fuse.c

Linux下fuse用户文件系统的的源代码

}

static void fuse_do_finish_interrupt(struct fuse *f, fuse_req_t req,
                                     struct fuse_intr_data *d)
{
    pthread_mutex_lock(&f->lock);
    d->finished = 1;
    pthread_cond_broadcast(&d->cond);
    pthread_mutex_unlock(&f->lock);
    fuse_req_interrupt_func(req, NULL, NULL);
    pthread_cond_destroy(&d->cond);
}

static void fuse_do_prepare_interrupt(fuse_req_t req, struct fuse_intr_data *d)
{
    d->id = pthread_self();
    pthread_cond_init(&d->cond, NULL);
    d->finished = 0;
    fuse_req_interrupt_func(req, fuse_interrupt, d);
}

static inline void fuse_finish_interrupt(struct fuse *f, fuse_req_t req,
                                         struct fuse_intr_data *d)
{
    if (f->conf.intr)
        fuse_do_finish_interrupt(f, req, d);
}

static inline void fuse_prepare_interrupt(struct fuse *f, fuse_req_t req,
                                          struct fuse_intr_data *d)
{
    if (f->conf.intr)
        fuse_do_prepare_interrupt(req, d);
}

static int fuse_do_getattr(struct fuse *f, fuse_req_t req, const char *path,
                           struct stat *buf)
{
    int res;
    struct fuse_intr_data d;
    fuse_prepare_interrupt(f, req, &d);
    res = f->op.getattr(path, buf);
    fuse_finish_interrupt(f, req, &d);
    return res;
}

static int fuse_do_fgetattr(struct fuse *f, fuse_req_t req, const char *path,
                            struct stat *buf, struct fuse_file_info *fi)
{
    int res;
    struct fuse_intr_data d;
    fuse_prepare_interrupt(f, req, &d);
    res = f->op.fgetattr(path, buf, fi);
    fuse_finish_interrupt(f, req, &d);
    return res;
}

static int fuse_do_rename(struct fuse *f, fuse_req_t req, const char *oldpath,
                          const char *newpath)
{
    int res;
    struct fuse_intr_data d;
    fuse_prepare_interrupt(f, req, &d);
    res = f->op.rename(oldpath, newpath);
    fuse_finish_interrupt(f, req, &d);
    return res;
}

static int fuse_do_unlink(struct fuse *f, fuse_req_t req, const char *path)
{
    int res;
    struct fuse_intr_data d;
    fuse_prepare_interrupt(f, req, &d);
    res = f->op.unlink(path);
    fuse_finish_interrupt(f, req, &d);
    return res;
}

static void fuse_do_release(struct fuse *f, fuse_req_t req, const char *path,
                            struct fuse_file_info *fi)
{
    struct fuse_intr_data d;
    fuse_prepare_interrupt(f, req, &d);
    f->op.release(path, fi);
    fuse_finish_interrupt(f, req, &d);
}

static int fuse_do_opendir(struct fuse *f, fuse_req_t req, char *path,
                           struct fuse_file_info *fi)
{
    int res;
    struct fuse_intr_data d;
    fuse_prepare_interrupt(f, req, &d);
    res = f->op.opendir(path, fi);
    fuse_finish_interrupt(f, req, &d);
    return res;
}

static int fuse_do_open(struct fuse *f, fuse_req_t req, char *path,
                           struct fuse_file_info *fi)
{
    int res;
    struct fuse_intr_data d;
    fuse_prepare_interrupt(f, req, &d);
    res = f->op.open(path, fi);
    fuse_finish_interrupt(f, req, &d);
    return res;
}

static int fuse_do_flush(struct fuse *f, fuse_req_t req, const char *path,
                         struct fuse_file_info *fi)
{
    int res;
    struct fuse_intr_data d;
    fuse_prepare_interrupt(f, req, &d);
    res = f->op.flush(path, fi);
    fuse_finish_interrupt(f, req, &d);
    return res;
}

static int fuse_do_statfs(struct fuse *f, fuse_req_t req, const char *path,
                          struct statvfs *buf)
{
    int res;
    struct fuse_intr_data d;
    fuse_prepare_interrupt(f, req, &d);
    res = f->op.statfs(path, buf);
    fuse_finish_interrupt(f, req, &d);
    return res;
}

static void fuse_do_releasedir(struct fuse *f, fuse_req_t req,
                               const char *path, struct fuse_file_info *fi)
{
    struct fuse_intr_data d;
    fuse_prepare_interrupt(f, req, &d);
    f->op.releasedir(path, fi);
    fuse_finish_interrupt(f, req, &d);
}

static int fuse_do_create(struct fuse *f, fuse_req_t req, const char *path,
                          mode_t mode, struct fuse_file_info *fi)
{
    int res;
    struct fuse_intr_data d;
    fuse_prepare_interrupt(f, req, &d);
    res = f->op.create(path, mode, fi);
    fuse_finish_interrupt(f, req, &d);
    return res;
}

static int fuse_do_lock(struct fuse *f, fuse_req_t req, const char *path,
                        struct fuse_file_info *fi, int cmd, struct flock *lock)
{
    int res;
    struct fuse_intr_data d;
    fuse_prepare_interrupt(f, req, &d);
    res = f->op.lock(path, fi, cmd, lock);
    fuse_finish_interrupt(f, req, &d);
    return res;
}

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_req_t req, 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;

    if (!f->op.getattr)
        return NULL;

    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_do_getattr(f, req, newpath, &buf);
        if (res != 0)
            break;
        free(newpath);
        newpath = NULL;
    } while(--failctr);

    return newpath;
}

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

    if (f->op.rename && f->op.unlink) {
        newpath = hidden_name(f, req, dir, oldname, newname, sizeof(newname));
        if (newpath) {
            err = fuse_do_rename(f, req, 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
#ifdef FUSE_STAT_HAS_NANOSEC
        && ST_MTIM(stbuf).tv_nsec == ts->tv_nsec
#endif
        ;
}

static void mtime_set(const struct stat *stbuf, struct timespec *ts)
{
#ifdef FUSE_STAT_HAS_NANOSEC
    *ts = ST_MTIM(stbuf);
#else
    ts->tv_sec = stbuf->st_mtime;
#endif
}

#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;
    mtime_set(stbuf, &node->mtime);
    node->size = stbuf->st_size;
    curr_time(&node->stat_updated);
}

static int lookup_path(struct fuse *f, fuse_req_t req, 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 && f->op.fgetattr)
        res = fuse_do_fgetattr(f, req, path, &e->attr, fi);
    else
        res = fuse_do_getattr(f, req, 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) {
                printf("   NODEID: %lu\n", (unsigned long) e->ino);
                fflush(stdout);
            }
        }
    }
    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;
    c->ctx.private_data = c->ctx.fuse->user_data;
    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);
}

static void fuse_data_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;
    c->ctx.private_data = f->user_data;

    if (f->op.init)
        f->user_data = f->op.init(conn);
}

static void fuse_data_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;
    c->ctx.private_data = f->user_data;

    if (f->op.destroy)
        f->op.destroy(f->user_data);
}

static void fuse_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) {
        if (f->conf.debug) {
            printf("LOOKUP %s\n", path);
            fflush(stdout);
        }
        err = -ENOSYS;
        if (f->op.getattr) {
            err = lookup_path(f, req, 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;
            }
        }
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    reply_entry(req, &e, err);
}

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

static void fuse_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;