From 92a8c888ba45f33db212f22d9082f2051e00c6d5 Mon Sep 17 00:00:00 2001
From: m-holger <m.holger@qpdf.org>
Date: Sat, 26 Jul 2025 17:17:33 +0100
Subject: [PATCH] Refactor `Pl_Base64` to add static `encode` and `decode` methods, streamline encoding/decoding logic, and simplify usage in `JSON_writer` and `QPDF_json`.

---
 libqpdf/Pl_Base64.cc        | 41 ++++++++++++++++++++++++++++-------------
 libqpdf/QPDF_json.cc        |  6 +++---
 libqpdf/qpdf/JSON_writer.hh |  6 ++----
 libqpdf/qpdf/Pl_Base64.hh   |  7 +++++--
 4 files changed, 38 insertions(+), 22 deletions(-)

diff --git a/libqpdf/Pl_Base64.cc b/libqpdf/Pl_Base64.cc
index a56392e..68d3fa3 100644
--- a/libqpdf/Pl_Base64.cc
+++ b/libqpdf/Pl_Base64.cc
@@ -33,9 +33,6 @@ Pl_Base64::Pl_Base64(char const* identifier, Pipeline* next, action_e action) :
     Pipeline(identifier, next),
     action(action)
 {
-    if (!next) {
-        throw std::logic_error("Attempt to create Pl_Base64 with nullptr as next");
-    }
 }
 
 void
@@ -44,9 +41,25 @@ Pl_Base64::write(unsigned char const* data, size_t len)
     in_buffer.append(reinterpret_cast<const char*>(data), len);
 }
 
-void
+std::string
 Pl_Base64::decode(std::string_view data)
 {
+    Pl_Base64 p("base64-decode", nullptr, a_decode);
+    p.decode_internal(data);
+    return std::move(p.out_buffer);
+}
+
+std::string
+Pl_Base64::encode(std::string_view data)
+{
+    Pl_Base64 p("base64-encode", nullptr, a_encode);
+    p.encode_internal(data);
+    return std::move(p.out_buffer);
+}
+
+void
+Pl_Base64::decode_internal(std::string_view data)
+{
     auto len = data.size();
     auto res = (len / 4u + 1u) * 3u;
     out_buffer.reserve(res);
@@ -71,7 +84,7 @@ Pl_Base64::decode(std::string_view data)
 }
 
 void
-Pl_Base64::encode(std::string_view data)
+Pl_Base64::encode_internal(std::string_view data)
 {
     auto len = data.size();
     static const size_t max_len = (std::string().max_size() / 4u - 1u) * 3u;
@@ -177,17 +190,19 @@ void
 Pl_Base64::finish()
 {
     if (action == a_decode) {
-        decode(in_buffer);
+        decode_internal(in_buffer);
 
     } else {
-        encode(in_buffer);
+        encode_internal(in_buffer);
+    }
+    if (next()) {
+        in_buffer.clear();
+        in_buffer.shrink_to_fit();
+        next()->write(reinterpret_cast<unsigned char const*>(out_buffer.data()), out_buffer.size());
+        out_buffer.clear();
+        out_buffer.shrink_to_fit();
+        next()->finish();
     }
-    in_buffer.clear();
-    in_buffer.shrink_to_fit();
-    next()->write(reinterpret_cast<unsigned char const*>(out_buffer.data()), out_buffer.size());
-    out_buffer.clear();
-    out_buffer.shrink_to_fit();
-    next()->finish();
 }
 
 void
diff --git a/libqpdf/QPDF_json.cc b/libqpdf/QPDF_json.cc
index 88afe93..e27a84b 100644
--- a/libqpdf/QPDF_json.cc
+++ b/libqpdf/QPDF_json.cc
@@ -216,10 +216,10 @@ static std::function<void(Pipeline*)>
 provide_data(std::shared_ptr<InputSource> is, qpdf_offset_t start, qpdf_offset_t end)
 {
     return [is, start, end](Pipeline* p) {
-        Pl_Base64 decode("base64-decode", p, Pl_Base64::a_decode);
         auto data = is->read(QIntC::to_size(end - start), start);
-        decode.write(reinterpret_cast<const unsigned char*>(data.data()), data.size());
-        decode.finish();
+        data = Pl_Base64::decode(data);
+        p->write(reinterpret_cast<const unsigned char*>(data.data()), data.size());
+        p->finish();
     };
 }
 
diff --git a/libqpdf/qpdf/JSON_writer.hh b/libqpdf/qpdf/JSON_writer.hh
index 3f770c5..a77138e 100644
--- a/libqpdf/qpdf/JSON_writer.hh
+++ b/libqpdf/qpdf/JSON_writer.hh
@@ -32,10 +32,8 @@ class JSON::Writer
     Writer&
     writeBase64(std::string_view sv)
     {
-        Pl_Concatenate cat{"writer concat", p};
-        Pl_Base64 base{"writer base64", &cat, Pl_Base64::a_encode};
-        base.write(reinterpret_cast<unsigned char const*>(sv.data()), sv.size());
-        base.finish();
+        auto encoded = Pl_Base64::encode(sv);
+        p->write(reinterpret_cast<unsigned char const*>(encoded.data()), encoded.size());
         return *this;
     }
 
diff --git a/libqpdf/qpdf/Pl_Base64.hh b/libqpdf/qpdf/Pl_Base64.hh
index aeb6e59..7d6c47d 100644
--- a/libqpdf/qpdf/Pl_Base64.hh
+++ b/libqpdf/qpdf/Pl_Base64.hh
@@ -12,9 +12,12 @@ class Pl_Base64 final: public Pipeline
     void write(unsigned char const* buf, size_t len) final;
     void finish() final;
 
+    static std::string encode(std::string_view data);
+    static std::string decode(std::string_view data);
+
   private:
-    void decode(std::string_view data);
-    void encode(std::string_view data);
+    void decode_internal(std::string_view data);
+    void encode_internal(std::string_view data);
     void flush_decode();
     void flush_encode();
     void reset();
--
libgit2 0.21.4