Add new protected inline method Pipeline::next

Also, tidy pipeline constructors and make subclasses final where possible.

Add new protected inline method Pipeline::next
Also, tidy pipeline constructors and make subclasses final where possible.
m-holger
1 parent 2cb2412f
Showing 37 changed files with 251 additions and 245 deletions
include/qpdf/Pipeline.hh
include/qpdf/Pl_Count.hh
include/qpdf/Pl_Function.hh
include/qpdf/Pl_QPDFTokenizer.hh
include/qpdf/Pl_RunLength.hh
libqpdf/Pipeline.cc
libqpdf/Pl_AES_PDF.cc
libqpdf/Pl_ASCII85Decoder.cc
libqpdf/Pl_ASCIIHexDecoder.cc
libqpdf/Pl_Base64.cc
libqpdf/Pl_Buffer.cc
libqpdf/Pl_Concatenate.cc
libqpdf/Pl_Count.cc
libqpdf/Pl_DCT.cc
libqpdf/Pl_Flate.cc
libqpdf/Pl_Function.cc
libqpdf/Pl_LZWDecoder.cc
libqpdf/Pl_MD5.cc
libqpdf/Pl_PNGFilter.cc
libqpdf/Pl_QPDFTokenizer.cc
@@ -98,13 +98,19 @@ class QPDF_DLL_CLASS Pipeline
   protected:
     QPDF_DLL
     Pipeline* getNext(bool allow_null = false);
+    QPDF_DLL
+    Pipeline*
+    next() const noexcept
+    {
+        return next_;
+    }
     std::string identifier;
   private:
     Pipeline(Pipeline const&) = delete;
     Pipeline& operator=(Pipeline const&) = delete;
-    Pipeline* next;
+    Pipeline* next_;
 };
 #endif // PIPELINE_HH
@@ -57,8 +57,8 @@ class QPDF_DLL_CLASS Pl_Count: public Pipeline
         Members(Members const&) = delete;
         // 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;
+        qpdf_offset_t count{0};
+        unsigned char last_char{'\0'};
     };
     std::shared_ptr<Members> m;
@@ -19,6 +19,10 @@
 #ifndef PL_FUNCTION_HH
 #define PL_FUNCTION_HH
+#include <qpdf/Pipeline.hh>
+
+#include <functional>
+
 // This pipeline calls an arbitrary function with whatever data is passed to it. This pipeline can
 // be reused.
 //
@@ -29,11 +33,6 @@
 //
 // It is okay to keep calling write() after a previous write throws an exception as long as the
 // delegated function allows it.
-
-#include <qpdf/Pipeline.hh>
-
-#include <functional>
-
 class QPDF_DLL_CLASS Pl_Function: public Pipeline
 {
   public:
@@ -64,7 +64,7 @@ class QPDF_DLL_CLASS Pl_QPDFTokenizer: public Pipeline
         Members();
         Members(Members const&) = delete;
-        QPDFObjectHandle::TokenFilter* filter;
+        QPDFObjectHandle::TokenFilter* filter{nullptr};
         QPDFTokenizer tokenizer;
         Pl_Buffer buf;
     };
@@ -59,9 +59,9 @@ class QPDF_DLL_CLASS Pl_RunLength: public Pipeline
         Members(Members const&) = delete;
         action_e action;
-        state_e state;
+        state_e state{st_top};
         unsigned char buf[128];
-        unsigned int length;
+        unsigned int length{0};
         std::string out;
     };
@@ -5,18 +5,18 @@
 Pipeline::Pipeline(char const* identifier, Pipeline* next) :
     identifier(identifier),
-    next(next)
+    next_(next)
 {
 }
 Pipeline*
 Pipeline::getNext(bool allow_null)
 {
-    if ((this->next == nullptr) && (!allow_null)) {
+    if (!next_ && !allow_null) {
         throw std::logic_error(
             this->identifier + ": Pipeline::getNext() called on pipeline with no next");
     }
-    return this->next;
+    return next_;
 }
 std::string
@@ -18,14 +18,11 @@ Pl_AES_PDF::Pl_AES_PDF(
     Pipeline(identifier, next),
     crypto(QPDFCryptoProvider::getImpl()),
     encrypt(encrypt),
-    cbc_mode(true),
-    first(true),
-    offset(0),
-    key_bytes(key_bytes),
-    use_zero_iv(false),
-    use_specified_iv(false),
-    disable_padding(false)
+    key_bytes(key_bytes)
 {
+    if (!next) {
+        throw std::logic_error("Attempt to create Pl_AES_PDF with nullptr as next");
+    }
     this->key = std::make_unique<unsigned char[]>(key_bytes);
     std::memcpy(this->key.get(), key, key_bytes);
     std::memset(this->inbuf, 0, this->buf_size);
@@ -120,7 +117,7 @@ Pl_AES_PDF::finish()
         flush(!this->disable_padding);
     }
     this->crypto->rijndael_finalize();
-    getNext()->finish();
+    next()->finish();
 }
 void
@@ -157,7 +154,7 @@ Pl_AES_PDF::flush(bool strip_padding)
                 // output stream.
