/* pngpread.c - read a png file in push mode * * Last changed in libpng 1.6.15 [(PENDING RELEASE)] * Copyright (c) 1998-2014 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.) * * This code is released under the libpng license. * For conditions of distribution and use, see the disclaimer * and license in png.h */ #include "pngpriv.h" #ifdef PNG_PROGRESSIVE_READ_SUPPORTED /* Push model modes */ #define PNG_READ_SIG_MODE 0 #define PNG_READ_CHUNK_MODE 1 #define PNG_READ_IDAT_MODE 2 #define PNG_SKIP_MODE 3 #define PNG_READ_tEXt_MODE 4 #define PNG_READ_zTXt_MODE 5 #define PNG_READ_DONE_MODE 6 #define PNG_READ_iTXt_MODE 7 #define PNG_ERROR_MODE 8 #define PNG_PUSH_SAVE_BUFFER_IF_FULL \ if (png_ptr->push_length + 4 > png_ptr->buffer_size) \ { png_push_save_buffer(png_ptr); return; } #define PNG_PUSH_SAVE_BUFFER_IF_LT(N) \ if (png_ptr->buffer_size < N) \ { png_push_save_buffer(png_ptr); return; } void PNGAPI png_process_data(png_structrp png_ptr, png_inforp info_ptr, png_bytep buffer, png_size_t buffer_size) { if (png_ptr == NULL || info_ptr == NULL) return; png_push_restore_buffer(png_ptr, buffer, buffer_size); while (png_ptr->buffer_size) { png_process_some_data(png_ptr, info_ptr); } } png_size_t PNGAPI png_process_data_pause(png_structrp png_ptr, int save) { if (png_ptr != NULL) { /* It's easiest for the caller if we do the save; then the caller doesn't * have to supply the same data again: */ if (save != 0) png_push_save_buffer(png_ptr); else { /* This includes any pending saved bytes: */ png_size_t remaining = png_ptr->buffer_size; png_ptr->buffer_size = 0; /* So subtract the saved buffer size, unless all the data * is actually 'saved', in which case we just return 0 */ if (png_ptr->save_buffer_size < remaining) return remaining - png_ptr->save_buffer_size; } } return 0; } png_uint_32 PNGAPI png_process_data_skip(png_structrp png_ptr) { png_uint_32 remaining = 0; if (png_ptr != NULL && png_ptr->process_mode == PNG_SKIP_MODE && png_ptr->skip_length > 0) { /* At the end of png_process_data the buffer size must be 0 (see the loop * above) so we can detect a broken call here: */ if (png_ptr->buffer_size != 0) png_error(png_ptr, "png_process_data_skip called inside png_process_data"); /* If is impossible for there to be a saved buffer at this point - * otherwise we could not be in SKIP mode. This will also happen if * png_process_skip is called inside png_process_data (but only very * rarely.) */ if (png_ptr->save_buffer_size != 0) png_error(png_ptr, "png_process_data_skip called with saved data"); remaining = png_ptr->skip_length; png_ptr->skip_length = 0; png_ptr->process_mode = PNG_READ_CHUNK_MODE; } return remaining; } /* What we do with the incoming data depends on what we were previously * doing before we ran out of data... */ void /* PRIVATE */ png_process_some_data(png_structrp png_ptr, png_inforp info_ptr) { if (png_ptr == NULL) return; switch (png_ptr->process_mode) { case PNG_READ_SIG_MODE: { png_push_read_sig(png_ptr, info_ptr); break; } case PNG_READ_CHUNK_MODE: { png_push_read_chunk(png_ptr, info_ptr); break; } case PNG_READ_IDAT_MODE: { png_push_read_IDAT(png_ptr); break; } case PNG_SKIP_MODE: { png_push_crc_finish(png_ptr); break; } default: { png_ptr->buffer_size = 0; break; } } } /* Read any remaining signature bytes from the stream and compare them with * the correct PNG signature. It is possible that this routine is called * with bytes already read from the signature, either because they have been * checked by the calling application, or because of multiple calls to this * routine. */ void /* PRIVATE */ png_push_read_sig(png_structrp png_ptr, png_inforp info_ptr) { png_size_t num_checked = png_ptr->sig_bytes, /* SAFE, does not exceed 8 */ num_to_check = 8 - num_checked; if (png_ptr->buffer_size < num_to_check) { num_to_check = png_ptr->buffer_size; } png_push_fill_buffer(png_ptr, &(info_ptr->signature[num_checked]), num_to_check); png_ptr->sig_bytes = (png_byte)(png_ptr->sig_bytes + num_to_check); if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check)) { if (num_checked < 4 && png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4)) png_error(png_ptr, "Not a PNG file"); else png_error(png_ptr, "PNG file corrupted by ASCII conversion"); } else { if (png_ptr->sig_bytes >= 8) { png_ptr->process_mode = PNG_READ_CHUNK_MODE; } } } void /* PRIVATE */ png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr) { png_uint_32 chunk_name; #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED int keep; /* unknown handling method */ #endif /* First we make sure we have enough data for the 4-byte chunk name * and the 4-byte chunk length before proceeding with decoding the * chunk data. To fully decode each of these chunks, we also make * sure we have enough data in the buffer for the 4-byte CRC at the * end of every chunk (except IDAT, which is handled separately). */ if ((png_ptr->mode & PNG_HAVE_CHUNK_HEADER) == 0) { png_byte chunk_length[4]; png_byte chunk_tag[4]; PNG_PUSH_SAVE_BUFFER_IF_LT(8) png_push_fill_buffer(png_ptr, chunk_length, 4); png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length); png_reset_crc(png_ptr); png_crc_read(png_ptr, chunk_tag, 4); png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag); png_check_chunk_name(png_ptr, png_ptr->chunk_name); png_ptr->mode |= PNG_HAVE_CHUNK_HEADER; } chunk_name = png_ptr->chunk_name; if (chunk_name == png_IDAT) { if ((png_ptr->mode & PNG_AFTER_IDAT) != 0) png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT; /* If we reach an IDAT chunk, this means we have read all of the * header chunks, and we can start reading the image (or if this * is called after the image has been read - we have an error). */ if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) png_error(png_ptr, "Missing IHDR before IDAT"); else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE && (png_ptr->mode & PNG_HAVE_PLTE) == 0) png_error(png_ptr, "Missing PLTE before IDAT"); png_ptr->mode |= PNG_HAVE_IDAT; png_ptr->process_mode = PNG_READ_IDAT_MODE; if ((png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) == 0) if (png_ptr->push_length == 0) return; if ((png_ptr->mode & PNG_AFTER_IDAT) != 0) png_benign_error(png_ptr, "Too many IDATs found"); } if (chunk_name == png_IHDR) { if (png_ptr->push_length != 13) png_error(png_ptr, "Invalid IHDR length"); PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_IHDR(png_ptr, info_ptr, png_ptr->push_length); } else if (chunk_name == png_IEND) { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_IEND(png_ptr, info_ptr, png_ptr->push_length); png_ptr->process_mode = PNG_READ_DONE_MODE; png_push_have_end(png_ptr, info_ptr); } #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0) { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length, keep); if (chunk_name == png_PLTE) png_ptr->mode |= PNG_HAVE_PLTE; } #endif else if (chunk_name == png_PLTE) { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_PLTE(png_ptr, info_ptr, png_ptr->push_length); } else if (chunk_name == png_IDAT) { png_ptr->idat_size = png_ptr->push_length; png_ptr->process_mode = PNG_READ_IDAT_MODE; png_push_have_info(png_ptr, info_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; return; } #ifdef PNG_READ_gAMA_SUPPORTED else if (png_ptr->chunk_name == png_gAMA) { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_gAMA(png_ptr, info_ptr, png_ptr->push_length); } #endif #ifdef PNG_READ_sBIT_SUPPORTED else if (png_ptr->chunk_name == png_sBIT) { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_sBIT(png_ptr, info_ptr, png_ptr->push_length); } #endif #ifdef PNG_READ_cHRM_SUPPORTED