static int check_object_access()

in src/s3fs.cpp [505:579]

• 62 lines of code
• 21 McCabe index (conditional complexity)

static int check_object_access(const char* path, int mask, struct stat* pstbuf)
{
    int result;
    struct stat st;
    struct stat* pst = (pstbuf ? pstbuf : &st);
    struct fuse_context* pcxt;

    S3FS_PRN_DBG("[path=%s]", path);

    if(NULL == (pcxt = fuse_get_context())){
        return -EIO;
    }
    S3FS_PRN_DBG("[pid=%u,uid=%u,gid=%u]", (unsigned int)(pcxt->pid), (unsigned int)(pcxt->uid), (unsigned int)(pcxt->gid));

    if(0 != (result = get_object_attribute(path, pst))){
        // If there is not the target file(object), result is -ENOENT.
        return result;
    }
    if(0 == pcxt->uid){
        // root is allowed all accessing.
        return 0;
    }
    if(is_s3fs_uid && s3fs_uid == pcxt->uid){
        // "uid" user is allowed all accessing.
        return 0;
    }
    if(F_OK == mask){
        // if there is a file, always return allowed.
        return 0;
    }

    // for "uid", "gid" option
    uid_t  obj_uid = (is_s3fs_uid ? s3fs_uid : pst->st_uid);
    gid_t  obj_gid = (is_s3fs_gid ? s3fs_gid : pst->st_gid);

    // compare file mode and uid/gid + mask.
    mode_t mode;
    mode_t base_mask = S_IRWXO;
    if(is_s3fs_umask){
        // If umask is set, all object attributes set ~umask.
        mode = ((S_IRWXU | S_IRWXG | S_IRWXO) & ~s3fs_umask);
    }else{
        mode = pst->st_mode;
    }
    if(pcxt->uid == obj_uid){
        base_mask |= S_IRWXU;
    }
    if(pcxt->gid == obj_gid){
        base_mask |= S_IRWXG;
    }
    if(1 == is_uid_include_group(pcxt->uid, obj_gid)){
        base_mask |= S_IRWXG;
    }
    mode &= base_mask;

    if(X_OK == (mask & X_OK)){
        if(0 == (mode & (S_IXUSR | S_IXGRP | S_IXOTH))){
            return -EACCES;
        }
    }
    if(W_OK == (mask & W_OK)){
        if(0 == (mode & (S_IWUSR | S_IWGRP | S_IWOTH))){
            return -EACCES;
        }
    }
    if(R_OK == (mask & R_OK)){
        if(0 == (mode & (S_IRUSR | S_IRGRP | S_IROTH))){
            return -EACCES;
        }
    }
    if(0 == mode){
        return -EACCES;
    }
    return 0;
}