                 initializeVector();
                 if (!(this->use_zero_iv || this->use_specified_iv)) {
-                    getNext()->write(this->cbc_block, this->buf_size);
+                    next()->write(this->cbc_block, this->buf_size);
                 }
             } else if (this->use_zero_iv || this->use_specified_iv) {
                 // Initialize vector with zeroes; zero vector was not written to the beginning of
@@ -196,5 +193,5 @@ Pl_AES_PDF::flush(bool strip_padding)
         }
     }
     this->offset = 0;
-    getNext()->write(this->outbuf, bytes);
+    next()->write(this->outbuf, bytes);
 }
@@ -5,11 +5,11 @@
 #include <stdexcept>
 Pl_ASCII85Decoder::Pl_ASCII85Decoder(char const* identifier, Pipeline* next) :
-    Pipeline(identifier, next),
-    pos(0),
-    eod(0)
+    Pipeline(identifier, next)
 {
-    memset(this->inbuf, 117, 5);
+    if (!next) {
+        throw std::logic_error("Attempt to create Pl_ASCII85Decoder with nullptr as next");
+    }
 }
 void
@@ -52,7 +52,7 @@ Pl_ASCII85Decoder::write(unsigned char const* buf, size_t len)
                     QTC::TC("libtests", "Pl_ASCII85Decoder read z");
                     unsigned char zeroes[4];
                     memset(zeroes, '\0', 4);
-                    getNext()->write(zeroes, 4);
+                    next()->write(zeroes, 4);
                 }
                 break;
@@ -97,12 +97,12 @@ Pl_ASCII85Decoder::flush()
     this->pos = 0;
     memset(this->inbuf, 117, 5);
-    getNext()->write(outbuf, t);
+    next()->write(outbuf, t);
 }
 void
 Pl_ASCII85Decoder::finish()
 {
     flush();
-    getNext()->finish();
+    next()->finish();
 }
@@ -5,13 +5,11 @@
 #include <stdexcept>
 Pl_ASCIIHexDecoder::Pl_ASCIIHexDecoder(char const* identifier, Pipeline* next) :
-    Pipeline(identifier, next),
-    pos(0),
-    eod(false)
+    Pipeline(identifier, next)
 {
-    this->inbuf[0] = '0';
-    this->inbuf[1] = '0';
-    this->inbuf[2] = '\0';
+    if (!next) {
+        throw std::logic_error("Attempt to create Pl_ASCIIHexDecoder with nullptr as next");
+    }
 }
 void
@@ -85,12 +83,12 @@ Pl_ASCIIHexDecoder::flush()
     this->inbuf[1] = '0';
     this->inbuf[2] = '\0';
-    getNext()->write(&ch, 1);
+    next()->write(&ch, 1);
 }
 void
 Pl_ASCIIHexDecoder::finish()
 {
     flush();
-    getNext()->finish();
+    next()->finish();
 }
@@ -25,12 +25,11 @@ to_i(int i)
 Pl_Base64::Pl_Base64(char const* identifier, Pipeline* next, action_e action) :
     Pipeline(identifier, next),
-    action(action),
-    pos(0),
-    end_of_data(false),
-    finished(false)
+    action(action)
 {
-    reset();
+    if (!next) {
+        throw std::logic_error("Attempt to create Pl_Base64 with nullptr as next");
+    }
 }
 void
@@ -125,7 +124,7 @@ Pl_Base64::flush_decode()
         to_uc(0xff & outval),
     };
-    getNext()->write(out, QIntC::to_size(3 - pad));
+    next()->write(out, QIntC::to_size(3 - pad));
 }
 void
@@ -158,7 +157,7 @@ Pl_Base64::flush_encode()
     for (size_t i = 0; i < 3 - this->pos; ++i) {
         out[3 - i] = '=';
     }
-    getNext()->write(out, 4);
+    next()->write(out, 4);
 }
 void
@@ -176,7 +175,7 @@ Pl_Base64::finish()
         flush();
     }
     this->finished = true;
-    getNext()->finish();
+    next()->finish();
 }
 void
@@ -25,8 +25,8 @@ Pl_Buffer::write(unsigned char const* buf, size_t len)
     m->data.append(reinterpret_cast<char const*>(buf), len);
     m->ready = false;
-    if (getNext(true)) {
-        getNext()->write(buf, len);
+    if (next()) {
+        next()->write(buf, len);
     }
 }
@@ -34,8 +34,8 @@ void
 Pl_Buffer::finish()
 {
     m->ready = true;
-    if (getNext(true)) {
-        getNext()->finish();
+    if (next()) {
+        next()->finish();
     }
 }
 #include <qpdf/Pl_Concatenate.hh>
+#include <stdexcept>
+
 Pl_Concatenate::Pl_Concatenate(char const* identifier, Pipeline* next) :
     Pipeline(identifier, next)
 {
+    if (!next) {
+        throw std::logic_error("Attempt to create Pl_Concatenate with nullptr as next");
+    }
 }
 Pl_Concatenate::~Pl_Concatenate() // NOLINT (modernize-use-equals-default)
@@ -13,7 +18,7 @@ Pl_Concatenate::~Pl_Concatenate() // NOLINT (modernize-use-equals-default)
 void
 Pl_Concatenate::write(unsigned char const* data, size_t len)
 {
-    getNext()->write(data, len);
+    next()->write(data, len);
 }
 void
@@ -24,5 +29,5 @@ Pl_Concatenate::finish()
 void
 Pl_Concatenate::manualFinish()
 {
-    getNext()->finish();
+    next()->finish();
 }
@@ -2,9 +2,7 @@
 #include <qpdf/QIntC.hh>
-Pl_Count::Members::Members() :
-    count(0),
-    last_char('\0')
+Pl_Count::Members::Members()
 {
 }
@@ -12,6 +10,9 @@ Pl_Count::Pl_Count(char const* identifier, Pipeline* next) :
     Pipeline(identifier, next),
     m(new Members())
 {
+    if (!next) {
+        throw std::logic_error("Attempt to create Pl_Count with nullptr as next");
+    }
 }
 Pl_Count::~Pl_Count() // NOLINT (modernize-use-equals-default)
@@ -25,14 +26,14 @@ Pl_Count::write(unsigned char const* buf, size_t len)
     if (len) {
         m->count += QIntC::to_offset(len);
         m->last_char = buf[len - 1];
-        getNext()->write(buf, len);
+        next()->write(buf, len);
     }
 }
 void
 Pl_Count::finish()
 {
-    getNext()->finish();
+    next()->finish();
 }
 qpdf_offset_t
@@ -78,6 +78,9 @@ Pl_DCT::Pl_DCT(char const* identifier, Pipeline* next) :
     Pipeline(identifier, next),
     m(new Members())
 {
+    if (!next) {
+        throw std::logic_error("Attempt to create Pl_DCT with nullptr as next");
+    }
 }
 void
@@ -133,7 +136,7 @@ Pl_DCT::finish()
         // Special case: empty data will never succeed and probably means we're calling finish a
         // second time from an exception handler.
