紧接上一篇
查看 zpipe 源码发现压缩使用 zlib 算法，其中也包含了解压的代码，但直接执行发现并不好使，有bug。很明显 mtk
并没有真正用过解压，那就需要我们自己来修复一下了，总比没有代码需要我们自己新写容易些。
知识储备，关于 zlib 使用介绍可以参考这篇
对 zlib 有一定认知后，我们就来看看 zpipe 源码
一、分析源码
主看 main 函数，一开始做了参数类型判断，参数一 -l 就走 compress 逻辑，否则就 decompress 逻辑
源码中提示的执行指令为 compress -l 9 logo.raw battery.raw
input 对应 battery.raw output 对应 logo.raw
根据实际传参数量申请大小为 filenum*4 的 unsigned int pinfo ，然后将数据全部初始化为 0 memset((void)pinfo, 0, sizeof(int)*filenum);
关键代码来了
if(sizeof(int)filenum != fwrite(pinfo, 1, filenumsizeof(int), output)) 将文件数量数据写入 output 头部
pinfo[pinfo[0]+2]=ftell(output); 将指针移动到头部数据后一位，同时 pinfo[2] 存储头部数据大小
if (Z_OK != def(input, output, level)) 执行压缩算法，压缩数据跟在头部数据后面
{
ret = -2;
goto done;
}
pinfo[0] = pinfo[0]+1; 记录压缩了几次
for (i = 5; i < argc; i++)
{
fclose(input);
input = fopen(argv[i], "rb"); 重新赋值input，重复上面核心逻辑
pinfo[pinfo[0]+2]=ftell(output);
if (Z_OK != def(input, output, level))
{
fprintf(stderr, "compress error\n");
ret = -2;
goto done;
}
pinfo[0] = pinfo[0]+1;
}
done:
fseek(output, 0L, SEEK_END); 文件指针移动到末尾
pinfo[1] = ftell(output); 获取 output 完整数据
fseek(output, 0L, SEEK_SET); 恢复文件指针位置
fwrite(pinfo, 1, filenum*sizeof(int), output); 写入完整数据
假如执行指令为 ./zpipe -l 9 log.raw wxganl_bat_animation_01.raw wxganl_bat_animation_02.raw wxganl_bat_animation_03.raw
压缩过程为
wxganl_bat_animation_01.raw --> log.raw
wxganl_bat_animation_02.raw --> log.raw
wxganl_bat_animation_03.raw --> log.raw
pinfo[0]=压缩次数 pinfo[1]=第一次压缩后数据大小 pinfo[2]=要压缩文件数量大小 pinfo[3]=第一次压缩后数据大小 pinfo[4]=第一次压缩后数据大小
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include "zlib.h"
#if defined(MSDOS) || defined(OS2) || defined(WIN32) || defined(__CYGWIN__)
# include <fcntl.h>
# include <io.h>
# define SET_BINARY_MODE(file) setmode(fileno(file), O_BINARY)
#else
# define SET_BINARY_MODE(file)
#endif
#define CHUNK 16384
/* Compress from file source to file dest until EOF on source.
def() returns Z_OK on success, Z_MEM_ERROR if memory could not be
allocated for processing, Z_STREAM_ERROR if an invalid compression
level is supplied, 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. */
int def(FILE *source, FILE *dest, int level)
{
int ret, flush;
unsigned have;
z_stream strm;
unsigned char in[CHUNK];
unsigned char out[CHUNK];
/* allocate deflate state */
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
ret = deflateInit(&strm, level);
if (ret != Z_OK)
return ret;
/* compress until end of file */
do
{
strm.avail_in = fread(in, 1, CHUNK, source);
if (ferror(source))
{
(void)deflateEnd(&strm);
return Z_ERRNO;
}
flush = feof(source) ? Z_FINISH : Z_NO_FLUSH;
strm.next_in = in;
/* run deflate() on input until output buffer not full, finish
compression if all of source has been read in */
do
{
strm.avail_out = CHUNK;
strm.next_out = out;
ret = deflate(&strm, flush); /* no bad return value */
assert(ret != Z_STREAM_ERROR); /* state not clobbered */
have = CHUNK - strm.avail_out;
if (fwrite(out, 1, have, dest) != have || ferror(dest))
{
(void)inflateEnd(&strm);
return Z_ERRNO;
}
} while (strm.avail_out == 0);
assert(strm.avail_in == 0); /* all input will be used */
/* done when last data in file processed */
} while (flush != Z_FINISH);
assert(ret == Z_STREAM_END); /* stream will be complete */
/* clean up and return */
(void)deflateEnd(&strm);
return Z_OK;
}
/* 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. */
int inf(FILE *source, FILE *dest)
{
int ret;
unsigned int 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 = CHUNK - strm.avail_out;
if (fwrite(out, 1, have, dest) != have || ferror(dest))
{
(void)inflateEnd(&strm);
return Z_ERRNO;
}
} while (strm.avail_out == 0);
/* done when inflate() says it's done */
} while (ret != Z_STREAM_END);
/* clean up and return */
(void)inflateEnd(&strm);
return ret == Z_STREAM_END ? Z_OK : Z_DATA_ERROR;
}
/* report a zlib or i/o error */
void zerr(int ret)
{
fputs("zpipe: ", stderr);
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);
}
}
