c - zlib 压缩和解压使用

Question

我正在尝试使用 compress() 和 uncompress() 函数以最简单的方式使用 zlib 压缩和解压缩随机生成的字符串。但是在执行 uncompress() 函数后，我得到了一个 Z_DATA_ERROR (-3)。有人知道我的错误在哪里吗？

代码如下:

int
main(int argc __attribute ((unused)),char **argv __attribute ((unused)))
{
    unsigned char* cara_in;
    unsigned char* cara_inter;
    unsigned char* cara_out; 

    size_t i;
    size_t len = 1024*50; //50 KBytes
    int ret;

    cara_in = (unsigned char*)malloc(sizeof(unsigned char*)*len);
    cara_inter = (unsigned char*)malloc(sizeof(unsigned char*)*len);
    cara_out = (unsigned char*)malloc(sizeof(unsigned char*)*len);

    uLongf size_cara_inter;
    uLongf size_cara_out;

    srand(time (NULL));

    /* Generating */
    for(i=0; i < len-1;i++)
    {
        cara_in[i] = (int)(rand() %24 +65);
    }

    size_cara_inter = 2*len;

    ret = compress(
                cara_inter,
                &size_cara_inter,
                cara_in,
                (uLongf)strlen((const char*)cara_in)
                );
    if(ret != Z_OK)
    {
        /* error */
        return EXIT_FAILURE;
    }

    size_cara_out = 2*len;

    ret = uncompress(
                cara_out,
                &size_cara_out,
                cara_inter,
                (uLongf)strlen((const char*)cara_inter)
                );
    if(ret != Z_OK)
    {
        /* error */
        return EXIT_FAILURE;
    }

    /* compare */
    ret = strcmp((const char*)cara_in, (const char*)cara_out);
    if(ret != 0){
        /*problem*/
        fprintf(stderr, "\nOuups! :(\nResult of cmp is %d", ret);
        fflush(stderr);

        fprintf(
                    stderr,
                    "\ncara_in length : %d, cara_out length : %d\n",
                    (unsigned)strlen((const char*)cara_in), (unsigned)strlen((const char*)cara_out)
                    );
        fflush(stderr);
    }

    return EXIT_SUCCESS;
}

Answer 1

这里是更正后的源代码，感谢 Francis:

int
main(int argc __attribute ((unused)),char **argv __attribute ((unused)))
{
    unsigned char* cara_in;
    unsigned char* cara_inter;
    unsigned char* cara_out; 

    size_t i;
    size_t len = 1024*50; //50 KBytes
    int ret;

    cara_in = (unsigned char*)malloc(sizeof(unsigned char*)*len);
    cara_inter = (unsigned char*)malloc(sizeof(unsigned char*)*len);
    cara_out = (unsigned char*)malloc(sizeof(unsigned char*)*len);

    uLongf size_cara_inter;
    uLongf size_cara_out;

    srand(time (NULL));

    /* Generating */
    for(i=0; i < len-1;i++)
    {
        cara_in[i] = (int)(rand() %24 +65);
    }

    cara_in[len] = '\0';

    size_cara_inter = 2*len;

    ret = compress(
                cara_inter,
                &size_cara_inter,
                cara_in,
                (uLongf)strlen((const char*)cara_in)
                );
    if(ret != Z_OK)
    {
        /* error */
        return EXIT_FAILURE;
    }

    size_cara_out = 2*len;

    ret = uncompress(
                cara_out,
                &size_cara_out,
                cara_inter,
                size_cara_inter
                );
    if(ret != Z_OK)
    {
        /* error */
        return EXIT_FAILURE;
    }

    /* compare */
    ret = strcmp((const char*)cara_in, (const char*)cara_out);
    if(ret != 0){
        /*problem*/
        fprintf(stderr, "\nOuups! :(\nResult of cmp is %d", ret);
        fflush(stderr);

        fprintf(
                    stderr,
                    "\ncara_in length : %d, cara_out length : %d\n",
                    (unsigned)strlen((const char*)cara_in), (unsigned)strlen((const char*)cara_out)
                    );
        fflush(stderr);
    }

    return EXIT_SUCCESS;
}