members();
+
+      private:
+        Members();
+        Members(Members const&);
+
+        // Must be qpdf_offset_t, not size_t, to handle writing more than
+        // size_t can handle.
+        qpdf_offset_t count;
+        unsigned char last_char;
+    };
+
+    PointerHolder<Members> m;
 };
  
 #endif // PL_COUNT_HH
@@ -68,17 +68,37 @@ class Pl_DCT: public Pipeline
  
     enum action_e { a_compress, a_decompress };
  
-    action_e action;
-    Pl_Buffer buf;
+    class Members
+    {
+        friend class Pl_DCT;
+
+      public:
+        QPDF_DLL
+        ~Members();
  
-    // Used for compression
-    JDIMENSION image_width;
-    JDIMENSION image_height;
-    int components;
-    J_COLOR_SPACE color_space;
+      private:
+        Members(action_e action,
+                char const* buf_description,
+                JDIMENSION image_width = 0,
+                JDIMENSION image_height = 0,
+                int components = 1,
+                J_COLOR_SPACE color_space = JCS_GRAYSCALE,
+                CompressConfig* config_callback = 0);
+        Members(Members const&);
  
-    CompressConfig* config_callback;
+        action_e action;
+        Pl_Buffer buf;
+
+        // Used for compression
+        JDIMENSION image_width;
+        JDIMENSION image_height;
+        int components;
+        J_COLOR_SPACE color_space;
+
+        CompressConfig* config_callback;
+    };
  
+    PointerHolder<Members> m;
 };
  
 #endif // PL_DCT_HH
@@ -41,6 +41,22 @@ class Pl_Discard: public Pipeline
     virtual void write(unsigned char*, size_t);
     QPDF_DLL
     virtual void finish();
+
+  private:
+    class Members
+    {
+        friend class Pl_Discard;
+
+      public:
+        QPDF_DLL
+        ~Members();
+
+      private:
+        Members();
+        Members(Members const&);
+    };
+
+    PointerHolder<Members> m;
 };
  
 #endif // PL_DISCARD_HH
@@ -46,11 +46,26 @@ class Pl_Flate: public Pipeline
     void handleData(unsigned char* data, size_t len, int flush);
     void checkError(char const* prefix, int error_code);
  
-    unsigned char* outbuf;
-    size_t out_bufsize;
-    action_e action;
-    bool initialized;
-    void* zdata;
+    class Members
+    {
+        friend class Pl_Flate;
+
+      public:
+        QPDF_DLL
+        ~Members();
+
+      private:
+        Members(size_t out_bufsize, action_e action);
+        Members(Members const&);
+
+        unsigned char* outbuf;
+        size_t out_bufsize;
+        action_e action;
+        bool initialized;
+        void* zdata;
+    };
+
+    PointerHolder<Members> m;
 };
  
 #endif // PL_FLATE_HH
@@ -47,10 +47,25 @@ class Pl_RunLength: public Pipeline
  
     enum state_e { st_top, st_copying, st_run };
  
-    action_e action;
-    state_e state;
-    unsigned char buf[128];
-    unsigned int length;
+    class Members
+    {
+        friend class Pl_RunLength;
+
+      public:
+        QPDF_DLL
+        ~Members();
+
+      private:
+        Members(action_e);
+        Members(Members const&);
+
+        action_e action;
+        state_e state;
+        unsigned char buf[128];
+        unsigned int length;
+    };
+
+    PointerHolder<Members> m;
 };
  
 #endif // PL_RUNLENGTH_HH
@@ -48,7 +48,22 @@ class Pl_StdioFile: public Pipeline
     virtual void finish();
  
   private:
-    FILE* file;
+    class Members
+    {
+        friend class Pl_StdioFile;
+
+      public:
+        QPDF_DLL
+        ~Members();
+
+      private:
+        Members(FILE*);
+        Members(Members const&);
+
+        FILE* file;
+    };
+
+    PointerHolder<Members> m;
 };
  
 #endif // PL_STDIOFILE_HH
@@ -24,8 +24,8 @@
  
 #include <qpdf/DLL.h>
 #include <qpdf/Types.h>
-
 #include <qpdf/Constants.h>
+
 #include <string>
 #include <stdexcept>
  
@@ -70,6 +70,9 @@ class QPDF_DLL_CLASS QPDFExc: public std::runtime_error
 				  qpdf_offset_t offset,
 				  std::string const& message);
  
+    // This class does not use the Members pattern to avoid needless
+    // memory allocations during exception handling.
+
     qpdf_error_code_e error_code;
     std::string filename;
     std::string object;
@@ -44,6 +44,9 @@ class QPDFObjGen
     int getGen() const;
  
   private:
+    // This class does not use the Members pattern to avoid a memory
+    // allocation for every one of these. A lot of these get created
+    // and destroyed.
     int obj;
     int gen;
 };
@@ -24,8 +24,8 @@
  
 #include <qpdf/DLL.h>
 #include <qpdf/Types.h>
-
 #include <qpdf/Constants.h>
+
 #include <string>
 #include <stdexcept>
  
@@ -51,6 +51,9 @@ class QPDF_DLL_CLASS QPDFSystemError: public std::runtime_error
     static std::string createWhat(std::string const& description,
 				  int system_errno);
  
+    // This class does not use the Members pattern to avoid needless
+    // memory allocations during exception handling.
+
     std::string description;
     int system_errno;
 };
@@ -49,6 +49,8 @@ class QPDFXRefEntry
     int getObjStreamIndex() const;	// only for type 2
  
   private:
+    // This class does not use the Members pattern to avoid a memory
+    // allocation for every one of these. A lot of these get created.
     int type;
     qpdf_offset_t field1;
     int field2;
 #include <qpdf/Buffer.hh>
  