         delete b;
-        this->getNext()->finish();
+        next()->finish();
         return;
     }
@@ -300,7 +303,7 @@ Pl_DCT::compress(void* cinfo_p, Buffer* b)
     static int const BUF_SIZE = 65536;
     auto outbuffer_ph = std::make_unique<unsigned char[]>(BUF_SIZE);
     unsigned char* outbuffer = outbuffer_ph.get();
-    jpeg_pipeline_dest(cinfo, outbuffer, BUF_SIZE, this->getNext());
+    jpeg_pipeline_dest(cinfo, outbuffer, BUF_SIZE, next());
     cinfo->image_width = m->image_width;
     cinfo->image_height = m->image_height;
@@ -326,7 +329,7 @@ Pl_DCT::compress(void* cinfo_p, Buffer* b)
         (void)jpeg_write_scanlines(cinfo, row_pointer, 1);
     }
     jpeg_finish_compress(cinfo);
-    this->getNext()->finish();
+    next()->finish();
 }
 void
@@ -370,8 +373,8 @@ Pl_DCT::decompress(void* cinfo_p, Buffer* b)
     (void)jpeg_start_decompress(cinfo);
     while (cinfo->output_scanline < cinfo->output_height) {
         (void)jpeg_read_scanlines(cinfo, buffer, 1);
-        getNext()->write(buffer[0], width * sizeof(buffer[0][0]));
+        next()->write(buffer[0], width * sizeof(buffer[0][0]));
     }
     (void)jpeg_finish_decompress(cinfo);
-    getNext()->finish();
+    next()->finish();
 }
@@ -61,6 +61,9 @@ Pl_Flate::Pl_Flate(
     Pipeline(identifier, next),
     m(new Members(QIntC::to_size(out_bufsize_int), action))
 {
+    if (!next) {
+        throw std::logic_error("Attempt to create Pl_Flate with nullptr as next");
+    }
 }
 Pl_Flate::~Pl_Flate() // NOLINT (modernize-use-equals-default)
@@ -187,7 +190,7 @@ Pl_Flate::handleData(unsigned char const* data, size_t len, int flush)
                             throw std::runtime_error("PL_Flate memory limit exceeded");
                         }
                     }
-                    this->getNext()->write(m->outbuf.get(), ready);
+                    next()->write(m->outbuf.get(), ready);
                     zstream.next_out = m->outbuf.get();
                     zstream.avail_out = QIntC::to_uint(m->out_bufsize);
                 }
@@ -228,13 +231,13 @@ Pl_Flate::finish()
         }
     } catch (std::exception& e) {
         try {
-            this->getNext()->finish();
+            next()->finish();
         } catch (...) {
             // ignore secondary exception
         }
         throw std::runtime_error(e.what());
     }
-    this->getNext()->finish();
+    next()->finish();
 }
 void
@@ -48,15 +48,15 @@ void
 Pl_Function::write(unsigned char const* buf, size_t len)
 {
     m->fn(buf, len);
-    if (getNext(true)) {
-        getNext()->write(buf, len);
+    if (next()) {
+        next()->write(buf, len);
     }
 }
 void
 Pl_Function::finish()
 {
-    if (getNext(true)) {
-        getNext()->finish();
+    if (next()) {
+        next()->finish();
     }
 }
@@ -8,25 +8,20 @@
 Pl_LZWDecoder::Pl_LZWDecoder(char const* identifier, Pipeline* next, bool early_code_change) :
     Pipeline(identifier, next),
-    code_size(9),
-    next(0),
-    byte_pos(0),
-    bit_pos(0),
-    bits_available(0),
-    code_change_delta(early_code_change),
-    eod(false),
-    last_code(256)
+    code_change_delta(early_code_change)
 {
-    memset(buf, 0, 3);
+    if (!next) {
+        throw std::logic_error("Attempt to create Pl_LZWDecoder with nullptr as next");
+    }
 }
 void
 Pl_LZWDecoder::write(unsigned char const* bytes, size_t len)
 {
     for (size_t i = 0; i < len; ++i) {
-        this->buf[next++] = bytes[i];
-        if (this->next == 3) {
-            this->next = 0;
+        buf[next_char_++] = bytes[i];
+        if (next_char_ == 3) {
+            next_char_ = 0;
         }
         this->bits_available += 8;
         if (this->bits_available >= this->code_size) {
@@ -38,7 +33,7 @@ Pl_LZWDecoder::write(unsigned char const* bytes, size_t len)
 void
 Pl_LZWDecoder::finish()
 {
-    getNext()->finish();
+    next()->finish();
 }
 void
@@ -101,7 +96,7 @@ Pl_LZWDecoder::getFirstChar(unsigned int code)
 }
 void
-Pl_LZWDecoder::addToTable(unsigned char next)
+Pl_LZWDecoder::addToTable(unsigned char c)
 {
     unsigned int last_size = 0;
     unsigned char const* last_data = nullptr;
@@ -128,7 +123,7 @@ Pl_LZWDecoder::addToTable(unsigned char next)
     Buffer entry(1 + last_size);
     unsigned char* new_data = entry.getBuffer();
     memcpy(new_data, last_data, last_size);
-    new_data[last_size] = next;
+    new_data[last_size] = c;
     this->table.push_back(std::move(entry));
 }
@@ -151,11 +146,11 @@ Pl_LZWDecoder::handleCode(unsigned int code)
         if (this->last_code != 256) {
             // Add to the table from last time.  New table entry would be what we read last plus the
             // first character of what we're reading now.