/* compress or decompress from stdin to stdout */
int process(int argc, char **argv)
{
int ret;
/* avoid end-of-line conversions */
SET_BINARY_MODE(stdin);
SET_BINARY_MODE(stdout);
/* do compression if no arguments */
if (argc == 1)
{
ret = def(stdin, stdout, Z_DEFAULT_COMPRESSION);
if (ret != Z_OK)
zerr(ret);
return ret;
}
/* do decompression if -d specified */
else if (argc == 2 && strcmp(argv[1], "-d") == 0)
{
ret = inf(stdin, stdout);
if (ret != Z_OK)
zerr(ret);
return ret;
}
/* otherwise, report usage */
else
{
fputs("zpipe usage: zpipe [-d] < source > dest\n", stderr);
return 1;
}
}
int main(int argc, char **argv)
{
int ret = 0;
int i;
FILE *input, *output;
if (argc < 4 || (strcmp(argv[1], "-l") && strcmp(argv[1], "-d")))
{
printf("[Usage] compress -l n output input1 [input2]\n");
printf("Example: compress -l 9 logo.raw battery.raw\n");
return -1;
}
// compress
if(!strcmp(argv[1], "-l"))
{
char *ptemp;
unsigned int *pinfo;
int level = -1;
int filenum = argc - 2;
level = atoi(argv[2]);
input = fopen(argv[4], "rb");
output = fopen(argv[3], "wb");
ptemp = (char*)malloc(1024*1024);
pinfo = (unsigned int*)malloc(filenum*sizeof(int));
if(input < 0 || output < 0 || ptemp == NULL || pinfo == NULL)
{
fprintf(stderr, "open file and allocate temp buffer fail\n");
fprintf(stderr, "input = %d, output = %d, ptemp = 0x%08x, pinfo = 0x%08x\n", input, output, ptemp, pinfo);
ret = -1;
goto done;
}
// structre of pinfo:
// pinfo[0] ==> size of pinfo
// pinfo[1] ==> offset of zip chunk[1]
// pinfo[2] ==> offset of zip chunk[2]
// ...
// pinfo[n] ==> offset of zip chunk[n]
// "offset" is the distance from the begining of the file, not the zip chunk
memset((void*)pinfo, 0, sizeof(int)*filenum);
// write information header to output first
if(sizeof(int)*filenum != fwrite(pinfo, 1, filenum*sizeof(int), output))
{
ret = -2;
goto done;
}
pinfo[pinfo[0]+2]=ftell(output);
if (Z_OK != def(input, output, level))
{
ret = -2;
goto done;
}
pinfo[0] = pinfo[0]+1;
for (i = 5; i < argc; i++)
{
fclose(input);
input = fopen(argv[i], "rb");
pinfo[pinfo[0]+2]=ftell(output);
if (Z_OK != def(input, output, level))
{
fprintf(stderr, "compress error\n");
ret = -2;
goto done;
}
pinfo[0] = pinfo[0]+1;
}
done:
fseek(output, 0L, SEEK_END);
pinfo[1] = ftell(output);
fseek(output, 0L, SEEK_SET);
fwrite(pinfo, 1, filenum*sizeof(int), output);
fclose(input);
fclose(output);
free(ptemp);
free(pinfo);
return ret;
}
// decompress
else
{
unsigned int temp;
unsigned int *pinfo;
char outputfilename[256];
input = fopen(argv[3], "rb");
if(input < 0)
{
printf("open file fail\n");
printf("input = %d\n", input);
ret = -1;
goto done2;
}
fread(&temp, 1, sizeof(int), input);
printf("temp=%d\n", temp);
pinfo = malloc(temp*sizeof(int));
if(pinfo == NULL)
{
printf("allocate pinfo failed\n");
ret = -1;
goto done2;
}
fread(pinfo, 1, temp*sizeof(int), input);
for(i=0;i<temp;i++)
printf("pinfo[%d]=%d\n", i, pinfo[i]);
for(i = 0;i < temp;i++)
{
sprintf(outputfilename, "%d_%s", i, argv[2]);
output = fopen(outputfilename, "wb");
if(output < 0)
{
printf("create output file %s fail\n", outputfilename);
goto done2;
}
fseek(input, pinfo[i], SEEK_SET);
if(Z_OK != inf(input, output))
{
printf("decompress error\n");
ret = -2;
goto done2;
}
fclose(output);
output = 0;
}
done2:
fclose(input);
if(output) fclose(output);
return ret;
}
}
二、改造源码
直接执行解压指令 ./zpipe -d xx ./logo.raw 会报错 decompress error
经过分析是解压文件数量计算不对导致循环出错，结合上面的压缩过程结论，
需要跳过包含 pinfo[x]=要压缩文件数量大小 无效数据
然后我们增加参数 -d 判断， xx 就是解压后文件命名，最终会得到 0_xx.raw 1_xx.raw 等
可以通过文件 md5 指令比对压缩前原文件和解压后的文件
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <assert.h>
#include <zlib.h>
#if defined(MSDOS) || defined(OS2) || defined(WIN32) || defined(__CYGWIN__)
# include <fcntl.h>
# include <io.h>
# define SET_BINARY_MODE(file) setmode(fileno(file), O_BINARY)
#else
# define SET_BINARY_MODE(file)
#endif
#define CHUNK 16384
/* Compress from file source to file dest until EOF on source.