else if (png_ptr->chunk_name == png_cHRM) { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_cHRM(png_ptr, info_ptr, png_ptr->push_length); } #endif #ifdef PNG_READ_sRGB_SUPPORTED else if (chunk_name == png_sRGB) { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_sRGB(png_ptr, info_ptr, png_ptr->push_length); } #endif #ifdef PNG_READ_iCCP_SUPPORTED else if (png_ptr->chunk_name == png_iCCP) { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_iCCP(png_ptr, info_ptr, png_ptr->push_length); } #endif #ifdef PNG_READ_sPLT_SUPPORTED else if (chunk_name == png_sPLT) { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_sPLT(png_ptr, info_ptr, png_ptr->push_length); } #endif #ifdef PNG_READ_tRNS_SUPPORTED else if (chunk_name == png_tRNS) { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_tRNS(png_ptr, info_ptr, png_ptr->push_length); } #endif #ifdef PNG_READ_bKGD_SUPPORTED else if (chunk_name == png_bKGD) { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_bKGD(png_ptr, info_ptr, png_ptr->push_length); } #endif #ifdef PNG_READ_hIST_SUPPORTED else if (chunk_name == png_hIST) { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_hIST(png_ptr, info_ptr, png_ptr->push_length); } #endif #ifdef PNG_READ_pHYs_SUPPORTED else if (chunk_name == png_pHYs) { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_pHYs(png_ptr, info_ptr, png_ptr->push_length); } #endif #ifdef PNG_READ_oFFs_SUPPORTED else if (chunk_name == png_oFFs) { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_oFFs(png_ptr, info_ptr, png_ptr->push_length); } #endif #ifdef PNG_READ_pCAL_SUPPORTED else if (chunk_name == png_pCAL) { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_pCAL(png_ptr, info_ptr, png_ptr->push_length); } #endif #ifdef PNG_READ_sCAL_SUPPORTED else if (chunk_name == png_sCAL) { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_sCAL(png_ptr, info_ptr, png_ptr->push_length); } #endif #ifdef PNG_READ_tIME_SUPPORTED else if (chunk_name == png_tIME) { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_tIME(png_ptr, info_ptr, png_ptr->push_length); } #endif #ifdef PNG_READ_tEXt_SUPPORTED else if (chunk_name == png_tEXt) { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length); } #endif #ifdef PNG_READ_zTXt_SUPPORTED else if (chunk_name == png_zTXt) { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length); } #endif #ifdef PNG_READ_iTXt_SUPPORTED else if (chunk_name == png_iTXt) { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length); } #endif else { PNG_PUSH_SAVE_BUFFER_IF_FULL png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length, PNG_HANDLE_CHUNK_AS_DEFAULT); } png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER; } void /* PRIVATE */ png_push_crc_skip(png_structrp png_ptr, png_uint_32 skip) { png_ptr->process_mode = PNG_SKIP_MODE; png_ptr->skip_length = skip; } void /* PRIVATE */ png_push_crc_finish(png_structrp png_ptr) { if (png_ptr->skip_length != 0 && png_ptr->save_buffer_size != 0) { png_size_t save_size = png_ptr->save_buffer_size; png_uint_32 skip_length = png_ptr->skip_length; /* We want the smaller of 'skip_length' and 'save_buffer_size', but * they are of different types and we don't know which variable has the * fewest bits. Carefully select the smaller and cast it to the type of * the larger - this cannot overflow. Do not cast in the following test * - it will break on either 16 or 64 bit platforms. */ if (skip_length < save_size) save_size = (png_size_t)skip_length; else skip_length = (png_uint_32)save_size; png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size); png_ptr->skip_length -= skip_length; png_ptr->buffer_size -= save_size; png_ptr->save_buffer_size -= save_size; png_ptr->save_buffer_ptr += save_size; } if (png_ptr->skip_length != 0 && png_ptr->current_buffer_size != 