-            unsigned char next = ' = '\0';';
+            unsigned char next_c = ' = '\0';';
             unsigned int table_size = QIntC::to_uint(table.size());
             if (code < 256) {
-                // just read < 256; last time's next was code
-                next = static_cast<unsigned char>(code);
+                // just read < 256; last time's next_c was code
+                next_c = static_cast<unsigned char>(code);
             } else if (code > 257) {
                 size_t idx = code - 258;
                 if (idx > table_size) {
@@ -164,16 +159,16 @@ Pl_LZWDecoder::handleCode(unsigned int code)
                     // The encoder would have just created this entry, so the first character of
                     // this entry would have been the same as the first character of the last entry.
                     QTC::TC("libtests", "Pl_LZWDecoder last was table size");
-                    next = getFirstChar(this->last_code);
+                    next_c = getFirstChar(this->last_code);
                 } else {
-                    next = getFirstChar(code);
+                    next_c = getFirstChar(code);
                 }
             }
             unsigned int new_idx = 258 + table_size;
             if (new_idx == 4096) {
                 throw std::runtime_error("LZWDecoder: table full");
             }
-            addToTable(next);
+            addToTable(next_c);
             unsigned int change_idx = new_idx + code_change_delta;
             if ((change_idx == 511) || (change_idx == 1023) || (change_idx == 2047)) {
                 ++this->code_size;
@@ -182,14 +177,14 @@ Pl_LZWDecoder::handleCode(unsigned int code)
         if (code < 256) {
             auto ch = static_cast<unsigned char>(code);
-            getNext()->write(&ch, 1);
+            next()->write(&ch, 1);
         } else {
             unsigned int idx = code - 258;
             if (idx >= table.size()) {
                 throw std::runtime_error("Pl_LZWDecoder::handleCode: table overflow");
             }
             Buffer& b = table.at(idx);
-            getNext()->write(b.getBuffer(), b.getSize());
+            next()->write(b.getBuffer(), b.getSize());
         }
     }
@@ -3,11 +3,11 @@
 #include <stdexcept>
 Pl_MD5::Pl_MD5(char const* identifier, Pipeline* next) :
-    Pipeline(identifier, next),
-    in_progress(false),
-    enabled(true),
-    persist_across_finish(false)
+    Pipeline(identifier, next)
 {
+    if (!next) {
+        throw std::logic_error("Attempt to create Pl_MD5 with nullptr as next");
+    }
 }
 void
@@ -31,13 +31,13 @@ Pl_MD5::write(unsigned char const* buf, size_t len)
         }
     }
-    this->getNext()->write(buf, len);
+    next()->write(buf, len);
 }
 void
 Pl_MD5::finish()
 {
-    this->getNext()->finish();
+    next()->finish();
     if (!this->persist_across_finish) {
         this->in_progress = false;
     }
@@ -26,13 +26,11 @@ Pl_PNGFilter::Pl_PNGFilter(
     unsigned int samples_per_pixel,
     unsigned int bits_per_sample) :
     Pipeline(identifier, next),
-    action(action),
-    cur_row(nullptr),
-    prev_row(nullptr),
-    buf1(nullptr),
-    buf2(nullptr),
-    pos(0)
+    action(action)
 {
+    if (!next) {
+        throw std::logic_error("Attempt to create Pl_PNGFilter with nullptr as next");
+    }
     if (samples_per_pixel < 1) {
         throw std::runtime_error("PNGFilter created with invalid samples_per_pixel");
     }
@@ -130,7 +128,7 @@ Pl_PNGFilter::decodeRow()
         }
     }
-    getNext()->write(this->cur_row + 1, this->bytes_per_row);
+    next()->write(this->cur_row + 1, this->bytes_per_row);
 }
 void
@@ -230,14 +228,14 @@ Pl_PNGFilter::encodeRow()
 {
     // For now, hard-code to using UP filter.
