171 lines
5.3 KiB
C
171 lines
5.3 KiB
C
/* *****************************************************************************
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* decode/std/picture.c -- decode a picture file.
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* Copyright (C) 2017 Thomas "Cakeisalie5" Touhey <thomas@touhey.fr>
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*
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* This file is part of libg1m.
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* libg1m is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 3.0 of the License,
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* or (at your option) any later version.
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*
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* libg1m is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with libg1m; if not, see <http://www.gnu.org/licenses/>.
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* ************************************************************************** */
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#include <libg1m/internals.h>
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#include <zlib.h>
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/* ************************************************************************** */
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/* Obfuscation-related functions */
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/* ************************************************************************** */
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/**
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* g3p_deobfuscate:
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* De-obfuscate the image data.
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*
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* @arg buf the buffer.
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* @arg n the buffer size.
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*/
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static void g3p_deobfuscate(uint8_t *buf, size_t n)
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{
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while (n--) {
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int byte = *buf;
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*buf++ = ~((byte << 5) | (byte >> 3)) & 0xFF;
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}
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}
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/* ************************************************************************** */
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/* Prizm Picture decoding function */
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/* ************************************************************************** */
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/**
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* g1m_decode_std_g3p:
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* Decode a G3P file.
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*
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* @arg handle the handle.
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* @arg buffer the buffer to read from.
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* @arg std the standard header.
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* @arg pic the standard picture header.
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* @return the error code (0 if ok).
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*/
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int g1m_decode_std_g3p(g1m_t **h, g1m_buffer_t *buffer,
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struct standard_header *std, struct standard_picheader *pic)
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{
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int err; *h = NULL;
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uint8_t *defbuf = NULL, *infbuf = NULL;
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/* start a checksum */
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uint32_t check = g1m_checksum32((void*)std,
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sizeof(struct standard_header), 0);
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check = g1m_checksum32((void*)pic,
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sizeof(struct standard_picheader), check);
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/* read the image header */
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DREAD(ihd, g3p_subheader)
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check = g1m_checksum32(&ihd, sizeof(struct g3p_subheader), check);
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unsigned int width = be16toh(ihd.width), height = be16toh(ihd.height);
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int color_depth = be16toh(ihd.color_depth);
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/* log info */
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log_info("Width: %upx, height: %upx", width, height);
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log_info("Pixel depth: %s",
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(color_depth == g3p_color_4bit) ? "4-bit" : "16-bit");
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log_info("Generator ID: 0x%04X", be16toh(ihd.generator_id));
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log_info("-");
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/* read deflated image */
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size_t deflated_image_size = be32toh(ihd.data_size) - 6;
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log_info("Reading %" PRIuSIZE "B of deflated data", deflated_image_size);
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err = g1m_error_alloc;
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defbuf = malloc(deflated_image_size);
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if (!defbuf) goto fail;
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READ(defbuf, deflated_image_size)
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/* unobfuscate if required */
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int is_obfuscated =
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((std->obfuscated + 8) & 0xff) != ((std->filesize & 0xff00) >> 8);
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if (is_obfuscated) {
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log_info("Is obfuscated, let's deobfuscate!");
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g3p_deobfuscate(defbuf, deflated_image_size);
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}
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/* make the destination buffer */
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size_t rawsize = color_depth == g3p_color_4bit
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? g1m_picturesize_4bit_code(width, height)
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: g1m_picturesize_16bit(width, height);
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err = g1m_error_alloc;
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infbuf = malloc(rawsize);
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if (!infbuf) goto fail;
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/* uncompress */
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uLongf inflated_size = 0L; // rawsize?
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int z_err = uncompress(infbuf, &inflated_size, defbuf, deflated_image_size);
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if (z_err) {
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log_fatal("Zlib error: error #%d", z_err);
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err = g1m_error_magic;
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goto fail;
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}
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free(defbuf); defbuf = NULL;
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/* check the checksum */
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uint32_t checksum; READ(&checksum, sizeof(uint32_t))
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uLong adl = adler32(0, defbuf, deflated_image_size);
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if (adl != (uLong)checksum) {
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log_fatal("Incorrect Adler32 checksum!");
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log_fatal("Expected 0x%08" PRIX32 ", got 0x%08lX",
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checksum, adl);
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err = g1m_error_checksum;
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goto fail;
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}
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/* make the handle */
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err = g1m_make_picture(h, ihd.width, ihd.height);
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if (err) goto fail;
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g1m_t *handle = *h;
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/* then store it */
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g1m_decode_picture(handle->pixels, ihd.color_depth == g3p_color_4bit
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? g1m_pictureformat_4bit_code : g1m_pictureformat_16bit,
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infbuf, handle->width, handle->height);
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free(infbuf); infbuf = NULL;
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/* TODO: footers? */
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/* no error */
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return (0);
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fail:
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g1m_free(*h); *h = NULL;
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free(infbuf); free(defbuf);
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return (err);
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}
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/* ************************************************************************** */
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/* Classpad Picture decoding function */
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/* ************************************************************************** */
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/**
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* g1m_decode_std_c2p:
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* Decode Classpad images.
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*
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* @arg handle the handle.
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* @arg buffer the buffer to read from.
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* @arg std the standard header.
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* @arg pic the standard picture header.
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* @return the error code (0 if ok).
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*/
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int g1m_decode_std_c2p(g1m_t **h, g1m_buffer_t *buffer,
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struct standard_header *std, struct standard_picheader *pic)
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{
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(void)h; (void)buffer;
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(void)std; (void)pic;
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/* TODO */
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log_info("C2P files are not managed yet.");
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/* no error */
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return (g1m_error_magic);
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}
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