From 296033668c8003421b1c5d10cf58a9a7f0ed57e4 Mon Sep 17 00:00:00 2001
From: Justin Gassner <justin.gassner@mailbox.org>
Date: Sun, 5 Mar 2023 19:23:26 +0100
Subject: Support and force zopfli compression

Original patch developed by jarnoh [1] and ported by me.

[1] https://github.com/jarnoh/qpdf
---
 .gitmodules              |  3 +++
 include/qpdf/Pl_Flate.hh |  3 +++
 libqpdf/Pl_Flate.cc      | 62 +++++++++++++++++++++++++++++++++++++++++++++++-
 zopfli                   |  1 +
 4 files changed, 68 insertions(+), 1 deletion(-)
 create mode 100644 .gitmodules
 create mode 160000 zopfli

diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 00000000..827f1bd3
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "zopfli"]
+	path = zopfli
+	url = https://github.com/google/zopfli
diff --git a/include/qpdf/Pl_Flate.hh b/include/qpdf/Pl_Flate.hh
index 41ae7e4a..325c84b6 100644
--- a/include/qpdf/Pl_Flate.hh
+++ b/include/qpdf/Pl_Flate.hh
@@ -90,6 +90,9 @@ class QPDF_DLL_CLASS Pl_Flate: public Pipeline
         std::function<void(char const*, int)> callback;
     };
 
+    unsigned char* inbuf; /* additional buffer for zopfli input */
+    size_t inbuf_size;
+
     std::shared_ptr<Members> m;
 };
 
diff --git a/libqpdf/Pl_Flate.cc b/libqpdf/Pl_Flate.cc
index d332e635..7fe8cc01 100644
--- a/libqpdf/Pl_Flate.cc
+++ b/libqpdf/Pl_Flate.cc
@@ -7,6 +7,29 @@
 #include <qpdf/QIntC.hh>
 #include <qpdf/QUtil.hh>
 
+#define USE_ZOPFLI 1
+
+#if USE_ZOPFLI
+// quick hack, link zopfli here
+extern "C" {
+#define adler32 zopfli_adler32
+#include "../zopfli/src/zopfli/zopfli.h"
+#include "../zopfli/src/zopfli/blocksplitter.c"
+#include "../zopfli/src/zopfli/cache.c"
+#include "../zopfli/src/zopfli/deflate.c"
+#include "../zopfli/src/zopfli/hash.c"
+#include "../zopfli/src/zopfli/gzip_container.c"
+#include "../zopfli/src/zopfli/katajainen.c"
+#include "../zopfli/src/zopfli/lz77.c"
+#include "../zopfli/src/zopfli/squeeze.c"
+#include "../zopfli/src/zopfli/tree.c"
+#include "../zopfli/src/zopfli/util.c"
+#include "../zopfli/src/zopfli/zlib_container.c"
+#include "../zopfli/src/zopfli/zopfli_lib.c"
+#undef adler32
+}
+#endif
+
 int Pl_Flate::compression_level = Z_DEFAULT_COMPRESSION;
 
 Pl_Flate::Members::Members(size_t out_bufsize, action_e action) :
@@ -54,13 +77,18 @@ Pl_Flate::Members::~Members()
 Pl_Flate::Pl_Flate(
     char const* identifier, Pipeline* next, action_e action, unsigned int out_bufsize_int) :
     Pipeline(identifier, next),
-    m(new Members(QIntC::to_size(out_bufsize_int), action))
+    m(new Members(QIntC::to_size(out_bufsize_int), action)),
+    inbuf(0), inbuf_size(0)
 {
 }
 
 Pl_Flate::~Pl_Flate() // NOLINT (modernize-use-equals-default)
 {
     // Must be explicit and not inline -- see QPDF_DLL_CLASS in README-maintainer
+
+#if USE_ZOPFLI
+    free(inbuf); inbuf = 0;
+#endif
 }
 
 void
@@ -109,6 +137,17 @@ Pl_Flate::handleData(unsigned char const* data, size_t len, int flush)
     zstream.next_in = const_cast<unsigned char*>(data);
     zstream.avail_in = QIntC::to_uint(len);
 
+#if USE_ZOPFLI
+    if (this->m->action == a_deflate)
+    {
+        inbuf = static_cast<unsigned char*>(realloc(inbuf, inbuf_size+len));
+        if(!inbuf) throw std::runtime_error("realloc failed");
+        memcpy(inbuf+inbuf_size, data, len);
+        inbuf_size += len;
+        return;
+    }
+#endif
+
     if (!m->initialized) {
         int err = Z_OK;
 
@@ -188,6 +227,27 @@ void
 Pl_Flate::finish()
 {
     try {
+#if USE_ZOPFLI
+        if (m->action == a_deflate)
+        {
+          ZopfliOptions options;
+          ZopfliInitOptions(&options);
+
+          unsigned char* out = 0;
+          size_t out_size = 0;
+
+          ZopfliCompress(&options, ZOPFLI_FORMAT_ZLIB, inbuf, inbuf_size, &out, &out_size);
+          free(inbuf); inbuf = 0;
+
+          if(inbuf_size!=0 && out_size==0) throw std::runtime_error("zopfli failed");
+
+          getNext()->write(out, out_size);
+          getNext()->finish();
+          free(out); out = 0;
+
+          return;
+        }
+#endif
         if (m->outbuf.get()) {
             if (m->initialized) {
                 z_stream& zstream = *(static_cast<z_stream*>(m->zdata));
diff --git a/zopfli b/zopfli
new file mode 160000
index 00000000..831773bc
--- /dev/null
+++ b/zopfli
@@ -0,0 +1 @@
+Subproject commit 831773bc28e318b91a3255fa12c9fcde1606058b
-- 
cgit v1.2.3-54-g00ecf