0) { png_size_t save_size = png_ptr->current_buffer_size; png_uint_32 skip_length = png_ptr->skip_length; /* We want the smaller of 'skip_length' and 'current_buffer_size', here, * the same problem exists as above and the same solution. */ if (skip_length < save_size) save_size = (png_size_t)skip_length; else skip_length = (png_uint_32)save_size; png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size); png_ptr->skip_length -= skip_length; png_ptr->buffer_size -= save_size; png_ptr->current_buffer_size -= save_size; png_ptr->current_buffer_ptr += save_size; } if (png_ptr->skip_length == 0) { PNG_PUSH_SAVE_BUFFER_IF_LT(4) png_crc_finish(png_ptr, 0); png_ptr->process_mode = PNG_READ_CHUNK_MODE; } } void PNGCBAPI png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length) { png_bytep ptr; if (png_ptr == NULL) return; ptr = buffer; if (png_ptr->save_buffer_size != 0) { png_size_t save_size; if (length < png_ptr->save_buffer_size) save_size = length; else save_size = png_ptr->save_buffer_size; memcpy(ptr, png_ptr->save_buffer_ptr, save_size); length -= save_size; ptr += save_size; png_ptr->buffer_size -= save_size; png_ptr->save_buffer_size -= save_size; png_ptr->save_buffer_ptr += save_size; } if (length != 0 && png_ptr->current_buffer_size != 0) { png_size_t save_size; if (length < png_ptr->current_buffer_size) save_size = length; else save_size = png_ptr->current_buffer_size; memcpy(ptr, png_ptr->current_buffer_ptr, save_size); png_ptr->buffer_size -= save_size; png_ptr->current_buffer_size -= save_size; png_ptr->current_buffer_ptr += save_size; } } void /* PRIVATE */ png_push_save_buffer(png_structrp png_ptr) { if (png_ptr->save_buffer_size != 0) { if (png_ptr->save_buffer_ptr != png_ptr->save_buffer) { png_size_t i, istop; png_bytep sp; png_bytep dp; istop = png_ptr->save_buffer_size; for (i = 0, sp = png_ptr->save_buffer_ptr, dp = png_ptr->save_buffer; i < istop; i++, sp++, dp++) { *dp = *sp; } } } if (png_ptr->save_buffer_size + png_ptr->current_buffer_size > png_ptr->save_buffer_max) { png_size_t new_max; png_bytep old_buffer; if (png_ptr->save_buffer_size > PNG_SIZE_MAX - (png_ptr->current_buffer_size + 256)) { png_error(png_ptr, "Potential overflow of save_buffer"); } new_max = png_ptr->save_buffer_size + png_ptr->current_buffer_size + 256; old_buffer = png_ptr->save_buffer; png_ptr->save_buffer = (png_bytep)png_malloc_warn(png_ptr, (png_size_t)new_max); if (png_ptr->save_buffer == NULL) { png_free(png_ptr, old_buffer); old_buffer = NULL; png_error(png_ptr, "Insufficient memory for save_buffer"); } memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size); png_free(png_ptr, old_buffer); old_buffer = NULL; png_ptr->save_buffer_max = new_max; } if (png_ptr->current_buffer_size) { memcpy(png_ptr->save_buffer + png_ptr->save_buffer_size, png_ptr->current_buffer_ptr, png_ptr->current_buffer_size); png_ptr->save_buffer_size += png_ptr->current_buffer_size; png_ptr->current_buffer_size = 0; } png_ptr->save_buffer_ptr = png_ptr->save_buffer; png_ptr->buffer_size = 0; } void /* PRIVATE */ png_push_restore_buffer(png_structrp png_ptr, png_bytep buffer, png_size_t buffer_length) { png_ptr->current_buffer = buffer; png_ptr->current_buffer_size = buffer_length; png_ptr->buffer_size = buffer_length + png_ptr->save_buffer_size; png_ptr->current_buffer_ptr = png_ptr->current_buffer; } void /* PRIVATE */ png_push_read_IDAT(png_structrp png_ptr) { if ((png_ptr->mode & PNG_HAVE_CHUNK_HEADER) == 0) { png_byte chunk_length[4]; png_byte chunk_tag[4]; /* TODO: this code can be commoned up with the same code in push_read */ PNG_PUSH_SAVE_BUFFER_IF_LT(8) png_push_fill_buffer(png_ptr, chunk_length, 4); png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length); png_reset_crc(png_ptr); png_crc_read(png_ptr, chunk_tag, 