12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 */
24
25 /* pngpread.c - read a png file in push mode
26 *
27 * This file is available under and governed by the GNU General Public
28 * License version 2 only, as published by the Free Software Foundation.
29 * However, the following notice accompanied the original version of this
30 * file and, per its terms, should not be removed:
31 *
32 * Last changed in libpng 1.6.24 [August 4, 2016]
33 * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
34 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
35 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
36 *
37 * This code is released under the libpng license.
38 * For conditions of distribution and use, see the disclaimer
39 * and license in png.h
40 */
41
42 #include "pngpriv.h"
43
44 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
45
46 /* Push model modes */
47 #define PNG_READ_SIG_MODE 0
48 #define PNG_READ_CHUNK_MODE 1
49 #define PNG_READ_IDAT_MODE 2
50 #define PNG_READ_tEXt_MODE 4
51 #define PNG_READ_zTXt_MODE 5
52 #define PNG_READ_DONE_MODE 6
53 #define PNG_READ_iTXt_MODE 7
200 #endif
201
202 /* First we make sure we have enough data for the 4-byte chunk name
203 * and the 4-byte chunk length before proceeding with decoding the
204 * chunk data. To fully decode each of these chunks, we also make
205 * sure we have enough data in the buffer for the 4-byte CRC at the
206 * end of every chunk (except IDAT, which is handled separately).
207 */
208 if ((png_ptr->mode & PNG_HAVE_CHUNK_HEADER) == 0)
209 {
210 png_byte chunk_length[4];
211 png_byte chunk_tag[4];
212
213 PNG_PUSH_SAVE_BUFFER_IF_LT(8)
214 png_push_fill_buffer(png_ptr, chunk_length, 4);
215 png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
216 png_reset_crc(png_ptr);
217 png_crc_read(png_ptr, chunk_tag, 4);
218 png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
219 png_check_chunk_name(png_ptr, png_ptr->chunk_name);
220 png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
221 }
222
223 chunk_name = png_ptr->chunk_name;
224
225 if (chunk_name == png_IDAT)
226 {
227 if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
228 png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
229
230 /* If we reach an IDAT chunk, this means we have read all of the
231 * header chunks, and we can start reading the image (or if this
232 * is called after the image has been read - we have an error).
233 */
234 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
235 png_error(png_ptr, "Missing IHDR before IDAT");
236
237 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
238 (png_ptr->mode & PNG_HAVE_PLTE) == 0)
239 png_error(png_ptr, "Missing PLTE before IDAT");
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12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 */
24
25 /* pngpread.c - read a png file in push mode
26 *
27 * This file is available under and governed by the GNU General Public
28 * License version 2 only, as published by the Free Software Foundation.
29 * However, the following notice accompanied the original version of this
30 * file and, per its terms, should not be removed:
31 *
32 * Last changed in libpng 1.6.32 [August 24, 2017]
33 * Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
34 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
35 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
36 *
37 * This code is released under the libpng license.
38 * For conditions of distribution and use, see the disclaimer
39 * and license in png.h
40 */
41
42 #include "pngpriv.h"
43
44 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
45
46 /* Push model modes */
47 #define PNG_READ_SIG_MODE 0
48 #define PNG_READ_CHUNK_MODE 1
49 #define PNG_READ_IDAT_MODE 2
50 #define PNG_READ_tEXt_MODE 4
51 #define PNG_READ_zTXt_MODE 5
52 #define PNG_READ_DONE_MODE 6
53 #define PNG_READ_iTXt_MODE 7
200 #endif
201
202 /* First we make sure we have enough data for the 4-byte chunk name
203 * and the 4-byte chunk length before proceeding with decoding the
204 * chunk data. To fully decode each of these chunks, we also make
205 * sure we have enough data in the buffer for the 4-byte CRC at the
206 * end of every chunk (except IDAT, which is handled separately).
207 */
208 if ((png_ptr->mode & PNG_HAVE_CHUNK_HEADER) == 0)
209 {
210 png_byte chunk_length[4];
211 png_byte chunk_tag[4];
212
213 PNG_PUSH_SAVE_BUFFER_IF_LT(8)
214 png_push_fill_buffer(png_ptr, chunk_length, 4);
215 png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
216 png_reset_crc(png_ptr);
217 png_crc_read(png_ptr, chunk_tag, 4);
218 png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
219 png_check_chunk_name(png_ptr, png_ptr->chunk_name);
220 png_check_chunk_length(png_ptr, png_ptr->push_length);
221 png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
222 }
223
224 chunk_name = png_ptr->chunk_name;
225
226 if (chunk_name == png_IDAT)
227 {
228 if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
229 png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
230
231 /* If we reach an IDAT chunk, this means we have read all of the
232 * header chunks, and we can start reading the image (or if this
233 * is called after the image has been read - we have an error).
234 */
235 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
236 png_error(png_ptr, "Missing IHDR before IDAT");
237
238 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
239 (png_ptr->mode & PNG_HAVE_PLTE) == 0)
240 png_error(png_ptr, "Missing PLTE before IDAT");
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