Update libpng to version 1.2.44

third_party/libpng/pngpread.c

Index: third_party/libpng/pngpread.c
diff --git a/third_party/libpng/pngpread.c b/third_party/libpng/pngpread.c
index 52f41a20c51186f1c7e1fe1b94b902afd66b998c..48608f6a194224af57e078a5d48761e38c60f1e1 100644
--- a/third_party/libpng/pngpread.c
+++ b/third_party/libpng/pngpread.c
@@ -1,7 +1,7 @@
 
 /* pngpread.c - read a png file in push mode
  *
- * Last changed in libpng 1.2.43 [February 25, 2010]
+ * Last changed in libpng 1.2.44 [June 26, 2010]
  * Copyright (c) 1998-2010 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -783,8 +783,7 @@ png_push_read_IDAT(png_structp png_ptr)
 
       png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
 
-      if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
-         png_process_IDAT_data(png_ptr, png_ptr->save_buffer_ptr, save_size);
+      png_process_IDAT_data(png_ptr, png_ptr->save_buffer_ptr, save_size);
 
       png_ptr->idat_size -= save_size;
       png_ptr->buffer_size -= save_size;
@@ -807,8 +806,7 @@ png_push_read_IDAT(png_structp png_ptr)
          save_size = png_ptr->current_buffer_size;
 
       png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
-      if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
-         png_process_IDAT_data(png_ptr, png_ptr->current_buffer_ptr, save_size);
+      png_process_IDAT_data(png_ptr, png_ptr->current_buffer_ptr, save_size);
 
       png_ptr->idat_size -= save_size;
       png_ptr->buffer_size -= save_size;
@@ -833,62 +831,101 @@ void /* PRIVATE */
 png_process_IDAT_data(png_structp png_ptr, png_bytep buffer,
    png_size_t buffer_length)
 {
-   int ret;
-
-   if ((png_ptr->flags & PNG_FLAG_ZLIB_FINISHED) && buffer_length)
-      png_error(png_ptr, "Extra compression data");
+   /* The caller checks for a non-zero buffer length. */
+   if (!(buffer_length > 0) || buffer == NULL)
+      png_error(png_ptr, "No IDAT data (internal error)");
 
+   /* This routine must process all the data it has been given
+    * before returning, calling the row callback as required to
+    * handle the uncompressed results.
+    */
    png_ptr->zstream.next_in = buffer;
    png_ptr->zstream.avail_in = (uInt)buffer_length;
-   for (;;)
+
+   /* Keep going until the decompressed data is all processed
+    * or the stream marked as finished.
+    */
+   while (png_ptr->zstream.avail_in > 0 &&
+	  !(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
    {
-      ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
-      if (ret != Z_OK)
+      int ret;
+      /* We have data for zlib, but we must check that zlib
+       * has somewhere to put the results.  It doesn't matter
+       * if we don't expect any results -- it may be the input
+       * data is just the LZ end code.
+       */
+      if (!(png_ptr->zstream.avail_out > 0))
       {
-         if (ret == Z_STREAM_END)
-         {
-            if (png_ptr->zstream.avail_in)
-               png_error(png_ptr, "Extra compressed data");
-
-            if (!(png_ptr->zstream.avail_out))
-            {
-               png_push_process_row(png_ptr);
-            }
+         png_ptr->zstream.avail_out =
+             (uInt) PNG_ROWBYTES(png_ptr->pixel_depth,
+             png_ptr->iwidth) + 1;
+         png_ptr->zstream.next_out = png_ptr->row_buf;
+      }
 
-            png_ptr->mode |= PNG_AFTER_IDAT;
-            png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
-            break;
-         }
-         else if (ret == Z_BUF_ERROR)
-            break;
+      /* Using Z_SYNC_FLUSH here means that an unterminated
+       * LZ stream can still be handled (a stream with a missing
+       * end code), otherwise (Z_NO_FLUSH) a future zlib
+       * implementation might defer output and, therefore,
+       * change the current behavior.  (See comments in inflate.c
+       * for why this doesn't happen at present with zlib 1.2.5.)
+       */
+      ret = inflate(&png_ptr->zstream, Z_SYNC_FLUSH);
 
+      /* Check for any failure before proceeding. */
+      if (ret != Z_OK && ret != Z_STREAM_END)
+      {
+         /* Terminate the decompression. */
+         png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
+         /* This may be a truncated stream (missing or
+          * damaged end code).  Treat that as a warning.
+          */
+         if (png_ptr->row_number >= png_ptr->num_rows ||
+            png_ptr->pass > 6)
+	         png_warning(png_ptr, "Truncated compressed data in IDAT");
          else
-            png_error(png_ptr, "Decompression Error");
+           png_error(png_ptr, "Decompression error in IDAT");
+
+         /* Skip the check on unprocessed input */
+         return;
       }
-      if (!(png_ptr->zstream.avail_out))
+
+      /* Did inflate output any data? */
+      if (png_ptr->zstream.next_out != png_ptr->row_buf)
       {
-         if ((
-#ifdef PNG_READ_INTERLACING_SUPPORTED
-             png_ptr->interlaced && png_ptr->pass > 6) ||
-             (!png_ptr->interlaced &&
-#endif
-             png_ptr->row_number == png_ptr->num_rows))
+        /* Is this unexpected data after the last row?
+         * If it is, artificially terminate the LZ output
+         * here.
+         */
+         if (png_ptr->row_number >= png_ptr->num_rows ||
+            png_ptr->pass > 6)
          {
-           if (png_ptr->zstream.avail_in)
-             png_warning(png_ptr, "Too much data in IDAT chunks");
+           /* Extra data. */
+           png_warning(png_ptr, "Extra compressed data in IDAT");
            png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
-           break;
+           /* Do no more processing; skip the unprocessed
+            * input check below.
+            */
+            return;
          }
-         png_push_process_row(png_ptr);
-         png_ptr->zstream.avail_out =
-             (uInt) PNG_ROWBYTES(png_ptr->pixel_depth,
-             png_ptr->iwidth) + 1;
-         png_ptr->zstream.next_out = png_ptr->row_buf;
+
+ 	       /* Do we have a complete row? */
+         if (png_ptr->zstream.avail_out == 0)
+           png_push_process_row(png_ptr);
       }
 
       else
          break;
+      /* And check for the end of the stream. */
+      if (ret == Z_STREAM_END)
+        png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
    }
+
+   /* All the data should have been processed, if anything
+    * is left at this point we have bytes of IDAT data
+    * after the zlib end code.
+    */
+   if (png_ptr->zstream.avail_in > 0)
+      png_warning(png_ptr, "Extra compression data");
 }
 
 void /* PRIVATE */