fuse.c

linux下的用户文件系统fuse-2.5.2

        if (fuse_reply_open(req, fi) == -ENOENT) {
            /* The open syscall was interrupted, so it must be cancelled */
            if(f->op.release && path != NULL)
                fuse_do_release(f, path, fi);
        } else {
            struct node *node = get_node(f, ino);
            node->open_count ++;
        }
        pthread_mutex_unlock(&f->lock);
    } else
        reply_err(req, err);

    if (path)
        free(path);
    pthread_rwlock_unlock(&f->tree_lock);
}

static void fuse_read(fuse_req_t req, fuse_ino_t ino, size_t size, off_t off,
                      struct fuse_file_info *fi)
{
    struct fuse *f = req_fuse_prepare(req);
    char *path;
    char *buf;
    int res;

    buf = (char *) malloc(size);
    if (buf == NULL) {
        reply_err(req, -ENOMEM);
        return;
    }

    res = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        if (f->conf.debug) {
            printf("READ[%llu] %u bytes from %llu\n",
                   (unsigned long long) fi->fh, size, off);
            fflush(stdout);
        }

        res = -ENOSYS;
        if (f->op.read)
            res = f->op.read(path, buf, size, off, fi);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);

    if (res >= 0) {
        if (f->conf.debug) {
            printf("   READ[%llu] %u bytes\n", (unsigned long long) fi->fh,
                   res);
            fflush(stdout);
        }
        if ((size_t) res > size)
            fprintf(stderr, "fuse: read too many bytes");
        fuse_reply_buf(req, buf, res);
    } else
        reply_err(req, res);

    free(buf);
}

static void fuse_write(fuse_req_t req, fuse_ino_t ino, const char *buf,
                       size_t size, off_t off, struct fuse_file_info *fi)
{
    struct fuse *f = req_fuse_prepare(req);
    char *path;
    int res;

    res = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        if (f->conf.debug) {
            printf("WRITE%s[%llu] %u bytes to %llu\n",
                   fi->writepage ? "PAGE" : "", (unsigned long long) fi->fh,
                   size, off);
            fflush(stdout);
        }

        res = -ENOSYS;
        if (f->op.write)
            res = f->op.write(path, buf, size, off, fi);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);

    if (res >= 0) {
        if (f->conf.debug) {
            printf("   WRITE%s[%llu] %u bytes\n",
                   fi->writepage ? "PAGE" : "", (unsigned long long) fi->fh,
                   res);
            fflush(stdout);
        }
        if ((size_t) res > size)
            fprintf(stderr, "fuse: wrote too many bytes");
        fuse_reply_write(req, res);
    } else
        reply_err(req, res);
}

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

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        if (f->conf.debug) {
            printf("FLUSH[%llu]\n", (unsigned long long) fi->fh);
            fflush(stdout);
        }
        err = -ENOSYS;
        if (f->op.flush)
            err = f->op.flush(path, fi);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    reply_err(req, err);
}

static void fuse_release(fuse_req_t req, fuse_ino_t ino,
                         struct fuse_file_info *fi)
{
    struct fuse *f = req_fuse_prepare(req);
    char *path;
    struct node *node;
    int unlink_hidden;

    pthread_mutex_lock(&f->lock);
    node = get_node(f, ino);
    assert(node->open_count > 0);
    --node->open_count;
    unlink_hidden = (node->is_hidden && !node->open_count);
    pthread_mutex_unlock(&f->lock);

    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (f->conf.debug) {
        printf("RELEASE[%llu] flags: 0x%x\n", (unsigned long long) fi->fh,
               fi->flags);
        fflush(stdout);
    }
    if (f->op.release)
        fuse_do_release(f, path, fi);

    if(unlink_hidden && path)
        f->op.unlink(path);

    if (path)
        free(path);
    pthread_rwlock_unlock(&f->tree_lock);

    reply_err(req, 0);
}

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

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        if (f->conf.debug) {
            printf("FSYNC[%llu]\n", (unsigned long long) fi->fh);
            fflush(stdout);
        }
        err = -ENOSYS;
        if (f->op.fsync)
            err = f->op.fsync(path, datasync, fi);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    reply_err(req, err);
}

static struct fuse_dirhandle *get_dirhandle(const struct fuse_file_info *llfi,
                                            struct fuse_file_info *fi)
{
    struct fuse_dirhandle *dh = (struct fuse_dirhandle *) (uintptr_t) llfi->fh;
    memset(fi, 0, sizeof(struct fuse_file_info));
    fi->fh = dh->fh;
    fi->fh_old = dh->fh;
    return dh;
}

