subdir.c

UNIX/LINUX下面的用户文件系统

static int subdir_utimens(const char *path, const struct timespec ts[2])
{
    struct subdir *d = subdir_get();
    char *newpath = subdir_addpath(d, path);
    int err = -ENOMEM;
    if (newpath) {
        err = fuse_fs_utimens(d->next, newpath, ts);
        free(newpath);
    }
    return err;
}

static int subdir_create(const char *path, mode_t mode, struct fuse_file_info *fi)
{
    struct subdir *d = subdir_get();
    char *newpath = subdir_addpath(d, path);
    int err = -ENOMEM;
    if (newpath) {
        err = fuse_fs_create(d->next, newpath, mode, fi);
        free(newpath);
    }
    return err;
}

static int subdir_open(const char *path, struct fuse_file_info *fi)
{
    struct subdir *d = subdir_get();
    char *newpath = subdir_addpath(d, path);
    int err = -ENOMEM;
    if (newpath) {
        err = fuse_fs_open(d->next, newpath, fi);
        free(newpath);
    }
    return err;
}

static int subdir_read(const char *path, char *buf, size_t size, off_t offset,
                    struct fuse_file_info *fi)
{
    struct subdir *d = subdir_get();
    char *newpath = subdir_addpath(d, path);
    int err = -ENOMEM;
    if (newpath) {
        err = fuse_fs_read(d->next, newpath, buf, size, offset, fi);
        free(newpath);
    }
    return err;
}

static int subdir_write(const char *path, const char *buf, size_t size,
                     off_t offset, struct fuse_file_info *fi)
{
    struct subdir *d = subdir_get();
    char *newpath = subdir_addpath(d, path);
    int err = -ENOMEM;
    if (newpath) {
        err = fuse_fs_write(d->next, newpath, buf, size, offset, fi);
        free(newpath);
    }
    return err;
}

static int subdir_statfs(const char *path, struct statvfs *stbuf)
{
    struct subdir *d = subdir_get();
    char *newpath = subdir_addpath(d, path);
    int err = -ENOMEM;
    if (newpath) {
        err = fuse_fs_statfs(d->next, newpath, stbuf);
        free(newpath);
    }
    return err;
}

static int subdir_flush(const char *path, struct fuse_file_info *fi)
{
    struct subdir *d = subdir_get();
    char *newpath = subdir_addpath(d, path);
    int err = -ENOMEM;
    if (newpath) {
        err = fuse_fs_flush(d->next, newpath, fi);
        free(newpath);
    }
    return err;
}

static int subdir_release(const char *path, struct fuse_file_info *fi)
{
    struct subdir *d = subdir_get();
    char *newpath = subdir_addpath(d, path);
    int err = -ENOMEM;
    if (newpath) {
        err = fuse_fs_release(d->next, newpath, fi);
        free(newpath);
    }
    return err;
}

static int subdir_fsync(const char *path, int isdatasync,
                        struct fuse_file_info *fi)
{
    struct subdir *d = subdir_get();
    char *newpath = subdir_addpath(d, path);
    int err = -ENOMEM;
    if (newpath) {
        err = fuse_fs_fsync(d->next, newpath, isdatasync, fi);
        free(newpath);
    }
    return err;
}

static int subdir_fsyncdir(const char *path, int isdatasync,
                           struct fuse_file_info *fi)
{
    struct subdir *d = subdir_get();
    char *newpath = subdir_addpath(d, path);
    int err = -ENOMEM;
    if (newpath) {
        err = fuse_fs_fsyncdir(d->next, newpath, isdatasync, fi);
        free(newpath);
    }
    return err;
}

static int subdir_setxattr(const char *path, const char *name, const char *value,
                        size_t size, int flags)
{
    struct subdir *d = subdir_get();
    char *newpath = subdir_addpath(d, path);
    int err = -ENOMEM;
    if (newpath) {
        err = fuse_fs_setxattr(d->next, newpath, name, value, size, flags);
        free(newpath);
    }
    return err;
}

static int subdir_getxattr(const char *path, const char *name, char *value,
                    size_t size)
{
    struct subdir *d = subdir_get();
    char *newpath = subdir_addpath(d, path);
    int err = -ENOMEM;
    if (newpath) {
        err = fuse_fs_getxattr(d->next, newpath, name, value, size);
        free(newpath);
    }
    return err;
}

static int subdir_listxattr(const char *path, char *list, size_t size)
{
    struct subdir *d = subdir_get();
    char *newpath = subdir_addpath(d, path);
    int err = -ENOMEM;
    if (newpath) {
        err = fuse_fs_listxattr(d->next, newpath, list, size);
        free(newpath);
    }
    return err;
}

static int subdir_removexattr(const char *path, const char *name)
{
    struct subdir *d = subdir_get();
    char *newpath = subdir_addpath(d, path);
    int err = -ENOMEM;
    if (newpath) {
        err = fuse_fs_removexattr(d->next, newpath, name);
        free(newpath);
    }
    return err;
}

