lib/libfuse/fuse.c was using a EINTR return from kevent() to detect when
a signal had occurred, but in a multi-threaded process the signal may
not have been delivered to the thread blocking on kevent(). This changes
makes it so the signals are caught using EVFILT_SIGNAL filters so they
can be detected even when they happen on another thread.
Index: lib/libfuse/fuse.c
===================================================================
RCS file: /cvs/src/lib/libfuse/fuse.c,v
retrieving revision 1.49
diff -u -p -u -p -r1.49 fuse.c
--- lib/libfuse/fuse.c 5 Jul 2018 10:57:31 -0000 1.49
+++ lib/libfuse/fuse.c 5 Oct 2018 22:13:41 -0000
@@ -32,8 +32,6 @@
#include "fuse_private.h"
#include "debug.h"
-static volatile sig_atomic_t sigraised = 0;
-static volatile sig_atomic_t signum = 0;
static struct fuse_context *ictx = NULL;
enum {
@@ -116,21 +114,10 @@ static struct fuse_opt fuse_mount_opts[]
};
static void
-ifuse_sighdlr(int num)
-{
- if (!sigraised || (num == SIGCHLD)) {
- sigraised = 1;
- signum = num;
- }
-}
-
-static void
ifuse_try_unmount(struct fuse *f)
{
pid_t child;
- signal(SIGCHLD, ifuse_sighdlr);
-
/* unmount in another thread so fuse_loop() doesn't deadlock */
child = fork();
@@ -152,7 +139,6 @@ ifuse_child_exit(const struct fuse *f)
{
int status;
- signal(SIGCHLD, SIG_DFL);
if (waitpid(WAIT_ANY, &status, WNOHANG) == -1)
fprintf(stderr, "fuse: %s\n", strerror(errno));
@@ -160,7 +146,6 @@ ifuse_child_exit(const struct fuse *f)
fprintf(stderr, "fuse: %s: %s\n",
f->fc->dir, strerror(WEXITSTATUS(status)));
- sigraised = 0;
return;
}
@@ -170,6 +155,7 @@ fuse_loop(struct fuse *fuse)
struct fusebuf fbuf;
struct fuse_context ctx;
struct fb_ioctl_xch ioexch;
+ struct kevent event[5];
struct kevent ev;
ssize_t n;
int ret;
@@ -181,28 +167,39 @@ fuse_loop(struct fuse *fuse)
if (fuse->fc->kq == -1)
return (-1);
- EV_SET(&fuse->fc->event, fuse->fc->fd, EVFILT_READ, EV_ADD |
+ EV_SET(&event[0], fuse->fc->fd, EVFILT_READ, EV_ADD |
EV_ENABLE, 0, 0, 0);
+ /* signal events */
+ EV_SET(&event[1], SIGCHLD, EVFILT_SIGNAL, EV_ADD |
+ EV_ENABLE, 0, 0, 0);
+ EV_SET(&event[2], SIGHUP, EVFILT_SIGNAL, EV_ADD |
+ EV_ENABLE, 0, 0, 0);
+ EV_SET(&event[3], SIGINT, EVFILT_SIGNAL, EV_ADD |
+ EV_ENABLE, 0, 0, 0);
+ EV_SET(&event[4], SIGTERM, EVFILT_SIGNAL, EV_ADD |
+ EV_ENABLE, 0, 0, 0);
+
while (!fuse->fc->dead) {
- ret = kevent(fuse->fc->kq, &fuse->fc->event, 1, &ev, 1,
NULL);
+ ret = kevent(fuse->fc->kq, &event[0], 5, &ev, 1, NULL);
if (ret == -1) {
- if (errno == EINTR) {
- switch (signum) {
- case SIGCHLD:
- ifuse_child_exit(fuse);
- break;
- case SIGHUP:
- case SIGINT:
