ref: eb2b5bb10754da426b4ea9da78fbb017f0bcb9ec
dir: /src/type1/t1parse.c/
/****************************************************************************
*
* t1parse.c
*
* Type 1 parser (body).
*
* Copyright (C) 1996-2020 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.
*
*/
/**************************************************************************
*
* The Type 1 parser is in charge of the following:
*
* - provide an implementation of a growing sequence of objects called
* a `T1_Table' (used to build various tables needed by the loader).
*
* - opening .pfb and .pfa files to extract their top-level and private
* dictionaries.
*
* - read numbers, arrays & strings from any dictionary.
*
* See `t1load.c' to see how data is loaded from the font file.
*
*/
#include <freetype/internal/ftdebug.h>
#include <freetype/internal/ftstream.h>
#include <freetype/internal/psaux.h>
#include "t1parse.h"
#include "t1errors.h"
/**************************************************************************
*
* 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 t1parse
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/***** *****/
/***** INPUT STREAM PARSER *****/
/***** *****/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/* see Adobe Technical Note 5040.Download_Fonts.pdf */
static FT_Error
read_pfb_tag( FT_Stream stream,
FT_UShort *atag,
FT_ULong *asize )
{
FT_Error error;
FT_UShort tag;
FT_ULong size;
*atag = 0;
*asize = 0;
if ( !FT_READ_USHORT( tag ) )
{
if ( tag == 0x8001U || tag == 0x8002U )
{
if ( !FT_READ_ULONG_LE( size ) )
*asize = size;
}
*atag = tag;
}
return error;
}
static FT_Error
check_type1_format( FT_Stream stream,
const char* header_string,
size_t header_length )
{
FT_Error error;
FT_UShort tag;
FT_ULong dummy;
if ( FT_STREAM_SEEK( 0 ) )
goto Exit;
error = read_pfb_tag( stream, &tag, &dummy );
if ( error )
goto Exit;
/* We assume that the first segment in a PFB is always encoded as */
/* text. This might be wrong (and the specification doesn't insist */
/* on that), but we have never seen a counterexample. */
if ( tag != 0x8001U && FT_STREAM_SEEK( 0 ) )
goto Exit;
if ( !FT_FRAME_ENTER( header_length ) )
{
error = FT_Err_Ok;
if ( ft_memcmp( stream->cursor, header_string, header_length ) != 0 )
error = FT_THROW( Unknown_File_Format );
FT_FRAME_EXIT();
}
Exit:
return error;
}
FT_LOCAL_DEF( FT_Error )
T1_New_Parser( T1_Parser parser,
FT_Stream stream,
FT_Memory memory,
PSAux_Service psaux )
{
FT_Error error;
FT_UShort tag;
FT_ULong size;
psaux->ps_parser_funcs->init( &parser->root, NULL, NULL, memory );
parser->stream = stream;
parser->base_len = 0;
parser->base_dict = NULL;
parser->private_len = 0;
parser->private_dict = NULL;
parser->in_pfb = 0;
parser->in_memory = 0;
parser->single_block = 0;
/* check the header format */
error = check_type1_format( stream, "%!PS-AdobeFont", 14 );
if ( error )
{
if ( FT_ERR_NEQ( error, Unknown_File_Format ) )
goto Exit;
error = check_type1_format( stream, "%!FontType", 10 );
if ( error )
{
FT_TRACE2(( " not a Type 1 font\n" ));
goto Exit;
}
}
/*******************************************************************
*
* Here a short summary of what is going on:
*
* When creating a new Type 1 parser, we try to locate and load
* the base dictionary if this is possible (i.e., for PFB
* files). Otherwise, we load the whole font into memory.
*
* When `loading' the base dictionary, we only setup pointers
* in the case of a memory-based stream. Otherwise, we
* allocate and load the base dictionary in it.
*
* parser->in_pfb is set if we are in a binary (`.pfb') font.
* parser->in_memory is set if we have a memory stream.
