#include <cstddef>
#include <cstdint>
#include <memory>
#include <optional>
#include <span>
#include <string_view>
#include "donner/base/fonts/CffOutlineComplexity.h"

Include dependency graph for SfntUtils.h:

This graph shows which files directly or indirectly include this file:

Classes
struct	donner::fonts::SfntValidationOptions
	Caller-selected limits for one sfnt validation. More...
struct	donner::fonts::SfntValidationMetrics
	Work and limiting outcome observed while validating one sfnt. More...
class	donner::fonts::SfntFont
	Validated, allocation-bounded index for one sfnt font. More...
struct	donner::fonts::SfntFont::TableRecord
	A table location validated against the original font byte span. More...
struct	donner::fonts::SfntFont::GlyphOutlineComplexity
	Allocation and CPU-work ceiling proved for one glyph outline. More...

Namespaces
namespace	donner
	Top-level Donner namespace, which is split into different sub-namespaces such as donner::svg and donner::css.

Functions
uint16_t	donner::fonts::ReadBe16 (const uint8_t *p)
	Read a 16-bit big-endian unsigned integer from `p`.
uint32_t	donner::fonts::ReadBe32 (const uint8_t *p)
	Read a 32-bit big-endian unsigned integer from `p`.
uint32_t	donner::fonts::SfntTag (std::string_view tag)
	Convert a four-byte sfnt tag to its big-endian integer representation.
uint32_t	donner::fonts::SfntTableChecksum (std::span< const uint8_t > data, uint32_t initial=0)
	Compute an sfnt table-directory checksum: the sum, modulo 2^32, of the table's big-endian 32-bit words, with a final partial word padded with zero bytes.
bool	donner::fonts::ValidateSfnt (std::span< const uint8_t > data)
	Return true when `data` passes the bounded sfnt and outline validation policy.
std::optional< std::span< const uint8_t > >	donner::fonts::FindSfntTable (std::span< const uint8_t > data, std::string_view tag)
	Return a bounded sfnt table by its four-byte tag.

Variables
constexpr size_t	donner::fonts::kMaximumSfntTables = 4096
	Maximum number of entries accepted in an sfnt table directory.
constexpr size_t	donner::fonts::kMaximumCompoundGlyphDepth = 32
	Maximum number of glyph frames reached while expanding a TrueType compound glyph.
constexpr size_t	donner::fonts::kMaximumCompoundComponentRecords = 65536
	Maximum component records stored or expanded by one accepted TrueType font.
constexpr size_t	donner::fonts::kMaximumSimpleGlyphPoints = 16 * 1024 * 1024
	Maximum simple-glyph points examined while validating one TrueType font.
constexpr size_t	donner::fonts::kMaximumExpandedGlyphVertices = 1024 * 1024
	Maximum vertices that stb_truetype may allocate while expanding one TrueType glyph.
constexpr size_t	donner::fonts::kMaximumGlyphOutlineWork = 16 * 1024 * 1024
	Maximum decode, transform, and prefix-copy work allowed for one TrueType glyph outline.

Class Documentation

◆ donner::fonts::SfntFont::TableRecord

struct donner::fonts::SfntFont::TableRecord

A table location validated against the original font byte span.

Class Members
uint32_t	length = 0
uint32_t	offset = 0
uint32_t	tag = 0

◆ donner::fonts::SfntFont::GlyphOutlineComplexity

struct donner::fonts::SfntFont::GlyphOutlineComplexity

Allocation and CPU-work ceiling proved for one glyph outline.

Class Members
uint32_t	maximumVertices = 0
uint32_t	work = 0

Function Documentation

◆ FindSfntTable()

std::optional< std::span< const uint8_t > > donner::fonts::FindSfntTable	(	std::span< const uint8_t >	data,
		std::string_view	tag )

Return a bounded sfnt table by its four-byte tag.

This compatibility helper performs a fresh, explicitly bounded validation. Repeated callers should retain a donner::fonts::SfntFont and call donner::fonts::SfntFont::findTable instead.

◆ SfntTableChecksum()

uint32_t donner::fonts::SfntTableChecksum	(	std::span< const uint8_t >	data,
		uint32_t	initial = 0 )

Compute an sfnt table-directory checksum: the sum, modulo 2^32, of the table's big-endian 32-bit words, with a final partial word padded with zero bytes.

Checksums of consecutive chunks add up, so a long table can be summed in pieces by passing each piece's result as the next piece's initial; every piece but the last must be a multiple of four bytes long.

Parameters

data	Table bytes, or the next chunk of them.
initial	Sum of the preceding chunks of the same table.

Returns: The checksum of everything summed so far.

Classes

Namespaces