- case SIGTERM:
- ifuse_try_unmount(fuse);
- break;
- default:
- fprintf(stderr, "%s: %s\n",
__func__,
- strsignal(signum));
- }
- } else
+ if (errno != EINTR)
DPERROR(__func__);
+ } else if (ret > 0 && ev.filter == EVFILT_SIGNAL) {
+ int signum = ev.ident;
+ switch (signum) {
+ case SIGCHLD:
+ ifuse_child_exit(fuse);
+ break;
+ case SIGHUP:
+ case SIGINT:
+ case SIGTERM:
+ ifuse_try_unmount(fuse);
+ break;
+ default:
+ fprintf(stderr, "%s: %s\n", __func__,
+ strsignal(signum));
+ }
} else if (ret > 0) {
n = read(fuse->fc->fd, &fbuf, sizeof(fbuf));
if (n != sizeof(fbuf)) {
@@ -479,20 +476,24 @@ fuse_remove_signal_handlers(unused struc
struct sigaction old_sa;
if (sigaction(SIGHUP, NULL, &old_sa) == 0)
- if (old_sa.sa_handler == ifuse_sighdlr)
+ if (old_sa.sa_handler == SIG_IGN)
signal(SIGHUP, SIG_DFL);
if (sigaction(SIGINT, NULL, &old_sa) == 0)
- if (old_sa.sa_handler == ifuse_sighdlr)
+ if (old_sa.sa_handler == SIG_IGN)
signal(SIGINT, SIG_DFL);
if (sigaction(SIGTERM, NULL, &old_sa) == 0)
- if (old_sa.sa_handler == ifuse_sighdlr)
+ if (old_sa.sa_handler == SIG_IGN)
signal(SIGTERM, SIG_DFL);
if (sigaction(SIGPIPE, NULL, &old_sa) == 0)
if (old_sa.sa_handler == SIG_IGN)
signal(SIGPIPE, SIG_DFL);
+
+ if (sigaction(SIGCHLD, NULL, &old_sa) == 0)
+ if (old_sa.sa_handler == SIG_IGN)
+ signal(SIGCHLD, SIG_DFL);
}
DEF(fuse_remove_signal_handlers);
@@ -504,22 +505,27 @@ fuse_set_signal_handlers(unused struct f
if (sigaction(SIGHUP, NULL, &old_sa) == -1)
return (-1);
if (old_sa.sa_handler == SIG_DFL)
- signal(SIGHUP, ifuse_sighdlr);
+ signal(SIGHUP, SIG_IGN);
if (sigaction(SIGINT, NULL, &old_sa) == -1)
return (-1);
if (old_sa.sa_handler == SIG_DFL)
- signal(SIGINT, ifuse_sighdlr);
+ signal(SIGINT, SIG_IGN);
if (sigaction(SIGTERM, NULL, &old_sa) == -1)
return (-1);
if (old_sa.sa_handler == SIG_DFL)
- signal(SIGTERM, ifuse_sighdlr);
+ signal(SIGTERM, SIG_IGN);
if (sigaction(SIGPIPE, NULL, &old_sa) == -1)
return (-1);
if (old_sa.sa_handler == SIG_DFL)
signal(SIGPIPE, SIG_IGN);
+
+ if (sigaction(SIGCHLD, NULL, &old_sa) == -1)
+ return (-1);
+ if (old_sa.sa_handler == SIG_DFL)
+ signal(SIGCHLD, SIG_IGN);
return (0);
}
Index: lib/libfuse/fuse_private.h
===================================================================
RCS file: /cvs/src/lib/libfuse/fuse_private.h,v
retrieving revision 1.21
diff -u -p -u -p -r1.21 fuse_private.h
--- lib/libfuse/fuse_private.h 19 Jun 2018 13:01:34 -0000 1.21
+++ lib/libfuse/fuse_private.h 5 Oct 2018 22:13:41 -0000
@@ -69,7 +69,6 @@ struct fuse_chan {
/* kqueue stuff */
int kq;
- struct kevent event;
};
struct fuse_config {