*/
/* try to compute the size of the base dictionary; */
/* look for a Postscript binary file tag, i.e., 0x8001 */
if ( FT_STREAM_SEEK( 0L ) )
goto Exit;
error = read_pfb_tag( stream, &tag, &size );
if ( error )
goto Exit;
if ( tag != 0x8001U )
{
/* assume that this is a PFA file for now; an error will */
/* be produced later when more things are checked */
if ( FT_STREAM_SEEK( 0L ) )
goto Exit;
size = stream->size;
}
else
parser->in_pfb = 1;
/* now, try to load `size' bytes of the `base' dictionary we */
/* found previously */
/* if it is a memory-based resource, set up pointers */
if ( !stream->read )
{
parser->base_dict = (FT_Byte*)stream->base + stream->pos;
parser->base_len = size;
parser->in_memory = 1;
/* check that the `size' field is valid */
if ( FT_STREAM_SKIP( size ) )
goto Exit;
}
else
{
/* read segment in memory -- this is clumsy, but so does the format */
if ( FT_ALLOC( parser->base_dict, size ) ||
FT_STREAM_READ( parser->base_dict, size ) )
goto Exit;
parser->base_len = size;
}
parser->root.base = parser->base_dict;
parser->root.cursor = parser->base_dict;
parser->root.limit = parser->root.cursor + parser->base_len;
Exit:
if ( error && !parser->in_memory )
FT_FREE( parser->base_dict );
return error;
}
FT_LOCAL_DEF( void )
T1_Finalize_Parser( T1_Parser parser )
{
FT_Memory memory = parser->root.memory;
/* always free the private dictionary */
FT_FREE( parser->private_dict );
/* free the base dictionary only when we have a disk stream */
if ( !parser->in_memory )
FT_FREE( parser->base_dict );
parser->root.funcs.done( &parser->root );
}
FT_LOCAL_DEF( FT_Error )
T1_Get_Private_Dict( T1_Parser parser,
PSAux_Service psaux )
{
FT_Stream stream = parser->stream;
FT_Memory memory = parser->root.memory;
FT_Error error = FT_Err_Ok;
FT_ULong size;
if ( parser->in_pfb )
{
/* in the case of the PFB format, the private dictionary can be */
/* made of several segments. We thus first read the number of */
/* segments to compute the total size of the private dictionary */
/* then re-read them into memory. */
FT_ULong start_pos = FT_STREAM_POS();
FT_UShort tag;
parser->private_len = 0;
for (;;)
{
error = read_pfb_tag( stream, &tag, &size );
if ( error )
goto Fail;
if ( tag != 0x8002U )
break;
parser->private_len += size;
if ( FT_STREAM_SKIP( size ) )
goto Fail;
}
/* Check that we have a private dictionary there */
/* and allocate private dictionary buffer */
if ( parser->private_len == 0 )
{
FT_ERROR(( "T1_Get_Private_Dict:"
" invalid private dictionary section\n" ));
error = FT_THROW( Invalid_File_Format );
goto Fail;
}
if ( FT_STREAM_SEEK( start_pos ) ||
FT_ALLOC( parser->private_dict, parser->private_len ) )
goto Fail;
parser->private_len = 0;
for (;;)
{
error = read_pfb_tag( stream, &tag, &size );
if ( error || tag != 0x8002U )
{
error = FT_Err_Ok;
break;
}
if ( FT_STREAM_READ( parser->private_dict + parser->private_len,
size ) )
goto Fail;
parser->private_len += size;
}
}
else
{
/* We have already `loaded' the whole PFA font file into memory; */
/* if this is a memory resource, allocate a new block to hold */
/* the private dict. Otherwise, simply overwrite into the base */
/* dictionary block in the heap. */
/* first of all, look at the `eexec' keyword */
FT_Byte* cur = parser->base_dict;
FT_Byte* limit = cur + parser->base_len;
FT_Pointer pos_lf;
FT_Bool test_cr;
Again:
for (;;)
{
if ( cur[0] == 'e' &&
cur + 9 < limit ) /* 9 = 5 letters for `eexec' + */
/* whitespace + 4 chars */
{
if ( cur[1] == 'e' &&
cur[2] == 'x' &&
cur[3] == 'e' &&
cur[4] == 'c' )
break;
}
cur++;
if ( cur >= limit )
{
FT_ERROR(( "T1_Get_Private_Dict:"
" could not find `eexec' keyword\n" ));
error = FT_THROW( Invalid_File_Format );
goto Exit;
}
}
/* check whether `eexec' was real -- it could be in a comment */
/* or string (as e.g. in u003043t.gsf from ghostscript) */
parser->root.cursor = parser->base_dict;
