Date: Fri, 29 Mar 2019 20:21:00 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: Bruce Evans <bde@FreeBSD.org> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r345696 - head/lib/libvgl Message-ID: <20190329182100.GZ1923@kib.kiev.ua> In-Reply-To: <201903291557.x2TFv9AW097226@repo.freebsd.org> References: <201903291557.x2TFv9AW097226@repo.freebsd.org>
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On Fri, Mar 29, 2019 at 03:57:09PM +0000, