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/* This file is part of Nekopack.
Copyright (C) 2017 Jakob Tsar-Fox, All Rights Reserved.
Nekopack is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation, either version 3 of the License, or (at
your option) any later version.
Nekopack is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with Nekopack. If not, see <http://www.gnu.org/licenses/>. */
#include <stdio.h>
#include <stdlib.h>
#include <zlib.h>
#include "defs.h"
#include "extract.h"
/* Returns a pointer to a buffer containing the
inflated contents of a given memory chunk. */
Bytef *inflate_chunk(Bytef *chunk, uint64_t chunk_size,
uint64_t decompressed_size) {
Bytef *decompressed_data = malloc(decompressed_size);
if (decompressed_data == NULL) {
fprintf(stderr, "Insufficient memory to decompress archive.\n");
free(decompressed_data);
return NULL;
}
z_stream data_stream;
data_stream.zalloc = Z_NULL;
data_stream.zfree = Z_NULL;
data_stream.opaque = Z_NULL;
data_stream.avail_in = 0;
data_stream.next_in = Z_NULL;
if (inflateInit(&data_stream) != Z_OK) {
fprintf(stderr, "Could not initialize zlib.\n");
free(decompressed_data);
return NULL;
}
int status_code;
do {
data_stream.avail_in = chunk_size;
if (data_stream.avail_in == 0)
break;
data_stream.next_in = chunk;
// Flushing probably isn't required here.
do {
data_stream.avail_out = decompressed_size;
data_stream.next_out = decompressed_data;
status_code = inflate(&data_stream, Z_NO_FLUSH);
} while (data_stream.avail_out == 0);
} while (status_code != Z_STREAM_END);
inflateEnd(&data_stream);
return decompressed_data;
}
/* Wrapper for inflate_chunk which operates on FILE pointers. The file
pointer's contents are inflated into a memory stream and returned. */
memory_stream decompress_file(FILE *archive, uint64_t sizes_offset) {
uint64_t compressed_size, decompressed_size;
fseek(archive, sizes_offset, SEEK_SET);
fread(&compressed_size, sizeof(uint64_t), 1, archive);
fread(&decompressed_size, sizeof(uint64_t), 1, archive);
/* Decompression is done in memory because it's $CURRENT_YEAR. */
Bytef *decompressed_data, *compressed_data = malloc(compressed_size);
/* This is a pretty shitty way of handling it, though. */
if (compressed_data == NULL) {
fprintf(stderr, "Insufficient memory to decompress archive.\n");
free(compressed_data);
fclose(archive);
exit(EXIT_FAILURE);
}
fread(compressed_data, compressed_size, 1, archive);
decompressed_data = inflate_chunk(compressed_data, compressed_size,
decompressed_size);
/* The compressed data is irrelevant at this point. */
free(compressed_data);
if (decompressed_data == NULL)
exit(EXIT_FAILURE);
return (memory_stream) {decompressed_size, decompressed_data,
decompressed_data};
}
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