-#include <string.h>
+#include <cstring>
  
-Buffer::Buffer()
+Buffer::Members::Members(size_t size, unsigned char* buf, bool own_memory) :
+    own_memory(own_memory),
+    size(size),
+    buf(0)
 {
-    init(0, 0, true);
+    if (own_memory)
+    {
+	this->buf = (size ? new unsigned char[size] : 0);
+    }
+    else
+    {
+	this->buf = buf;
+    }
 }
  
-Buffer::Buffer(size_t size)
+Buffer::Members::~Members()
 {
-    init(size, 0, true);
+    if (this->own_memory)
+    {
+	delete [] this->buf;
+    }
 }
  
-Buffer::Buffer(unsigned char* buf, size_t size)
+Buffer::Buffer() :
+    m(new Members(0, 0, true))
 {
-    init(size, buf, false);
 }
  
-Buffer::Buffer(Buffer const& rhs)
+Buffer::Buffer(size_t size) :
+    m(new Members(size, 0, true))
 {
-    init(0, 0, true);
-    copy(rhs);
 }
  
-Buffer&
-Buffer::operator=(Buffer const& rhs)
+Buffer::Buffer(unsigned char* buf, size_t size) :
+    m(new Members(size, buf, false))
 {
-    copy(rhs);
-    return *this;
 }
  
-Buffer::~Buffer()
+Buffer::Buffer(Buffer const& rhs)
 {
-    destroy();
+    copy(rhs);
 }
  
-void
-Buffer::init(size_t size, unsigned char* buf, bool own_memory)
+Buffer&
+Buffer::operator=(Buffer const& rhs)
 {
-    this->own_memory = own_memory;
-    this->size = size;
-    if (own_memory)
-    {
-	this->buf = (size ? new unsigned char[size] : 0);
-    }
-    else
-    {
-	this->buf = buf;
-    }
+    copy(rhs);
+    return *this;
 }
  
 void
@@ -55,40 +57,28 @@ Buffer::copy(Buffer const&amp; rhs)
 {
     if (this != &rhs)
     {
-	this->destroy();
-	this->init(rhs.size, 0, true);
-	if (this->size)
+        this->m = new Members(rhs.m->size, 0, true);
+	if (this->m->size)
 	{
-	    memcpy(this->buf, rhs.buf, this->size);
+	    memcpy(this->m->buf, rhs.m->buf, this->m->size);
 	}
     }
 }
  
-void
-Buffer::destroy()
-{
-    if (this->own_memory)
-    {
-	delete [] this->buf;
-    }
-    this->size = 0;
-    this->buf = 0;
-}
-
 size_t
 Buffer::getSize() const
 {
-    return this->size;
+    return this->m->size;
 }
  
 unsigned char const*
 Buffer::getBuffer() const
 {
-    return this->buf;
+    return this->m->buf;
 }
  
 unsigned char*
 Buffer::getBuffer()
 {
-    return this->buf;
+    return this->m->buf;
 }
@@ -4,8 +4,9 @@
 #include <stdexcept>
 #include <algorithm>
  
-BufferInputSource::BufferInputSource(std::string const& description,
-                                     Buffer* buf, bool own_memory) :
+BufferInputSource::Members::Members(bool own_memory,
+                                    std::string const& description,
+                                    Buffer* buf) :
     own_memory(own_memory),
     description(description),
     buf(buf),
@@ -13,70 +14,77 @@ BufferInputSource::BufferInputSource(std::string const&amp; description,
 {
 }
  
+BufferInputSource::Members::~Members()
+{
+}
+
+BufferInputSource::BufferInputSource(std::string const& description,
+                                     Buffer* buf, bool own_memory) :
+    m(new Members(own_memory, description, buf))
+{
+}
+
 BufferInputSource::BufferInputSource(std::string const& description,
                                      std::string const& contents) :
-    own_memory(true),
-    description(description),
-    buf(0),
-    cur_offset(0)
+    m(new Members(true, description, 0))
 {
-    this->buf = new Buffer(contents.length());
-    unsigned char* bp = buf->getBuffer();
+    this->m->buf = new Buffer(contents.length());
+    unsigned char* bp = this->m->buf->getBuffer();
     memcpy(bp, contents.c_str(), contents.length());
 }
  
 BufferInputSource::~BufferInputSource()
 {
-    if (own_memory)
+    if (this->m->own_memory)
     {
-	delete this->buf;
+	delete this->m->buf;
     }
 }
  
 qpdf_offset_t const
 BufferInputSource::bufSizeAsOffset() const
 {
-    return QIntC::to_offset(this->buf->getSize());
+    return QIntC::to_offset(this->m->buf->getSize());
 }
  
 qpdf_offset_t
 BufferInputSource::findAndSkipNextEOL()
 {
-    if (this->cur_offset < 0)
+    if (this->m->cur_offset < 0)
     {
         throw std::logic_error("INTERNAL ERROR: BufferInputSource offset < 0");
     }
     qpdf_offset_t end_pos = bufSizeAsOffset();
-    if (this->cur_offset >= end_pos)
+    if (this->m->cur_offset >= end_pos)
     {
 	this->last_offset = end_pos;
-        this->cur_offset = end_pos;
+        this->m->cur_offset = end_pos;
 	return end_pos;
     }
  
     qpdf_offset_t result = 0;
-    size_t len = QIntC::to_size(end_pos - this->cur_offset);
-    unsigned char const* buffer = this->buf->getBuffer();
+    size_t len = QIntC::to_size(end_pos - this->m->cur_offset);
+    unsigned char const* buffer = this->m->buf->getBuffer();
  
