The Tor Browser: gfx/thebes/gfxScriptItemizer.cpp@97036ab72558 (annotated)

gfx/thebes/gfxScriptItemizer.cpp@97036ab72558 (annotated)

gfx/thebes/gfxScriptItemizer.cpp

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 /*
  * This file is based on usc_impl.c from ICU 4.2.0.1, slightly adapted
  * for use within Mozilla Gecko, separate from a standard ICU build.
  *
  * The original ICU license of the code follows:
  *
  * ICU License - ICU 1.8.1 and later
  *
  * COPYRIGHT AND PERMISSION NOTICE
  *
  * Copyright (c) 1995-2009 International Business Machines Corporation and
  * others
  *
  * All rights reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, provided that the above copyright notice(s) and this
  * permission notice appear in all copies of the Software and that both the
  * above copyright notice(s) and this permission notice appear in supporting
  * documentation.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS.
  * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS NOTICE
  * BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES,
  * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
  * WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
  * ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  * SOFTWARE.
  *
  * Except as contained in this notice, the name of a copyright holder shall
  * not be used in advertising or otherwise to promote the sale, use or other
  * dealings in this Software without prior written authorization of the
  * copyright holder.
  *
  * All trademarks and registered trademarks mentioned herein are the property
  * of their respective owners.
  */
 #include "gfxScriptItemizer.h"
 #include "nsUnicodeProperties.h"
 #include "nsCharTraits.h"
 #include "harfbuzz/hb.h"
 #define MOD(sp) ((sp) % PAREN_STACK_DEPTH)
 #define LIMIT_INC(sp) (((sp) < PAREN_STACK_DEPTH)? (sp) + 1 : PAREN_STACK_DEPTH)
 #define INC(sp,count) (MOD((sp) + (count)))
 #define INC1(sp) (INC(sp, 1))
 #define DEC(sp,count) (MOD((sp) + PAREN_STACK_DEPTH - (count)))
 #define DEC1(sp) (DEC(sp, 1))
 #define STACK_IS_EMPTY() (pushCount <= 0)
 #define STACK_IS_NOT_EMPTY() (! STACK_IS_EMPTY())
 #define TOP() (parenStack[parenSP])
 #define SYNC_FIXUP() (fixupCount = 0)
 void
 gfxScriptItemizer::push(uint32_t endPairChar, int32_t scriptCode)
 {
     pushCount  = LIMIT_INC(pushCount);
     fixupCount = LIMIT_INC(fixupCount);
     parenSP = INC1(parenSP);
     parenStack[parenSP].endPairChar = endPairChar;
     parenStack[parenSP].scriptCode = scriptCode;
 }
 void
 gfxScriptItemizer::pop()
 {
     if (STACK_IS_EMPTY()) {
         return;
     }
     if (fixupCount > 0) {
         fixupCount -= 1;
     }
     pushCount -= 1;
     parenSP = DEC1(parenSP);
     /* If the stack is now empty, reset the stack
        pointers to their initial values.
      */
     if (STACK_IS_EMPTY()) {
         parenSP = -1;
     }
 }
 void
 gfxScriptItemizer::fixup(int32_t scriptCode)
 {
     int32_t fixupSP = DEC(parenSP, fixupCount);
     while (fixupCount-- > 0) {
         fixupSP = INC1(fixupSP);
         parenStack[fixupSP].scriptCode = scriptCode;
     }
 }
 static inline bool
 SameScript(int32_t runScript, int32_t currCharScript)
 {
     return runScript <= MOZ_SCRIPT_INHERITED ||
            currCharScript <= MOZ_SCRIPT_INHERITED ||
            currCharScript == runScript;
 }
 // Return whether the char has a mirrored-pair counterpart.
 // NOTE that this depends on the implementation of nsCharProps records in
 // nsUnicodeProperties, and may need to be updated if those structures change
 static inline bool
 HasMirroredChar(uint32_t aCh)
 {
     return GetCharProps1(aCh).mMirrorOffsetIndex != 0;
 }
 gfxScriptItemizer::gfxScriptItemizer(const char16_t *src, uint32_t length)
     : textPtr(src), textLength(length)
 {
     reset();
 }
 void
 gfxScriptItemizer::SetText(const char16_t *src, uint32_t length)
 {
     textPtr  = src;
     textLength = length;
