Add Pl_Function -- a generic function pipeline

include/qpdf/Pl_Function.hh

@@ -0,0 +1,73 @@
+// Copyright (c) 2005-2022 Jay Berkenbilt
+//
+// This file is part of qpdf.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Versions of qpdf prior to version 7 were released under the terms
+// of version 2.0 of the Artistic License. At your option, you may
+// continue to consider qpdf to be licensed under those terms. Please
+// see the manual for additional information.
+
+#ifndef PL_FUNCTION_HH
+#define PL_FUNCTION_HH
+
+// This pipeline calls an arbitrary function with whatever data is
+// passed to it. This pipeline can be reused.
+//
+// For this pipeline, "next" may be null. If a next pointer is
+// provided, this pipeline will also pass the data through to it and
+// will forward finish() to it.
+//
+// It is okay to not call finish() on this pipeline if it has no
+// "next".
+
+#include <qpdf/Pipeline.hh>
+
+#include <functional>
+
+class QPDF_DLL_CLASS Pl_Function: public Pipeline
+{
+  public:
+    typedef std::function<void(unsigned char const*, size_t)> writer_t;
+
+    QPDF_DLL
+    Pl_Function(char const* identifier, Pipeline* next, writer_t fn);
+    QPDF_DLL
+    virtual ~Pl_Function();
+
+    QPDF_DLL
+    virtual void write(unsigned char const* buf, size_t len);
+    QPDF_DLL
+    virtual void finish();
+
+  private:
+    class QPDF_DLL_PRIVATE Members
+    {
+        friend class Pl_Function;
+
+      public:
+        QPDF_DLL
+        ~Members() = default;
+
+      private:
+        Members(writer_t);
+        Members(Members const&) = delete;
+
+        writer_t fn;
+    };
+
+    std::shared_ptr<Members> m;
+};
+
+#endif // PL_FUNCTION_HH

include/qpdf/Pl_String.hh

@@ -30,11 +30,11 @@
 // provided, this pipeline will also pass the data through to it and
 // will forward finish() to it.
 //
-// It is okay to not call finish() on this pipeline. This makes it
-// easy to stick this in front of another pipeline to capture data
-// that is written to the other pipeline without interfering with when
-// finish is called on the other pipeline and without having to put a
-// Pl_Concatenate after it.
+// It is okay to not call finish() on this pipeline if it has no
+// "next". This makes it easy to stick this in front of another
+// pipeline to capture data that is written to the other pipeline
+// without interfering with when finish is called on the other
+// pipeline and without having to put a Pl_Concatenate after it.
 
 #include <qpdf/Pipeline.hh>
 

libqpdf/CMakeLists.txt

@@ -42,6 +42,7 @@ set(libqpdf_SOURCES
   Pl_DCT.cc
   Pl_Discard.cc
   Pl_Flate.cc
+  Pl_Function.cc
   Pl_LZWDecoder.cc
   Pl_MD5.cc
   Pl_OStream.cc

libqpdf/Pl_Function.cc

@@ -0,0 +1,39 @@
+#include <qpdf/Pl_Function.hh>
+
+#include <qpdf/QUtil.hh>
+#include <errno.h>
+#include <stdexcept>
+
+Pl_Function::Members::Members(writer_t fn) :
+    fn(fn)
+{
+}
+
+Pl_Function::Pl_Function(char const* identifier, Pipeline* next, writer_t fn) :
+    Pipeline(identifier, next),
+    m(new Members(fn))
+{
+}
+
+Pl_Function::~Pl_Function()
+{
+    // Must be explicit and not inline -- see QPDF_DLL_CLASS in
+    // README-maintainer
+}
+
+void
+Pl_Function::write(unsigned char const* buf, size_t len)
+{
+    this->m->fn(buf, len);
+    if (getNext(true)) {
+        getNext()->write(buf, len);
+    }
+}
+
+void
+Pl_Function::finish()
+{
+    if (getNext(true)) {
+        getNext()->finish();
+    }
+}

libtests/CMakeLists.txt

@@ -24,6 +24,7 @@ set(TEST_PROGRAMS
   nntree
   numrange
   pdf_version
+  pl_function
   pointer_holder
   predictors
   qintc

libtests/pl_function.cc

@@ -0,0 +1,29 @@
+#include <qpdf/assert_test.h>
+
+#include <qpdf/Pl_Function.hh>
+#include <qpdf/Pl_String.hh>
+#include <qpdf/Pl_Base64.hh>
+#include <iostream>
+
+int
+main(int argc, char* argv[])
+{
+    Pl_Function p1(
+        "p1", nullptr, [](unsigned char const* data, size_t len) {
+            std::cout << "p1: " << len << ": " << data << std::endl;
+        });
+    p1.write(reinterpret_cast<unsigned char const*>("potato"), 6);
+
+    std::string s;
+    Pl_String ps("string", nullptr, s);
+    Pl_Base64 b("base64", &ps, Pl_Base64::a_encode);
+    Pl_Function p2(
+        "p2", &b, [](unsigned char const* data, size_t len) {
+            std::cout << "p2: " << len << ": " << data << std::endl;
+        });
+    p2.write(reinterpret_cast<unsigned char const*>("salad"), 5);
+    p2.finish();
+    assert(s == "c2FsYWQ=");
+
+    return 0;
+}

libtests/qtest/pl_function.test

@@ -0,0 +1,17 @@
+#!/usr/bin/env perl
+require 5.008;
+use warnings;
+use strict;
+
+chdir("pl_function") or die "chdir testdir failed: $!\n";
+
+require TestDriver;
+
+my $td = new TestDriver('pl_function');
+
+$td->runtest("pl_function",
+             {$td->COMMAND => "pl_function"},
+             {$td->FILE => "exp", $td->EXIT_STATUS => 0},
+             $td->NORMALIZE_NEWLINES);
+
+$td->report(1);

libtests/qtest/pl_function/exp

@@ -0,0 +1,2 @@
+p1: 6: potato
+p2: 5: salad

qpdf/sizes.cc

@@ -16,6 +16,7 @@
 #include <qpdf/Pl_DCT.hh>
 #include <qpdf/Pl_Discard.hh>
 #include <qpdf/Pl_Flate.hh>
+#include <qpdf/Pl_Function.hh>
 #include <qpdf/Pl_OStream.hh>
 #include <qpdf/Pl_QPDFTokenizer.hh>
 #include <qpdf/Pl_RunLength.hh>
@@ -78,6 +79,7 @@ main()
     print_size(Pl_DCT);
     print_size(Pl_Discard);
     print_size(Pl_Flate);
+    print_size(Pl_Function);
     print_size(Pl_OStream);
     print_size(Pl_QPDFTokenizer);
     print_size(Pl_RunLength);