LzmaLib:C中的压缩/解压缩缓冲区

Question

我试图用LzmaLib的LzmaCompress()和LzmaDecompress()与缓冲,适应提供的例子在这里.

我正在使用~3MB缓冲区进行测试,并且压缩函数似乎工作正常(产生~1.2MB的压缩缓冲区),但是当我尝试解压缩时,它只提取~300字节并返回SZ_ERROR_DATA.

提取的少数字节是正确的,但我不知道为什么它会停在那里.

我的代码:

#include <stdio.h>
#include <stdlib.h>

#include "LzmaLib.h"

void compress(
    unsigned char **outBuf, size_t *dstLen,
    unsigned char *inBuf, size_t srcLen)
{
    unsigned propsSize = LZMA_PROPS_SIZE;
    *dstLen = srcLen + srcLen / 3 + 128;

    *outBuf = (unsigned char*)malloc(propsSize + *dstLen);

    int res = LzmaCompress(
        (unsigned char*)(*outBuf + LZMA_PROPS_SIZE), dstLen,
        inBuf, srcLen,
        *outBuf, &propsSize,
        -1, 0, -1, -1, -1, -1, -1);

    assert(res == SZ_OK);

    *dstLen = *dstLen + LZMA_PROPS_SIZE;
}

void uncompress(
    unsigned char **outBuf, size_t *dstLen,
    unsigned char *inBuf,  size_t srcLen
) {
    *dstLen = 5000000;
    *outBuf = (unsigned char*)malloc(*dstLen);

    srcLen = srcLen - LZMA_PROPS_SIZE;
    int res = LzmaUncompress(
        *outBuf, dstLen,
        (unsigned char*)(inBuf + LZMA_PROPS_SIZE), &srcLen,
        inBuf, LZMA_PROPS_SIZE);

    assert(res == SZ_OK);
}

void do_compress() {
    FILE* file = fopen("Module.dll", "r");
    size_t size, decSize;
    unsigned char *data, *dec = NULL;

    fseek(file, 0L, SEEK_END);
    size = ftell(file);
    fseek(file, 0L, SEEK_SET);

    data = (unsigned char*)malloc(size);
    fread(data, 1, size, file);
    fclose(file);

    compress((unsigned char**)&dec, &decSize, data, size);

    file = fopen("Module.lzma", "w");
    fwrite(dec, 1, decSize, file);
    fclose(file);
}

void do_uncompress() {
    FILE* file = fopen("Module.lzma", "r");
    size_t size, decSize;
    unsigned char *data, *dec = NULL;

    fseek(file, 0L, SEEK_END);
    size = ftell(file);
    fseek(file, 0L, SEEK_SET);

    data = (unsigned char*)malloc(size);
    fread(data, 1, size, file);
    fclose(file);

    uncompress((unsigned char**)&dec, &decSize, data, size);

    file = fopen("Module_DEC.dll", "w");
    fwrite(dec, 1, decSize, file);
    fclose(file);
}

int main()
{
    do_compress();
    do_uncompress();

    return 0;
}

如果这段代码不是用LzmaLib压缩缓冲区的更好方法,我很乐意接受建议.

Answer 1

我打赌这个问题潜伏在你如何读/写你的文件.您需要以二进制模式打开它们以防止在读/写操作期间进行任何替换.

更改以下所有实例:

• fopen(xxx, "r") - > fopen(xxx, "rb")
• fopen(xxx, "w") - > fopen(xxx, "wb")