     reset();
 }
 bool
 gfxScriptItemizer::Next(uint32_t& aRunStart, uint32_t& aRunLimit,
                         int32_t& aRunScript)
 {
     /* if we've fallen off the end of the text, we're done */
     if (scriptLimit >= textLength) {
         return false;
     }
     SYNC_FIXUP();
     scriptCode = MOZ_SCRIPT_COMMON;
     for (scriptStart = scriptLimit; scriptLimit < textLength; scriptLimit += 1) {
         uint32_t ch;
         int32_t sc;
         uint32_t startOfChar = scriptLimit;
         ch = textPtr[scriptLimit];
         /* decode UTF-16 (may be surrogate pair) */
         if (NS_IS_HIGH_SURROGATE(ch) && scriptLimit < textLength - 1) {
             uint32_t low = textPtr[scriptLimit + 1];
             if (NS_IS_LOW_SURROGATE(low)) {
                 ch = SURROGATE_TO_UCS4(ch, low);
                 scriptLimit += 1;
             }
         }
         // Get the nsCharProps2 record for the current character,
         // so we can read the script and (if needed) the gen category
         // without needing to do two multi-level lookups.
         // NOTE that this means we're relying on an implementation detail
         // of the nsUnicodeProperties tables, and might have to revise this
         // if the nsCharProps records used there are modified in future.
         const nsCharProps2& charProps = GetCharProps2(ch);
         // Initialize gc to UNASSIGNED; we'll only set it to the true GC
         // if the character has script=COMMON, otherwise we don't care.
         uint8_t gc = HB_UNICODE_GENERAL_CATEGORY_UNASSIGNED;
         sc = charProps.mScriptCode;
         if (sc == MOZ_SCRIPT_COMMON) {
             /*
              * Paired character handling:
              *
              * if it's an open character, push it onto the stack.
              * if it's a close character, find the matching open on the
              * stack, and use that script code. Any non-matching open
              * characters above it on the stack will be popped.
              *
              * We only do this if the script is COMMON; for chars with
              * specific script assignments, we just use them as-is.
              */
             gc = charProps.mCategory;
             if (gc == HB_UNICODE_GENERAL_CATEGORY_OPEN_PUNCTUATION) {
                 uint32_t endPairChar = mozilla::unicode::GetMirroredChar(ch);
                 if (endPairChar != ch) {
                     push(endPairChar, scriptCode);
                 }
             } else if (gc == HB_UNICODE_GENERAL_CATEGORY_CLOSE_PUNCTUATION &&
                 HasMirroredChar(ch))
             {
                 while (STACK_IS_NOT_EMPTY() && TOP().endPairChar != ch) {
                     pop();
                 }
                 if (STACK_IS_NOT_EMPTY()) {
                     sc = TOP().scriptCode;
                 }
             }
         }
         if (SameScript(scriptCode, sc)) {
             if (scriptCode <= MOZ_SCRIPT_INHERITED &&
                 sc > MOZ_SCRIPT_INHERITED)
             {
                 scriptCode = sc;
                 fixup(scriptCode);
             }
             /*
              * if this character is a close paired character,
              * pop the matching open character from the stack
              */
             if (gc == HB_UNICODE_GENERAL_CATEGORY_CLOSE_PUNCTUATION &&
                 HasMirroredChar(ch)) {
                 pop();
             }
         } else {
             /*
              * reset scriptLimit in case it was advanced during reading a
              * multiple-code-unit character
              */
             scriptLimit = startOfChar;
             break;
         }
     }
     aRunStart = scriptStart;
     aRunLimit = scriptLimit;
     aRunScript = scriptCode;
     return true;
 }

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gfx/thebes/gfxScriptItemizer.cpp@97036ab72558 (annotated)

gfx/thebes/gfxScriptItemizer.cpp