def() returns Z_OK on success, Z_MEM_ERROR if memory could not be
allocated for processing, Z_STREAM_ERROR if an invalid compression
level is supplied, 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. */
int def(FILE *source, FILE *dest, int level)
{
int ret, flush;
unsigned have;
z_stream strm;
unsigned char in[CHUNK];
unsigned char out[CHUNK];
/* allocate deflate state */
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
ret = deflateInit(&strm, level);
if (ret != Z_OK)
return ret;
/* compress until end of file */
do
{
strm.avail_in = fread(in, 1, CHUNK, source);
if (ferror(source))
{
(void)deflateEnd(&strm);
return Z_ERRNO;
}
flush = feof(source) ? Z_FINISH : Z_NO_FLUSH;
strm.next_in = in;
/* run deflate() on input until output buffer not full, finish
compression if all of source has been read in */
do
{
strm.avail_out = CHUNK;
strm.next_out = out;
ret = deflate(&strm, flush); /* no bad return value */
assert(ret != Z_STREAM_ERROR); /* state not clobbered */
have = CHUNK - strm.avail_out;
if (fwrite(out, 1, have, dest) != have || ferror(dest))
{
(void)inflateEnd(&strm);
return Z_ERRNO;
}
} while (strm.avail_out == 0);
assert(strm.avail_in == 0); /* all input will be used */
/* done when last data in file processed */
} while (flush != Z_FINISH);
assert(ret == Z_STREAM_END); /* stream will be complete */
/* clean up and return */
(void)deflateEnd(&strm);
return Z_OK;
}
/* 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. */
int inf(FILE *source, FILE *dest)
{
int ret;
unsigned int 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 = CHUNK - strm.avail_out;
if (fwrite(out, 1, have, dest) != have || ferror(dest))
{
(void)inflateEnd(&strm);
return Z_ERRNO;
}
} while (strm.avail_out == 0);
/* done when inflate() says it's done */
} while (ret != Z_STREAM_END);
/* clean up and return */
(void)inflateEnd(&strm);
return ret == Z_STREAM_END ? Z_OK : Z_DATA_ERROR;
}
/* report a zlib or i/o error */
void zerr(int ret)
{
fputs("zpipe: ", stderr);
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);
}
}
/* compress or decompress from stdin to stdout */
int process(int argc, char **argv)
{
int ret;
/* avoid end-of-line conversions */
SET_BINARY_MODE(stdin);
SET_BINARY_MODE(stdout);
/* do compression if no arguments */
if (argc == 1)
{
ret = def(stdin, stdout, Z_DEFAULT_COMPRESSION);
if (ret != Z_OK)
zerr(ret);
return ret;
}
/* do decompression if -d specified */
else if (argc == 2 && strcmp(argv[1], "-d") == 0)
{
ret = inf(stdin, stdout);
if (ret != Z_OK)
zerr(ret);
return ret;
}
/* otherwise, report usage */
else
{
fputs("zpipe usage: zpipe [-d] < source > dest\n", stderr);
return 1;
}
}
int main(int argc, char **argv)
{
int ret = 0;
int i;
FILE *input, *output;
if (argc < 4 || (strcmp(argv[1], "-l") && strcmp(argv[1], "-d")))
{
printf("[compress Example]: zpipe -l 9 logo.raw battery.raw\n");
printf("[decompress Example]: zpipe -d xx.raw logo.raw\n");
return -1;
}
// compress
if(!strcmp(argv[1], "-l"))
{
char *ptemp;
unsigned int *pinfo;
int level = -1;
int filenum = argc - 2;
level = atoi(argv[2]);
input = fopen(argv[4], "rb");
output = fopen(argv[3], "wb");
ptemp = (char*)malloc(1024*1024);
pinfo = (unsigned int*)malloc(filenum*sizeof(int));
if(input < 0 || output < 0 || ptemp == NULL || pinfo == NULL)
{
fprintf(stderr, "open file and allocate temp buffer fail\n");
fprintf(stderr, "input = %d, output = %d, ptemp = 0x%08x, pinfo = 0x%08x\n", input, output, ptemp, pinfo);
ret = -1;
goto done;
}
// structre of pinfo:
// pinfo[0] ==> size of pinfo
// pinfo[1] ==> offset of zip chunk[1]
// pinfo[2] ==> offset of zip chunk[2]
// ...
