fuse.c

UNIX/LINUX下面的用户文件系统

        return -ENOSYS;
}

int fuse_fs_lock(struct fuse_fs *fs, const char *path,
                 struct fuse_file_info *fi, int cmd, struct flock *lock)
{
    fuse_get_context()->private_data = fs->user_data;
    if (fs->op.lock)
        return fs->op.lock(path, fi, cmd, lock);
    else
        return -ENOSYS;
}

int fuse_fs_chown(struct fuse_fs *fs, const char *path, uid_t uid, gid_t gid)
{
    fuse_get_context()->private_data = fs->user_data;
    if (fs->op.chown)
        return fs->op.chown(path, uid, gid);
    else
        return -ENOSYS;
}

int fuse_fs_truncate(struct fuse_fs *fs, const char *path, off_t size)
{
    fuse_get_context()->private_data = fs->user_data;
    if (fs->op.truncate)
        return fs->op.truncate(path, size);
    else
        return -ENOSYS;
}

int fuse_fs_ftruncate(struct fuse_fs *fs, const char *path, off_t size,
                      struct fuse_file_info *fi)
{
    fuse_get_context()->private_data = fs->user_data;
    if (fs->op.ftruncate)
        return fs->op.ftruncate(path, size, fi);
    else if (fs->op.truncate)
        return fs->op.truncate(path, size);
    else
        return -ENOSYS;
}

int fuse_fs_utimens(struct fuse_fs *fs, const char *path,
                    const struct timespec tv[2])
{
    fuse_get_context()->private_data = fs->user_data;
    if (fs->op.utimens)
        return fs->op.utimens(path, tv);
    else if(fs->op.utime) {
        struct utimbuf buf;
        buf.actime = tv[0].tv_sec;
        buf.modtime = tv[1].tv_sec;
        return fs->op.utime(path, &buf);
    } else
        return -ENOSYS;
}

int fuse_fs_access(struct fuse_fs *fs, const char *path, int mask)
{
    fuse_get_context()->private_data = fs->user_data;
    if (fs->op.access)
        return fs->op.access(path, mask);
    else
        return -ENOSYS;
}

int fuse_fs_readlink(struct fuse_fs *fs, const char *path, char *buf,
                     size_t len)
{
    fuse_get_context()->private_data = fs->user_data;
    if (fs->op.readlink)
        return fs->op.readlink(path, buf, len);
    else
        return -ENOSYS;
}

int fuse_fs_mknod(struct fuse_fs *fs, const char *path, mode_t mode,
                  dev_t rdev)
{
    fuse_get_context()->private_data = fs->user_data;
    if (fs->op.mknod)
        return fs->op.mknod(path, mode, rdev);
    else
        return -ENOSYS;
}

int fuse_fs_mkdir(struct fuse_fs *fs, const char *path, mode_t mode)
{
    fuse_get_context()->private_data = fs->user_data;
    if (fs->op.mkdir)
        return fs->op.mkdir(path, mode);
    else
        return -ENOSYS;
}

int fuse_fs_setxattr(struct fuse_fs *fs, const char *path, const char *name,
                     const char *value, size_t size, int flags)
{
    fuse_get_context()->private_data = fs->user_data;
    if (fs->op.setxattr)
        return fs->op.setxattr(path, name, value, size, flags);
    else
        return -ENOSYS;
}

int fuse_fs_getxattr(struct fuse_fs *fs, const char *path, const char *name,
                     char *value, size_t size)
{
    fuse_get_context()->private_data = fs->user_data;
    if (fs->op.getxattr)
        return fs->op.getxattr(path, name, value, size);
    else
        return -ENOSYS;
}

int fuse_fs_listxattr(struct fuse_fs *fs, const char *path, char *list,
                      size_t size)
{
    fuse_get_context()->private_data = fs->user_data;
    if (fs->op.listxattr)
        return fs->op.listxattr(path, list, size);
    else
        return -ENOSYS;
}

int fuse_fs_bmap(struct fuse_fs *fs, const char *path, size_t blocksize,
                 uint64_t *idx)
{
    fuse_get_context()->private_data = fs->user_data;
    if (fs->op.bmap)
        return fs->op.bmap(path, blocksize, idx);
    else
        return -ENOSYS;
}

int fuse_fs_removexattr(struct fuse_fs *fs, const char *path, const char *name)
{
    fuse_get_context()->private_data = fs->user_data;
    if (fs->op.removexattr)
        return fs->op.removexattr(path, name);
    else
        return -ENOSYS;
}

static int is_open(struct fuse *f, fuse_ino_t dir, const char *name)
{
    struct node *node;
    int isopen = 0;
    pthread_mutex_lock(&f->lock);
    node = lookup_node(f, dir, name);
    if (node && node->open_count > 0)
        isopen = 1;
    pthread_mutex_unlock(&f->lock);
    return isopen;
}

