Linux readdir如何实现文件压缩与解压

在Linux环境下,readdir函数主要用于列出目录中的文件和子目录。尽管readdir本身并不提供文件压缩与解压的功能,但可以借助其他库和工具来完成这一任务。

下面是一个使用C语言及zlib库来实现文件压缩与解压的例子。在执行前,请确认系统已安装zlib库。

压缩文件

#include 
#include 
#include 
#include 

int compress_file(const char input_filename, const char output_filename) { FILE *input_file = fopen(input_filename, "rb"); if (!input_file) { perror("无法打开输入文件"); return -1; }

FILE *output_file = fopen(output_filename, "wb");
if (!output_file) {
    perror("无法打开输出文件");
    fclose(input_file);
    return -1;
}

int ret, flush;
unsigned have;
z_stream strm;
unsigned char in[4096];
unsigned char out[4096];

strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
ret = deflateInit(&strm, Z_DEFAULT_COMPRESSION);
if (ret != Z_OK) {
    fprintf(stderr, "deflateInit错误 %d\n", ret);
    fclose(input_file);
    fclose(output_file);
    return -1;
}

do {
    strm.avail_in = fread(in, 1, sizeof(in), input_file);
    if (ferror(input_file)) {
        (void)deflateEnd(&strm);
        fclose(input_file);
        fclose(output_file);
        return -1;
    }
    flush = feof(input_file) ? Z_FINISH : Z_NO_FLUSH;
    strm.next_in = in;

    do {
        strm.avail_out = sizeof(out);
        strm.next_out = out;
        ret = deflate(&strm, flush);
        have = sizeof(out) - strm.avail_out;
        if (fwrite(out, 1, have, output_file) != have || ferror(output_file)) {
            (void)deflateEnd(&strm);
            fclose(input_file);
            fclose(output_file);
            return -1;
        }
    } while (strm.avail_out == 0);
} while (flush != Z_FINISH);

(void)deflateEnd(&strm);
fclose(input_file);
fclose(output_file);
return 0;

}

解压文件

#include 

include

include

include

int decompress_file(const char input_filename, const char output_filename) { FILE *input_file = fopen(input_filename, "rb"); if (!input_file) { perror("无法打开输入文件"); return -1; }

FILE *output_file = fopen(output_filename, "wb");
if (!output_file) {
    perror("无法打开输出文件");
    fclose(input_file);
    return -1;
}

int ret, flush;
unsigned have;
z_stream strm;
unsigned char in[4096];
unsigned char out[4096];

strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
ret = inflateInit(&strm);
if (ret != Z_OK) {
    fprintf(stderr, "inflateInit错误 %d\n", ret);
    fclose(input_file);
    fclose(output_file);
    return -1;
}

do {
    strm.avail_in = fread(in, 1, sizeof(in), input_file);
    if (ferror(input_file)) {
        (void)inflateEnd(&strm);
        fclose(input_file);
        fclose(output_file);
        return -1;
    }
    flush = feof(input_file) ? Z_FINISH : Z_NO_FLUSH;
    strm.next_in = in;

    do {
        strm.avail_out = sizeof(out);
        strm.next_out = out;
        ret = inflate(&strm, flush);
        have = sizeof(out) - strm.avail_out;
        if (fwrite(out, 1, have, output_file) != have || ferror(output_file)) {
            (void)inflateEnd(&strm);
            fclose(input_file);
            fclose(output_file);
            return -1;
        }
    } while (strm.avail_out == 0);
} while (flush != Z_FINISH);

(void)inflateEnd(&strm);
fclose(input_file);
fclose(output_file);
return 0;

}

上述两个函数分别用于压缩和解压文件。你可以在需要时调用这些函数。需要注意的是,这里并未涉及readdir函数,因为它的作用是读取目录内容而非处理文件的压缩与解压。若要同时遍历目录并压缩或解压文件,则可在遍历过程中调用上述两个函数。