// pinfo[n] ==> offset of zip chunk[n]
// "offset" is the distance from the begining of the file, not the zip chunk
memset((void*)pinfo, 0, sizeof(int)*filenum);
// write information header to output first
//将文件个数写入第一位
if(sizeof(int)*filenum != fwrite(pinfo, 1, filenum*sizeof(int), output))
{
ret = -2;
goto done;
}
//获取当前指针位置，也就是文件个数写入内容的实际长度
pinfo[pinfo[0]+2]=ftell(output);
printf("pinfo[0]=%d\n", pinfo[0]);
printf("pinfo[pinfo[0]+2]=%d\n", pinfo[pinfo[0]+2]);
//开始压缩第一个文件
if (Z_OK != def(input, output, level))
{
fprintf(stderr, "compress error 111\n");
ret = -2;
goto done;
}
pinfo[0] = pinfo[0]+1;
printf("argc=%d\n", argc);
for (i = 5; i < argc; i++)
{
fclose(input);
//循环上面过程
input = fopen(argv[i], "rb");
pinfo[pinfo[0]+2]=ftell(output);
if (Z_OK != def(input, output, level))
{
fprintf(stderr, "compress error\n");
ret = -2;
goto done;
}
pinfo[0] = pinfo[0]+1;
}
done:
//将指针移动到文件末尾
fseek(output, 0L, SEEK_END);
//获取文件大小
pinfo[1] = ftell(output);
// printf("pinfo[1]=%d\n", pinfo[1]);
//将指针恢复到原来位置
fseek(output, 0L, SEEK_SET);
//写入数据
fwrite(pinfo, 1, filenum*sizeof(int), output);
for (int i = 0; i < filenum; ++i)
{
printf("pinfo[%d]=%d\n", i , pinfo[i]);
}
fclose(input);
fclose(output);
free(ptemp);
free(pinfo);
return ret;
}
// decompress
else
{
unsigned int temp;
unsigned int *pinfo;
char outputfilename[256];
//打开要解压的文件例如 logo.raw
input = fopen(argv[3], "rb");
if(input < 0)
{
printf("open file fail\n");
printf("input = %d\n", input);
ret = -1;
goto done2;
}
//将文件大小读取到 temp
fread(&temp, 1, sizeof(int), input);
printf("temp=%d\n", temp);
/*int tempLength = (temp+2)*sizeof(int);
printf("tempLength=%d\n", tempLength);*/
temp = temp + 1;//core
//申请指定大小空间
pinfo = malloc(temp*sizeof(int));
if(pinfo == NULL)
{
printf("allocate pinfo failed\n");
ret = -1;
goto done2;
}
//将文件数据读取到 pinfo
fread(pinfo, 1, temp*sizeof(int), input);
/*for(i=0;i<temp;i++)
printf("pinfo[%d]===%d\n", i, pinfo[i]);*/
// int seekIndex = 0;
for(i = 0;i < temp;i++)
{
if (i == 0)
{
printf("skip pinfo 0\n");
continue;//core
}
printf("pinfo[%d]=%d\n", i, pinfo[i]);
//拼接要保存的文件名称，0_xxx.raw
sprintf(outputfilename, "%d_%s", i, argv[2]);
//打开要保存文件流
output = fopen(outputfilename, "wb");
if(output < 0)
{
printf("create output file %s fail\n", outputfilename);
goto done2;
}
//跳过 pinfo[i]
fseek(input, pinfo[i], SEEK_SET);
/*if (i == 0){
seekIndex = tempLength;
}
printf("seekIndex=%d\n", seekIndex);
fseek(input, seekIndex, SEEK_SET);*/
//解压读取数据写入
if(Z_OK != inf(input, output))
{
printf("decompress error\n");
ret = -2;
goto done2;
}
fclose(output);
output = 0;
printf("decompress %s done\n", outputfilename);
// seekIndex += pinfo[i];
}
done2:
fclose(input);
if(output) fclose(output);
return ret;
}
}
三、编译指令
gcc -o zpipe zpipe.c -lz
四、解压 rawx 文件
使用方法
[compress Example]: zpipe -l 9 logo.raw battery.raw
[decompress Example]: zpipe -d xx.raw logo.raw