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[woff2] Read table and collection directory.

Browse Source 
* include/freetype/internal/wofftypes.h (WOFF2_TtcFontRec): New
structure.
(WOFF2_HeaderRec): Add more fields.

* src/sfnt/woff2.c (READ_255USHORT, READ_BASE128, ROUND4): New macros.
(Read255UShort, CollectionHeaderSize, compute_first_table_offset): New
functions.
(woff2_open_font): Add functionality to read table directory and
collection directory (if present).
GSoC-2019-nikhil
Nikhil Ramakrishnan 6 years ago
parent d614e8afbc
commit e635053045
2 changed files with 348 additions and 21 deletions
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  1. 42
      include/freetype/internal/wofftypes.h
  2. 327
      src/sfnt/sfwoff2.c

42
include/freetype/internal/wofftypes.h
Unescape View File

@ -104,6 +104,42 @@ FT_BEGIN_HEADER
} WOFF_TableRec, *WOFF_Table;
/**************************************************************************
*
* @struct:
* WOFF2_TtcFontRec
*
* @description:
* Metadata for a TTC font entry in WOFF2.
*
* @fields:
* flavor ::
* TTC font flavor.
*
* num_tables ::
* Number of tables in TTC, indicating number of elements in
* `table_indices`.
*
* dst_offset ::
* Uncompressed table offset.
*
* header_checksum ::
* Checksum for font header.
*
* table_indices ::
* Array of table indices for each TTC font.
*/
typedef struct WOFF2_TtcFontRec_
{
FT_ULong flavor;
FT_UShort num_tables;
FT_ULong dst_offset;
FT_ULong header_checksum;
FT_UShort* table_indices;
} WOFF2_TtcFontRec, *WOFF2_TtcFont;
/**************************************************************************
*
* @struct:
@ -123,7 +159,7 @@ FT_BEGIN_HEADER
* does not necessarily represent the actual size of the uncompressed
* SFNT font stream, so that is not included either.
*/
typedef struct WOFF2_HeaderRec
typedef struct WOFF2_HeaderRec_
{
FT_ULong signature;
FT_ULong flavor;
@ -137,7 +173,11 @@ FT_BEGIN_HEADER
FT_ULong privLength;
FT_ULong uncompressed_size;
FT_UInt64 compressed_offset;
FT_ULong header_version;
FT_UShort num_fonts;
WOFF2_TtcFont ttc_fonts;
} WOFF2_HeaderRec, *WOFF2_Header;