     unsigned char ch = 2;
-    getNext()->write(&ch, 1);
+    next()->write(&ch, 1);
     if (this->prev_row) {
         for (unsigned int i = 0; i < this->bytes_per_row; ++i) {
             ch = static_cast<unsigned char>(this->cur_row[i] - this->prev_row[i]);
-            getNext()->write(&ch, 1);
+            next()->write(&ch, 1);
         }
     } else {
-        getNext()->write(this->cur_row, this->bytes_per_row);
+        next()->write(this->cur_row, this->bytes_per_row);
     }
 }
@@ -253,5 +251,5 @@ Pl_PNGFilter::finish()
     this->pos = 0;
     memset(this->cur_row, 0, this->bytes_per_row + 1);
-    getNext()->finish();
+    next()->finish();
 }
@@ -5,7 +5,6 @@
 #include <stdexcept>
 Pl_QPDFTokenizer::Members::Members() :
-    filter(nullptr),
     buf("tokenizer buffer")
 {
 }
@@ -56,8 +55,7 @@ Pl_QPDFTokenizer::finish()
     }
     m->filter->handleEOF();
     QPDFObjectHandle::TokenFilter::PipelineAccessor::setPipeline(m->filter, nullptr);
-    Pipeline* next = this->getNext(true);
-    if (next) {
-        next->finish();
+    if (next()) {
+        next()->finish();
     }
 }
@@ -12,6 +12,9 @@ Pl_RC4::Pl_RC4(
     out_bufsize(out_bufsize),
     rc4(key_data, key_len)
 {
+    if (!next) {
+        throw std::logic_error("Attempt to create Pl_RC4 with nullptr as next");
+    }
     this->outbuf = QUtil::make_shared_array<unsigned char>(out_bufsize);
 }
@@ -31,13 +34,13 @@ Pl_RC4::write(unsigned char const* data, size_t len)
         // lgtm[cpp/weak-cryptographic-algorithm]
         rc4.process(p, bytes, outbuf.get());
         p += bytes;
-        getNext()->write(outbuf.get(), bytes);
+        next()->write(outbuf.get(), bytes);
     }
 }
 void
 Pl_RC4::finish()
 {
-    this->outbuf = nullptr;
-    this->getNext()->finish();
+    outbuf = nullptr;
+    next()->finish();
 }
@@ -4,9 +4,7 @@
 #include <qpdf/QUtil.hh>
 Pl_RunLength::Members::Members(action_e action) :
-    action(action),
-    state(st_top),
-    length(0)
+    action(action)
 {
 }
@@ -14,6 +12,9 @@ Pl_RunLength::Pl_RunLength(char const* identifier, Pipeline* next, action_e acti
     Pipeline(identifier, next),
     m(new Members(action))
 {
+    if (!next) {
+        throw std::logic_error("Attempt to create Pl_RunLength with nullptr as next");
+    }
 }
 Pl_RunLength::~Pl_RunLength() // NOLINT (modernize-use-equals-default)
@@ -119,12 +120,12 @@ Pl_RunLength::flush_encode()
             throw std::logic_error("Pl_RunLength: invalid length in flush_encode for run");
         }
         auto ch = static_cast<unsigned char>(257 - m->length);
-        this->getNext()->write(&ch, 1);
-        this->getNext()->write(&m->buf[0], 1);
+        next()->write(&ch, 1);
+        next()->write(&m->buf[0], 1);
     } else if (m->length > 0) {
         auto ch = static_cast<unsigned char>(m->length - 1);
-        this->getNext()->write(&ch, 1);
-        this->getNext()->write(m->buf, m->length);
+        next()->write(&ch, 1);
+        next()->write(m->buf, m->length);
     }
     m->state = st_top;
     m->length = 0;
@@ -136,13 +137,12 @@ Pl_RunLength::finish()
     // When decoding, we might have read a length byte not followed by data, which means the stream
     // was terminated early, but we will just ignore this case since this is the only sensible thing
     // to do.
-    auto next = getNext();
     if (m->action == a_encode) {
         flush_encode();
         unsigned char ch = 128;
-        next->write(&ch, 1);
+        next()->write(&ch, 1);
     } else {
-        next->writeString(m->out);
+        next()->writeString(m->out);
     }
-    next->finish();
+    next()->finish();
 }
@@ -31,16 +31,16 @@ Pl_SHA2::write(unsigned char const* buf, size_t len)
         data += bytes;
     }
-    if (this->getNext(true)) {
-        this->getNext()->write(buf, len);
+    if (next()) {
+        next()->write(buf, len);
     }
 }
 void
 Pl_SHA2::finish()
 {
-    if (this->getNext(true)) {
-        this->getNext()->finish();
+    if (next()) {
+        next()->finish();
     }
     this->crypto->SHA2_finalize();
     this->in_progress = false;
@@ -25,15 +25,15 @@ Pl_String::write(unsigned char const* buf, size_t len)
         return;
     }
     m->s.append(reinterpret_cast<char const*>(buf), len);
-    if (getNext(true)) {
-        getNext()->write(buf, len);
+    if (next()) {
+        next()->write(buf, len);
     }
 }
 void
 Pl_String::finish()
 {
-    if (getNext(true)) {
-        getNext()->finish();
+    if (next()) {
+        next()->finish();