static void fuse_opendir(fuse_req_t req, fuse_ino_t ino,
                       struct fuse_file_info *llfi)
{
    struct fuse *f = req_fuse_prepare(req);
    struct fuse_dirhandle *dh;

    dh = (struct fuse_dirhandle *) malloc(sizeof(struct fuse_dirhandle));
    if (dh == NULL) {
        reply_err(req, -ENOMEM);
        return;
    }
    memset(dh, 0, sizeof(struct fuse_dirhandle));
    dh->fuse = f;
    dh->contents = NULL;
    dh->len = 0;
    dh->filled = 0;
    dh->nodeid = ino;
    mutex_init(&dh->lock);

    llfi->fh = (uintptr_t) dh;

    if (f->op.opendir) {
        struct fuse_file_info fi;
        char *path;
        int err;

        memset(&fi, 0, sizeof(fi));
        fi.flags = llfi->flags;

        err = -ENOENT;
        pthread_rwlock_rdlock(&f->tree_lock);
        path = get_path(f, ino);
        if (path != NULL) {
            err = fuse_do_opendir(f, path, &fi);
            dh->fh = fi.fh;
        }
        if (!err) {
            pthread_mutex_lock(&f->lock);
            if (fuse_reply_open(req, llfi) == -ENOENT) {
                /* The opendir syscall was interrupted, so it must be
                   cancelled */
                if(f->op.releasedir)
                    f->op.releasedir(path, &fi);
                pthread_mutex_destroy(&dh->lock);
                free(dh);
            }
            pthread_mutex_unlock(&f->lock);
        } else {
            reply_err(req, err);
            free(dh);
        }
        free(path);
        pthread_rwlock_unlock(&f->tree_lock);
    } else
        fuse_reply_open(req, llfi);
}

static int fill_dir_common(struct fuse_dirhandle *dh, const char *name,
                           const struct stat *statp, off_t off)
{
    struct stat stbuf;
    unsigned namelen = strlen(name);
    unsigned entsize;
    unsigned newlen;

    if (statp)
        stbuf = *statp;
    else {
        memset(&stbuf, 0, sizeof(stbuf));
        stbuf.st_ino = FUSE_UNKNOWN_INO;
    }

    if (!dh->fuse->conf.use_ino) {
        stbuf.st_ino = FUSE_UNKNOWN_INO;
        if (dh->fuse->conf.readdir_ino) {
            struct node *node;
            pthread_mutex_lock(&dh->fuse->lock);
            node = lookup_node(dh->fuse, dh->nodeid, name);
            if (node)
                stbuf.st_ino  = (ino_t) node->nodeid;
            pthread_mutex_unlock(&dh->fuse->lock);
        }
    }

    entsize = fuse_dirent_size(namelen);
    newlen = dh->len + entsize;

    if (off) {
        dh->filled = 0;
        if (newlen > dh->needlen)
            return 1;
    }

    if (newlen > dh->size) {
        char *newptr;

        if (!dh->size)
            dh->size = 1024;
        while (newlen > dh->size)
            dh->size *= 2;

        newptr = (char *) realloc(dh->contents, dh->size);
        if (!newptr) {
            dh->error = -ENOMEM;
            return 1;
        }
        dh->contents = newptr;
    }
    fuse_add_dirent(dh->contents + dh->len, name, &stbuf, off ? off : newlen);
    dh->len = newlen;
    return 0;
}

static int fill_dir(void *buf, const char *name, const struct stat *stbuf,
                    off_t off)
{
    return fill_dir_common((struct fuse_dirhandle *) buf, name, stbuf, off);
}

static int fill_dir_old(struct fuse_dirhandle *dh, const char *name, int type,
                        ino_t ino)
{
    struct stat stbuf;

    memset(&stbuf, 0, sizeof(stbuf));
    stbuf.st_mode = type << 12;
    stbuf.st_ino = ino;

    fill_dir_common(dh, name, &stbuf, 0);
    return dh->error;
}

static int readdir_fill(struct fuse *f, fuse_ino_t ino, size_t size,
                        off_t off, struct fuse_dirhandle *dh,
                        struct fuse_file_info *fi)
{
    int err = -ENOENT;
    char *path;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        dh->len = 0;
        dh->error = 0;
        dh->needlen = size;
        dh->filled = 1;
        err = -ENOSYS;
        if (f->op.readdir)
            err = f->op.readdir(path, dh, fill_dir, off, fi);
        else if (f->op.getdir)
            err = f->op.getdir(path, dh, fill_dir_old);
        if (!err)
            err = dh->error;
        if (err)
            dh->filled = 0;
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    return err;
}