327
src/sfnt/sfwoff2.c
Unescape View File

@ -17,6 +17,7 @@
#include <ft2build.h>
#include "sfwoff2.h"
#include "woff2tags.h"
#include FT_TRUETYPE_TAGS_H
#include FT_INTERNAL_DEBUG_H
#include FT_INTERNAL_STREAM_H
@ -32,6 +33,57 @@
#define FT_COMPONENT sfwoff2
#define READ_255USHORT( var ) Read255UShort( stream, &var )
#define READ_BASE128( var ) ReadBase128( stream, &var )
#define ROUND4( var ) ( var + 3 ) & ~3
static FT_Error
Read255UShort( FT_Stream stream,
FT_UShort* value )
{
static const FT_Int oneMoreByteCode1 = 255;
static const FT_Int oneMoreByteCode2 = 254;
static const FT_Int wordCode = 253;
static const FT_Int lowestUCode = 253;
FT_Error error;
FT_Byte code;
FT_Byte result_byte = 0;
FT_UShort result_short = 0;
if( FT_READ_BYTE( code ) )
return FT_THROW( Invalid_Table );
if( code == wordCode )
{
/* Read next two bytes and store UInt16 value */
if( FT_READ_USHORT( result_short ) )
return FT_THROW( Invalid_Table );
*value = result_short;
return FT_Err_Ok;
}
else if( code == oneMoreByteCode1 )
{
if( FT_READ_BYTE( result_byte ) )
return FT_THROW( Invalid_Table );
*value = result_byte + lowestUCode;
return FT_Err_Ok;
}
else if( code == oneMoreByteCode2 )
{
if( FT_READ_BYTE( result_byte ) )
return FT_THROW( Invalid_Table );
*value = result_byte + lowestUCode * 2;
return FT_Err_Ok;
}
else
{
*value = code;
return FT_Err_Ok;
}
}
static FT_Error
ReadBase128( FT_Stream stream,
FT_ULong* value )
@ -39,11 +91,12 @@
FT_ULong result = 0;
FT_Int i;
FT_Byte code;
FT_Byte* p = stream->cursor;
FT_Error error;
for ( i = 0; i < 5; ++i ) {
code = 0;
code = FT_NEXT_BYTE( p );
if( FT_READ_BYTE( code ) )
return FT_THROW( Invalid_Table );
/* Leading zeros are invalid. */
if ( i == 0 && code == 0x80 ) {
@ -68,6 +121,41 @@
}
static FT_Offset
CollectionHeaderSize( FT_ULong header_version,
FT_UShort num_fonts )
{
FT_Offset size = 0;
if (header_version == 0x00020000)
size += 12; /* ulDsig{Tag,Length,Offset} */
if (header_version == 0x00010000 || header_version == 0x00020000) {
size += 12 /* TTCTag, Version, numFonts */
+ ( 4 * num_fonts ); /* OffsetTable[numFonts] */
}
return size;
}
static FT_Error
compute_first_table_offset( const WOFF2_Header woff2 )
{
FT_Int nn;
FT_Offset offset = WOFF2_SFNT_HEADER_SIZE +
( WOFF2_SFNT_ENTRY_SIZE *
(FT_Offset)( woff2->num_tables ) );
if(woff2->header_version)
{
offset = CollectionHeaderSize( woff2->header_version,
woff2->num_fonts )
+ WOFF2_SFNT_HEADER_SIZE * woff2->num_fonts;
for ( nn = 0; nn< woff2->num_fonts; nn++ ) {
offset += WOFF2_SFNT_ENTRY_SIZE * woff2->ttc_fonts[nn].num_tables;
}
}
return offset;
}
/* Replace `face->root.stream' with a stream containing the extracted */
/* SFNT of a WOFF2 font. */
@ -77,12 +165,23 @@
{
FT_Memory memory = stream->memory;
FT_Error error = FT_Err_Ok;
FT_Byte* p = stream->cursor;
FT_Byte* limit = stream->limit;
WOFF2_HeaderRec woff2;
WOFF2_Table tables = NULL;
WOFF2_Table* indices = NULL;
WOFF2_Table last_table;
FT_Int nn;
FT_ULong j;
FT_ULong flags;
FT_UShort xform_version;
FT_ULong src_offset = 0;
FT_UShort ttc_num_tables;
FT_UInt glyf_index;
FT_UInt loca_index;
FT_UInt64 first_table_offset;
FT_UInt64 file_offset;
static const FT_Frame_Field woff2_header_fields[] =
{
@ -105,14 +204,9 @@
FT_FRAME_END
};
FT_UNUSED( p );
FT_UNUSED( limit );
FT_UNUSED( tables );