     }
 }
@@ -23,9 +23,11 @@ Pl_TIFFPredictor::Pl_TIFFPredictor(
     action(action),
     columns(columns),
     samples_per_pixel(samples_per_pixel),
-    bits_per_sample(bits_per_sample),
-    p_next(getNext())
+    bits_per_sample(bits_per_sample)
 {
+    if (!next) {
+        throw std::logic_error("Attempt to create Pl_TIFFPredictor with nullptr as next");
+    }
     if (samples_per_pixel < 1) {
         throw std::runtime_error("TIFFPredictor created with invalid samples_per_pixel");
     }
@@ -74,7 +76,7 @@ Pl_TIFFPredictor::processRow()
     QTC::TC("libtests", "Pl_TIFFPredictor processRow", (action == a_decode ? 0 : 1));
     previous.assign(samples_per_pixel, 0);
     if (bits_per_sample != 8) {
-        BitWriter bw(p_next);
+        BitWriter bw(next());
         BitStream in(cur_row.data(), cur_row.size());
         for (unsigned int col = 0; col < this->columns; ++col) {
             for (auto& prev: previous) {
@@ -93,13 +95,14 @@ Pl_TIFFPredictor::processRow()
         bw.flush();
     } else {
         out.clear();
-        auto next = cur_row.begin();
+        auto next_it = cur_row.begin();
         auto cr_end = cur_row.end();
         auto pr_end = previous.end();
-        while (next != cr_end) {
-            for (auto prev = previous.begin(); prev != pr_end && next != cr_end; ++prev, ++next) {
-                long long sample = *next;
+        while (next_it != cr_end) {
+            for (auto prev = previous.begin(); prev != pr_end && next_it != cr_end;
+                 ++prev, ++next_it) {
+                long long sample = *next_it;
                 long long new_sample = sample;
                 if (action == a_encode) {
                     new_sample -= *prev;
@@ -111,7 +114,7 @@ Pl_TIFFPredictor::processRow()
                 out.push_back(static_cast<unsigned char>(255U & new_sample));
             }
         }
-        p_next->write(out.data(), out.size());
+        next()->write(out.data(), out.size());
     }
 }
@@ -124,5 +127,5 @@ Pl_TIFFPredictor::finish()
         processRow();
     }
     cur_row.clear();
-    p_next->finish();
+    next()->finish();
 }
@@ -14,19 +14,22 @@ namespace
         Pl_Track(char const* identifier, Pipeline* next) :
             Pipeline(identifier, next)
         {
+            if (!next) {
+                throw std::logic_error("Attempt to create Pl_Track with nullptr as next");
+            }
         }
         void
-        write(unsigned char const* data, size_t len) override
+        write(unsigned char const* data, size_t len) final
         {
-            this->used = true;
-            getNext()->write(data, len);
+            used = true;
+            next()->write(data, len);
         }
         void
-        finish() override
+        finish() final
         {
-            getNext()->finish();
+            next()->finish();
         }
         bool
@@ -181,13 +181,13 @@ QPDFObjectHandle::ParserCallbacks::terminateParsing()
 namespace
 {
-    class LastChar: public Pipeline
+    class LastChar final: public Pipeline
     {
       public:
-        LastChar(Pipeline* next);
-        ~LastChar() override = default;
-        void write(unsigned char const* data, size_t len) override;
-        void finish() override;
+        LastChar(Pipeline& next);
+        ~LastChar() final = default;
+        void write(unsigned char const* data, size_t len) final;
+        void finish() final;
         unsigned char getLastChar();
       private:
@@ -195,8 +195,8 @@ namespace
     };
 } // namespace
-LastChar::LastChar(Pipeline* next) :
-    Pipeline("lastchar", next)
+LastChar::LastChar(Pipeline& next) :
+    Pipeline("lastchar", &next)
 {
 }
@@ -206,13 +206,13 @@ LastChar::write(unsigned char const* data, size_t len)
     if (len > 0) {
         this->last_char = data[len - 1];
     }
-    getNext()->write(data, len);
+    next()->write(data, len);
 }
 void
 LastChar::finish()
 {
-    getNext()->finish();
+    next()->finish();
 }
 unsigned char
@@ -2073,7 +2073,7 @@ QPDFObjectHandle::pipeContentStreams(
         if (need_newline) {
             buf.writeCStr("\n");
         }
-        LastChar lc(&buf);
+        LastChar lc(buf);
         if (!stream.pipeStreamData(&lc, 0, qpdf_dl_specialized)) {
             QTC::TC("qpdf", "QPDFObjectHandle errors in parsecontent");
             throw QPDFExc(
@@ -7,8 +7,7 @@
 // This pipeline implements AES-128 and AES-256 with CBC and block padding as specified in the PDF
 // specification.
