bug 747816 - update OTS to upstream r.91 to resolve endianness bug and other fixes. r=emk

This commit is contained in:
Jonathan Kew 2012-05-23 16:59:26 +01:00
parent 5d6b02c511
commit 8eeac70d03
7 changed files with 276 additions and 55 deletions

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@ -1,8 +1,12 @@
This is the Sanitiser for OpenType project, from http://code.google.com/p/ots/.
Current revision: r81
Current revision: r91
Applied local patches:
ots-fix-vc10.patch - workaround for VS10 STL wrappers (bug 602558)
ots-fix-sparc64.patch - fix alignment error on sparc64 (bug 643137)
ots-graphite.patch - preserve Graphite layout tables (bug 631479)
ots-visibility.patch - make Process function externally visible for Windows DLL (bug 711079)

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@ -26,6 +26,7 @@
#endif
#if defined(_WIN32)
#include <stdlib.h>
typedef signed char int8_t;
typedef unsigned char uint8_t;
typedef short int16_t;
@ -34,7 +35,10 @@ typedef int int32_t;
typedef unsigned int uint32_t;
typedef __int64 int64_t;
typedef unsigned __int64 uint64_t;
#include <winsock2.h> // for htons/ntohs
#define ntohl(x) _byteswap_ulong (x)
#define ntohs(x) _byteswap_ushort (x)
#define htonl(x) _byteswap_ulong (x)
#define htons(x) _byteswap_ushort (x)
#else
#include <arpa/inet.h>
#include <stdint.h>

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@ -1,11 +1,11 @@
diff --git a/gfx/ots/include/opentype-sanitiser.h b/gfx/ots/include/opentype-sanitiser.h
--- a/gfx/ots/include/opentype-sanitiser.h
+++ b/gfx/ots/include/opentype-sanitiser.h
@@ -57,18 +57,20 @@ class OTSStream {
@@ -83,18 +83,20 @@ class OTSStream {
if (chksum_buffer_offset_ == 4) {
// TODO(yusukes): This cast breaks the strict-aliasing rule.
chksum_ += ntohl(*reinterpret_cast<const uint32_t*>(chksum_buffer_));
uint32_t chksum;
std::memcpy(&chksum, chksum_buffer_, 4);
chksum_ += ntohl(chksum);
chksum_buffer_offset_ = 0;
}

131
gfx/ots/ots-graphite.patch Normal file
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@ -0,0 +1,131 @@
diff --git a/gfx/ots/include/opentype-sanitiser.h b/gfx/ots/include/opentype-sanitiser.h
--- a/gfx/ots/include/opentype-sanitiser.h
+++ b/gfx/ots/include/opentype-sanitiser.h
@@ -176,18 +176,20 @@ class OTSStream {
// -----------------------------------------------------------------------------
// Process a given OpenType file and write out a sanitised version
// output: a pointer to an object implementing the OTSStream interface. The
// sanitisied output will be written to this. In the even of a failure,
// partial output may have been written.
// input: the OpenType file
// length: the size, in bytes, of |input|
+// preserve_graphite_tables: whether to preserve Graphite Layout tables
// -----------------------------------------------------------------------------
-bool Process(OTSStream *output, const uint8_t *input, size_t length);
+bool Process(OTSStream *output, const uint8_t *input, size_t length,
+ bool preserve_graphite_tables = false);
// Force to disable debug output even when the library is compiled with
// -DOTS_DEBUG.