FT_UNUSED( indices );
FT_UNUSED( memory );
/* DEBUG - Remove later */
FT_TRACE2(("woff2_open_font: Received Data.\n"));
FT_TRACE2(( "woff2_open_font: Received Data.\n" ));
FT_ASSERT( stream == face->root.stream );
FT_ASSERT( FT_STREAM_POS() == 0 );
@ -122,14 +216,14 @@
return error;
/* DEBUG - Remove later. */
FT_TRACE2(("signature -> 0x%X\n", woff2.signature));
FT_TRACE2(("flavor -> 0x%X\n", woff2.flavor));
FT_TRACE2(("length -> %lu\n", woff2.length));
FT_TRACE2(("num_tables -> %hu\n", woff2.num_tables));
FT_TRACE2(("metaOffset -> %hu\n", woff2.metaOffset));
FT_TRACE2(("metaLength -> %hu\n", woff2.metaLength));
FT_TRACE2(("privOffset -> %hu\n", woff2.privOffset));
FT_TRACE2(("privLength -> %hu\n", woff2.privLength));
FT_TRACE2(( "signature -> 0x%X\n", woff2.signature ));
FT_TRACE2(( "flavor -> 0x%X\n", woff2.flavor ));
FT_TRACE2(( "length -> %lu\n", woff2.length ));
FT_TRACE2(( "num_tables -> %hu\n", woff2.num_tables ));
FT_TRACE2(( "metaOffset -> %hu\n", woff2.metaOffset ));
FT_TRACE2(( "metaLength -> %hu\n", woff2.metaLength ));
FT_TRACE2(( "privOffset -> %hu\n", woff2.privOffset ));
FT_TRACE2(( "privLength -> %hu\n", woff2.privLength ));
/* Make sure we don't recurse back here. */
if ( woff2.flavor == TTAG_wOF2 )
@ -153,12 +247,205 @@
}
/* DEBUG - Remove later. */
else{
FT_TRACE2(("WOFF2 Header is valid.\n"));
FT_TRACE2(( "WOFF2 Header is valid.\n" ));
}
/* Read table directory. */
if ( FT_NEW_ARRAY( tables, woff2.num_tables ) ||
FT_NEW_ARRAY( indices, woff2.num_tables ) )
goto Exit;
FT_TRACE2(( "\n"
" tag flags transform origLen transformLen\n"
" --------------------------------------------------\n" ));
/* TODO check whether there is sufficient input before FT_READ_*. */
for ( nn = 0; nn < woff2.num_tables; nn++ )
{
WOFF2_Table table = tables + nn;
if( FT_READ_BYTE( table->FlagByte ) )
goto Exit;
if ( ( table->FlagByte & 0x3f ) == 0x3f )
{
if( FT_READ_ULONG( table->Tag ) )
goto Exit;
}
else
table->Tag = KnownTags[table->FlagByte & 0x3f];
flags = 0;
xform_version = ( table->FlagByte >> 6 ) & 0x03;
/* 0 means xform for glyph/loca, non-0 for others. */
if ( table->Tag == TTAG_glyf || table->Tag == TTAG_loca )
{
if ( xform_version == 0 )
flags |= WOFF2_FLAGS_TRANSFORM;
}
else if ( xform_version != 0 )
flags |= WOFF2_FLAGS_TRANSFORM;
flags |= xform_version;
if( READ_BASE128( table->OrigLength ) )
goto Exit;
table->TransformLength = table->OrigLength;
if ( ( flags & WOFF2_FLAGS_TRANSFORM ) != 0 )
{
if( READ_BASE128( table->TransformLength ) )
goto Exit;
if( table->Tag == TTAG_loca && table->TransformLength )
{
FT_ERROR(( "woff_font_open: Invalid loca `transformLength'.\n" ));
return FT_THROW( Invalid_Table );
}
}
if ( src_offset + table->TransformLength < src_offset )
{
FT_ERROR(( "woff_font_open: invalid WOFF2 table directory.\n" ));
return FT_THROW( Invalid_Table );
}
table->src_offset = src_offset;
table->src_length = table->TransformLength;
src_offset += table->TransformLength;
table->flags = flags;
FT_TRACE2(( " %c%c%c%c %08d %08d %08ld %08ld\n",
(FT_Char)( table->Tag >> 24 ),
(FT_Char)( table->Tag >> 16 ),
(FT_Char)( table->Tag >> 8 ),
(FT_Char)( table->Tag ),
table->FlagByte & 0x3f,
( table->FlagByte >> 6 ) & 0x03,
table->OrigLength,
table->TransformLength,
table->src_length,
table->src_offset ));
indices[nn] = table;
