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freetype/src/sfnt/sfwoff.c
Ben Wagner 58395dd200 [woff] Don't allocate table entries until needed 
* src/sfnt/sfwoff.c (woff_open_font): delay allocating space for the
table entries until they are actually written out with the data.
2022-06-13 15:32:28 -04:00

435 lines
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C
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/****************************************************************************
*
* sfwoff.c
*
* WOFF format management (base).
*
* Copyright (C) 1996-2022 by
* David Turner, Robert Wilhelm, and Werner Lemberg.
*
* This file is part of the FreeType project, and may only be used,
* modified, and distributed under the terms of the FreeType project
* license, LICENSE.TXT. By continuing to use, modify, or distribute
* this file you indicate that you have read the license and
* understand and accept it fully.
*
*/
#include "sfwoff.h"
#include <freetype/tttags.h>
#include <freetype/internal/ftdebug.h>
#include <freetype/internal/ftstream.h>
#include <freetype/ftgzip.h>
#ifdef FT_CONFIG_OPTION_USE_ZLIB
/**************************************************************************
*
* The macro FT_COMPONENT is used in trace mode. It is an implicit
* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log
* messages during execution.
*/
#undef FT_COMPONENT
#define FT_COMPONENT sfwoff
#define WRITE_USHORT( p, v ) \
do \
{ \
*(p)++ = (FT_Byte)( (v) >> 8 ); \
*(p)++ = (FT_Byte)( (v) >> 0 ); \
\
} while ( 0 )
#define WRITE_ULONG( p, v ) \
do \
{ \
*(p)++ = (FT_Byte)( (v) >> 24 ); \
*(p)++ = (FT_Byte)( (v) >> 16 ); \
*(p)++ = (FT_Byte)( (v) >> 8 ); \
*(p)++ = (FT_Byte)( (v) >> 0 ); \
\
} while ( 0 )
static void
sfnt_stream_close( FT_Stream stream )
{
FT_Memory memory = stream->memory;
FT_FREE( stream->base );
stream->size = 0;
stream->close = NULL;
}
FT_COMPARE_DEF( int )
compare_offsets( const void* a,
const void* b )
{
WOFF_Table table1 = *(WOFF_Table*)a;
WOFF_Table table2 = *(WOFF_Table*)b;
FT_ULong offset1 = table1->Offset;
FT_ULong offset2 = table2->Offset;
if ( offset1 > offset2 )
return 1;
else if ( offset1 < offset2 )
return -1;
else
return 0;
}
/* Replace `face->root.stream' with a stream containing the extracted */
/* SFNT of a WOFF font. */
FT_LOCAL_DEF( FT_Error )
woff_open_font( FT_Stream stream,
TT_Face face )
{
FT_Memory memory = stream->memory;
FT_Error error = FT_Err_Ok;
WOFF_HeaderRec woff;
WOFF_Table tables = NULL;
WOFF_Table* indices = NULL;
FT_ULong woff_offset;
FT_Byte* sfnt = NULL;
FT_Stream sfnt_stream = NULL;
FT_Byte* sfnt_header;
FT_ULong sfnt_offset;
FT_Int nn;
FT_Tag old_tag = 0;
static const FT_Frame_Field woff_header_fields[] =
{
#undef FT_STRUCTURE
#define FT_STRUCTURE WOFF_HeaderRec
FT_FRAME_START( 44 ),
FT_FRAME_ULONG ( signature ),
FT_FRAME_ULONG ( flavor ),
FT_FRAME_ULONG ( length ),
FT_FRAME_USHORT( num_tables ),
FT_FRAME_USHORT( reserved ),
FT_FRAME_ULONG ( totalSfntSize ),
FT_FRAME_USHORT( majorVersion ),
FT_FRAME_USHORT( minorVersion ),
FT_FRAME_ULONG ( metaOffset ),
FT_FRAME_ULONG ( metaLength ),
FT_FRAME_ULONG ( metaOrigLength ),
FT_FRAME_ULONG ( privOffset ),
FT_FRAME_ULONG ( privLength ),
FT_FRAME_END
};
FT_ASSERT( stream == face->root.stream );
FT_ASSERT( FT_STREAM_POS() == 0 );
if ( FT_STREAM_READ_FIELDS( woff_header_fields, &woff ) )
