From 7494f2443019edaed27694513e3b2507efdff3a3 Mon Sep 17 00:00:00 2001
From: Nico Weber <thakis@chromium.org>
Date: Wed, 14 Feb 2024 09:06:52 -0500
Subject: [PATCH] LibPDF/CFF: Store if a font program is CID-keyed

...and reject CID-keyed font programs for Type1 fonts.
---
 Userland/Libraries/LibPDF/Fonts/CFF.cpp            | 11 +++++++++++
 Userland/Libraries/LibPDF/Fonts/CFF.h              |  1 +
 Userland/Libraries/LibPDF/Fonts/Type1Font.cpp      |  4 ++++
 Userland/Libraries/LibPDF/Fonts/Type1FontProgram.h | 10 ++++++++++
 4 files changed, 26 insertions(+)

diff --git a/Userland/Libraries/LibPDF/Fonts/CFF.cpp b/Userland/Libraries/LibPDF/Fonts/CFF.cpp
index 54fd327638..76a30767e3 100644
--- a/Userland/Libraries/LibPDF/Fonts/CFF.cpp
+++ b/Userland/Libraries/LibPDF/Fonts/CFF.cpp
@@ -126,6 +126,11 @@ PDFErrorOr<NonnullRefPtr<CFF>> CFF::create(ReadonlyBytes const& cff_bytes, RefPt
         return error("CFFs with more than one font not yet implemented");
     auto const& top_dict = top_dicts[0];
 
+    if (top_dict.is_cid_keyed) {
+        // CFF spec, "18 CID-keyed Fonts"
+        cff->set_kind(CFF::Kind::CIDKeyed);
+    }
+
     auto strings = TRY(parse_strings(reader));
 
     // CFF spec "16 Local/Global Subrs INDEXes"
@@ -350,6 +355,12 @@ PDFErrorOr<Vector<CFF::TopDict>> CFF::parse_top_dicts(Reader& reader, ReadonlyBy
                 }));
                 break;
             }
+            case TopDictOperator::RegistryOrderingSupplement:
+                // CFF Spec, "18 CID-keyed Fonts"
+                // "The Top DICT begins with ROS operator which specifies the Registry-Ordering-Supplement for the font.
+                //  This will indicate to a CFF parser that special CID processing should be applied to this font."
+                top_dict.is_cid_keyed = true;
+                break;
             case TopDictOperator::FDSelect:
                 if (!operands.is_empty())
                     top_dict.fdselect_offset = operands[0].get<int>();
diff --git a/Userland/Libraries/LibPDF/Fonts/CFF.h b/Userland/Libraries/LibPDF/Fonts/CFF.h
index ee3735cffd..0228009b6a 100644
--- a/Userland/Libraries/LibPDF/Fonts/CFF.h
+++ b/Userland/Libraries/LibPDF/Fonts/CFF.h
@@ -126,6 +126,7 @@ public:
         Vector<ByteBuffer> local_subroutines;
         float defaultWidthX = 0;
         float nominalWidthX = 0;
+        bool is_cid_keyed = false;
         int fdselect_offset = 0;
         int fdarray_offset = 0;
     };
diff --git a/Userland/Libraries/LibPDF/Fonts/Type1Font.cpp b/Userland/Libraries/LibPDF/Fonts/Type1Font.cpp
index 9cb62b2357..5c1890ea22 100644
--- a/Userland/Libraries/LibPDF/Fonts/Type1Font.cpp
+++ b/Userland/Libraries/LibPDF/Fonts/Type1Font.cpp
@@ -44,6 +44,10 @@ PDFErrorOr<void> Type1Font::initialize(Document* document, NonnullRefPtr<DictObj
             m_font_program = TRY(PS1FontProgram::create(font_file_stream->bytes(), encoding(), length1, length2));
         }
     }
+
+    if (m_font_program && m_font_program->kind() == Type1FontProgram::Kind::CIDKeyed)
+        return Error::parse_error("Type1 fonts must not be CID-keyed"sv);
+
     if (!m_font_program) {
         m_font = TRY(replacement_for(base_font_name().to_lowercase(), font_size));
     }
diff --git a/Userland/Libraries/LibPDF/Fonts/Type1FontProgram.h b/Userland/Libraries/LibPDF/Fonts/Type1FontProgram.h
index 0f7be52214..76f5104250 100644
--- a/Userland/Libraries/LibPDF/Fonts/Type1FontProgram.h
+++ b/Userland/Libraries/LibPDF/Fonts/Type1FontProgram.h
@@ -20,10 +20,17 @@ class Encoding;
 class Type1FontProgram : public RefCounted<Type1FontProgram> {
 
 public:
+    enum Kind {
+        NameKeyed,
+        CIDKeyed,
+    };
+
     RefPtr<Gfx::Bitmap> rasterize_glyph(DeprecatedFlyString const& char_name, float width, Gfx::GlyphSubpixelOffset subpixel_offset);
     Gfx::FloatPoint glyph_translation(DeprecatedFlyString const& char_name, float width) const;
     RefPtr<Encoding> encoding() const { return m_encoding; }
 
+    Kind kind() const { return m_kind; }
+
 protected:
     struct AccentedCharacter {
         AccentedCharacter(u8 base_char_code, u8 accent_char_code, float adx, float ady)
@@ -111,10 +118,13 @@ protected:
 
     void consolidate_glyphs();
 
+    void set_kind(Kind kind) { m_kind = kind; }
+
 private:
     HashMap<DeprecatedFlyString, Glyph> m_glyph_map;
     Gfx::AffineTransform m_font_matrix;
     RefPtr<Encoding> m_encoding;
+    Kind m_kind { NameKeyed };
 
     Gfx::Path build_char(DeprecatedFlyString const& char_name, float width, Gfx::GlyphSubpixelOffset subpixel_offset);
     Gfx::AffineTransform glyph_transform_to_device_space(Glyph const& glyph, float width) const;