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// -*- c++ -*-
// Folve - A fuse filesystem that convolves audio files on-the-fly.
// Copyright (C) 2012 Henner Zeller <>
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <>.
#include <string>
#include <sys/types.h>
#include <unistd.h>
// Status about some handler, filled in by various subsystem.
// This is mostly used to be displayed in the UI.
// Data collected in this struct will survive after the FileHandler is long
// gone, to show 'retired' elements in the status server.
struct HandlerStats {
: duration_seconds(-1), access_progress(-1), buffer_progress(-1),
status(OPEN), last_access(0),
max_output_value(0), in_gapless(false), out_gapless(false) {}
std::string filename; // filesystem name.
std::string format; // File format info if recognized.
std::string message; // Per file (error) message if any.
int duration_seconds; // Audio file length if known; -1 otherwise.
float access_progress; // File access progress if known; -1 otherwise.
float buffer_progress; // File buffering progress if known.
enum Status { OPEN, IDLE, RETIRED };
Status status; // Status of this file handler.
double last_access; // Last access in hi-res seconds since epoch.
float max_output_value; // Clipping ? Absolute value, should be [0 .. 1].
bool in_gapless; // We were handed a processor to continue.
bool out_gapless; // We passed on our processor to the next.
std::string filter_dir; // The filter-id is in use. "" for pass-through.
class SoundProcessor;
// A handler that deals with operations on files. Since we only provide read
// access, this is limited to very few operations.
// Closing in particular is not done by this file handler as it might
// have a longer life-time than an open()/close() cycle we get from the
// fuse filesystem (see file-handler-cache.h for rationale)
class FileHandler {
explicit FileHandler(const std::string &filter) : filter_dir_(filter) {}
virtual ~FileHandler() {}
const std::string &filter_dir() const { return filter_dir_; }
// Returns bytes read or a negative value indicating a negative errno.
virtual int Read(char *buf, size_t size, off_t offset) = 0;
virtual int Stat(struct stat *st) = 0;
// Get handler status.
virtual void GetHandlerStatus(HandlerStats *s) = 0;
// Accept processor passed on from the previous file. Can return false
// if this FileHandler cannot use it (e.g. it alrady started convolving).
// The Receiver must not use this processor until
// NotifyPassedProcessorUnreferenced() is called.
virtual bool PassoverProcessor(SoundProcessor *s) { return false; }
// If we got a processor passed over, the caller will notify us once it
// is fully done with it.
virtual void NotifyPassedProcessorUnreferenced() { }
const std::string filter_dir_;