-    void* start = const_cast<unsigned char*>(buffer) + this->cur_offset;
+    void* start = const_cast<unsigned char*>(buffer) + this->m->cur_offset;
     unsigned char* p1 = static_cast<unsigned char*>(memchr(start, '\r', len));
     unsigned char* p2 = static_cast<unsigned char*>(memchr(start, '\n', len));
     unsigned char* p = (p1 && p2) ? std::min(p1, p2) : p1 ? p1 : p2;
     if (p)
     {
         result = p - buffer;
-        this->cur_offset = result + 1;
+        this->m->cur_offset = result + 1;
         ++p;
-        while ((this->cur_offset < end_pos) &&
+        while ((this->m->cur_offset < end_pos) &&
                ((*p == '\r') || (*p == '\n')))
         {
             ++p;
-            ++this->cur_offset;
+            ++this->m->cur_offset;
         }
     }
     else
     {
-        this->cur_offset = end_pos;
+        this->m->cur_offset = end_pos;
         result = end_pos;
     }
     return result;
@@ -85,13 +93,13 @@ BufferInputSource::findAndSkipNextEOL()
 std::string const&
 BufferInputSource::getName() const
 {
-    return this->description;
+    return this->m->description;
 }
  
 qpdf_offset_t
 BufferInputSource::tell()
 {
-    return this->cur_offset;
+    return this->m->cur_offset;
 }
  
 void
@@ -100,15 +108,15 @@ BufferInputSource::seek(qpdf_offset_t offset, int whence)
     switch (whence)
     {
       case SEEK_SET:
-	this->cur_offset = offset;
+	this->m->cur_offset = offset;
 	break;
  
       case SEEK_END:
-	this->cur_offset = bufSizeAsOffset() + offset;
+	this->m->cur_offset = bufSizeAsOffset() + offset;
 	break;
  
       case SEEK_CUR:
-	this->cur_offset += offset;
+	this->m->cur_offset += offset;
 	break;
  
       default:
@@ -117,46 +125,46 @@ BufferInputSource::seek(qpdf_offset_t offset, int whence)
 	break;
     }
  
-    if (this->cur_offset < 0)
+    if (this->m->cur_offset < 0)
     {
         throw std::runtime_error(
-            this->description + ": seek before beginning of buffer");
+            this->m->description + ": seek before beginning of buffer");
     }
 }
  
 void
 BufferInputSource::rewind()
 {
-    this->cur_offset = 0;
+    this->m->cur_offset = 0;
 }
  
 size_t
 BufferInputSource::read(char* buffer, size_t length)
 {
-    if (this->cur_offset < 0)
+    if (this->m->cur_offset < 0)
     {
         throw std::logic_error("INTERNAL ERROR: BufferInputSource offset < 0");
     }
     qpdf_offset_t end_pos = bufSizeAsOffset();
-    if (this->cur_offset >= end_pos)
+    if (this->m->cur_offset >= end_pos)
     {
 	this->last_offset = end_pos;
 	return 0;
     }
  
-    this->last_offset = this->cur_offset;
+    this->last_offset = this->m->cur_offset;
     size_t len = std::min(
-        QIntC::to_size(end_pos - this->cur_offset), length);
-    memcpy(buffer, buf->getBuffer() + this->cur_offset, len);
-    this->cur_offset += QIntC::to_offset(len);
+        QIntC::to_size(end_pos - this->m->cur_offset), length);
+    memcpy(buffer, this->m->buf->getBuffer() + this->m->cur_offset, len);
+    this->m->cur_offset += QIntC::to_offset(len);
     return len;
 }
  
 void
 BufferInputSource::unreadCh(char ch)
 {
-    if (this->cur_offset > 0)
+    if (this->m->cur_offset > 0)
     {
-	--this->cur_offset;
+	--this->m->cur_offset;
     }
 }
@@ -4,45 +4,45 @@
 #include <qpdf/QPDFExc.hh>
 #include <algorithm>
  
-FileInputSource::FileInputSource() :
-    close_file(false),
+FileInputSource::Members::Members(bool close_file) :
+    close_file(close_file),
     file(0)
 {
 }
  
+FileInputSource::Members::~Members()
+{
+    if (this->file && this->close_file)
+    {
+	fclose(this->file);
+    }
+}
+
+FileInputSource::FileInputSource() :
+    m(new Members(false))
+{
+}
+
 void
 FileInputSource::setFilename(char const* filename)
 {
-    destroy();
-    this->filename = filename;
-    this->close_file = true;
-    this->file = QUtil::safe_fopen(this->filename.c_str(), "rb");
+    this->m = new Members(true);
+    this->m->filename = filename;
+    this->m->file = QUtil::safe_fopen(filename, "rb");
 }
  
 void
 FileInputSource::setFile(
     char const* description, FILE* filep, bool close_file)
 {
-    destroy();
-    this->filename = description;
-    this->close_file = close_file;
-    this->file = filep;
+    this->m = new Members(close_file);
+    this->m->filename = description;
+    this->m->file = filep;
     this->seek(0, SEEK_SET);
 }
  