void DisableDebugOutput();
} // namespace ots
#endif // OPENTYPE_SANITISER_H_
diff --git a/gfx/ots/src/ots.cc b/gfx/ots/src/ots.cc
--- a/gfx/ots/src/ots.cc
+++ b/gfx/ots/src/ots.cc
@@ -138,16 +138,27 @@ const struct {
{ "GPOS", ots::ots_gpos_parse, ots::ots_gpos_serialise,
ots::ots_gpos_should_serialise, ots::ots_gpos_free, false },
{ "GSUB", ots::ots_gsub_parse, ots::ots_gsub_serialise,
ots::ots_gsub_should_serialise, ots::ots_gsub_free, false },
{ "vhea", ots::ots_vhea_parse, ots::ots_vhea_serialise,
ots::ots_vhea_should_serialise, ots::ots_vhea_free, false },
{ "vmtx", ots::ots_vmtx_parse, ots::ots_vmtx_serialise,
ots::ots_vmtx_should_serialise, ots::ots_vmtx_free, false },
+ // SILGraphite layout tables - not actually parsed, just copied
+ { "Silf", ots::ots_silf_parse, ots::ots_silf_serialise,
+ ots::ots_silf_should_serialise, ots::ots_silf_free, false },
+ { "Sill", ots::ots_sill_parse, ots::ots_sill_serialise,
+ ots::ots_sill_should_serialise, ots::ots_sill_free, false },
+ { "Gloc", ots::ots_gloc_parse, ots::ots_gloc_serialise,
+ ots::ots_gloc_should_serialise, ots::ots_gloc_free, false },
+ { "Glat", ots::ots_glat_parse, ots::ots_glat_serialise,
+ ots::ots_glat_should_serialise, ots::ots_glat_free, false },
+ { "Feat", ots::ots_feat_parse, ots::ots_feat_serialise,
+ ots::ots_feat_should_serialise, ots::ots_feat_free, false },
// TODO(bashi): Support mort, base, and jstf tables.
{ 0, NULL, NULL, NULL, NULL, false },
};
bool IsValidVersionTag(uint32_t tag) {
return tag == Tag("\x00\x01\x00\x00") ||
// OpenType fonts with CFF data have 'OTTO' tag.
tag == Tag("OTTO") ||
@@ -581,22 +592,25 @@ bool ProcessGeneric(ots::OpenTypeFile *h
} // namespace
namespace ots {
void DisableDebugOutput() {
g_debug_output = false;
}
-bool Process(OTSStream *output, const uint8_t *data, size_t length) {
+bool Process(OTSStream *output, const uint8_t *data, size_t length,
+ bool preserveGraphite) {
OpenTypeFile header;
if (length < 4) {
return OTS_FAILURE();
}
+ header.preserve_graphite = preserveGraphite;
+
bool result;
if (data[0] == 'w' && data[1] == 'O' && data[2] == 'F' && data[3] == 'F') {
result = ProcessWOFF(&header, output, data, length);
} else {
result = ProcessTTF(&header, output, data, length);
}
for (unsigned i = 0; ; ++i) {
diff --git a/gfx/ots/src/ots.h b/gfx/ots/src/ots.h
--- a/gfx/ots/src/ots.h
+++ b/gfx/ots/src/ots.h
@@ -178,17 +178,22 @@ class Buffer {
F(maxp, MAXP) \
F(name, NAME) \
F(os2, OS2) \
F(post, POST) \
F(prep, PREP) \
F(vdmx, VDMX) \
F(vorg, VORG) \
F(vhea, VHEA) \
- F(vmtx, VMTX)
+ F(vmtx, VMTX) \
+ F(silf, SILF) \
+ F(sill, SILL) \
+ F(glat, GLAT) \
+ F(gloc, GLOC) \
+ F(feat, FEAT)
#define F(name, capname) struct OpenType##capname;
FOR_EACH_TABLE_TYPE
#undef F
struct OpenTypeFile {
OpenTypeFile() {
#define F(name, capname) name = NULL;
@@ -197,16 +202,20 @@ struct OpenTypeFile {
}
uint32_t version;
uint16_t num_tables;
uint16_t search_range;
uint16_t entry_selector;
uint16_t range_shift;
+ // This is used to tell the relevant parsers whether to preserve the
+ // Graphite layout tables (currently _without_ any checking)
+ bool preserve_graphite;
+
#define F(name, capname) OpenType##capname *name;
FOR_EACH_TABLE_TYPE
#undef F
};
#define F(name, capname) \
bool ots_##name##_parse(OpenTypeFile *f, const uint8_t *d, size_t l); \
bool ots_##name##_should_serialise(OpenTypeFile *f); \

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@ -0,0 +1,60 @@
diff --git a/gfx/ots/include/opentype-sanitiser.h b/gfx/ots/include/opentype-sanitiser.h
--- a/gfx/ots/include/opentype-sanitiser.h
+++ b/gfx/ots/include/opentype-sanitiser.h
@@ -1,15 +1,35 @@
// Copyright (c) 2009 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef OPENTYPE_SANITISER_H_
#define OPENTYPE_SANITISER_H_
+#if defined(_WIN32) || defined(__CYGWIN__)
+ #define OTS_DLL_IMPORT __declspec(dllimport)
+ #define OTS_DLL_EXPORT __declspec(dllexport)
+#else
+ #if __GNUC__ >= 4
+ #define OTS_DLL_IMPORT __attribute__((visibility ("default")))
+ #define OTS_DLL_EXPORT __attribute__((visibility ("default")))
+ #endif
+#endif
+
+#ifdef OTS_DLL
+ #ifdef OTS_DLL_EXPORTS
+ #define OTS_API OTS_DLL_EXPORT
+ #else
+ #define OTS_API OTS_DLL_IMPORT
+ #endif
+#else
+ #define OTS_API
+#endif
+
#if defined(_WIN32)
#include <stdlib.h>
typedef signed char int8_t;
typedef unsigned char uint8_t;
typedef short int16_t;
typedef unsigned short uint16_t;
typedef int int32_t;
typedef unsigned int uint32_t;
@@ -178,18 +198,18 @@ class OTSStream {
// Process a given OpenType file and write out a sanitised version
// output: a pointer to an object implementing the OTSStream interface. The
// sanitisied output will be written to this. In the even of a failure,
// partial output may have been written.
// input: the OpenType file
// length: the size, in bytes, of |input|
// preserve_graphite_tables: whether to preserve Graphite Layout tables
// -----------------------------------------------------------------------------
-bool Process(OTSStream *output, const uint8_t *input, size_t length,
- bool preserve_graphite_tables = false);
+bool OTS_API Process(OTSStream *output, const uint8_t *input, size_t length,
+ bool preserve_graphite_tables = false);
// Force to disable debug output even when the library is compiled with
// -DOTS_DEBUG.
void DisableDebugOutput();
} // namespace ots
#endif // OPENTYPE_SANITISER_H_

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@ -1,4 +1,4 @@
// Copyright (c) 2009 The Chromium Authors. All rights reserved.
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
@ -11,8 +11,8 @@
#include "cff_type2_charstring.h"
// CFF - PostScript font program (Compact Font Format) table
// http://www.microsoft.com/opentype/otspec/cff.htm
// http://www.microsoft.com/opentype/otspec/5176.CFF.pdf
// http://www.microsoft.com/typography/otspec/cff.htm
// http://www.microsoft.com/typography/otspec/cffspec.htm
namespace {
@ -27,6 +27,12 @@ enum DICT_DATA_TYPE {
DICT_DATA_FDARRAY,
};
enum FONT_FORMAT {
FORMAT_UNKNOWN,
FORMAT_CID_KEYED,
FORMAT_OTHER, // Including synthetic fonts
};
// see Appendix. A
const size_t kNStdString = 390;
@ -417,7 +423,7 @@ bool ParsePrivateDictData(
return OTS_FAILURE(); // not reached.
}
local_subrs_index = out_cff->local_subrs_per_font.back();
} else if (type == DICT_DATA_TOPLEVEL) {
} else { // type == DICT_DATA_TOPLEVEL
if (out_cff->local_subrs) {
return OTS_FAILURE(); // two or more local_subrs?
