nullfs.c++

/*
    FUSE: Filesystem in Userspace
    Copyright (C) 2001-2005  Miklos Szeredi <miklos@szeredi.hu>

    This program can be distributed under the terms of the GNU GPL.
    See the file COPYING.
*/

#define _FILE_OFFSET_BITS 64
#define FUSE_USE_VERSION 26
#include <fuse.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>

#include <set>
#include <string>
using std::string;
using std::set;
set<string> dirs;       /* global register of directories */
set<string> files;      /* global register of files */

static int strendswith(const char *str, const char *sfx) {
    size_t sfx_len = strlen(sfx);
    size_t str_len = strlen(str);
    if (str_len < sfx_len) return 0;
    return (strncmp(str + (str_len - sfx_len), sfx, sfx_len) == 0);
};

static int nullfs_isdir(const char *path) {
    set<string>::const_iterator pos = dirs.find(string(path));
    if (pos != dirs.end()) return 1;
    return (strendswith(path, "/") || strendswith(path, "/..")
        || strendswith(path, "/.") || (strcmp(path, "..") == 0)
        || (strcmp(path, ".") == 0));
};

static int nullfs_isfile(const char *path) {
    if (strendswith(path, "/foo") || (strcmp(path, "foo") == 0))
        return 1;
    set<string>::const_iterator pos = files.find(string(path));
    return (pos != files.end());
};

static int nullfs_getattr(const char *path, struct stat *stbuf) {
    int res = 0;

    memset(stbuf, 0, sizeof(struct stat));
    if (nullfs_isdir(path)) {
        stbuf->st_mode = S_IFDIR | 0777;
        stbuf->st_nlink = 3;
    } else if (nullfs_isfile(path)) {
        stbuf->st_mode = S_IFREG | 0666;
        stbuf->st_nlink = 1;
        stbuf->st_size = 0;
    } else {
        res = -ENOENT;
    };

    return res;
};

static int nullfs_readdir(const char *path, void *buf, fuse_fill_dir_t
filler, off_t offset, struct fuse_file_info *fi) {
    (void) offset;
    (void) fi;

    /*if (! nullfs_isdir(path)) return -ENOENT;*/

    filler(buf, ".", NULL, 0);
    filler(buf, "..", NULL, 0);
    filler(buf, "foo", NULL, 0);

    return 0;
};

static int nullfs_open(const char *path, struct fuse_file_info *fi) {
    (void) fi;

    if (! nullfs_isfile(path)) return -ENOENT;

    return 0;
};

static int nullfs_read(const char *path, char *buf, size_t size,
off_t offset, struct fuse_file_info *fi) {
    (void) buf;
    (void) size;
    (void) offset;
    (void) fi;

    if (! nullfs_isfile(path)) return -ENOENT;

    return 0;
};

static int nullfs_write(const char *path, const char *buf, size_t size,
off_t offset, struct fuse_file_info *fi) {
    (void) buf;
    (void) offset;
    (void) fi;

    if (! nullfs_isfile(path)) return -ENOENT;

    return (int) size;
};

static int nullfs_mkdir(const char *path, mode_t m) {
    (void) m;

    dirs.insert(string(path));

    return 0;
};

static int nullfs_create(const char *path, mode_t m,
struct fuse_file_info *fi) {
    (void) m;
    (void) fi;

    files.insert(string(path));

    return 0;
};

static int nullfs_mknod(const char *path, mode_t m, dev_t d) {
    (void) m;
    (void) d;

    files.insert(string(path));

    return 0;
};

static int nullfs_unlink(const char *path) {
    (void) path;

    files.erase(string(path));

    return 0;
};

static int nullfs_rename(const char *src, const char *dst) {
    (void) src;
    (void) dst;

    if (nullfs_isdir(src)) {
        dirs.erase(string(src));
        dirs.insert(string(dst));
    } else if (nullfs_isfile(src)) {
        files.erase(string(src));
        files.insert(string(dst));
    } else {
        return -ENOENT;
    };

    return 0;
};

static int nullfs_truncate(const char *path, off_t o) {
    (void) path;
    (void) o;

    return 0;
};

static int nullfs_chmod(const char *path, mode_t m) {
    (void) path;
    (void) m;

    return 0;
};

static int nullfs_chown(const char *path, uid_t u, gid_t g) {
    (void) path;
    (void) u;
    (void) g;

    return 0;
};

static int nullfs_utimens(const char *path, const struct timespec ts[2]) {
    (void) path;
    (void) ts;

    return 0;
};

static struct fuse_operations nullfs_oper;

int main(int argc, char *argv[]) {
    nullfs_oper.getattr = nullfs_getattr;
    nullfs_oper.readdir = nullfs_readdir;
    nullfs_oper.open = nullfs_open;
    nullfs_oper.read = nullfs_read;
    nullfs_oper.write = nullfs_write;
    nullfs_oper.create = nullfs_create;
    nullfs_oper.mknod = nullfs_mknod;
    nullfs_oper.mkdir = nullfs_mkdir;
    nullfs_oper.unlink = nullfs_unlink;
    nullfs_oper.rmdir = nullfs_unlink;
    nullfs_oper.truncate = nullfs_truncate;
    nullfs_oper.rename = nullfs_rename;
    nullfs_oper.chmod = nullfs_chmod;
    nullfs_oper.utimens = nullfs_utimens;
    return fuse_main(argc, argv, &nullfs_oper, NULL);
};

/* vi:set sw=4 et tw=72: */