 FileInputSource::~FileInputSource()
 {
-    destroy();
-}
-
-void
-FileInputSource::destroy()
-{
-    if (this->file && this->close_file)
-    {
-	fclose(this->file);
-	this->file = 0;
-    }
 }
  
 qpdf_offset_t
@@ -53,7 +53,7 @@ FileInputSource::findAndSkipNextEOL()
     char buf[10240];
     while (! done)
     {
-        qpdf_offset_t cur_offset = QUtil::tell(this->file);
+        qpdf_offset_t cur_offset = QUtil::tell(this->m->file);
         size_t len = this->read(buf, sizeof(buf));
         if (len == 0)
         {
@@ -93,41 +93,42 @@ FileInputSource::findAndSkipNextEOL()
 std::string const&
 FileInputSource::getName() const
 {
-    return this->filename;
+    return this->m->filename;
 }
  
 qpdf_offset_t
 FileInputSource::tell()
 {
-    return QUtil::tell(this->file);
+    return QUtil::tell(this->m->file);
 }
  
 void
 FileInputSource::seek(qpdf_offset_t offset, int whence)
 {
-    QUtil::os_wrapper(std::string("seek to ") + this->filename + ", offset " +
+    QUtil::os_wrapper(std::string("seek to ") +
+                      this->m->filename + ", offset " +
 		      QUtil::int_to_string(offset) + " (" +
 		      QUtil::int_to_string(whence) + ")",
-		      QUtil::seek(this->file, offset, whence));
+		      QUtil::seek(this->m->file, offset, whence));
 }
  
 void
 FileInputSource::rewind()
 {
-    ::rewind(this->file);
+    ::rewind(this->m->file);
 }
  
 size_t
 FileInputSource::read(char* buffer, size_t length)
 {
     this->last_offset = this->tell();
-    size_t len = fread(buffer, 1, length, this->file);
+    size_t len = fread(buffer, 1, length, this->m->file);
     if (len == 0)
     {
-        if (ferror(this->file))
+        if (ferror(this->m->file))
         {
             throw QPDFExc(qpdf_e_system,
-                          this->filename, "",
+                          this->m->filename, "",
                           this->last_offset,
                           std::string("read ") +
                           QUtil::uint_to_string(length) + " bytes");
@@ -144,6 +145,6 @@ FileInputSource::read(char* buffer, size_t length)
 void
 FileInputSource::unreadCh(char ch)
 {
-    QUtil::os_wrapper(this->filename + ": unread character",
-		      ungetc(static_cast<unsigned char>(ch), this->file));
+    QUtil::os_wrapper(this->m->filename + ": unread character",
+		      ungetc(static_cast<unsigned char>(ch), this->m->file));
 }
@@ -5,6 +5,13 @@
 #include <qpdf/PointerHolder.hh>
 #include <qpdf/QIntC.hh>
  
+InputSource::Members::Members()
+{
+}
+
+InputSource::Members::~Members()
+{
+}
  
 void
 InputSource::setLastOffset(qpdf_offset_t offset)
 #include <qpdf/Pipeline.hh>
 #include <stdexcept>
  
+Pipeline::Members::Members(Pipeline* next) :
+    next(next)
+{
+}
+
+Pipeline::Members::~Members()
+{
+}
+
 Pipeline::Pipeline(char const* identifier, Pipeline* next) :
     identifier(identifier),
-    next(next)
+    m(new Members(next))
 {
 }
  
@@ -14,11 +23,11 @@ Pipeline::~Pipeline()
 Pipeline*
 Pipeline::getNext(bool allow_null)
 {
-    if ((next == 0) && (! allow_null))
+    if ((this->m->next == 0) && (! allow_null))
     {
 	throw std::logic_error(
 	    this->identifier +
 	    ": Pipeline::getNext() called on pipeline with no next");
     }
-    return this->next;
+    return this->m->next;
 }
@@ -4,13 +4,22 @@
 #include <assert.h>
 #include <string.h>
  
-Pl_Buffer::Pl_Buffer(char const* identifier, Pipeline* next) :
-    Pipeline(identifier, next),
+Pl_Buffer::Members::Members() :
     ready(true),
     total_size(0)
 {
 }
  
+Pl_Buffer::Members::~Members()
+{
+}
+
+Pl_Buffer::Pl_Buffer(char const* identifier, Pipeline* next) :
+    Pipeline(identifier, next),
+    m(new Members())
+{
+}
+
 Pl_Buffer::~Pl_Buffer()
 {
 }
@@ -18,32 +27,25 @@ Pl_Buffer::~Pl_Buffer()
 void
 Pl_Buffer::write(unsigned char* buf, size_t len)
 {
-    PointerHolder<Buffer> cur_buf;
-    size_t cur_size = 0;
-    if (! this->data.empty())
+    if (this->m->data.getPointer() == 0)
     {
-        cur_buf = this->data.back();
-        cur_size = cur_buf->getSize();
+        this->m->data = new Buffer(len);
     }
-    size_t left = cur_size - this->total_size;
+    size_t cur_size = this->m->data->getSize();
+    size_t left = cur_size - this->m->total_size;
     if (left < len)
     {
-        size_t new_size = std::max(this->total_size + len, 2 * cur_size);
-        Buffer* b = new Buffer(new_size);
-        if (cur_buf.getPointer())
-        {
-            memcpy(b->getBuffer(), cur_buf->getBuffer(), this->total_size);
-        }
-        this->data.clear();
-        cur_buf = b;
-        this->data.push_back(cur_buf);
+        size_t new_size = std::max(this->m->total_size + len, 2 * cur_size);
+        PointerHolder<Buffer> b = new Buffer(new_size);
+        memcpy(b->getBuffer(), this->m->data->getBuffer(), this->m->total_size);
+        this->m->data = b;
     }
     if (len)
     {
-        memcpy(cur_buf->getBuffer() + this->total_size, buf, len);
-        this->total_size += len;
+        memcpy(this->m->data->getBuffer() + this->m->total_size, buf, len);
+        this->m->total_size += len;
     }
-    this->ready = false;
+    this->m->ready = false;
  
     if (getNext(true))
     {
@@ -54,7 +56,7 @@ Pl_Buffer::write(unsigned char* buf, size_t len)
 void
 Pl_Buffer::finish()
 {
-    this->ready = true;
+    this->m->ready = true;
     if (getNext(true))
     {
 	getNext()->finish();
@@ -64,21 +66,17 @@ Pl_Buffer::finish()
 Buffer*
 Pl_Buffer::getBuffer()
 {
-    if (! this->ready)
+    if (! this->m->ready)
     {
 	throw std::logic_error("Pl_Buffer::getBuffer() called when not ready");
     }
  
