mergerfs/libfuse/lib/fuse_signals.c

/*
  FUSE: Filesystem in Userspace
  Copyright (C) 2001-2007  Miklos Szeredi <miklos@szeredi.hu>

  This program can be distributed under the terms of the GNU LGPLv2.
  See the file COPYING.LIB
*/

#include "fuse.h"

#include <stdio.h>
#include <string.h>
#include <signal.h>

static struct fuse_session *fuse_instance;

static
void
exit_handler(int sig)
{
  (void) sig;
  if (fuse_instance)
    fuse_session_exit(fuse_instance);
}

static
void
sigusr1_handler(int sig_)
{
  int enabled;

  enabled = fuse_log_metrics_get();
  enabled = !enabled;
  fuse_log_metrics_set(enabled);
}

static
int
set_one_signal_handler(int sig,
                       void (*handler)(int),
                       int remove)
{
  struct sigaction sa;
  struct sigaction old_sa;

  memset(&sa, 0, sizeof(struct sigaction));
  sa.sa_handler = remove ? SIG_DFL : handler;
  sigemptyset(&(sa.sa_mask));
  sa.sa_flags = 0;

  if (sigaction(sig, NULL, &old_sa) == -1) {
    perror("fuse: cannot get old signal handler");
    return 1;
  }

  if(old_sa.sa_handler == (remove ? handler : SIG_DFL) &&
      sigaction(sig, &sa, NULL) == -1) {
    perror("fuse: cannot set signal handler");
    return 1;
  }

  return 0;
}

int
fuse_set_signal_handlers(struct fuse_session *se)
{
  int rv;

  rv = 0;
  rv |= set_one_signal_handler(SIGUSR1,sigusr1_handler,0);
  rv |= set_one_signal_handler(SIGHUP,exit_handler,0);
  rv |= set_one_signal_handler(SIGINT,exit_handler,0);
  rv |= set_one_signal_handler(SIGTERM,exit_handler,0);
  rv |= set_one_signal_handler(SIGPIPE,SIG_IGN,0);

  if(rv == 0)
    fuse_instance = se;

  return rv;
}

void
fuse_remove_signal_handlers(struct fuse_session *se)
{
  if(fuse_instance != se)
    fprintf(stderr,"fuse: fuse_remove_signal_handlers: unknown session\n");
  else
    fuse_instance = NULL;

  set_one_signal_handler(SIGUSR1,sigusr1_handler,1);
  set_one_signal_handler(SIGHUP,exit_handler,1);
  set_one_signal_handler(SIGINT,exit_handler,1);
  set_one_signal_handler(SIGTERM,exit_handler,1);
  set_one_signal_handler(SIGPIPE,SIG_IGN,1);
}