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/*
* A tool for reading the zlib compressed calibration data
* found in AVM Fritz!Box based devices).
*
* Copyright (c) 2017 Christian Lamparter <chunkeey@googlemail.com>
*
* Based on zpipe, which is an example of proper use of zlib's inflate().
* that is Not copyrighted -- provided to the public domain
* Version 1.4 11 December 2005 Mark Adler
*
* This program 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 2 of the License, or
* (at your option) any later version.
*
* This program 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 this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <unistd.h>
#include <stdint.h>
#include <stdlib.h>
#include <endian.h>
#include <errno.h>
#include "zlib.h"
#define CHUNK 1024
static inline size_t special_min(size_t a, size_t b)
{
return a == 0 ? b : (a < b ? a : b);
}
/* Decompress from file source to file dest until stream ends or EOF.
inf() returns Z_OK on success, Z_MEM_ERROR if memory could not be
allocated for processing, Z_DATA_ERROR if the deflate data is
invalid or incomplete, Z_VERSION_ERROR if the version of zlib.h and
the version of the library linked do not match, or Z_ERRNO if there
is an error reading or writing the files. */
static int inf(FILE *source, FILE *dest, size_t limit, size_t skip)
{
int ret;
size_t have;
z_stream strm;
unsigned char in[CHUNK];
unsigned char out[CHUNK];
/* allocate inflate state */
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = 0;
strm.next_in = Z_NULL;
ret = inflateInit(&strm);
if (ret != Z_OK)
return ret;
/* decompress until deflate stream ends or end of file */
do {
strm.avail_in = fread(in, 1, CHUNK, source);
if (ferror(source)) {
(void)inflateEnd(&strm);
return Z_ERRNO;
}
if (strm.avail_in == 0)
break;
strm.next_in = in;
/* run inflate() on input until output buffer not full */
do {
strm.avail_out = CHUNK;
strm.next_out = out;
ret = inflate(&strm, Z_NO_FLUSH);
assert(ret != Z_STREAM_ERROR); /* state not clobbered */
switch (ret) {
case Z_NEED_DICT:
ret = Z_DATA_ERROR; /* and fall through */
case Z_DATA_ERROR:
case Z_MEM_ERROR:
(void)inflateEnd(&strm);
return ret;
}
have = special_min(limit, CHUNK - strm.avail_out) - skip;
if (fwrite(&out[skip], have, 1, dest) != 1 || ferror(dest)) {
(void)inflateEnd(&strm);
return Z_ERRNO;
}
skip = 0;
limit -= have;
} while (strm.avail_out == 0 && limit > 0);
/* done when inflate() says it's done */
} while (ret != Z_STREAM_END && limit > 0);
/* clean up and return */
(void)inflateEnd(&strm);
return (limit == 0 ? Z_OK : (ret == Z_STREAM_END ? Z_OK : Z_DATA_ERROR));
}
/* report a zlib or i/o error */
static void zerr(int ret)
{
switch (ret) {
case Z_ERRNO:
if (ferror(stdin))
fputs("error reading stdin\n", stderr);
if (ferror(stdout))
fputs("error writing stdout\n", stderr);
break;
case Z_STREAM_ERROR:
fputs("invalid compression level\n", stderr);
break;
case Z_DATA_ERROR:
fputs("invalid or incomplete deflate data\n", stderr);
break;
case Z_MEM_ERROR:
fputs("out of memory\n", stderr);
break;
case Z_VERSION_ERROR:
fputs("zlib version mismatch!\n", stderr);
}
}
static unsigned int get_num(char *str)
{
if (!strncmp("0x", str, 2))
return strtoul(str+2, NULL, 16);
else
return strtoul(str, NULL, 10);
}
static void usage(void)
{
fprintf(stderr, "Usage: fritz_cal_extract [-s seek offset] [-i skip] [-o output file] [-l limit] [infile] -e entry_id\n"
"Finds and extracts zlib compressed calibration data in the EVA loader\n");
exit(EXIT_FAILURE);
}
struct cal_entry {
uint16_t id;
uint16_t len;
} __attribute__((packed));
/* compress or decompress from stdin to stdout */
int main(int argc, char **argv)
{
struct cal_entry cal = { .len = 0 };
FILE *in = stdin;
FILE *out = stdout;
size_t limit = 0, skip = 0;
int initial_offset = 0;
int entry = -1;
int ret;
int opt;
while ((opt = getopt(argc, argv, "s:e:o:l:i:")) != -1) {
switch (opt) {
case 's':
initial_offset = (int)get_num(optarg);
if (errno) {
perror("Failed to parse seek offset");
goto out_bad;
}
break;
case 'e':
entry = (int) htobe16(get_num(optarg));
if (errno) {
perror("Failed to entry id");
goto out_bad;
}
break;
case 'o':
out = fopen(optarg, "w");
if (!out) {
perror("Failed to create output file");
goto out_bad;
}
break;
case 'l':
limit = (size_t)get_num(optarg);
if (errno) {
perror("Failed to parse limit");
goto out_bad;
}
break;
case 'i':
skip = (size_t)get_num(optarg);
if (errno) {
perror("Failed to parse skip");
goto out_bad;
}
break;
default: /* '?' */
usage();
}
}
if (entry == -1)
usage();
if (argc > 1 && optind <= argc) {
in = fopen(argv[optind], "r");
if (!in) {
perror("Failed to create output file");
goto out_bad;
}
}
if (initial_offset) {
ret = fseek(in, initial_offset, SEEK_CUR);
if (ret) {
perror("Failed to seek to calibration table");
goto out_bad;
}
}
do {
ret = fseek(in, be16toh(cal.len), SEEK_CUR);
if (feof(in)) {
fprintf(stderr, "Reached end of file, but didn't find the matching entry\n");
goto out_bad;
} else if (ferror(in)) {
perror("Failure during seek");
goto out_bad;
}
ret = fread(&cal, 1, sizeof cal, in);
if (ret != sizeof cal)
goto out_bad;
} while (entry != cal.id || cal.id == 0xffff);
if (cal.id == 0xffff) {
fprintf(stderr, "Reached end of filesystem, but didn't find the matching entry\n");
goto out_bad;
}
ret = inf(in, out, limit, skip);
if (ret == Z_OK)
goto out;
zerr(ret);
out_bad:
ret = EXIT_FAILURE;
out:
fclose(in);
fclose(out);
return ret;
}
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