用户空间中的文件系统（FUSE）

Question

我正在尝试使用fuse实现文件系统。需要为＆＃34;读取目录＆＃34;实现的fuse_operations的功能是什么？和＆＃34;读取文件＆＃34;操作

我尝试通过在网上学习一些教程来实现它，但是无法完全理解它（bbfs文件系统教程https://www.cs.nmsu.edu/~pfeiffer/fuse-tutorial/）并且我的代码给出了分段错误？

    #define FUSE_USE_VERSION 30
    #include <stdio.h>
    #include <ctype.h>
    #include <dirent.h>
    #include <errno.h>
    #include <fcntl.h>
    #include <fuse.h>
    #include <string.h>
    #include <libgen.h>
    #include <limits.h>
    #include <unistd.h>
    #include <sys/types.h>
    #include <sys/xattr.h>

    struct uafs_state {
         char *rootdir;
    };

    #define UAFS_DATA ((struct uafs_state *) fuse_get_context()->private_data)

    static void uafs_fullpath(char fpath[PATH_MAX], const char *path)
    {
        strcpy(fpath, UAFS_DATA->rootdir);
        strncat(fpath, path, PATH_MAX);
    }

    int error_check(int retstat)
    {
        if (retstat < 0) {
            retstat = -errno;
        }

        return retstat;
    }

    int uafs_getattr(const char *path, struct stat *buf)
    {
        printf("Reading Attributes.........\n");
        int retstat;
        char fpath[PATH_MAX];

        uafs_fullpath(fpath, path);
        retstat = error_check(lstat(fpath, buf));

        return retstat;
    }

    int uafs_readdir(const char *path, void *buf, fuse_fill_dir_t       filler, off_t offset, struct fuse_file_info *fi)
    {
        printf("Reading Directory.....\n");
        int retstat = 0;
        DIR *dp;
        struct dirent *de;
        dp = (DIR *) (uintptr_t) fi->fh;
        de = readdir(dp);
        if (de == 0) {
            retstat = -errno;
            return retstat;
        }

        do {
            if (filler(buf, de->d_name, NULL, 0) != 0) {
                return -ENOMEM;
            }
        } while ((de == readdir(dp)) != NULL);

        return retstat;
    }

    int uafs_read(const char *path, char *buf, size_t size, off_t offset, struct fuse_file_info *fi)
    {
        printf("Reading file.....\n");
        int retstat = 0;
        retstat = pread(fi->fh, buf, size, offset);
        return error_check(retstat);
    }

    struct fuse_operations uafs_oper = {
        .getattr = uafs_getattr,
        .readdir = uafs_readdir,    
        .read = uafs_read,
    };

    int main(int argc, char *argv[])
    {
        int fuse_stat;
        struct uafs_state *uafs_data;

        if ((getuid() == 0) || (geteuid() == 0)) {
            printf("Error\n");
            return 1;
        } 

        if ((argc < 3) || (argv[argc-2][0] == '-') || (argv[argc-1][0] == '-')) {
            abort();
        }
        uafs_data = malloc(sizeof(struct uafs_state));
        if (uafs_data == NULL) {
            abort();
        }

        uafs_data->rootdir = realpath(argv[argc-2], NULL);
        argv[argc-2] = argv[argc-1];
        argv[argc-1] = NULL;

        fuse_stat = fuse_main(argc, argv, &uafs_oper, uafs_data);

        return fuse_stat;
     }