static char *hidden_name(struct fuse *f, fuse_ino_t dir, const char *oldname,
                         char *newname, size_t bufsize)
{
    struct stat buf;
    struct node *node;
    struct node *newnode;
    char *newpath;
    int res;
    int failctr = 10;

    do {
        pthread_mutex_lock(&f->lock);
        node = lookup_node(f, dir, oldname);
        if (node == NULL) {
            pthread_mutex_unlock(&f->lock);
            return NULL;
        }
        do {
            f->hidectr ++;
            snprintf(newname, bufsize, ".fuse_hidden%08x%08x",
                     (unsigned int) node->nodeid, f->hidectr);
            newnode = lookup_node(f, dir, newname);
        } while(newnode);
        pthread_mutex_unlock(&f->lock);

        newpath = get_path_name(f, dir, newname);
        if (!newpath)
            break;

        res = fuse_fs_getattr(f->fs, newpath, &buf);
        if (res == -ENOENT)
            break;
        free(newpath);
        newpath = NULL;
    } while(res == 0 && --failctr);

    return newpath;
}

static int hide_node(struct fuse *f, const char *oldpath,
                     fuse_ino_t dir, const char *oldname)
{
    char newname[64];
    char *newpath;
    int err = -EBUSY;

    newpath = hidden_name(f, dir, oldname, newname, sizeof(newname));
    if (newpath) {
        err = fuse_fs_rename(f->fs, oldpath, newpath);
        if (!err)
            err = rename_node(f, dir, oldname, dir, newname, 1);
        free(newpath);
    }
    return err;
}

static int mtime_eq(const struct stat *stbuf, const struct timespec *ts)
{
    return stbuf->st_mtime == ts->tv_sec && ST_MTIM_NSEC(stbuf) == ts->tv_nsec;
}

#ifndef CLOCK_MONOTONIC
#define CLOCK_MONOTONIC CLOCK_REALTIME
#endif

static void curr_time(struct timespec *now)
{
    static clockid_t clockid = CLOCK_MONOTONIC;
    int res = clock_gettime(clockid, now);
    if (res == -1 && errno == EINVAL) {
        clockid = CLOCK_REALTIME;
        res = clock_gettime(clockid, now);
    }
    if (res == -1) {
        perror("fuse: clock_gettime");
        abort();
    }
}

static void update_stat(struct node *node, const struct stat *stbuf)
{
    if (node->cache_valid && (!mtime_eq(stbuf, &node->mtime) ||
                              stbuf->st_size != node->size))
        node->cache_valid = 0;
    node->mtime.tv_sec = stbuf->st_mtime;
    node->mtime.tv_nsec = ST_MTIM_NSEC(stbuf);
    node->size = stbuf->st_size;
    curr_time(&node->stat_updated);
}

static int lookup_path(struct fuse *f, fuse_ino_t nodeid,
                       const char *name, const char *path,
                       struct fuse_entry_param *e, struct fuse_file_info *fi)
{
    int res;

    memset(e, 0, sizeof(struct fuse_entry_param));
    if (fi)
        res = fuse_fs_fgetattr(f->fs, path, &e->attr, fi);
    else
        res = fuse_fs_getattr(f->fs, path, &e->attr);
    if (res == 0) {
        struct node *node;

        node = find_node(f, nodeid, name);
        if (node == NULL)
            res = -ENOMEM;
        else {
            e->ino = node->nodeid;
            e->generation = node->generation;
            e->entry_timeout = f->conf.entry_timeout;
            e->attr_timeout = f->conf.attr_timeout;
            if (f->conf.auto_cache) {
                pthread_mutex_lock(&f->lock);
                update_stat(node, &e->attr);
                pthread_mutex_unlock(&f->lock);
            }
            set_stat(f, e->ino, &e->attr);
            if (f->conf.debug)
                fprintf(stderr, "   NODEID: %lu\n", (unsigned long) e->ino);
        }
    }
    return res;
}

static struct fuse_context_i *fuse_get_context_internal(void)
{
    struct fuse_context_i *c;

    c = (struct fuse_context_i *) pthread_getspecific(fuse_context_key);
    if (c == NULL) {
        c = (struct fuse_context_i *) malloc(sizeof(struct fuse_context_i));
        if (c == NULL) {
            /* This is hard to deal with properly, so just abort.  If
               memory is so low that the context cannot be allocated,
               there's not much hope for the filesystem anyway */ 
            fprintf(stderr, "fuse: failed to allocate thread specific data\n");
            abort();
        }
        pthread_setspecific(fuse_context_key, c);
    }
    return c;
}

