C语言实现tar文件的打包

在C语言中，可以使用libtar库来实现tar文件的打包。下面是一个简单的示例代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <utime.h>
#include <tar.h>

int create_tar(const char *filename, const char *files[], int count) {
    int fd;
    size_t i, bytes_written;
    struct stat stat_buf;
    struct utimbuf time_buf;
    char header_buf[T_BLOCKSIZE];
    tar_header_t *header = (tar_header_t *) header_buf;
    memset(header_buf, 0, T_BLOCKSIZE);
    header->typeflag = REGTYPE;
    for (i = 0; i < count; ++i) {
        if (stat(files[i], &stat_buf) != 0) {
            perror("stat");
            return -1;
        }
        strncpy(header->name, files[i], T_NAMESIZE);
        snprintf(header->size, T_SIZESIZE, "%011lo", (unsigned long) stat_buf.st_size);
        snprintf(header->mode, T_MODESIZE, "%07o", stat_buf.st_mode & 07777);
        snprintf(header->mtime, T_MTIMELEN, "%011lo", (unsigned long) stat_buf.st_mtime);
        snprintf(header->uid, T_UIDSIZE, "%07o", stat_buf.st_uid);
        snprintf(header->gid, T_GIDSIZE, "%07o", stat_buf.st_gid);
        snprintf(header->magic, T_MAGICSIZE, "%s", TMAGIC);
        snprintf(header->version, T_VERSIONSIZE, "%s", TVERSION);
        snprintf(header->uname, T_UNAMESIZE, "%s", "");
        snprintf(header->gname, T_GNAMESIZE, "%s", "");
        snprintf(header->devmajor, T_DEVSIZE, "%s", "");
        snprintf(header->devminor, T_DEVSIZE, "%s", "");
        if ((fd = open(files[i], O_RDONLY)) == -1) {
            perror("open");
            return -1;
        }
        bytes_written = write(1, header_buf, T_BLOCKSIZE);
        if (bytes_written != T_BLOCKSIZE) {
            perror("write");
            return -1;
        }
        bytes_written = 0;
        while (bytes_written < stat_buf.st_size) {
            bytes_written += sendfile(1, fd, NULL, stat_buf.st_size);
            if (bytes_written == -1) {
                perror("sendfile");
                return -1;
            }
        }
        close(fd);
        time_buf.actime = stat_buf.st_atime;
        time_buf.modtime = stat_buf.st_mtime;
        if (utime(files[i], &time_buf) != 0) {
            perror("utime");
            return -1;
        }
        if (stat(files[i], &stat_buf) != 0) {
            perror("stat");
            return -1;
        }
        if (S_ISDIR(stat_buf.st_mode)) {
            memset(header_buf, 0, T_BLOCKSIZE);
            header->typeflag = DIRTYPE;
            snprintf(header->name, T_NAMESIZE, "%s/", files[i]);
            bytes_written = write(1, header_buf, T_BLOCKSIZE);
            if (bytes_written != T_BLOCKSIZE) {
                perror("write");
                return -1;
            }
        }
    }
    memset(header_buf, 0, T_BLOCKSIZE);
    bytes_written = write(1, header_buf, T_BLOCKSIZE);
    if (bytes_written != T_BLOCKSIZE) {
        perror("write");
        return -1;
    }
    return 0;
}

int main(int argc, char *argv[]) {
    char *files[] = {"file1.txt", "file2.txt", "directory"};
    if (create_tar("archive.tar", files, 3) != 0) {
        fprintf(stderr, "Failed to create archive\n");
        return 1;
    }
    return 0;
}

该代码会将给定的文件和目录打包成一个名为`archive.tar`的tar文件，并输出到标准输出。其中，`create_tar`函数接受一个文件名、一个文件名列表和文件数作为参数，返回0表示成功，-1表示失败。在函数中，首先使用`stat`函数获取每个文件的元数据信息，然后填充tar头部，写入tar文件。如果文件是一个目录，需要单独处理，并将目录名后面加上斜线。最后，需要在tar文件结尾写入一个空的tar块，以表示tar文件结束。