+png_read_IDAT_data(png_structrp png_ptr, png_bytep output,
+ png_alloc_size_t avail_out)
+{
+ /* Loop reading IDATs and decompressing the result into output[avail_out] */
+ png_ptr->zstream.next_out = output;
+ png_ptr->zstream.avail_out = 0; /* safety: set below */
+
+ if (output == NULL)
+ avail_out = 0;
+
+ do
+ {
+ int ret;
+ png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
+
+ if (png_ptr->zstream.avail_in == 0)
+ {
+ uInt avail_in;
+ png_bytep buffer;
+
+ while (png_ptr->idat_size == 0)
+ {
+ png_crc_finish(png_ptr, 0);
+
+ png_ptr->idat_size = png_read_chunk_header(png_ptr);
+ /* This is an error even in the 'check' case because the code just
+ * consumed a non-IDAT header.
+ */
+ if (png_ptr->chunk_name != png_IDAT)
+ png_error(png_ptr, "Not enough image data");
+ }
+
+ avail_in = png_ptr->IDAT_read_size;
+
+ if (avail_in > png_ptr->idat_size)
+ avail_in = (uInt)png_ptr->idat_size;
+
+ /* A PNG with a gradually increasing IDAT size will defeat this attempt
+ * to minimize memory usage by causing lots of re-allocs, but
+ * realistically doing IDAT_read_size re-allocs is not likely to be a
+ * big problem.
+ */
+ buffer = png_read_buffer(png_ptr, avail_in, 0/*error*/);
+
+ png_crc_read(png_ptr, buffer, avail_in);
+ png_ptr->idat_size -= avail_in;
+
+ png_ptr->zstream.next_in = buffer;
+ png_ptr->zstream.avail_in = avail_in;
+ }
+
+ /* And set up the output side. */
+ if (output != NULL) /* standard read */
+ {
+ uInt out = ZLIB_IO_MAX;
+
+ if (out > avail_out)
+ out = (uInt)avail_out;
+
+ avail_out -= out;
+ png_ptr->zstream.avail_out = out;
+ }
+
+ else /* after last row, checking for end */
+ {
+ png_ptr->zstream.next_out = tmpbuf;
+ png_ptr->zstream.avail_out = (sizeof tmpbuf);
+ }
+
+ /* Use NO_FLUSH; this gives zlib the maximum opportunity to optimize the
+ * process. If the LZ stream is truncated the sequential reader will
+ * terminally damage the stream, above, by reading the chunk header of the
+ * following chunk (it then exits with png_error).
+ *
+ * TODO: deal more elegantly with truncated IDAT lists.
+ */
+ ret = inflate(&png_ptr->zstream, Z_NO_FLUSH);
+
+ /* Take the unconsumed output back. */
+ if (output != NULL)
+ avail_out += png_ptr->zstream.avail_out;
+
+ else /* avail_out counts the extra bytes */
+ avail_out += (sizeof tmpbuf) - png_ptr->zstream.avail_out;
+
+ png_ptr->zstream.avail_out = 0;
+
+ if (ret == Z_STREAM_END)
+ {
+ /* Do this for safety; we won't read any more into this row. */
+ png_ptr->zstream.next_out = NULL;
+
+ png_ptr->mode |= PNG_AFTER_IDAT;
+ png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
+
+ if (png_ptr->zstream.avail_in > 0 || png_ptr->idat_size > 0)
+ png_chunk_benign_error(png_ptr, "Extra compressed data");
+ break;
+ }
+
+ if (ret != Z_OK)
+ {
+ png_zstream_error(png_ptr, ret);
+
+ if (output != NULL)
+ png_chunk_error(png_ptr, png_ptr->zstream.msg);
+
+ else /* checking */
+ {
+ png_chunk_benign_error(png_ptr, png_ptr->zstream.msg);
+ return;
+ }
+ }
+ } while (avail_out > 0);
+
+ if (avail_out > 0)
+ {
+ /* The stream ended before the image; this is the same as too few IDATs so
+ * should be handled the same way.
+ */
+ if (output != NULL)
+ png_error(png_ptr, "Not enough image data");
+
+ else /* the deflate stream contained extra data */
+ png_chunk_benign_error(png_ptr, "Too much image data");
+ }
+}
+
+void /* PRIVATE */
+png_read_finish_IDAT(png_structrp png_ptr)
+{
+ /* We don't need any more data and the stream should have ended, however the
+ * LZ end code may actually not have been processed. In this case we must
+ * read it otherwise stray unread IDAT data or, more likely, an IDAT chunk
+ * may still remain to be consumed.
+ */
+ if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
+ {
+ /* The NULL causes png_read_IDAT_data to swallow any remaining bytes in
+ * the compressed stream, but the stream may be damaged too, so even after
+ * this call we may need to terminate the zstream ownership.
+ */
+ png_read_IDAT_data(png_ptr, NULL, 0);
+ png_ptr->zstream.next_out = NULL; /* safety */
+
+ /* Now clear everything out for safety; the following may not have been
+ * done.
+ */
+ if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
+ {
+ png_ptr->mode |= PNG_AFTER_IDAT;
+ png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
+ }
+ }
+
+ /* If the zstream has not been released do it now *and* terminate the reading
+ * of the final IDAT chunk.
+ */
+ if (png_ptr->zowner == png_IDAT)
+ {
+ /* Always do this; the pointers otherwise point into the read buffer. */
+ png_ptr->zstream.next_in = NULL;
+ png_ptr->zstream.avail_in = 0;
+
+ /* Now we no longer own the zstream. */
+ png_ptr->zowner = 0;
+
+ /* The slightly weird semantics of the sequential IDAT reading is that we
+ * are always in or at the end of an IDAT chunk, so we always need to do a
+ * crc_finish here. If idat_size is non-zero we also need to read the
+ * spurious bytes at the end of the chunk now.
+ */
+ (void)png_crc_finish(png_ptr, png_ptr->idat_size);
+ }
+}
+
+void /* PRIVATE */
+png_read_finish_row(png_structrp png_ptr)
projects / wxWidgets.git / blobdiff