-    Buffer* b = new Buffer(this->total_size);
-    unsigned char* p = b->getBuffer();
-    if (! this->data.empty())
+    Buffer* b = new Buffer(this->m->total_size);
+    if (this->m->total_size > 0)
     {
-        PointerHolder<Buffer> bp = this->data.back();
-        this->data.clear();
-        memcpy(p, bp->getBuffer(), this->total_size);
+        unsigned char* p = b->getBuffer();
+        memcpy(p, this->m->data->getBuffer(), this->m->total_size);
     }
-    this->total_size = 0;
-    this->ready = false;
-
+    this->m = new Members();
     return b;
 }
 #include <qpdf/Pl_Concatenate.hh>
  
+Pl_Concatenate::Members::Members()
+{
+}
+
+Pl_Concatenate::Members::~Members()
+{
+}
+
 Pl_Concatenate::Pl_Concatenate(char const* identifier, Pipeline* next) :
     Pipeline(identifier, next)
 {
 #include <qpdf/Pl_Count.hh>
 #include <qpdf/QIntC.hh>
  
-Pl_Count::Pl_Count(char const* identifier, Pipeline* next) :
-    Pipeline(identifier, next),
+Pl_Count::Members::Members() :
     count(0),
     last_char('\0')
 {
 }
  
+Pl_Count::Members::~Members()
+{
+}
+
+Pl_Count::Pl_Count(char const* identifier, Pipeline* next) :
+    Pipeline(identifier, next),
+    m(new Members())
+{
+}
+
 Pl_Count::~Pl_Count()
 {
 }
@@ -17,9 +26,9 @@ Pl_Count::write(unsigned char* buf, size_t len)
 {
     if (len)
     {
-	this->count += QIntC::to_offset(len);
+	this->m->count += QIntC::to_offset(len);
 	getNext()->write(buf, len);
-	this->last_char = buf[len - 1];
+	this->m->last_char = buf[len - 1];
     }
 }
  
@@ -32,11 +41,11 @@ Pl_Count::finish()
 qpdf_offset_t
 Pl_Count::getCount() const
 {
-    return this->count;
+    return this->m->count;
 }
  
 unsigned char
 Pl_Count::getLastChar() const
 {
-    return this->last_char;
+    return this->m->last_char;
 }
@@ -31,10 +31,30 @@ error_handler(j_common_ptr cinfo)
     longjmp(jerr->jmpbuf, 1);
 }
  
+Pl_DCT::Members::Members(action_e action,
+                         char const* buf_description,
+                         JDIMENSION image_width,
+                         JDIMENSION image_height,
+                         int components,
+                         J_COLOR_SPACE color_space,
+                         CompressConfig* config_callback) :
+    action(action),
+    buf(buf_description),
+    image_width(image_width),
+    image_height(image_height),
+    components(components),
+    color_space(color_space),
+    config_callback(config_callback)
+{
+}
+
+Pl_DCT::Members::~Members()
+{
+}
+
 Pl_DCT::Pl_DCT(char const* identifier, Pipeline* next) :
     Pipeline(identifier, next),
-    action(a_decompress),
-    buf("DCT compressed image")
+    m(new Members(a_decompress, "DCT compressed image"))
 {
 }
  
@@ -45,13 +65,8 @@ Pl_DCT::Pl_DCT(char const* identifier, Pipeline* next,
                J_COLOR_SPACE color_space,
                CompressConfig* config_callback) :
     Pipeline(identifier, next),
-    action(a_compress),
-    buf("DCT uncompressed image"),
-    image_width(image_width),
-    image_height(image_height),
-    components(components),
-    color_space(color_space),
-    config_callback(config_callback)
+    m(new Members(a_compress, "DCT uncompressed image",
+      image_width, image_height, components, color_space, config_callback))
 {
 }
  
@@ -62,18 +77,18 @@ Pl_DCT::~Pl_DCT()
 void
 Pl_DCT::write(unsigned char* data, size_t len)
 {
-    this->buf.write(data, len);
+    this->m->buf.write(data, len);
 }
  
 void
 Pl_DCT::finish()
 {
-    this->buf.finish();
+    this->m->buf.finish();
  
     // Using a PointerHolder<Buffer> here and passing it into compress
     // and decompress causes a memory leak with setjmp/longjmp. Just
     // use a pointer and delete it.
-    Buffer* b = this->buf.getBuffer();
+    Buffer* b = this->m->buf.getBuffer();
     if (b->getSize() == 0)
     {
         // Special case: empty data will never succeed and probably
@@ -99,7 +114,7 @@ Pl_DCT::finish()
     {
         try
         {
-            if (this->action == a_compress)
+            if (this->m->action == a_compress)
             {
                 compress(reinterpret_cast<void*>(&cinfo_compress), b);
             }
@@ -123,11 +138,11 @@ Pl_DCT::finish()
     }
     delete b;
  
-    if (this->action == a_compress)
+    if (this->m->action == a_compress)
     {
         jpeg_destroy_compress(&cinfo_compress);
     }
-    if (this->action == a_decompress)
+    if (this->m->action == a_decompress)
     {
         jpeg_destroy_decompress(&cinfo_decompress);
     }
@@ -272,14 +287,14 @@ Pl_DCT::compress(void* cinfo_p, Buffer* b)
     unsigned char* outbuffer = outbuffer_ph.getPointer();
     jpeg_pipeline_dest(cinfo, outbuffer, BUF_SIZE, this->getNext());
  