-
-class Pl_AES_PDF: public Pipeline
+class Pl_AES_PDF final: public Pipeline
 {
   public:
     // key should be a pointer to key_bytes bytes of data
@@ -18,10 +17,10 @@ class Pl_AES_PDF: public Pipeline
         bool encrypt,
         unsigned char const* key,
         size_t key_bytes);
-    ~Pl_AES_PDF() override = default;
+    ~Pl_AES_PDF() final = default;
-    void write(unsigned char const* data, size_t len) override;
-    void finish() override;
+    void write(unsigned char const* data, size_t len) final;
+    void finish() final;
     // Use zero initialization vector; needed for AESV3
     void useZeroIV();
@@ -45,18 +44,18 @@ class Pl_AES_PDF: public Pipeline
     std::shared_ptr<QPDFCryptoImpl> crypto;
     bool encrypt;
-    bool cbc_mode;
-    bool first;
-    size_t offset; // offset into memory buffer
+    bool cbc_mode{true};
+    bool first{true};
+    size_t offset{0}; // offset into memory buffer
     std::unique_ptr<unsigned char[]> key;
-    size_t key_bytes;
+    size_t key_bytes{0};
     unsigned char inbuf[buf_size];
     unsigned char outbuf[buf_size];
     unsigned char cbc_block[buf_size];
     unsigned char specified_iv[buf_size];
-    bool use_zero_iv;
-    bool use_specified_iv;
-    bool disable_padding;
+    bool use_zero_iv{false};
+    bool use_specified_iv{false};
+    bool disable_padding{false};
 };
 #endif // PL_AES_PDF_HH
@@ -3,20 +3,20 @@
 #include <qpdf/Pipeline.hh>
-class Pl_ASCII85Decoder: public Pipeline
+class Pl_ASCII85Decoder final: public Pipeline
 {
   public:
     Pl_ASCII85Decoder(char const* identifier, Pipeline* next);
-    ~Pl_ASCII85Decoder() override = default;
-    void write(unsigned char const* buf, size_t len) override;
-    void finish() override;
+    ~Pl_ASCII85Decoder() final = default;
+    void write(unsigned char const* buf, size_t len) final;
+    void finish() final;
   private:
     void flush();
-    unsigned char inbuf[5];
-    size_t pos;
-    size_t eod;
+    unsigned char inbuf[5]{117, 117, 117, 117, 117};
+    size_t pos{0};
+    size_t eod{0};
 };
 #endif // PL_ASCII85DECODER_HH
@@ -3,20 +3,20 @@
 #include <qpdf/Pipeline.hh>
-class Pl_ASCIIHexDecoder: public Pipeline
+class Pl_ASCIIHexDecoder final: public Pipeline
 {
   public:
     Pl_ASCIIHexDecoder(char const* identifier, Pipeline* next);
-    ~Pl_ASCIIHexDecoder() override = default;
-    void write(unsigned char const* buf, size_t len) override;
-    void finish() override;
+    ~Pl_ASCIIHexDecoder() final = default;
+    void write(unsigned char const* buf, size_t len) final;
+    void finish() final;
   private:
     void flush();
-    char inbuf[3];
-    size_t pos;
-    bool eod;
+    char inbuf[3]{'0', '0', '\0'};
+    size_t pos{0};
+    bool eod{false};
 };
 #endif // PL_ASCIIHEXDECODER_HH
@@ -3,14 +3,14 @@
 #include <qpdf/Pipeline.hh>
-class Pl_Base64: public Pipeline
+class Pl_Base64 final: public Pipeline
 {
   public:
     enum action_e { a_encode, a_decode };
     Pl_Base64(char const* identifier, Pipeline* next, action_e);
-    ~Pl_Base64() override = default;
-    void write(unsigned char const* buf, size_t len) override;
-    void finish() override;
+    ~Pl_Base64() final = default;
+    void write(unsigned char const* buf, size_t len) final;
+    void finish() final;
   private:
     void decode(unsigned char const* buf, size_t len);
@@ -21,10 +21,10 @@ class Pl_Base64: public Pipeline
     void reset();
     action_e action;
-    unsigned char buf[4];
-    size_t pos;
-    bool end_of_data;
-    bool finished;
+    unsigned char buf[4]{0, 0, 0, 0};
+    size_t pos{0};
+    bool end_of_data{false};
+    bool finished{false};
 };
 #endif // PL_BASE64_HH
@@ -6,13 +6,13 @@
 #include <qpdf/Buffer.hh>
 #include <vector>
-class Pl_LZWDecoder: public Pipeline
+class Pl_LZWDecoder final: public Pipeline
 {
   public:
     Pl_LZWDecoder(char const* identifier, Pipeline* next, bool early_code_change);
-    ~Pl_LZWDecoder() override = default;
-    void write(unsigned char const* buf, size_t len) override;
-    void finish() override;
+    ~Pl_LZWDecoder() final = default;
+    void write(unsigned char const* buf, size_t len) final;
+    void finish() final;
   private:
     void sendNextCode();
@@ -21,18 +21,18 @@ class Pl_LZWDecoder: public Pipeline
     void addToTable(unsigned char next);
     // members used for converting bits to codes
-    unsigned char buf[3];
-    unsigned int code_size;
-    unsigned int next;
-    unsigned int byte_pos;
-    unsigned int bit_pos; // left to right: 01234567
-    unsigned int bits_available;
+    unsigned char buf[3]{0, 0, 0};
+    unsigned int code_size{9};
+    unsigned int next_char_{0};
+    unsigned int byte_pos{0};
+    unsigned int bit_pos{0}; // left to right: 01234567
+    unsigned int bits_available{0};
     // members used for handle LZW decompression
-    bool code_change_delta;
-    bool eod;
+    bool code_change_delta{false};
+    bool eod{false};
     std::vector<Buffer> table;
-    unsigned int last_code;
+    unsigned int last_code{256};
 };
 #endif // PL_LZWDECODER_HH
 #ifndef PL_MD5_HH
 #define PL_MD5_HH
+#include <qpdf/MD5.hh>
+#include <qpdf/Pipeline.hh>
+
 // This pipeline sends its output to its successor unmodified.  After calling finish, the MD5
 // checksum of the data that passed through the pipeline is available.
 // This pipeline is reusable; i.e., it is safe to call write() after calling finish().  The first
 // call to write() after a call to finish() initializes a new MD5 object.
