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LibTTF: Memory map TTF fonts instead of reading them into heap memory

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All GUI applications currently load all TTF fonts on startup
(to populate the Gfx::FontDatabase. This could probably be smarter.)

Before this patch, everyone would open the files and read them into
heap-allocated storage. Now we simply mmap() them instead. :^)
This commit is contained in:
Andreas Kling 2021-07-04 20:21:24 +02:00
parent 560109bd42
commit 49d0b9e808
3 changed files with 25 additions and 21 deletions
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5
Meta/Lagom/Fuzzers/FuzzTTF.cpp
View file

@ -8,9 +8,8 @@
#include <stddef.h> #include <stddef.h>
#include <stdint.h> #include <stdint.h>
extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) extern "C" int LLVMFuzzerTestOneInput(u8 const* data, size_t size)
{ {
ByteBuffer font_data = ByteBuffer::copy(data, size); (void)TTF::Font::try_load_from_externally_owned_memory({ data, size });
(void)TTF::Font::try_load_from_memory(font_data);
return 0; return 0;
} }

25
Userland/Libraries/LibTTF/Font.cpp
View file

@ -1,11 +1,12 @@
/* /*
* Copyright (c) 2020, Srimanta Barua <srimanta.barua1@gmail.com> * Copyright (c) 2020, Srimanta Barua <srimanta.barua1@gmail.com>
* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
* *
* SPDX-License-Identifier: BSD-2-Clause * SPDX-License-Identifier: BSD-2-Clause
*/ */
#include "AK/ByteBuffer.h"
#include <AK/Checked.h> #include <AK/Checked.h>
#include <AK/MappedFile.h>
#include <AK/Utf32View.h> #include <AK/Utf32View.h>
#include <AK/Utf8View.h> #include <AK/Utf8View.h>
#include <LibCore/File.h> #include <LibCore/File.h>
@ -15,6 +16,7 @@
#include <LibTTF/Tables.h> #include <LibTTF/Tables.h>
#include <LibTextCodec/Decoder.h> #include <LibTextCodec/Decoder.h>
#include <math.h> #include <math.h>
#include <sys/mman.h>
namespace TTF { namespace TTF {
@ -207,19 +209,20 @@ GlyphHorizontalMetrics Hmtx::get_glyph_horizontal_metrics(u32 glyph_id) const
Result<NonnullRefPtr<Font>, String> Font::try_load_from_file(String path, unsigned index) Result<NonnullRefPtr<Font>, String> Font::try_load_from_file(String path, unsigned index)
{ {
auto file_or_error = Core::File::open(move(path), Core::OpenMode::ReadOnly); auto file_or_error = MappedFile::map(path);
if (file_or_error.is_error()) if (file_or_error.is_error())
return file_or_error.error(); return String { file_or_error.error().string() };
auto file = file_or_error.value(); auto& file = *file_or_error.value();
if (!file->open(Core::OpenMode::ReadOnly)) auto result = try_load_from_externally_owned_memory(file.bytes(), index);
return String { "Could not open file" }; if (result.is_error())
return result.error();
auto buffer = file->read_all(); auto& font = *result.value();
return try_load_from_memory(buffer, index); font.m_mapped_file = file_or_error.release_value();
return result;
} }
Result<NonnullRefPtr<Font>, String> Font::try_load_from_memory(ByteBuffer& buffer, unsigned index) Result<NonnullRefPtr<Font>, String> Font::try_load_from_externally_owned_memory(ReadonlyBytes buffer, unsigned index)
{ {
if (buffer.size() < 4) if (buffer.size() < 4)
return String { "Font file too small" }; return String { "Font file too small" };
@ -243,7 +246,7 @@ Result<NonnullRefPtr<Font>, String> Font::try_load_from_memory(ByteBuffer& buffe
} }
// FIXME: "loca" and "glyf" are not available for CFF fonts. // FIXME: "loca" and "glyf" are not available for CFF fonts.
Result<NonnullRefPtr<Font>, String> Font::try_load_from_offset(ByteBuffer&& buffer, u32 offset) Result<NonnullRefPtr<Font>, String> Font::try_load_from_offset(ReadonlyBytes buffer, u32 offset)
{ {
if (Checked<u32>::addition_would_overflow(offset, (u32)Sizes::OffsetTable)) if (Checked<u32>::addition_would_overflow(offset, (u32)Sizes::OffsetTable))
return String { "Invalid offset in font header" }; return String { "Invalid offset in font header" };

16
Userland/Libraries/LibTTF/Font.h
View file

@ -6,7 +6,6 @@
#pragma once #pragma once
#include <AK/ByteBuffer.h>
#include <AK/HashMap.h> #include <AK/HashMap.h>
#include <AK/Noncopyable.h> #include <AK/Noncopyable.h>
#include <AK/RefCounted.h> #include <AK/RefCounted.h>
@ -47,7 +46,7 @@ class Font : public RefCounted<Font> {
public: public:
static Result<NonnullRefPtr<Font>, String> try_load_from_file(String path, unsigned index = 0); static Result<NonnullRefPtr<Font>, String> try_load_from_file(String path, unsigned index = 0);
static Result<NonnullRefPtr<Font>, String> try_load_from_memory(ByteBuffer&, unsigned index = 0); static Result<NonnullRefPtr<Font>, String> try_load_from_externally_owned_memory(ReadonlyBytes bytes, unsigned index = 0);
ScaledFontMetrics metrics(float x_scale, float y_scale) const; ScaledFontMetrics metrics(float x_scale, float y_scale) const;
ScaledGlyphMetrics glyph_metrics(u32 glyph_id, float x_scale, float y_scale) const; ScaledGlyphMetrics glyph_metrics(u32 glyph_id, float x_scale, float y_scale) const;
@ -72,9 +71,10 @@ private:
TableRecord = 16, TableRecord = 16,
}; };
static Result<NonnullRefPtr<Font>, String> try_load_from_offset(ByteBuffer&&, unsigned index = 0); static Result<NonnullRefPtr<Font>, String> try_load_from_offset(ReadonlyBytes, unsigned index = 0);
Font(ByteBuffer&& buffer, Head&& head, Name&& name, Hhea&& hhea, Maxp&& maxp, Hmtx&& hmtx, Cmap&& cmap, Loca&& loca, Glyf&& glyf)
: m_buffer(move(buffer)) Font(ReadonlyBytes bytes, Head&& head, Name&& name, Hhea&& hhea, Maxp&& maxp, Hmtx&& hmtx, Cmap&& cmap, Loca&& loca, Glyf&& glyf)
: m_buffer(move(bytes))
, m_head(move(head)) , m_head(move(head))
, m_name(move(name)) , m_name(move(name))
, m_hhea(move(hhea)) , m_hhea(move(hhea))
@ -86,8 +86,10 @@ private:
{ {
} }
// This owns the font data RefPtr<MappedFile> m_mapped_file;
ByteBuffer m_buffer;
ReadonlyBytes m_buffer;
// These are stateful wrappers around non-owning slices // These are stateful wrappers around non-owning slices
Head m_head; Head m_head;
Name m_name; Name m_name;