-    cinfo->image_width = this->image_width;
-    cinfo->image_height = this->image_height;
-    cinfo->input_components = this->components;
-    cinfo->in_color_space = this->color_space;
+    cinfo->image_width = this->m->image_width;
+    cinfo->image_height = this->m->image_height;
+    cinfo->input_components = this->m->components;
+    cinfo->in_color_space = this->m->color_space;
     jpeg_set_defaults(cinfo);
-    if (this->config_callback)
+    if (this->m->config_callback)
     {
-        this->config_callback->apply(cinfo);
+        this->m->config_callback->apply(cinfo);
     }
  
     jpeg_start_compress(cinfo, TRUE);
@@ -2,6 +2,14 @@
  
 // Exercised in md5 test suite
  
+Pl_Discard::Members::Members()
+{
+}
+
+Pl_Discard::Members::~Members()
+{
+}
+
 Pl_Discard::Pl_Discard() :
     Pipeline("discard", 0)
 {
@@ -6,12 +6,12 @@
 #include <qpdf/QUtil.hh>
 #include <qpdf/QIntC.hh>
  
-Pl_Flate::Pl_Flate(char const* identifier, Pipeline* next,
-		   action_e action, unsigned int out_bufsize_int) :
-    Pipeline(identifier, next),
-    out_bufsize(QIntC::to_size(out_bufsize_int)),
+Pl_Flate::Members::Members(size_t out_bufsize,
+                           action_e action) :
+    out_bufsize(out_bufsize),
     action(action),
-    initialized(false)
+    initialized(false),
+    zdata(0)
 {
     this->outbuf = new unsigned char[out_bufsize];
     // Indirect through zdata to reach the z_stream so we don't have
@@ -38,7 +38,7 @@ Pl_Flate::Pl_Flate(char const* identifier, Pipeline* next,
     zstream.avail_out = QIntC::to_uint(out_bufsize);
 }
  
-Pl_Flate::~Pl_Flate()
+Pl_Flate::Members::~Members()
 {
     delete [] this->outbuf;
     this->outbuf = 0;
@@ -60,10 +60,21 @@ Pl_Flate::~Pl_Flate()
     this->zdata = 0;
 }
  
+Pl_Flate::Pl_Flate(char const* identifier, Pipeline* next,
+		   action_e action, unsigned int out_bufsize_int) :
+    Pipeline(identifier, next),
+    m(new Members(QIntC::to_size(out_bufsize_int), action))
+{
+}
+
+Pl_Flate::~Pl_Flate()
+{
+}
+
 void
 Pl_Flate::write(unsigned char* data, size_t len)
 {
-    if (this->outbuf == 0)
+    if (this->m->outbuf == 0)
     {
 	throw std::logic_error(
 	    this->identifier +
@@ -79,7 +90,7 @@ Pl_Flate::write(unsigned char* data, size_t len)
     {
 	size_t bytes = (bytes_left >= max_bytes ? max_bytes : bytes_left);
         handleData(buf, bytes,
-                   (action == a_inflate ? Z_SYNC_FLUSH : Z_NO_FLUSH));
+                   (this->m->action == a_inflate ? Z_SYNC_FLUSH : Z_NO_FLUSH));
 	bytes_left -= bytes;
         buf += bytes;
     }
@@ -94,11 +105,11 @@ Pl_Flate::handleData(unsigned char* data, size_t len, int flush)
             "Pl_Flate: zlib doesn't support data"
             " blocks larger than int");
     }
-    z_stream& zstream = *(static_cast<z_stream*>(this->zdata));
+    z_stream& zstream = *(static_cast<z_stream*>(this->m->zdata));
     zstream.next_in = data;
     zstream.avail_in = QIntC::to_uint(len);
  
-    if (! this->initialized)
+    if (! this->m->initialized)
     {
 	int err = Z_OK;
  
@@ -109,7 +120,7 @@ Pl_Flate::handleData(unsigned char* data, size_t len, int flush)
 #       pragma GCC diagnostic push
 #       pragma GCC diagnostic ignored "-Wold-style-cast"
 #endif
-	if (this->action == a_deflate)
+	if (this->m->action == a_deflate)
 	{
 	    err = deflateInit(&zstream, Z_DEFAULT_COMPRESSION);
 	}
@@ -123,7 +134,7 @@ Pl_Flate::handleData(unsigned char* data, size_t len, int flush)
 #endif
  
 	checkError("Init", err);
-	this->initialized = true;
+	this->m->initialized = true;
     }
  
     int err = Z_OK;
@@ -131,7 +142,7 @@ Pl_Flate::handleData(unsigned char* data, size_t len, int flush)
     bool done = false;
     while (! done)
     {
-	if (action == a_deflate)
+	if (this->m->action == a_deflate)
 	{
 	    err = deflate(&zstream, flush);
 	}
@@ -139,7 +150,7 @@ Pl_Flate::handleData(unsigned char* data, size_t len, int flush)
 	{
 	    err = inflate(&zstream, flush);
 	}
-        if ((action == a_inflate) && (err != Z_OK) && zstream.msg &&
+        if ((this->m->action == a_inflate) && (err != Z_OK) && zstream.msg &&
             (strcmp(zstream.msg, "incorrect data check") == 0))
         {
             // Other PDF readers ignore this specific error. Combining
@@ -172,12 +183,12 @@ Pl_Flate::handleData(unsigned char* data, size_t len, int flush)
 		    done = true;
 		}
 		uLong ready =
-                    QIntC::to_ulong(this->out_bufsize - zstream.avail_out);
+                    QIntC::to_ulong(this->m->out_bufsize - zstream.avail_out);
 		if (ready > 0)
 		{
-		    this->getNext()->write(this->outbuf, ready);
-		    zstream.next_out = this->outbuf;
-		    zstream.avail_out = QIntC::to_uint(this->out_bufsize);
+		    this->getNext()->write(this->m->outbuf, ready);
+		    zstream.next_out = this->m->outbuf;
+		    zstream.avail_out = QIntC::to_uint(this->m->out_bufsize);
 		}
 	    }
 	    break;
@@ -194,16 +205,16 @@ Pl_Flate::finish()
 {
     try
     {
-        if (this->outbuf)
+        if (this->m->outbuf)
         {
-            if (this->initialized)
+            if (this->m->initialized)
             {
-                z_stream& zstream = *(static_cast<z_stream*>(this->zdata));
+                z_stream& zstream = *(static_cast<z_stream*>(this->m->zdata));
                 unsigned char buf[1];
                 buf[0] = '\0';
                 handleData(buf, 0, Z_FINISH);
                 int err = Z_OK;
-                if (action == a_deflate)
+                if (this->m->action == a_deflate)
                 {
                     err = deflateEnd(&zstream);
                 }
@@ -211,12 +222,12 @@ Pl_Flate::finish()
                 {
                     err = inflateEnd(&zstream);
                 }
-                this->initialized = false;
+                this->m->initialized = false;
                 checkError("End", err);
             }
  