-
-#include <qpdf/MD5.hh>
-#include <qpdf/Pipeline.hh>
-
-class Pl_MD5: public Pipeline
+class Pl_MD5 final: public Pipeline
 {
   public:
     Pl_MD5(char const* identifier, Pipeline* next);
-    ~Pl_MD5() override = default;
-    void write(unsigned char const*, size_t) override;
-    void finish() override;
+    ~Pl_MD5() final = default;
+    void write(unsigned char const*, size_t) final;
+    void finish() final;
     std::string getHexDigest();
     // Enable/disable. Disabling the pipeline causes it to become a pass-through. This makes it
     // possible to stick an MD5 pipeline in a pipeline when it may or may not be required. Disabling
@@ -27,10 +26,10 @@ class Pl_MD5: public Pipeline
     void persistAcrossFinish(bool);
   private:
-    bool in_progress;
+    bool in_progress{false};
     MD5 md5;
-    bool enabled;
-    bool persist_across_finish;
+    bool enabled{true};
+    bool persist_across_finish{false};
 };
 #endif // PL_MD5_HH
 #ifndef PL_PNGFILTER_HH
 #define PL_PNGFILTER_HH
+#include <qpdf/Pipeline.hh>
+
 // This pipeline applies or reverses the application of a PNG filter as described in the PNG
 // specification.
-
+//
 // NOTE: In its current implementation, this filter always encodes using the "up" filter, but it
 // decodes all the filters.
-
-#include <qpdf/Pipeline.hh>
-
-class Pl_PNGFilter: public Pipeline
+class Pl_PNGFilter final: public Pipeline
 {
   public:
     // Encoding is only partially supported
@@ -22,14 +21,14 @@ class Pl_PNGFilter: public Pipeline
         unsigned int columns,
         unsigned int samples_per_pixel = 1,
         unsigned int bits_per_sample = 8);
-    ~Pl_PNGFilter() override = default;
+    ~Pl_PNGFilter() final = default;
     // Limit the memory used.
     // NB This is a static option affecting all Pl_PNGFilter instances.
     static void setMemoryLimit(unsigned long long limit);
-    void write(unsigned char const* data, size_t len) override;
-    void finish() override;
+    void write(unsigned char const* data, size_t len) final;
+    void finish() final;
   private:
     void decodeSub();
@@ -44,12 +43,12 @@ class Pl_PNGFilter: public Pipeline
     action_e action;
     unsigned int bytes_per_row;
     unsigned int bytes_per_pixel;
-    unsigned char* cur_row;  // points to buf1 or buf2
-    unsigned char* prev_row; // points to buf1 or buf2
+    unsigned char* cur_row{nullptr};  // points to buf1 or buf2
+    unsigned char* prev_row{nullptr}; // points to buf1 or buf2
     std::shared_ptr<unsigned char> buf1;
     std::shared_ptr<unsigned char> buf2;
-    size_t pos;
-    size_t incoming;
+    size_t pos{0};
+    size_t incoming{0};
 };
 #endif // PL_PNGFILTER_HH
@@ -5,7 +5,7 @@
 #include <qpdf/RC4.hh>
-class Pl_RC4: public Pipeline
+class Pl_RC4 final: public Pipeline
 {
   public:
     static size_t const def_bufsize = 65536;
@@ -17,10 +17,10 @@ class Pl_RC4: public Pipeline
         unsigned char const* key_data,
         int key_len = -1,
         size_t out_bufsize = def_bufsize);
-    ~Pl_RC4() override = default;
+    ~Pl_RC4() final = default;
-    void write(unsigned char const* data, size_t len) override;
-    void finish() override;
+    void write(unsigned char const* data, size_t len) final;
+    void finish() final;
   private:
     std::shared_ptr<unsigned char> outbuf;
 #ifndef PL_SHA2_HH
 #define PL_SHA2_HH
+#include <qpdf/Pipeline.hh>
+#include <qpdf/QPDFCryptoImpl.hh>
+#include <memory>
+
 // Bits must be a supported number of bits, currently only 256, 384, or 512.  Passing 0 as bits
 // leaves the pipeline uncommitted, in which case resetBits must be called before the pipeline is
 // used. If a next is provided, this pipeline sends its output to its successor unmodified.  After
 // calling finish, the SHA2 checksum of the data that passed through the pipeline is available.
-
+//
 // This pipeline is reusable; i.e., it is safe to call write() after calling finish().  The first
 // call to write() after a call to finish() initializes a new SHA2 object.  resetBits may also be
 // called between finish and the next call to write.
-
-#include <qpdf/Pipeline.hh>
-#include <qpdf/QPDFCryptoImpl.hh>
-#include <memory>
-
-class Pl_SHA2: public Pipeline
+class Pl_SHA2 final: public Pipeline
 {
   public:
     Pl_SHA2(int bits = 0, Pipeline* next = nullptr);
-    ~Pl_SHA2() override = default;
-    void write(unsigned char const*, size_t) override;
-    void finish() override;
+    ~Pl_SHA2() final = default;
+    void write(unsigned char const*, size_t) final;
+    void finish() final;
     void resetBits(int bits);
     std::string getHexDigest();
     std::string getRawDigest();
@@ -40,7 +40,6 @@ class Pl_TIFFPredictor: public Pipeline
     std::vector<unsigned char> cur_row;
     std::vector<long long> previous;
     std::vector<unsigned char> out;
-    Pipeline* p_next;
 };
 #endif // PL_TIFFPREDICTOR_HH