4); png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag); png_ptr->mode |= PNG_HAVE_CHUNK_HEADER; if (png_ptr->chunk_name != png_IDAT) { png_ptr->process_mode = PNG_READ_CHUNK_MODE; if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0) png_error(png_ptr, "Not enough compressed data"); return; } png_ptr->idat_size = png_ptr->push_length; } if (png_ptr->idat_size != 0 && png_ptr->save_buffer_size != 0) { png_size_t save_size = png_ptr->save_buffer_size; png_uint_32 idat_size = png_ptr->idat_size; /* We want the smaller of 'idat_size' and 'current_buffer_size', but they * are of different types and we don't know which variable has the fewest * bits. Carefully select the smaller and cast it to the type of the * larger - this cannot overflow. Do not cast in the following test - it * will break on either 16 or 64 bit platforms. */ if (idat_size < save_size) save_size = (png_size_t)idat_size; else idat_size = (png_uint_32)save_size; png_calculate_crc(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 -= idat_size; png_ptr->buffer_size -= save_size; png_ptr->save_buffer_size -= save_size; png_ptr->save_buffer_ptr += save_size; } if (png_ptr->idat_size != 0 && png_ptr->current_buffer_size != 0) { png_size_t save_size = png_ptr->current_buffer_size; png_uint_32 idat_size = png_ptr->idat_size; /* We want the smaller of 'idat_size' and 'current_buffer_size', but they * are of different types and we don't know which variable has the fewest * bits. Carefully select the smaller and cast it to the type of the * larger - this cannot overflow. */ if (idat_size < save_size) save_size = (png_size_t)idat_size; else idat_size = (png_uint_32)save_size; png_calculate_crc(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 -= idat_size; png_ptr->buffer_size -= save_size; png_ptr->current_buffer_size -= save_size; png_ptr->current_buffer_ptr += save_size; } if (png_ptr->idat_size == 0) { PNG_PUSH_SAVE_BUFFER_IF_LT(4) png_crc_finish(png_ptr, 0); png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER; png_ptr->mode |= PNG_AFTER_IDAT; png_ptr->zowner = 0; } } void /* PRIVATE */ png_process_IDAT_data(png_structrp png_ptr, png_bytep buffer, png_size_t buffer_length) { /* 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; /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */ png_ptr->zstream.avail_in = (uInt)buffer_length; /* 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_ZSTREAM_ENDED)) { int ret; /* We have data for zlib, but we must check that zlib * has someplace 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)) { /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */ 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; } /* Using Z_SYNC_FLUSH here means that an unterminated * LZ stream (a stream with a missing end code) can still * be handled, 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_ZSTREAM_ENDED; png_ptr->zowner = 0; /* 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 in IDAT"); /* Skip the check on unprocessed input */ return; } /* Did inflate output any data? */ if (png_ptr->zstream.next_out != png_ptr->row_buf) { /* 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) { /* Extra data. */ png_warning(png_ptr, "Extra compressed data in IDAT"); png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED; png_ptr->zowner = 0; /* Do no more processing; skip the unprocessed * input check below. */ return; } /* Do we have a complete row? */ if (png_ptr->zstream.avail_out == 0) png_push_process_row(png_ptr); } /* And check for the end of the stream. */ if (ret == Z_STREAM_END) png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED; } /* 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 in IDAT"); } void /* PRIVATE */ png_push_process_row(png_structrp png_ptr) { /* 1.5.6: row_info moved out of png_struct to a local