-            delete [] this->outbuf;
-            this->outbuf = 0;
+            delete [] this->m->outbuf;
+            this->m->outbuf = 0;
         }
     }
     catch (std::exception& e)
@@ -230,10 +241,11 @@ Pl_Flate::finish()
 void
 Pl_Flate::checkError(char const* prefix, int error_code)
 {
-    z_stream& zstream = *(static_cast<z_stream*>(this->zdata));
+    z_stream& zstream = *(static_cast<z_stream*>(this->m->zdata));
     if (error_code != Z_OK)
     {
-	char const* action_str = (action == a_deflate ? "deflate" : "inflate");
+	char const* action_str =
+            (this->m->action == a_deflate ? "deflate" : "inflate");
 	std::string msg =
 	    this->identifier + ": " + action_str + ": " + prefix + ": ";
  
@@ -3,15 +3,24 @@
 #include <qpdf/QUtil.hh>
 #include <qpdf/QTC.hh>
  
-Pl_RunLength::Pl_RunLength(char const* identifier, Pipeline* next,
-                           action_e action) :
-    Pipeline(identifier, next),
+Pl_RunLength::Members::Members(action_e action) :
     action(action),
     state(st_top),
     length(0)
 {
 }
  
+Pl_RunLength::Members::~Members()
+{
+}
+
+Pl_RunLength::Pl_RunLength(char const* identifier, Pipeline* next,
+                           action_e action) :
+    Pipeline(identifier, next),
+    m(new Members(action))
+{
+}
+
 Pl_RunLength::~Pl_RunLength()
 {
 }
@@ -19,7 +28,7 @@ Pl_RunLength::~Pl_RunLength()
 void
 Pl_RunLength::write(unsigned char* data, size_t len)
 {
-    if (this->action == a_encode)
+    if (this->m->action == a_encode)
     {
         encode(data, len);
     }
@@ -34,41 +43,41 @@ Pl_RunLength::encode(unsigned char* data, size_t len)
 {
     for (size_t i = 0; i < len; ++i)
     {
-        if ((this->state == st_top) != (this->length <= 1))
+        if ((this->m->state == st_top) != (this->m->length <= 1))
         {
             throw std::logic_error(
                 "Pl_RunLength::encode: state/length inconsistency");
         }
         unsigned char ch = data[i];
-        if ((this->length > 0) &&
-            ((this->state == st_copying) || (this->length < 128)) &&
-            (ch == this->buf[this->length-1]))
+        if ((this->m->length > 0) &&
+            ((this->m->state == st_copying) || (this->m->length < 128)) &&
+            (ch == this->m->buf[this->m->length-1]))
         {
             QTC::TC("libtests", "Pl_RunLength: switch to run",
-                    (this->length == 128) ? 0 : 1);
-            if (this->state == st_copying)
+                    (this->m->length == 128) ? 0 : 1);
+            if (this->m->state == st_copying)
             {
-                --this->length;
+                --this->m->length;
                 flush_encode();
-                this->buf[0] = ch;
-                this->length = 1;
+                this->m->buf[0] = ch;
+                this->m->length = 1;
             }
-            this->state = st_run;
-            this->buf[this->length] = ch;
-            ++this->length;
+            this->m->state = st_run;
+            this->m->buf[this->m->length] = ch;
+            ++this->m->length;
         }
         else
         {
-            if ((this->length == 128) || (this->state == st_run))
+            if ((this->m->length == 128) || (this->m->state == st_run))
             {
                 flush_encode();
             }
-            else if (this->length > 0)
+            else if (this->m->length > 0)
             {
-                this->state = st_copying;
+                this->m->state = st_copying;
             }
-            this->buf[this->length] = ch;
-            ++this->length;
+            this->m->buf[this->m->length] = ch;
+            ++this->m->length;
         }
     }
 }
@@ -79,20 +88,20 @@ Pl_RunLength::decode(unsigned char* data, size_t len)
     for (size_t i = 0; i < len; ++i)
     {
         unsigned char ch = data[i];
-        switch (this->state)
+        switch (this->m->state)
         {
           case st_top:
             if (ch < 128)
             {
                 // length represents remaining number of bytes to copy
-                this->length = 1U + ch;
-                this->state = st_copying;
+                this->m->length = 1U + ch;
+                this->m->state = st_copying;
             }
             else if (ch > 128)
             {
                 // length represents number of copies of next byte
-                this->length = 257U - ch;
-                this->state = st_run;
+                this->m->length = 257U - ch;
+                this->m->state = st_run;
             }
             else // ch == 128
             {
@@ -102,18 +111,18 @@ Pl_RunLength::decode(unsigned char* data, size_t len)
  
