When we read from a RemoteFontStream (might happen maybe with other streams), stream's data might b…

src/pdf/SkPDFFont.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include <ctype.h>
 
 #include "SkData.h"
@@ skipping 530 matching lines @@
     // Use C-style cast to cast away const and cast type simultaneously.
     delete[] (unsigned char*)ptr;
 }
 #endif
 
 static int get_subset_font_stream(const char* fontName,
                                   const SkTypeface* typeface,
                                   const SkTDArray<uint32_t>& subset,
                                   SkPDFStream** fontStream) {
     int ttcIndex;
     SkAutoTUnref<SkStream> fontData(typeface->openStream(&ttcIndex));

[vandebo (ex-Chrome), 2013/03/21 00:55:11]

Shouldn't typeface->openStream() return a stream at the beginning?

[bungeman-skia, 2013/03/21 03:25:12]

I have to agree, this is an issue with reed's changes to
SkFontHost_fontconfig.cpp::open_stream. We shouldn't try to band-aid this here
and leave this to still happen elsewhere.

It looks like on Windows and Mac we always create a new stream on OpenStream.
With the fontconfig font host, it looks like we're often just ref-ing and
returning. This seems iffy, the old code made a copy, maybe this is why? It
seems what we want there is a shallow stream copy.

[edisonn, 2013/03/21 13:33:08]

done; added issue 1176 for the thread safety. right now we will fix simply by
rewinding in open_stream

On 2013/03/21 03:25:12, bungeman1 wrote:

+    fontData->rewind();

[edisonn, 2013/03/21 13:33:08]

Steve's comments:
1) openStream should give already a stream at the beginning, I agree
2) multithreading ... multiple readers would interfere reading the data! I
suggested a lock, but Steve thinks that we need independent seek pointers, but
this might require a new interface for all SkStream classes

 
     int fontSize = fontData->getLength();
 
 #if defined (SK_SFNTLY_SUBSETTER)
     // Read font into buffer.
     SkPDFStream* subsetFontStream = NULL;
     SkTDArray<unsigned char> originalFont;
     originalFont.setCount(fontSize);
     if (fontData->read(originalFont.begin(), fontSize) == (size_t)fontSize) {
         unsigned char* subsetFont = NULL;
@@ skipping 845 matching lines @@
 
     insert("FontBBox", makeFontBBox(bbox, 1000))->unref();
     insertInt("FirstChar", firstGlyphID());
     insertInt("LastChar", lastGlyphID());
     insert("Widths", widthArray.get());
     insertName("CIDToGIDMap", "Identity");
 
     populateToUnicodeTable(NULL);
     return true;
 }