static void fuse_freecontext(void *data)
{
    free(data);
}

static int fuse_create_context_key(void)
{
    int err = 0;
    pthread_mutex_lock(&fuse_context_lock);
    if (!fuse_context_ref) {
        err = pthread_key_create(&fuse_context_key, fuse_freecontext);
        if (err) {
            fprintf(stderr, "fuse: failed to create thread specific key: %s\n",
                    strerror(err));
            pthread_mutex_unlock(&fuse_context_lock);
            return -1;
        }
    }
    fuse_context_ref++;
    pthread_mutex_unlock(&fuse_context_lock);
    return 0;
}

static void fuse_delete_context_key(void)
{
    pthread_mutex_lock(&fuse_context_lock);
    fuse_context_ref--;
    if (!fuse_context_ref) {
        free(pthread_getspecific(fuse_context_key));
        pthread_key_delete(fuse_context_key);
    }
    pthread_mutex_unlock(&fuse_context_lock);
}

static struct fuse *req_fuse_prepare(fuse_req_t req)
{
    struct fuse_context_i *c = fuse_get_context_internal();
    const struct fuse_ctx *ctx = fuse_req_ctx(req);
    c->req = req;
    c->ctx.fuse = req_fuse(req);
    c->ctx.uid = ctx->uid;
    c->ctx.gid = ctx->gid;
    c->ctx.pid = ctx->pid;
    return c->ctx.fuse;
}

static inline void reply_err(fuse_req_t req, int err)
{
    /* fuse_reply_err() uses non-negated errno values */
    fuse_reply_err(req, -err);
}

static void reply_entry(fuse_req_t req, const struct fuse_entry_param *e,
                        int err)
{
    if (!err) {
        struct fuse *f = req_fuse(req);
        if (fuse_reply_entry(req, e) == -ENOENT)
            forget_node(f, e->ino, 1);
    } else
        reply_err(req, err);
}

void fuse_fs_init(struct fuse_fs *fs, struct fuse_conn_info *conn)
{
    fuse_get_context()->private_data = fs->user_data;
    if (fs->op.init)
        fs->user_data = fs->op.init(conn);
}

static void fuse_lib_init(void *data, struct fuse_conn_info *conn)
{
    struct fuse *f = (struct fuse *) data;
    struct fuse_context_i *c = fuse_get_context_internal();

    memset(c, 0, sizeof(*c));
    c->ctx.fuse = f;
    fuse_fs_init(f->fs, conn);
}

void fuse_fs_destroy(struct fuse_fs *fs)
{
    fuse_get_context()->private_data = fs->user_data;
    if (fs->op.destroy)
        fs->op.destroy(fs->user_data);
    if (fs->m)
        fuse_put_module(fs->m);
    free(fs);
}

static void fuse_lib_destroy(void *data)
{
    struct fuse *f = (struct fuse *) data;
    struct fuse_context_i *c = fuse_get_context_internal();

    memset(c, 0, sizeof(*c));
    c->ctx.fuse = f;
    fuse_fs_destroy(f->fs);
    f->fs = NULL;
}

static void fuse_lib_lookup(fuse_req_t req, fuse_ino_t parent,
                            const char *name)
{
    struct fuse *f = req_fuse_prepare(req);
    struct fuse_entry_param e;
    char *path;
    int err;

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path_name(f, parent, name);
    if (path != NULL) {
        struct fuse_intr_data d;
        if (f->conf.debug)
            fprintf(stderr, "LOOKUP %s\n", path);
        fuse_prepare_interrupt(f, req, &d); 
        err = lookup_path(f, parent, name, path, &e, NULL);
        if (err == -ENOENT && f->conf.negative_timeout != 0.0) {
            e.ino = 0;
            e.entry_timeout = f->conf.negative_timeout;
            err = 0;
        }
        fuse_finish_interrupt(f, req, &d);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    reply_entry(req, &e, err);
}

static void fuse_lib_forget(fuse_req_t req, fuse_ino_t ino,
                            unsigned long nlookup)
{
    struct fuse *f = req_fuse(req);
    if (f->conf.debug)
        fprintf(stderr, "FORGET %llu/%lu\n", (unsigned long long)ino, nlookup);
    forget_node(f, ino, nlookup);
    fuse_reply_none(req);
}

static void fuse_lib_getattr(fuse_req_t req, fuse_ino_t ino,
                             struct fuse_file_info *fi)
{
    struct fuse *f = req_fuse_prepare(req);
    struct stat buf;
    char *path;
    int err;

    (void) fi;
    memset(&buf, 0, sizeof(buf));

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        struct fuse_intr_data d;
        fuse_prepare_interrupt(f, req, &d);
        err = fuse_fs_getattr(f->fs, path, &buf);
        fuse_finish_interrupt(f, req, &d);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    if (!err) {
        if (f->conf.auto_cache) {
            pthread_mutex_lock(&f->lock);
            update_stat(get_node(f, ino), &buf);
            pthread_mutex_unlock(&f->lock);
        }
        set_stat(f, ino, &buf);
        fuse_reply_attr(req, &buf, f->conf.attr_timeout);
    } else
        reply_err(req, err);
}