Add new Pl_String Pipeline

ChangeLog

@@ -1,5 +1,8 @@
 2022-05-03  Jay Berkenbilt  <ejb@ql.org>
 
+        * Add new Pipeline class Pl_String which appends to a std::string&
+        passed to it at construction.
+
         * Add new Pipeline class Pl_OStream, similar to Pl_StdioFile but
         takes a std::ostream instead of a FILE*.
 

TODO

@@ -46,9 +46,6 @@ Output JSON v2
 ----
 notes from 5/2:
 
-Need new pipelines:
-* Pl_String to std::string with semantics like Pl_Buffer
-
 See if I can change all output and error messages issued by the
 library, when context is available, to have a pipeline rather than a
 FILE* or std::ostream. This makes it possible for people to capture

include/qpdf/Pl_String.hh

@@ -0,0 +1,63 @@
+// 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.
+
+// End-of-line pipeline that simply writes its data to a stdio FILE* object.
+
+#ifndef PL_STRING_HH
+#define PL_STRING_HH
+
+#include <qpdf/Pipeline.hh>
+
+#include <string>
+
+class QPDF_DLL_CLASS Pl_String: public Pipeline
+{
+  public:
+    QPDF_DLL
+    Pl_String(char const* identifier, std::string& s);
+    QPDF_DLL
+    virtual ~Pl_String();
+
+    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_String;
+
+      public:
+        QPDF_DLL
+        ~Members() = default;
+
+      private:
+        Members(std::string&);
+        Members(Members const&) = delete;
+
+        std::string& s;
+    };
+
+    std::shared_ptr<Members> m;
+};
+
+#endif // PL_STRING_HH

libqpdf/CMakeLists.txt

@@ -51,6 +51,7 @@ set(libqpdf_SOURCES
   Pl_RunLength.cc
   Pl_SHA2.cc
   Pl_StdioFile.cc
+  Pl_String.cc
   Pl_TIFFPredictor.cc
   QPDF.cc
   QPDFAcroFormDocumentHelper.cc

libqpdf/Pl_String.cc

@@ -0,0 +1,33 @@
+#include <qpdf/Pl_String.hh>
+
+#include <qpdf/QUtil.hh>
+#include <errno.h>
+#include <stdexcept>
+
+Pl_String::Members::Members(std::string& s) :
+    s(s)
+{
+}
+
+Pl_String::Pl_String(char const* identifier, std::string& s) :
+    Pipeline(identifier, 0),
+    m(new Members(s))
+{
+}
+
+Pl_String::~Pl_String()
+{
+    // Must be explicit and not inline -- see QPDF_DLL_CLASS in
+    // README-maintainer
+}
+
+void
+Pl_String::write(unsigned char const* buf, size_t len)
+{
+    this->m->s.append(reinterpret_cast<char const*>(buf), len);
+}
+
+void
+Pl_String::finish()
+{
+}

manual/release-notes.rst

@@ -120,6 +120,9 @@ For a detailed list of changes, please see the file
     - Add new ``Pipeline`` type ``Pl_OStream`` to write to a
       ``std::ostream``.
 
+    - Add new ``Pipeline`` type ``Pl_String`` to append to a
+      ``std::string``.
+
   - Other changes
 
     - A new chapter on contributing to qpdf has been added to the

qpdf/sizes.cc

@@ -20,6 +20,7 @@
 #include <qpdf/Pl_QPDFTokenizer.hh>
 #include <qpdf/Pl_RunLength.hh>
 #include <qpdf/Pl_StdioFile.hh>
+#include <qpdf/Pl_String.hh>
 #include <qpdf/QPDF.hh>
 #include <qpdf/QPDFAcroFormDocumentHelper.hh>
 #include <qpdf/QPDFAnnotationObjectHelper.hh>
@@ -80,6 +81,7 @@ main()
     print_size(Pl_QPDFTokenizer);
     print_size(Pl_RunLength);
     print_size(Pl_StdioFile);
+    print_size(Pl_String);
     print_size(QPDF);
     print_size(QPDFAcroFormDocumentHelper);
     print_size(QPDFAnnotationObjectHelper);

qpdf/test_driver.cc

@@ -10,6 +10,7 @@
 #include <qpdf/Pl_Discard.hh>
 #include <qpdf/Pl_Flate.hh>
 #include <qpdf/Pl_StdioFile.hh>
+#include <qpdf/Pl_String.hh>
 #include <qpdf/QIntC.hh>
 #include <qpdf/QPDFAcroFormDocumentHelper.hh>
 #include <qpdf/QPDFEmbeddedFileDocumentHelper.hh>
@@ -435,16 +436,13 @@ test_6(QPDF& pdf, char const* arg2)
     if (!metadata.isStream()) {
         throw std::logic_error("test 6 run on file with no metadata");
     }
-    Pl_Buffer bufpl("buffer");
+    std::string buf;
+    Pl_String bufpl("buffer", buf);
     metadata.pipeStreamData(&bufpl, 0, qpdf_dl_none);
-    Buffer* buf = bufpl.getBuffer();
-    unsigned char const* data = buf->getBuffer();
     bool cleartext = false;
-    if ((buf->getSize() > 9) &&
-        (strncmp(reinterpret_cast<char const*>(data), "<?xpacket", 9) == 0)) {
+    if (buf.substr(0, 9) == "<?xpacket") {
         cleartext = true;
     }
-    delete buf;
     std::cout << "encrypted=" << (pdf.isEncrypted() ? 1 : 0)
               << "; cleartext=" << (cleartext ? 1 : 0) << std::endl;
 }