/* set limit to `eexec' + whitespace + 4 characters */
parser->root.limit = cur + 10;
cur = parser->root.cursor;
limit = parser->root.limit;
while ( cur < limit )
{
if ( cur[0] == 'e' &&
cur + 5 < limit )
{
if ( cur[1] == 'e' &&
cur[2] == 'x' &&
cur[3] == 'e' &&
cur[4] == 'c' )
goto Found;
}
T1_Skip_PS_Token( parser );
if ( parser->root.error )
break;
T1_Skip_Spaces ( parser );
cur = parser->root.cursor;
}
/* we haven't found the correct `eexec'; go back and continue */
/* searching */
cur = limit;
limit = parser->base_dict + parser->base_len;
if ( cur >= limit )
{
FT_ERROR(( "T1_Get_Private_Dict:"
" premature end in private dictionary\n" ));
error = FT_THROW( Invalid_File_Format );
goto Exit;
}
goto Again;
/* now determine where to write the _encrypted_ binary private */
/* dictionary. We overwrite the base dictionary for disk-based */
/* resources and allocate a new block otherwise */
Found:
parser->root.limit = parser->base_dict + parser->base_len;
T1_Skip_PS_Token( parser );
cur = parser->root.cursor;
limit = parser->root.limit;
/* According to the Type 1 spec, the first cipher byte must not be */
/* an ASCII whitespace character code (blank, tab, carriage return */
/* or line feed). We have seen Type 1 fonts with two line feed */
/* characters... So skip now all whitespace character codes. */
/* */
/* On the other hand, Adobe's Type 1 parser handles fonts just */
/* fine that are violating this limitation, so we add a heuristic */
/* test to stop at \r only if it is not used for EOL. */
pos_lf = ft_memchr( cur, '\n', (size_t)( limit - cur ) );
test_cr = FT_BOOL( !pos_lf ||
pos_lf > ft_memchr( cur,
'\r',
(size_t)( limit - cur ) ) );
while ( cur < limit &&
( *cur == ' ' ||
*cur == '\t' ||
(test_cr && *cur == '\r' ) ||
*cur == '\n' ) )
cur++;
if ( cur >= limit )
{
FT_ERROR(( "T1_Get_Private_Dict:"
" `eexec' not properly terminated\n" ));
error = FT_THROW( Invalid_File_Format );
goto Exit;
}
size = parser->base_len - (FT_ULong)( cur - parser->base_dict );
if ( parser->in_memory )
{
/* note that we allocate one more byte to put a terminating `0' */
if ( FT_ALLOC( parser->private_dict, size + 1 ) )
goto Fail;
parser->private_len = size;
}
else
{
parser->single_block = 1;
parser->private_dict = parser->base_dict;
parser->private_len = size;
parser->base_dict = NULL;
parser->base_len = 0;
}
/* now determine whether the private dictionary is encoded in binary */
/* or hexadecimal ASCII format -- decode it accordingly */
/* we need to access the next 4 bytes (after the final whitespace */
/* following the `eexec' keyword); if they all are hexadecimal */
/* digits, then we have a case of ASCII storage */
if ( cur + 3 < limit &&
ft_isxdigit( cur[0] ) && ft_isxdigit( cur[1] ) &&
ft_isxdigit( cur[2] ) && ft_isxdigit( cur[3] ) )
{
/* ASCII hexadecimal encoding */
FT_ULong len;
parser->root.cursor = cur;
(void)psaux->ps_parser_funcs->to_bytes( &parser->root,
parser->private_dict,
parser->private_len,
&len,
0 );
parser->private_len = len;
/* put a safeguard */
parser->private_dict[len] = '\0';
}
else
/* binary encoding -- copy the private dict */
FT_MEM_MOVE( parser->private_dict, cur, size );
}
/* we now decrypt the encoded binary private dictionary */
psaux->t1_decrypt( parser->private_dict, parser->private_len, 55665U );
if ( parser->private_len < 4 )
{
FT_ERROR(( "T1_Get_Private_Dict:"
" invalid private dictionary section\n" ));
error = FT_THROW( Invalid_File_Format );
goto Fail;
}
/* replace the four random bytes at the beginning with whitespace */
parser->private_dict[0] = ' ';
parser->private_dict[1] = ' ';
parser->private_dict[2] = ' ';
parser->private_dict[3] = ' ';
parser->root.base = parser->private_dict;
parser->root.cursor = parser->private_dict;
parser->root.limit = parser->root.cursor + parser->private_len;
Fail:
Exit:
return error;
}
/* END */