func populateFuseArgs()

in component/libfuse/libfuse2_handler.go [190:260]

• 51 lines of code
• 11 McCabe index (conditional complexity)

func populateFuseArgs(opts *C.fuse_options_t, args *C.fuse_args_t) (*C.fuse_options_t, C.int) {
	log.Trace("Libfuse::populateFuseArgs")
	if args == nil {
		return nil, 1
	}
	args.argc = 0
	args.allocated = 1

	arguments := make([]string, 0)
	options := fmt.Sprintf("entry_timeout=%d,attr_timeout=%d,negative_timeout=%d",
		opts.entry_expiry,
		opts.attr_expiry,
		opts.negative_expiry)

	if opts.allow_other {
		options += ",allow_other"
	}

	if opts.allow_root {
		options += ",allow_root"
	}

	if opts.non_empty {
		options += ",nonempty"
	}

	if opts.readonly {
		options += ",ro"
	}

	if opts.umask != 0 {
		options += fmt.Sprintf(",umask=%04d", opts.umask)
	}

	// force the fuse library to always pass O_TRUNC flag on open call
	// Not checking the options since we don't allow user to configure this flag.
	// This is the default behaviour for the fuse3 hence we don't pass this flag there.
	// ref: https://github.com/libfuse/libfuse/blob/7f86f3be7148b15b71b63357813c66dd32177cf6/lib/fuse_lowlevel.c#L2161C2-L2161C16
	options += ",atomic_o_trunc"

	// direct_io option is used to bypass the kernel cache. It disables the use of
	// page cache (file content cache) in the kernel for the filesystem.
	if fuseFS.directIO {
		options += ",direct_io"
	} else {
		options += ",kernel_cache"
	}

	// Why we pass -f
	// CGo is not very good with handling forks - so if the user wants to run blobfuse in the
	// background we fork on mount in GO (mount.go) and we just always force libfuse to mount in foreground
	arguments = append(arguments, "blobfuse2",
		C.GoString(opts.mount_path),
		"-o", options,
		"-f", "-ofsname=blobfuse2")
	if opts.trace_enable {
		arguments = append(arguments, "-d")
	}

	for _, a := range arguments {
		log.Debug("Libfuse::populateFuseArgs : opts : %s", a)
		arg := C.CString(a)
		defer C.free(unsafe.Pointer(arg))
		err := C.fuse_opt_add_arg(args, arg)
		if err != 0 {
			return nil, err
		}
	}

	return opts, 0
}