}
@ -464,6 +470,7 @@ bool ParseDictData(const uint8_t *data, size_t table_length,
std::vector<std::pair<uint32_t, DICT_OPERAND_TYPE> > operands;
FONT_FORMAT font_format = FORMAT_UNKNOWN;
bool have_ros = false;
size_t glyphs = 0;
size_t charset_offset = 0;
@ -522,6 +529,10 @@ bool ParseDictData(const uint8_t *data, size_t table_length,
case (12U << 8) + 5: // PaintType
case (12U << 8) + 8: // StrokeWidth
case (12U << 8) + 20: // SyntheticBase
if (operands.size() != 1) {
return OTS_FAILURE();
}
break;
case (12U << 8) + 31: // CIDFontVersion
case (12U << 8) + 32: // CIDFontRevision
case (12U << 8) + 33: // CIDFontType
@ -530,6 +541,9 @@ bool ParseDictData(const uint8_t *data, size_t table_length,
if (operands.size() != 1) {
return OTS_FAILURE();
}
if (font_format != FORMAT_CID_KEYED) {
return OTS_FAILURE();
}
break;
case (12U << 8) + 6: // CharstringType
if (operands.size() != 1) {
@ -780,9 +794,10 @@ bool ParseDictData(const uint8_t *data, size_t table_length,
// ROS
case (12U << 8) + 30:
if (type != DICT_DATA_TOPLEVEL) {
if (font_format != FORMAT_UNKNOWN) {
return OTS_FAILURE();
}
font_format = FORMAT_CID_KEYED;
if (operands.size() != 3) {
return OTS_FAILURE();
}
@ -805,6 +820,10 @@ bool ParseDictData(const uint8_t *data, size_t table_length,
return OTS_FAILURE();
}
operands.clear();
if (font_format == FORMAT_UNKNOWN) {
font_format = FORMAT_OTHER;
}
}
// parse "13. Charsets"

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@ -49,6 +49,12 @@ bool CheckTag(uint32_t tag_value) {
return true;
}
uint32_t Tag(const char *tag_str) {
uint32_t ret;
std::memcpy(&ret, tag_str, 4);
return ret;
}
struct OutputTable {
uint32_t tag;
size_t offset;
@ -81,92 +87,88 @@ struct Arena {
std::vector<uint8_t*> hunks_;
};
// Use a macro instead of a function because gcc 4.4.3 creates static
// initializers in that case. Note this macro assumes a little-endian system.
#define TAG(a, b, c, d) (a | (b << 8) | (c << 16) | (d << 24))
const struct {
uint32_t tag;
const char* tag;
bool (*parse)(ots::OpenTypeFile *otf, const uint8_t *data, size_t length);
bool (*serialise)(ots::OTSStream *out, ots::OpenTypeFile *file);
bool (*should_serialise)(ots::OpenTypeFile *file);
void (*free)(ots::OpenTypeFile *file);
bool required;
} table_parsers[] = {
{ TAG('m', 'a', 'x', 'p'), ots::ots_maxp_parse, ots::ots_maxp_serialise,
{ "maxp", ots::ots_maxp_parse, ots::ots_maxp_serialise,
ots::ots_maxp_should_serialise, ots::ots_maxp_free, true },
{ TAG('h', 'e', 'a', 'd'), ots::ots_head_parse, ots::ots_head_serialise,
{ "head", ots::ots_head_parse, ots::ots_head_serialise,
ots::ots_head_should_serialise, ots::ots_head_free, true },
{ TAG('O', 'S', '/', '2'), ots::ots_os2_parse, ots::ots_os2_serialise,
{ "OS/2", ots::ots_os2_parse, ots::ots_os2_serialise,
ots::ots_os2_should_serialise, ots::ots_os2_free, true },
{ TAG('c', 'm', 'a', 'p'), ots::ots_cmap_parse, ots::ots_cmap_serialise,
{ "cmap", ots::ots_cmap_parse, ots::ots_cmap_serialise,
ots::ots_cmap_should_serialise, ots::ots_cmap_free, true },
{ TAG('h', 'h', 'e', 'a'), ots::ots_hhea_parse, ots::ots_hhea_serialise,
