From 3237ef70fb77ce323394de1e2793abdb5ae85384 Mon Sep 17 00:00:00 2001
From: m-holger <m-holger@kubitscheck.org>
Date: Thu, 16 Nov 2023 16:26:04 +0000
Subject: [PATCH] Add new method Pl_Buffer::getString

---
 include/qpdf/Pl_Buffer.hh             |  4 ++++
 libqpdf/Pl_Buffer.cc                  | 11 +++++++++++
 libqpdf/QPDFAcroFormDocumentHelper.cc |  3 +--
 libqpdf/QPDFObjectHandle.cc           |  3 +--
 libqpdf/QPDFWriter.cc                 |  5 +----
 libqpdf/QPDF_encryption.cc            |  9 +++------
 6 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/include/qpdf/Pl_Buffer.hh b/include/qpdf/Pl_Buffer.hh
index 6cf4560a..5def8b4f 100644
--- a/include/qpdf/Pl_Buffer.hh
+++ b/include/qpdf/Pl_Buffer.hh
@@ -64,6 +64,10 @@ class QPDF_DLL_CLASS Pl_Buffer: public Pipeline
     QPDF_DLL
     void getMallocBuffer(unsigned char** buf, size_t* len);
 
+    // Same as getBuffer but returns the result as a string.
+    QPDF_DLL
+    std::string getString();
+
   private:
     class QPDF_DLL_PRIVATE Members
     {
diff --git a/libqpdf/Pl_Buffer.cc b/libqpdf/Pl_Buffer.cc
index 072b04d4..05d2ebdb 100644
--- a/libqpdf/Pl_Buffer.cc
+++ b/libqpdf/Pl_Buffer.cc
@@ -53,6 +53,17 @@ Pl_Buffer::getBuffer()
     return b;
 }
 
+std::string
+Pl_Buffer::getString()
+{
+    if (!m->ready) {
+        throw std::logic_error("Pl_Buffer::getString() called when not ready");
+    }
+    auto s = std::move(m->data);
+    m->data.clear();
+    return s;
+}
+
 std::shared_ptr<Buffer>
 Pl_Buffer::getBufferSharedPointer()
 {
diff --git a/libqpdf/QPDFAcroFormDocumentHelper.cc b/libqpdf/QPDFAcroFormDocumentHelper.cc
index 5a54bf75..f2daa0c7 100644
--- a/libqpdf/QPDFAcroFormDocumentHelper.cc
+++ b/libqpdf/QPDFAcroFormDocumentHelper.cc
@@ -584,8 +584,7 @@ QPDFAcroFormDocumentHelper::adjustDefaultAppearances(
     ResourceReplacer rr(dr_map, rf.getNamesByResourceType());
     Pl_Buffer buf_pl("filtered DA");
     da_stream.filterAsContents(&rr, &buf_pl);
-    auto buf = buf_pl.getBufferSharedPointer();
-    std::string new_da(reinterpret_cast<char*>(buf->getBuffer()), buf->getSize());
+    std::string new_da = buf_pl.getString();
     obj.replaceKey("/DA", QPDFObjectHandle::newString(new_da));
 }
 
diff --git a/libqpdf/QPDFObjectHandle.cc b/libqpdf/QPDFObjectHandle.cc
index d5ac137a..d543f98e 100644
--- a/libqpdf/QPDFObjectHandle.cc
+++ b/libqpdf/QPDFObjectHandle.cc
@@ -1708,8 +1708,7 @@ QPDFObjectHandle::pipeContentStreams(
         need_newline = (lc.getLastChar() != static_cast<unsigned char>('\n'));
         QTC::TC("qpdf", "QPDFObjectHandle need_newline", need_newline ? 0 : 1);
     }
-    std::unique_ptr<Buffer> b(buf.getBuffer());
-    p->write(b->getBuffer(), b->getSize());
+    p->writeString(buf.getString());
     p->finish();
 }
 
diff --git a/libqpdf/QPDFWriter.cc b/libqpdf/QPDFWriter.cc
index db3b42e0..664ea5ff 100644
--- a/libqpdf/QPDFWriter.cc
+++ b/libqpdf/QPDFWriter.cc
@@ -1579,10 +1579,7 @@ QPDFWriter::unparseObject(
                     m->cur_data_key.length());
                 pl.writeString(val);
                 pl.finish();
-                auto buf = bufpl.getBufferSharedPointer();
-                val = QPDF_String(
-                          std::string(reinterpret_cast<char*>(buf->getBuffer()), buf->getSize()))
-                          .unparse(true);
+                val = QPDF_String(bufpl.getString()).unparse(true);
             } else {
                 auto tmp_ph = QUtil::make_unique_cstr(val);
                 char* tmp = tmp_ph.get();
diff --git a/libqpdf/QPDF_encryption.cc b/libqpdf/QPDF_encryption.cc
index b5cc44ee..d405b4dd 100644
--- a/libqpdf/QPDF_encryption.cc
+++ b/libqpdf/QPDF_encryption.cc
@@ -229,13 +229,11 @@ process_with_aes(
         aes.writeString(data);
     }
     aes.finish();
-    auto bufp = buffer.getBufferSharedPointer();
     if (outlength == 0) {
-        outlength = bufp->getSize();
+        return buffer.getString();
     } else {
-        outlength = std::min(outlength, bufp->getSize());
+        return buffer.getString().substr(0, outlength);
     }
-    return {reinterpret_cast<char*>(bufp->getBuffer()), outlength};
 }
 
 static std::string
@@ -1021,8 +1019,7 @@ QPDF::decryptString(std::string& str, QPDFObjGen const& og)
                 key.length());
             pl.writeString(str);
             pl.finish();
-            auto buf = bufpl.getBufferSharedPointer();
-            str = std::string(reinterpret_cast<char*>(buf->getBuffer()), buf->getSize());
+            str = bufpl.getString();
         } else {
             QTC::TC("qpdf", "QPDF_encryption rc4 decode string");
             size_t vlen = str.length();