129 lines
3.1 KiB
C
129 lines
3.1 KiB
C
/*
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* originally from tinfgzip - tiny gzip decompressor
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*
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* Copyright (c) 2003-2019 Joergen Ibsen
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* Copyright (c) 2023 mintsuki and contributors to the Limine project
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*
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* This software is provided 'as-is', without any express or implied
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* warranty. In no event will the authors be held liable for any damages
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* arising from the use of this software.
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*
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* Permission is granted to anyone to use this software for any purpose,
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* including commercial applications, and to alter it and redistribute it
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* freely, subject to the following restrictions:
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*
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* 1. The origin of this software must not be misrepresented; you must
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* not claim that you wrote the original software. If you use this
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* software in a product, an acknowledgment in the product
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* documentation would be appreciated but is not required.
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*
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* 2. Altered source versions must be plainly marked as such, and must
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* not be misrepresented as being the original software.
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*
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* 3. This notice may not be removed or altered from any source
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* distribution.
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*/
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#include <stdint.h>
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#include <stb/stb_image.h>
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typedef enum {
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FTEXT = 1,
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FHCRC = 2,
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FEXTRA = 4,
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FNAME = 8,
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FCOMMENT = 16
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} gzip_flag;
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void *gzip_uncompress(const void *source, uint64_t sourceLen, uint64_t *outsize) {
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const uint8_t *src = (const uint8_t *) source;
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const uint8_t *start;
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int res;
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uint8_t flg;
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/* -- Check header -- */
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/* Check room for at least 10 byte header and 8 byte trailer */
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if (sourceLen < 18) {
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return NULL;
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}
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/* Check id bytes */
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if (src[0] != 0x1F || src[1] != 0x8B) {
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return NULL;
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}
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/* Check method is deflate */
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if (src[2] != 8) {
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return NULL;
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}
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/* Get flag byte */
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flg = src[3];
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/* Check that reserved bits are zero */
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if (flg & 0xE0) {
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return NULL;
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}
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/* -- Find start of compressed data -- */
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/* Skip base header of 10 bytes */
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start = src + 10;
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/* Skip extra data if present */
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if (flg & FEXTRA) {
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uint64_t xlen = *((uint16_t *)start);
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if (xlen > sourceLen - 12) {
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return NULL;
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}
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start += xlen + 2;
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}
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/* Skip file name if present */
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if (flg & FNAME) {
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do {
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if (((uint64_t)(start - src)) >= sourceLen) {
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return NULL;
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}
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} while (*start++);
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}
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/* Skip file comment if present */
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if (flg & FCOMMENT) {
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do {
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if (((uint64_t)(start - src)) >= sourceLen) {
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return NULL;
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}
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} while (*start++);
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}
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if (flg & FHCRC) {
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start += 2;
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}
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/* -- Get decompressed length -- */
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uint32_t dlen = *((uint32_t *)&src[sourceLen - 4]);
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/* -- Decompress data -- */
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if ((src + sourceLen) - start < 8) {
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return NULL;
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}
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void *buf = ext_mem_alloc(dlen);
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res = stbi_zlib_decode_noheader_buffer(buf, dlen, (const char *)start, (src + sourceLen) - start - 8);
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if (res == -1) {
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pmm_free(buf, dlen);
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return NULL;
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}
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*outsize = (uint64_t)dlen;
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return buf;
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}
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