Make Jpeg decoding more fault resistant.

src/images/SkImageDecoder_libjpeg.cpp

 /*
  * Copyright 2007 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "SkImageDecoder.h"
 #include "SkImageEncoder.h"
@@ skipping 36 matching lines @@
     cinfo->mem->max_memory_to_use = 30 * 1024 * 1024;
 #else
     cinfo->mem->max_memory_to_use = 5 * 1024 * 1024;
 #endif
 #endif // SK_BUILD_FOR_ANDROID
 }
 
 //////////////////////////////////////////////////////////////////////////
 //////////////////////////////////////////////////////////////////////////
 
+static void do_nothing(jpeg_common_struct*, int) {  /* do nothing */ }

[scroggo, 2013/10/01 22:04:14]

Could you make this name more specific? Though it does, in fact, do nothing,
maybe it should be something like do_nothing_emit_message so it's more clear
what it's for.

+
 static void initialize_info(jpeg_decompress_struct* cinfo, skjpeg_source_mgr* src_mgr) {
     SkASSERT(cinfo != NULL);
     SkASSERT(src_mgr != NULL);
     jpeg_create_decompress(cinfo);
     overwrite_mem_buffer_size(cinfo);
     cinfo->src = src_mgr;
+    cinfo->err->emit_message = &do_nothing;

[scroggo, 2013/10/01 22:04:14]

Why not do this inside an

#if !defined(SK_DEBUG)

block. Then we can still see this error message in debug mode.

 }
 
 #ifdef SK_BUILD_FOR_ANDROID
 class SkJPEGImageIndex {
 public:
     SkJPEGImageIndex(SkStreamRewindable* stream, SkImageDecoder* decoder)
         : fSrcMgr(stream, decoder)
         , fInfoInitialized(false)
         , fHuffmanCreated(false)
         , fDecompressStarted(false)
@@ skipping 476 matching lines @@
                 cinfo.out_color_space == JCS_RGB_565)))
     {
         JSAMPLE* rowptr = (JSAMPLE*)bm->getPixels();
         INT32 const bpr =  bm->rowBytes();
 
         while (cinfo.output_scanline < cinfo.output_height) {
             int row_count = jpeg_read_scanlines(&cinfo, &rowptr, 1);
             // if row_count == 0, then we didn't get a scanline, so abort.
             // if we supported partial images, we might return true in this case
             if (0 == row_count) {
-                return return_false(cinfo, *bm, "read_scanlines");
+                // Ignore error: return_false(cinfo, *bm, "read_scanlines");

[scroggo, 2013/10/01 22:04:14]

This line can be removed. Same for the other cases.

+                return true;

[scroggo, 2013/10/01 22:04:14]

Like I said before, this will leave the remainder of the bitmap uninitialized.
Same for the other cases.

             }
             if (this->shouldCancelDecode()) {
                 return return_false(cinfo, *bm, "shouldCancelDecode");
             }
             rowptr += bpr;
         }
         jpeg_finish_decompress(&cinfo);
         return true;
     }
 #endif
@@ skipping 29 matching lines @@
     //  Possibly skip initial rows [sampler.srcY0]
     if (!skip_src_rows(&cinfo, srcRow, sampler.srcY0())) {
         return return_false(cinfo, *bm, "skip rows");
     }
 
     // now loop through scanlines until y == bm->height() - 1
     for (int y = 0;; y++) {
         JSAMPLE* rowptr = (JSAMPLE*)srcRow;
         int row_count = jpeg_read_scanlines(&cinfo, &rowptr, 1);
         if (0 == row_count) {
-            return return_false(cinfo, *bm, "read_scanlines");
+            // Ignore error: return_false(cinfo, *bm, "read_scanlines");
+            return true;
         }
         if (this->shouldCancelDecode()) {
             return return_false(cinfo, *bm, "shouldCancelDecode");
         }
 
         if (JCS_CMYK == cinfo.out_color_space) {
             convert_CMYK_to_RGB(srcRow, cinfo.output_width);
         }
 
         sampler.next(srcRow);
@@ skipping 161 matching lines @@
         INT32 const bpr = bitmap.rowBytes();
         int rowTotalCount = 0;
 
         while (rowTotalCount < height) {
             int rowCount = jpeg_read_tile_scanline(cinfo,
                                                    fImageIndex->huffmanIndex(),
                                                    &rowptr);
             // if row_count == 0, then we didn't get a scanline, so abort.
             // if we supported partial images, we might return true in this case
             if (0 == rowCount) {
-                return return_false(*cinfo, bitmap, "read_scanlines");
+                // Ignore error: return_false(*cinfo, bitmap, "read_scanlines");
+                return true;
             }
             if (this->shouldCancelDecode()) {
                 return return_false(*cinfo, bitmap, "shouldCancelDecode");
             }
             rowTotalCount += rowCount;
             rowptr += bpr;
         }
 
         if (swapOnly) {
             bm->swap(bitmap);
@@ skipping 36 matching lines @@
     //  Possibly skip initial rows [sampler.srcY0]
     if (!skip_src_rows_tile(cinfo, fImageIndex->huffmanIndex(), srcRow, sampler.srcY0())) {
         return return_false(*cinfo, bitmap, "skip rows");
     }
 
     // now loop through scanlines until y == bitmap->height() - 1
     for (int y = 0;; y++) {
         JSAMPLE* rowptr = (JSAMPLE*)srcRow;
         int row_count = jpeg_read_tile_scanline(cinfo, fImageIndex->huffmanIndex(), &rowptr);
         if (0 == row_count) {
-            return return_false(*cinfo, bitmap, "read_scanlines");
+            // Ignore error: return_false(*cinfo, bitmap, "read_scanlines");
+            return true;
         }
         if (this->shouldCancelDecode()) {
             return return_false(*cinfo, bitmap, "shouldCancelDecode");
         }
 
         if (JCS_CMYK == cinfo->out_color_space) {
             convert_CMYK_to_RGB(srcRow, width);
         }
 
         sampler.next(srcRow);
@@ skipping 293 matching lines @@
     return SkImageDecoder::kUnknown_Format;
 }
 
 static SkImageEncoder* sk_libjpeg_efactory(SkImageEncoder::Type t) {
     return (SkImageEncoder::kJPEG_Type == t) ? SkNEW(SkJPEGImageEncoder) : NULL;
 }
 
 static SkImageDecoder_DecodeReg gDReg(sk_libjpeg_dfactory);
 static SkImageDecoder_FormatReg gFormatReg(get_format_jpeg);
 static SkImageEncoder_EncodeReg gEReg(sk_libjpeg_efactory);