return error;
/* Make sure we don't recurse back here or hit TTC code. */
if ( woff.flavor == TTAG_wOFF || woff.flavor == TTAG_ttcf )
return FT_THROW( Invalid_Table );
/* Miscellaneous checks. */
if ( woff.length != stream->size ||
woff.num_tables == 0 ||
44 + woff.num_tables * 20UL >= woff.length ||
12 + woff.num_tables * 16UL >= woff.totalSfntSize ||
( woff.totalSfntSize & 3 ) != 0 ||
( woff.metaOffset == 0 && ( woff.metaLength != 0 ||
woff.metaOrigLength != 0 ) ) ||
( woff.metaLength != 0 && woff.metaOrigLength == 0 ) ||
( woff.privOffset == 0 && woff.privLength != 0 ) )
{
FT_ERROR(( "woff_font_open: invalid WOFF header\n" ));
return FT_THROW( Invalid_Table );
}
/* Don't trust `totalSfntSize' before thorough checks. */
if ( FT_QALLOC( sfnt, 12 ) || FT_NEW( sfnt_stream ) )
goto Exit;
sfnt_header = sfnt;
/* Write sfnt header. */
{
FT_UInt searchRange, entrySelector, rangeShift, x;
x = woff.num_tables;
entrySelector = 0;
while ( x )
{
x >>= 1;
entrySelector += 1;
}
entrySelector--;
searchRange = ( 1 << entrySelector ) * 16;
rangeShift = woff.num_tables * 16 - searchRange;
WRITE_ULONG ( sfnt_header, woff.flavor );
WRITE_USHORT( sfnt_header, woff.num_tables );
WRITE_USHORT( sfnt_header, searchRange );
WRITE_USHORT( sfnt_header, entrySelector );
WRITE_USHORT( sfnt_header, rangeShift );
}
/* While the entries in the sfnt header must be sorted by the */
/* tag value, the tables themselves are not. We thus have to */
/* sort them by offset and check that they don't overlap. */
if ( FT_QNEW_ARRAY( tables, woff.num_tables ) ||
FT_QNEW_ARRAY( indices, woff.num_tables ) )
goto Exit;
FT_TRACE2(( "\n" ));
FT_TRACE2(( " tag offset compLen origLen checksum\n" ));
FT_TRACE2(( " -------------------------------------------\n" ));
if ( FT_FRAME_ENTER( 20L * woff.num_tables ) )
goto Exit;
for ( nn = 0; nn < woff.num_tables; nn++ )
{
WOFF_Table table = tables + nn;
table->Tag = FT_GET_TAG4();
table->Offset = FT_GET_ULONG();
table->CompLength = FT_GET_ULONG();
table->OrigLength = FT_GET_ULONG();
table->CheckSum = FT_GET_ULONG();
FT_TRACE2(( " %c%c%c%c %08lx %08lx %08lx %08lx\n",
(FT_Char)( table->Tag >> 24 ),
(FT_Char)( table->Tag >> 16 ),
(FT_Char)( table->Tag >> 8 ),
(FT_Char)( table->Tag ),
table->Offset,
table->CompLength,
table->OrigLength,
table->CheckSum ));
if ( table->Tag <= old_tag )
{
FT_FRAME_EXIT();
FT_ERROR(( "woff_font_open: table tags are not sorted\n" ));
error = FT_THROW( Invalid_Table );
goto Exit;
}
old_tag = table->Tag;
indices[nn] = table;
}
FT_FRAME_EXIT();
/* Sort by offset. */
ft_qsort( indices,
woff.num_tables,
sizeof ( WOFF_Table ),
compare_offsets );
/* Check offsets and lengths. */
woff_offset = 44 + woff.num_tables * 20L;
sfnt_offset = 12 + woff.num_tables * 16L;
for ( nn = 0; nn < woff.num_tables; nn++ )
{
WOFF_Table table = indices[nn];
if ( table->Offset != woff_offset ||
table->CompLength > woff.length ||
table->Offset > woff.length - table->CompLength ||
table->OrigLength > woff.totalSfntSize ||
sfnt_offset > woff.totalSfntSize - table->OrigLength ||
table->CompLength > table->OrigLength )
{
FT_ERROR(( "woff_font_open: invalid table offsets\n" ));
error = FT_THROW( Invalid_Table );
goto Exit;
}
table->OrigOffset = sfnt_offset;
/* The offsets must be multiples of 4. */
woff_offset += ( table->CompLength + 3 ) & ~3U;
sfnt_offset += ( table->OrigLength + 3 ) & ~3U;
}
/*
* Final checks!