}
/* TODO Read table directory. */
/* End of last table is uncompressed size. */
last_table = indices[woff2.num_tables - 1];
woff2.uncompressed_size = last_table->src_offset
+ last_table->src_length;
if( woff2.uncompressed_size < last_table->src_offset )
return FT_THROW( Invalid_Table );
/* DEBUG - Remove later. */
FT_TRACE2(( "Uncompressed size: %ld\n", woff2.uncompressed_size ));
FT_TRACE2(( "Table directory successfully parsed.\n" ));
/* Check for and read collection directory. */
woff2.header_version = 0;
if( woff2.flavor == TTAG_ttcf ){
FT_TRACE2(( "Font is a TTC, reading collection directory.\n" ));
if( FT_READ_ULONG( woff2.header_version ) )
goto Exit;
/* DEBUG - Remove later */
FT_TRACE2(( "Header version: %lx\n", woff2.header_version ));
if( woff2.header_version != 0x00010000 &&
woff2.header_version != 0x00020000 )
return FT_THROW( Invalid_Table );
if( READ_255USHORT( woff2.num_fonts ) )
goto Exit;
/* DEBUG - Remove later */
FT_TRACE2(( "Number of fonts in TTC: %ld\n", woff2.num_fonts ));
if( FT_NEW_ARRAY( woff2.ttc_fonts, woff2.num_fonts ) )
goto Exit;
for ( nn = 0; nn < woff2.num_fonts; nn++ )
{
WOFF2_TtcFont ttc_font = woff2.ttc_fonts + nn;
if( READ_255USHORT( ttc_num_tables ) )
goto Exit;
if( FT_READ_ULONG( ttc_font->flavor ) )
goto Exit;
if( FT_NEW_ARRAY( ttc_font->table_indices, ttc_num_tables ) )
goto Exit;
/* DEBUG - Change to TRACE4 */
FT_TRACE2(( "Number of tables in font %d: %ld\n",
nn, ttc_num_tables ));
/* DEBUG - Change to TRACE5 */
FT_TRACE2(( " Indices: " ));
glyf_index = 0;
loca_index = 0;
for ( j = 0; j < ttc_num_tables; j++ )
{
FT_UShort table_index;
WOFF2_Table table;
if( READ_255USHORT( table_index ) )
goto Exit;
/* DEBUG - Change to TRACE5 */
FT_TRACE2(("%hu ", table_index));
ttc_font->table_indices[j] = table_index;
table = indices[table_index];
if( table->Tag == TTAG_loca )
loca_index = table_index;
if( table->Tag == TTAG_glyf )
glyf_index = table_index;
}
/* DEBUG - Change to TRACE5 */
FT_TRACE2(( "\n" ));
/* glyf and loca must be consecutive */
if( glyf_index > 0 || loca_index > 0 )
{
if(glyf_index > loca_index || loca_index - glyf_index != 1)
return FT_THROW( Invalid_Table );
/* DEBUG - Remove later */
else
FT_TRACE2(( "Glyf and loca are valid.\n" ));
}
}
/* Collection directory reading complete. */
FT_TRACE2(( "WOFF2 collection dirtectory is valid.\n" ));
}
first_table_offset = compute_first_table_offset( &woff2 );
FT_TRACE2(( "Offset to first table: %ld\n", first_table_offset ));
woff2.compressed_offset = FT_STREAM_POS();
file_offset = ROUND4( woff2.compressed_offset +
woff2.totalCompressedSize );
/* Few more checks before we start reading the tables */
if( file_offset > woff2.length )
return FT_THROW( Invalid_Table );
if ( woff2.metaOffset )
{
if ( file_offset != woff2.metaOffset )
return FT_THROW( Invalid_Table );
file_offset = ROUND4(woff2.metaOffset + woff2.metaLength);
}
if( woff2.privOffset )
{
if( file_offset != woff2.privOffset )
return FT_THROW( Invalid_Table );
file_offset = ROUND4(woff2.privOffset + woff2.privLength);
}
if( file_offset != ( ROUND4( woff2.length ) ) )
return FT_THROW( Invalid_Table );
error = FT_THROW( Unimplemented_Feature );
FT_TRACE2(( "Reached end without errors.\n" ));
goto Exit;
Exit:

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