here. */ png_row_info row_info; row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */ row_info.color_type = png_ptr->color_type; row_info.bit_depth = png_ptr->bit_depth; row_info.channels = png_ptr->channels; row_info.pixel_depth = png_ptr->pixel_depth; row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width); if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE) { if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST) png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1, png_ptr->prev_row + 1, png_ptr->row_buf[0]); else png_error(png_ptr, "bad adaptive filter value"); } /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before * 1.5.6, while the buffer really is this big in current versions of libpng * it may not be in the future, so this was changed just to copy the * interlaced row count: */ memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1); #ifdef PNG_READ_TRANSFORMS_SUPPORTED if (png_ptr->transformations != 0) png_do_read_transformations(png_ptr, &row_info); #endif /* The transformed pixel depth should match the depth now in row_info. */ if (png_ptr->transformed_pixel_depth == 0) { png_ptr->transformed_pixel_depth = row_info.pixel_depth; if (row_info.pixel_depth > png_ptr->maximum_pixel_depth) png_error(png_ptr, "progressive row overflow"); } else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth) png_error(png_ptr, "internal progressive row size calculation error"); #ifdef PNG_READ_INTERLACING_SUPPORTED /* Expand interlaced rows to full size */ if (png_ptr->interlaced != 0 && (png_ptr->transformations & PNG_INTERLACE) != 0) { if (png_ptr->pass < 6) png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass, png_ptr->transformations); switch (png_ptr->pass) { case 0: { int i; for (i = 0; i < 8 && png_ptr->pass == 0; i++) { png_push_have_row(png_ptr, png_ptr->row_buf + 1); png_read_push_finish_row(png_ptr); /* Updates png_ptr->pass */ } if (png_ptr->pass == 2) /* Pass 1 might be empty */ { for (i = 0; i < 4 && png_ptr->pass == 2; i++) { png_push_have_row(png_ptr, NULL); png_read_push_finish_row(png_ptr); } } if (png_ptr->pass == 4 && png_ptr->height <= 4) { for (i = 0; i < 2 && png_ptr->pass == 4; i++) { png_push_have_row(png_ptr, NULL); png_read_push_finish_row(png_ptr); } } if (png_ptr->pass == 6 && png_ptr->height <= 4) { png_push_have_row(png_ptr, NULL); png_read_push_finish_row(png_ptr); } break; } case 1: { int i; for (i = 0; i < 8 && png_ptr->pass == 1; i++) { png_push_have_row(png_ptr, png_ptr->row_buf + 1); png_read_push_finish_row(png_ptr); } if (png_ptr->pass == 2) /* Skip top 4 generated rows */ { for (i = 0; i < 4 && png_ptr->pass == 2; i++) { png_push_have_row(png_ptr, NULL); png_read_push_finish_row(png_ptr); } } break; } case 2: { int i; for (i = 0; i < 4 && png_ptr->pass == 2; i++) { png_push_have_row(png_ptr, png_ptr->row_buf + 1); png_read_push_finish_row(png_ptr); } for (i = 0; i < 4 && png_ptr->pass == 2; i++) { png_push_have_row(png_ptr, NULL); png_read_push_finish_row(png_ptr); } if (png_ptr->pass == 4) /* Pass 3 might be empty */ { for (i = 0; i < 2 && png_ptr->pass == 4; i++) { png_push_have_row(png_ptr, NULL); png_read_push_finish_row(png_ptr); } } break; } case 3: { int i; for (i = 0; i < 4 && png_ptr->pass == 3; i++) { png_push_have_row(png_ptr, png_ptr->row_buf + 1); png_read_push_finish_row(png_ptr); } if (png_ptr->pass == 4) /* Skip top two generated rows */ { for (i = 0; i < 2 && png_ptr->pass == 4; i++) { png_push_have_row(png_ptr, NULL); png_read_push_finish_row(png_ptr); } } break; } case 4: { int i; for (i = 0; i < 2 && png_ptr->pass == 4; i++) { png_push_have_row(png_ptr, png_ptr->row_buf + 1); png_read_push_finish_row(png_ptr); } for (i = 0; i < 2 && png_ptr->pass == 4; i++) { png_push_have_row(png_ptr, NULL); png_read_push_finish_row(png_ptr); } if (png_ptr->pass == 6) /* Pass 5 might be empty */ { png_push_have_row(png_ptr, NULL); png_read_push_finish_row(png_ptr); } break; } case 5: { int i; for (i = 0; i < 2 && png_ptr->pass == 5; i++) { png_push_have_row(png_ptr, png_ptr->row_buf + 1); png_read_push_finish_row(png_ptr); } if (png_ptr->pass == 6) /* Skip top generated row */ { png_push_have_row(png_ptr, NULL); png_read_push_finish_row(png_ptr); } break; } default: case 6: { png_push_have_row(png_ptr, png_ptr->row_buf + 1); png_read_push_finish_row(png_ptr); if (png_ptr->pass != 6) break; png_push_have_row(png_ptr, NULL); png_read_push_finish_row(png_ptr); } } } else { png_push_have_row(png_ptr, png_ptr->row_buf + 1); png_read_push_finish_row(png_ptr); } } void /* PRIVATE */ png_read_push_finish_row(png_structrp png_ptr) { /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */ /* Start of interlace block */ static PNG_CONST png_byte png_pass_start[] = {0, 4, 0, 2, 0, 1, 0}; /* Offset to next interlace block */ static PNG_CONST png_byte png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1}; /* Start of interlace block in the y direction */ static PNG_CONST png_byte png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1}; /* Offset to next interlace block in the y direction */ static PNG_CONST png_byte png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2}; /* Height of interlace block. This is not currently used - if you need * it, uncomment it here and in png.h static PNG_CONST png_byte png_pass_height[] = {8, 8, 4, 4, 2, 2, 1}; */ #endif png_ptr->row_number++; if (png_ptr->row_number < png_ptr->num_rows) return; if (png_ptr->interlaced != 0) { png_ptr->row_number = 0; memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1); do { png_ptr->pass++; if ((png_ptr->pass == 1 && png_ptr->width < 5) || (png_ptr->pass == 3 && png_ptr->width < 3) || (png_ptr->pass == 5 && png_ptr->width < 2)) png_ptr->pass++; if (png_ptr->pass > 7) png_ptr->pass--; if (png_ptr->pass >= 7) break; png_ptr->iwidth = (png_ptr->width + png_pass_inc[png_ptr->pass] - 1 - png_pass_start[png_ptr->pass]) / png_pass_inc[png_ptr->pass]; if ((png_ptr->transformations & PNG_INTERLACE) != 0) break; png_ptr->num_rows = (png_ptr->height + png_pass_yinc[png_ptr->pass] - 1 - png_pass_ystart[png_ptr->pass]) / png_pass_yinc[png_ptr->pass]; } while (png_ptr->iwidth == 0 || png_ptr->num_rows == 0); } } void /* PRIVATE */ png_push_have_info(png_structrp png_ptr, png_inforp info_ptr) { if (png_ptr->info_fn != NULL) (*(png_ptr->info_fn))(png_ptr, info_ptr); } void /* PRIVATE */ png_push_have_end(png_structrp png_ptr, png_inforp info_ptr) { if (png_ptr->end_fn != NULL) (*(png_ptr->end_fn))(png_ptr, info_ptr); } void /* PRIVATE */ png_push_have_row(png_structrp png_ptr, png_bytep row) { if (png_ptr->row_fn != NULL) (*(png_ptr->row_fn))(png_ptr, row, png_ptr->row_number, (int)png_ptr->pass); } void PNGAPI png_progressive_combine_row(png_const_structrp png_ptr, png_bytep old_row, png_const_bytep new_row) { if (png_ptr == NULL) return; /* new_row is a flag here - if it is NULL then the app callback was called * from an empty row (see the calls to png_struct::row_fn below), otherwise * it must be png_ptr->row_buf+1 */ if (new_row != NULL) png_combine_row(png_ptr, old_row, 1/*blocky display*/); } void PNGAPI png_set_progressive_read_fn(png_structrp png_ptr, png_voidp progressive_ptr, png_progressive_info_ptr info_fn, png_progressive_row_ptr row_fn, png_progressive_end_ptr end_fn) { if (png_ptr == NULL) return; png_ptr->info_fn = info_fn; png_ptr->row_fn = row_fn; png_ptr->end_fn = end_fn; png_set_read_fn(png_ptr, progressive_ptr, png_push_fill_buffer); } png_voidp PNGAPI png_get_progressive_ptr(png_const_structrp png_ptr) { if (png_ptr == NULL) return (NULL); return png_ptr->io_ptr; } #endif /* PROGRESSIVE_READ */