*
* We don't decode and check the metadata block.
* We don't check table checksums either.
* But other than those, I think we implement all
* `MUST' checks from the spec.
*/
if ( woff.metaOffset )
{
if ( woff.metaOffset != woff_offset ||
woff.metaOffset + woff.metaLength > woff.length )
{
FT_ERROR(( "woff_font_open:"
" invalid `metadata' offset or length\n" ));
error = FT_THROW( Invalid_Table );
goto Exit;
}
/* We have padding only ... */
woff_offset += woff.metaLength;
}
if ( woff.privOffset )
{
/* ... if it isn't the last block. */
woff_offset = ( woff_offset + 3 ) & ~3U;
if ( woff.privOffset != woff_offset ||
woff.privOffset + woff.privLength > woff.length )
{
FT_ERROR(( "woff_font_open: invalid `private' offset or length\n" ));
error = FT_THROW( Invalid_Table );
goto Exit;
}
/* No padding for the last block. */
woff_offset += woff.privLength;
}
if ( sfnt_offset != woff.totalSfntSize ||
woff_offset != woff.length )
{
FT_ERROR(( "woff_font_open: invalid `sfnt' table structure\n" ));
error = FT_THROW( Invalid_Table );
goto Exit;
}
/* Now use `totalSfntSize'. */
if ( FT_QREALLOC( sfnt, 12, woff.totalSfntSize ) )
goto Exit;
sfnt_header = sfnt + 12;
/* Write the tables. */
for ( nn = 0; nn < woff.num_tables; nn++ )
{
WOFF_Table table = tables + nn;
/* Write SFNT table entry. */
WRITE_ULONG( sfnt_header, table->Tag );
WRITE_ULONG( sfnt_header, table->CheckSum );
WRITE_ULONG( sfnt_header, table->OrigOffset );
WRITE_ULONG( sfnt_header, table->OrigLength );
/* Write table data. */
if ( FT_STREAM_SEEK( table->Offset ) ||
FT_FRAME_ENTER( table->CompLength ) )
goto Exit;
if ( table->CompLength == table->OrigLength )
{
/* Uncompressed data; just copy. */
ft_memcpy( sfnt + table->OrigOffset,
stream->cursor,
table->OrigLength );
}
else
{
/* Uncompress with zlib. */
FT_ULong output_len = table->OrigLength;
error = FT_Gzip_Uncompress( memory,
sfnt + table->OrigOffset, &output_len,
stream->cursor, table->CompLength );
if ( error )
goto Exit1;
if ( output_len != table->OrigLength )
{
FT_ERROR(( "woff_font_open: compressed table length mismatch\n" ));
error = FT_THROW( Invalid_Table );
goto Exit1;
}
}
FT_FRAME_EXIT();
/* We don't check whether the padding bytes in the WOFF file are */
/* actually '\0'. For the output, however, we do set them properly. */
sfnt_offset = table->OrigOffset + table->OrigLength;
while ( sfnt_offset & 3 )
{
sfnt[sfnt_offset] = '\0';
sfnt_offset++;
}
}
/* Ok! Finally ready. Swap out stream and return. */
FT_Stream_OpenMemory( sfnt_stream, sfnt, woff.totalSfntSize );
sfnt_stream->memory = stream->memory;
sfnt_stream->close = sfnt_stream_close;
FT_Stream_Free(
face->root.stream,
( face->root.face_flags & FT_FACE_FLAG_EXTERNAL_STREAM ) != 0 );
face->root.stream = sfnt_stream;
face->root.face_flags &= ~FT_FACE_FLAG_EXTERNAL_STREAM;
Exit:
FT_FREE( tables );
FT_FREE( indices );
if ( error )
{
FT_FREE( sfnt );
FT_Stream_Close( sfnt_stream );
FT_FREE( sfnt_stream );
}
return error;
Exit1:
FT_FRAME_EXIT();
goto Exit;
}
#undef WRITE_USHORT
#undef WRITE_ULONG
#else /* !FT_CONFIG_OPTION_USE_ZLIB */
/* ANSI C doesn't like empty source files */
typedef int _sfwoff_dummy;
#endif /* !FT_CONFIG_OPTION_USE_ZLIB */
/* END */
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