static void fuse_readdir(fuse_req_t req, fuse_ino_t ino, size_t size,
                         off_t off, struct fuse_file_info *llfi)
{
    struct fuse *f = req_fuse_prepare(req);
    struct fuse_file_info fi;
    struct fuse_dirhandle *dh = get_dirhandle(llfi, &fi);

    pthread_mutex_lock(&dh->lock);
    /* According to SUS, directory contents need to be refreshed on
       rewinddir() */
    if (!off)
        dh->filled = 0;

    if (!dh->filled) {
        int err = readdir_fill(f, ino, size, off, dh, &fi);
        if (err) {
            reply_err(req, err);
            goto out;
        }
    }
    if (dh->filled) {
        if (off < dh->len) {
            if (off + size > dh->len)
                size = dh->len - off;
        } else
            size = 0;
    } else {
        size = dh->len;
        off = 0;
    }
    fuse_reply_buf(req, dh->contents + off, size);
 out:
    pthread_mutex_unlock(&dh->lock);
}

static void fuse_releasedir(fuse_req_t req, fuse_ino_t ino,
                            struct fuse_file_info *llfi)
{
    struct fuse *f = req_fuse_prepare(req);
    struct fuse_file_info fi;
    struct fuse_dirhandle *dh = get_dirhandle(llfi, &fi);
    if (f->op.releasedir) {
        char *path;

        pthread_rwlock_rdlock(&f->tree_lock);
        path = get_path(f, ino);
        f->op.releasedir(path ? path : "-", &fi);
        free(path);
        pthread_rwlock_unlock(&f->tree_lock);
    }
    pthread_mutex_lock(&dh->lock);
    pthread_mutex_unlock(&dh->lock);
    pthread_mutex_destroy(&dh->lock);
    free(dh->contents);
    free(dh);
    reply_err(req, 0);
}

static void fuse_fsyncdir(fuse_req_t req, fuse_ino_t ino, int datasync,
                          struct fuse_file_info *llfi)
{
    struct fuse *f = req_fuse_prepare(req);
    struct fuse_file_info fi;
    char *path;
    int err;

    get_dirhandle(llfi, &fi);

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        err = -ENOSYS;
        if (f->op.fsyncdir)
            err = f->op.fsyncdir(path, datasync, &fi);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    reply_err(req, err);
}

static int default_statfs(struct statvfs *buf)
{
    buf->f_namemax = 255;
    buf->f_bsize = 512;
    return 0;
}

static void fuse_statfs(fuse_req_t req)
{
    struct fuse *f = req_fuse_prepare(req);
    struct statvfs buf;
    int err;

    memset(&buf, 0, sizeof(buf));
    if (f->op.statfs) {
        err = fuse_do_statfs(f, "/", &buf);
    } else
        err = default_statfs(&buf);

    if (!err)
        fuse_reply_statfs(req, &buf);
    else
        reply_err(req, err);
}

static void fuse_setxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
                          const char *value, size_t size, int flags)
{
    struct fuse *f = req_fuse_prepare(req);
    char *path;
    int err;

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        err = -ENOSYS;
        if (f->op.setxattr)
            err = f->op.setxattr(path, name, value, size, flags);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    reply_err(req, err);
}

static int common_getxattr(struct fuse *f, fuse_ino_t ino, const char *name,
                           char *value, size_t size)
{
    int err;
    char *path;

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        err = -ENOSYS;
        if (f->op.getxattr)
            err = f->op.getxattr(path, name, value, size);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    return err;
}

static void fuse_getxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
                        size_t size)
{
    struct fuse *f = req_fuse_prepare(req);
    int res;

    if (size) {
        char *value = (char *) malloc(size);
        if (value == NULL) {
            reply_err(req, -ENOMEM);
            return;
        }
        res = common_getxattr(f, ino, name, value, size);
        if (res > 0)
            fuse_reply_buf(req, value, res);
        else
            reply_err(req, res);
        free(value);
    } else {
        res = common_getxattr(f, ino, name, NULL, 0);
        if (res >= 0)
            fuse_reply_xattr(req, res);
        else
            reply_err(req, res);
    }
}

static int common_listxattr(struct fuse *f, fuse_ino_t ino, char *list,
                            size_t size)
{
    char *path;
    int err;

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        err = -ENOSYS;
        if (f->op.listxattr)
            err = f->op.listxattr(path, list, size);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    return err;
}