           case st_copying:
             this->getNext()->write(&ch, 1);
-            if (--this->length == 0)
+            if (--this->m->length == 0)
             {
-                this->state = st_top;
+                this->m->state = st_top;
             }
             break;
  
           case st_run:
-            for (unsigned int j = 0; j < this->length; ++j)
+            for (unsigned int j = 0; j < this->m->length; ++j)
             {
                 this->getNext()->write(&ch, 1);
             }
-            this->state = st_top;
+            this->m->state = st_top;
             break;
         }
     }
@@ -122,36 +131,36 @@ Pl_RunLength::decode(unsigned char* data, size_t len)
 void
 Pl_RunLength::flush_encode()
 {
-    if (this->length == 128)
+    if (this->m->length == 128)
     {
         QTC::TC("libtests", "Pl_RunLength flush full buffer",
-                (this->state == st_copying ? 0 :
-                 this->state == st_run ? 1 :
+                (this->m->state == st_copying ? 0 :
+                 this->m->state == st_run ? 1 :
                  -1));
     }
-    if (this->length == 0)
+    if (this->m->length == 0)
     {
         QTC::TC("libtests", "Pl_RunLength flush empty buffer");
     }
-    if (this->state == st_run)
+    if (this->m->state == st_run)
     {
-        if ((this->length < 2) || (this->length > 128))
+        if ((this->m->length < 2) || (this->m->length > 128))
         {
             throw std::logic_error(
                 "Pl_RunLength: invalid length in flush_encode for run");
         }
-        unsigned char ch = static_cast<unsigned char>(257 - this->length);
+        unsigned char ch = static_cast<unsigned char>(257 - this->m->length);
         this->getNext()->write(&ch, 1);
-        this->getNext()->write(&this->buf[0], 1);
+        this->getNext()->write(&this->m->buf[0], 1);
     }
-    else if (this->length > 0)
+    else if (this->m->length > 0)
     {
-        unsigned char ch = static_cast<unsigned char>(this->length - 1);
+        unsigned char ch = static_cast<unsigned char>(this->m->length - 1);
         this->getNext()->write(&ch, 1);
-        this->getNext()->write(this->buf, this->length);
+        this->getNext()->write(this->m->buf, this->m->length);
     }
-    this->state = st_top;
-    this->length = 0;
+    this->m->state = st_top;
+    this->m->length = 0;
 }
  
 void
@@ -161,7 +170,7 @@ Pl_RunLength::finish()
     // data, which means the stream was terminated early, but we will
     // just ignore this case since this is the only sensible thing to
     // do.
-    if (this->action == a_encode)
+    if (this->m->action == a_encode)
     {
         flush_encode();
         unsigned char ch = 128;
@@ -4,9 +4,18 @@
 #include <stdexcept>
 #include <errno.h>
  
+Pl_StdioFile::Members::Members(FILE* f) :
+    file(f)
+{
+}
+
+Pl_StdioFile::Members::~Members()
+{
+}
+
 Pl_StdioFile::Pl_StdioFile(char const* identifier, FILE* f) :
     Pipeline(identifier, 0),
-    file(f)
+    m(new Members(f))
 {
 }
  
@@ -20,7 +29,7 @@ Pl_StdioFile::write(unsigned char* buf, size_t len)
     size_t so_far = 0;
     while (len > 0)
     {
-	so_far = fwrite(buf, 1, len, this->file);
+	so_far = fwrite(buf, 1, len, this->m->file);
 	if (so_far == 0)
 	{
 	    QUtil::throw_system_error(
@@ -37,7 +46,7 @@ Pl_StdioFile::write(unsigned char* buf, size_t len)
 void
 Pl_StdioFile::finish()
 {
-    if ((fflush(this->file) == -1) &&
+    if ((fflush(this->m->file) == -1) &&
         (errno == EBADF))
     {
 	throw std::logic_error(
@@ -5,6 +5,7 @@
 #include <stdlib.h>
 #include <stdexcept>
 #include <iostream>
+#include <cassert>
  
 static unsigned char* uc(char const* s)
 {
@@ -13,6 +14,25 @@ static unsigned char* uc(char const* s)
  
 int main()
 {
+    {
+        // Test that buffers can be copied by value.
+        Buffer bc1(2);
+        unsigned char* bc1p = bc1.getBuffer();
+        bc1p[0] = 'Q';
+        bc1p[1] = 'W';
+        Buffer bc2(bc1);
+        bc1p[0] = 'R';
+        unsigned char* bc2p = bc2.getBuffer();
+        assert(bc2p != bc1p);
+        assert(bc2p[0] == 'Q');
+        assert(bc2p[1] == 'W');
+        bc2 = bc1;
+        bc2p = bc2.getBuffer();
+        assert(bc2p != bc1p);
+        assert(bc2p[0] == 'R');
+        assert(bc2p[1] == 'W');
+    }
+
     try
     {
 	Pl_Discard discard;
@@ -68,6 +88,16 @@ int main()
         b = bp3.getBuffer();
         std::cout << "size: " << b->getSize() << std::endl;
         delete b;
+        // Should be able to call getBuffer again and get an empty buffer
+        b = bp3.getBuffer();
+        std::cout << "size: " << b->getSize() << std::endl;
+        delete b;
+        // Also can write 0 and do it.
+        bp3.write(uc(""), 0);
+        bp3.finish();
+        b = bp3.getBuffer();
+        std::cout << "size: " << b->getSize() << std::endl;
+        delete b;
     }
     catch (std::exception& e)
     {
@@ -9,4 +9,6 @@ Pl_Buffer::getBuffer() called when not ready
 size: 9
 data: mooquack
 size: 0
+size: 0
+size: 0
 done