{ "hhea", ots::ots_hhea_parse, ots::ots_hhea_serialise,
ots::ots_hhea_should_serialise, ots::ots_hhea_free, true },
{ TAG('h', 'm', 't', 'x'), ots::ots_hmtx_parse, ots::ots_hmtx_serialise,
{ "hmtx", ots::ots_hmtx_parse, ots::ots_hmtx_serialise,
ots::ots_hmtx_should_serialise, ots::ots_hmtx_free, true },
{ TAG('n', 'a', 'm', 'e'), ots::ots_name_parse, ots::ots_name_serialise,
{ "name", ots::ots_name_parse, ots::ots_name_serialise,
ots::ots_name_should_serialise, ots::ots_name_free, true },
{ TAG('p', 'o', 's', 't'), ots::ots_post_parse, ots::ots_post_serialise,
{ "post", ots::ots_post_parse, ots::ots_post_serialise,
ots::ots_post_should_serialise, ots::ots_post_free, true },
{ TAG('l', 'o', 'c', 'a'), ots::ots_loca_parse, ots::ots_loca_serialise,
{ "loca", ots::ots_loca_parse, ots::ots_loca_serialise,
ots::ots_loca_should_serialise, ots::ots_loca_free, false },
{ TAG('g', 'l', 'y', 'f'), ots::ots_glyf_parse, ots::ots_glyf_serialise,
{ "glyf", ots::ots_glyf_parse, ots::ots_glyf_serialise,
ots::ots_glyf_should_serialise, ots::ots_glyf_free, false },
{ TAG('C', 'F', 'F', ' '), ots::ots_cff_parse, ots::ots_cff_serialise,
{ "CFF ", ots::ots_cff_parse, ots::ots_cff_serialise,
ots::ots_cff_should_serialise, ots::ots_cff_free, false },
{ TAG('V', 'D', 'M', 'X'), ots::ots_vdmx_parse, ots::ots_vdmx_serialise,
{ "VDMX", ots::ots_vdmx_parse, ots::ots_vdmx_serialise,
ots::ots_vdmx_should_serialise, ots::ots_vdmx_free, false },
{ TAG('h', 'd', 'm', 'x'), ots::ots_hdmx_parse, ots::ots_hdmx_serialise,
{ "hdmx", ots::ots_hdmx_parse, ots::ots_hdmx_serialise,
ots::ots_hdmx_should_serialise, ots::ots_hdmx_free, false },
{ TAG('g', 'a', 's', 'p'), ots::ots_gasp_parse, ots::ots_gasp_serialise,
{ "gasp", ots::ots_gasp_parse, ots::ots_gasp_serialise,
ots::ots_gasp_should_serialise, ots::ots_gasp_free, false },
{ TAG('c', 'v', 't', ' '), ots::ots_cvt_parse, ots::ots_cvt_serialise,
{ "cvt ", ots::ots_cvt_parse, ots::ots_cvt_serialise,
ots::ots_cvt_should_serialise, ots::ots_cvt_free, false },
{ TAG('f', 'p', 'g', 'm'), ots::ots_fpgm_parse, ots::ots_fpgm_serialise,
{ "fpgm", ots::ots_fpgm_parse, ots::ots_fpgm_serialise,
ots::ots_fpgm_should_serialise, ots::ots_fpgm_free, false },
{ TAG('p', 'r', 'e', 'p'), ots::ots_prep_parse, ots::ots_prep_serialise,
{ "prep", ots::ots_prep_parse, ots::ots_prep_serialise,
ots::ots_prep_should_serialise, ots::ots_prep_free, false },
{ TAG('L', 'T', 'S', 'H'), ots::ots_ltsh_parse, ots::ots_ltsh_serialise,
{ "LTSH", ots::ots_ltsh_parse, ots::ots_ltsh_serialise,
ots::ots_ltsh_should_serialise, ots::ots_ltsh_free, false },
{ TAG('V', 'O', 'R', 'G'), ots::ots_vorg_parse, ots::ots_vorg_serialise,
{ "VORG", ots::ots_vorg_parse, ots::ots_vorg_serialise,
ots::ots_vorg_should_serialise, ots::ots_vorg_free, false },
{ TAG('k', 'e', 'r', 'n'), ots::ots_kern_parse, ots::ots_kern_serialise,
{ "kern", ots::ots_kern_parse, ots::ots_kern_serialise,
ots::ots_kern_should_serialise, ots::ots_kern_free, false },
// We need to parse GDEF table in advance of parsing GSUB/GPOS tables
// because they could refer GDEF table.