static int subdir_lock(const char *path, struct fuse_file_info *fi, int cmd,
                    struct flock *lock)
{
    struct subdir *d = subdir_get();
    char *newpath = subdir_addpath(d, path);
    int err = -ENOMEM;
    if (newpath) {
        err = fuse_fs_lock(d->next, newpath, fi, cmd, lock);
        free(newpath);
    }
    return err;
}

static int subdir_bmap(const char *path, size_t blocksize, uint64_t *idx)
{
    struct subdir *d = subdir_get();
    char *newpath = subdir_addpath(d, path);
    int err = -ENOMEM;
    if (newpath) {
        err = fuse_fs_bmap(d->next, newpath, blocksize, idx);
        free(newpath);
    }
    return err;
}

static void *subdir_init(struct fuse_conn_info *conn)
{
    struct subdir *d = subdir_get();
    fuse_fs_init(d->next, conn);
    return d;
}

static void subdir_destroy(void *data)
{
    struct subdir *d = data;
    fuse_fs_destroy(d->next);
    free(d->base);
    free(d);
}

static struct fuse_operations subdir_oper = {
    .destroy	= subdir_destroy,
    .init	= subdir_init,
    .getattr	= subdir_getattr,
    .fgetattr	= subdir_fgetattr,
    .access	= subdir_access,
    .readlink	= subdir_readlink,
    .opendir	= subdir_opendir,
    .readdir	= subdir_readdir,
    .releasedir	= subdir_releasedir,
    .mknod	= subdir_mknod,
    .mkdir	= subdir_mkdir,
    .symlink	= subdir_symlink,
    .unlink	= subdir_unlink,
    .rmdir	= subdir_rmdir,
    .rename	= subdir_rename,
    .link	= subdir_link,
    .chmod	= subdir_chmod,
    .chown	= subdir_chown,
    .truncate	= subdir_truncate,
    .ftruncate	= subdir_ftruncate,
    .utimens	= subdir_utimens,
    .create	= subdir_create,
    .open	= subdir_open,
    .read	= subdir_read,
    .write	= subdir_write,
    .statfs	= subdir_statfs,
    .flush	= subdir_flush,
    .release	= subdir_release,
    .fsync	= subdir_fsync,
    .fsyncdir	= subdir_fsyncdir,
    .setxattr	= subdir_setxattr,
    .getxattr	= subdir_getxattr,
    .listxattr	= subdir_listxattr,
    .removexattr= subdir_removexattr,
    .lock	= subdir_lock,
    .bmap	= subdir_bmap,
};

static struct fuse_opt subdir_opts[] = {
    FUSE_OPT_KEY("-h", 0),
    FUSE_OPT_KEY("--help", 0),
    { "subdir=%s", offsetof(struct subdir, base), 0 },
    { "rellinks", offsetof(struct subdir, rellinks), 1 },
    { "norellinks", offsetof(struct subdir, rellinks), 0 },
    FUSE_OPT_END
};

static void subdir_help(void)
{
    fprintf(stderr,
"    -o subdir=DIR          prepend this directory to all paths (mandatory)\n"
"    -o [no]rellinks        transform absolute symlinks to relative\n");
}

static int subdir_opt_proc(void *data, const char *arg, int key,
                           struct fuse_args *outargs)
{
    (void) data; (void) arg; (void) outargs;

    if (!key) {
        subdir_help();
        return -1;
    }

    return 1;
}

static struct fuse_fs *subdir_new(struct fuse_args *args,
                                  struct fuse_fs *next[])
{
    struct fuse_fs *fs;
    struct subdir *d;

    d = calloc(1, sizeof(struct subdir));
    if (d == NULL) {
        fprintf(stderr, "fuse-subdir: memory allocation failed\n");
        return NULL;
    }

    if (fuse_opt_parse(args, d, subdir_opts, subdir_opt_proc) == -1)
        goto out_free;

    if (!next[0] || next[1]) {
        fprintf(stderr, "fuse-subdir: exactly one next filesystem required\n");
        goto out_free;
    }

    if (!d->base) {
        fprintf(stderr, "fuse-subdir: missing 'subdir' option\n");
        goto out_free;
    }

    if (d->base[0] && d->base[strlen(d->base)-1] != '/') {
        char *tmp = realloc(d->base, strlen(d->base) + 2);
        if (!tmp) {
            fprintf(stderr, "fuse-subdir: memory allocation failed\n");
            goto out_free;
        }
        d->base = tmp;
        strcat(d->base, "/");
    }
    d->baselen = strlen(d->base);
    d->next = next[0];
    fs = fuse_fs_new(&subdir_oper, sizeof(subdir_oper), d);
    if (!fs)
        goto out_free;
    return fs;

 out_free:
    free(d->base);
    free(d);
    return NULL;
}

FUSE_REGISTER_MODULE(subdir, subdir_new);