{ TAG('G', 'D', 'E', 'F'), ots::ots_gdef_parse, ots::ots_gdef_serialise,
{ "GDEF", ots::ots_gdef_parse, ots::ots_gdef_serialise,
ots::ots_gdef_should_serialise, ots::ots_gdef_free, false },
{ TAG('G', 'P', 'O', 'S'), ots::ots_gpos_parse, ots::ots_gpos_serialise,
{ "GPOS", ots::ots_gpos_parse, ots::ots_gpos_serialise,
ots::ots_gpos_should_serialise, ots::ots_gpos_free, false },
{ TAG('G', 'S', 'U', 'B'), ots::ots_gsub_parse, ots::ots_gsub_serialise,
{ "GSUB", ots::ots_gsub_parse, ots::ots_gsub_serialise,
ots::ots_gsub_should_serialise, ots::ots_gsub_free, false },
{ TAG('v', 'h', 'e', 'a'), ots::ots_vhea_parse, ots::ots_vhea_serialise,
{ "vhea", ots::ots_vhea_parse, ots::ots_vhea_serialise,
ots::ots_vhea_should_serialise, ots::ots_vhea_free, false },
{ TAG('v', 'm', 't', 'x'), ots::ots_vmtx_parse, ots::ots_vmtx_serialise,
{ "vmtx", ots::ots_vmtx_parse, ots::ots_vmtx_serialise,
ots::ots_vmtx_should_serialise, ots::ots_vmtx_free, false },
// SILGraphite layout tables - not actually parsed, just copied
{ TAG('S', 'i', 'l', 'f'), ots::ots_silf_parse, ots::ots_silf_serialise,
{ "Silf", ots::ots_silf_parse, ots::ots_silf_serialise,
ots::ots_silf_should_serialise, ots::ots_silf_free, false },
{ TAG('S', 'i', 'l', 'l'), ots::ots_sill_parse, ots::ots_sill_serialise,
{ "Sill", ots::ots_sill_parse, ots::ots_sill_serialise,
ots::ots_sill_should_serialise, ots::ots_sill_free, false },
{ TAG('G', 'l', 'o', 'c'), ots::ots_gloc_parse, ots::ots_gloc_serialise,
{ "Gloc", ots::ots_gloc_parse, ots::ots_gloc_serialise,
ots::ots_gloc_should_serialise, ots::ots_gloc_free, false },
{ TAG('G', 'l', 'a', 't'), ots::ots_glat_parse, ots::ots_glat_serialise,
{ "Glat", ots::ots_glat_parse, ots::ots_glat_serialise,
ots::ots_glat_should_serialise, ots::ots_glat_free, false },
{ TAG('F', 'e', 'a', 't'), ots::ots_feat_parse, ots::ots_feat_serialise,
{ "Feat", ots::ots_feat_parse, ots::ots_feat_serialise,
ots::ots_feat_should_serialise, ots::ots_feat_free, false },
// TODO(bashi): Support mort, base, and jstf tables.
{ 0, NULL, NULL, NULL, NULL, false },
};
bool IsValidVersionTag(uint32_t tag) {
return tag == TAG('\x00', '\x01', '\x00', '\x00') ||
return tag == Tag("\x00\x01\x00\x00") ||
// OpenType fonts with CFF data have 'OTTO' tag.
tag == TAG('O', 'T', 'T', 'O') ||
tag == Tag("OTTO") ||
// Older Mac fonts might have 'true' or 'typ1' tag.
tag == TAG('t', 'r', 'u', 'e') ||
tag == TAG('t', 'y', 'p', '1');
tag == Tag("true") ||
tag == Tag("typ1");
}
bool ProcessGeneric(ots::OpenTypeFile *header, ots::OTSStream *output,
@ -264,7 +266,7 @@ bool ProcessWOFF(ots::OpenTypeFile *header,
return OTS_FAILURE();
}
if (woff_tag != TAG('w', 'O', 'F', 'F')) {
if (woff_tag != Tag("wOFF")) {
return OTS_FAILURE();
}
@ -512,7 +514,7 @@ bool ProcessGeneric(ots::OpenTypeFile *header, ots::OTSStream *output,
if (table_parsers[i].parse == NULL) break;
const std::map<uint32_t, OpenTypeTable>::const_iterator it
= table_map.find(table_parsers[i].tag);
= table_map.find(Tag(table_parsers[i].tag));
if (it == table_map.end()) {
if (table_parsers[i].required) {
@ -547,7 +549,7 @@ bool ProcessGeneric(ots::OpenTypeFile *header, ots::OTSStream *output,
if (header->cff) {
// font with PostScript glyph
if (header->version != TAG('O', 'T', 'T', 'O')) {
if (header->version != Tag("OTTO")) {
return OTS_FAILURE();
}
if (header->glyf || header->loca) {
@ -607,11 +609,12 @@ bool ProcessGeneric(ots::OpenTypeFile *header, ots::OTSStream *output,
}
OutputTable out;
out.tag = table_parsers[i].tag;
uint32_t tag = Tag(table_parsers[i].tag);
out.tag = tag;
out.offset = output->Tell();
output->ResetChecksum();
if (table_parsers[i].tag == TAG('h', 'e', 'a', 'd')) {
if (tag == Tag("head")) {
head_table_offset = out.offset;
}
if (!table_parsers[i].serialise(output, header)) {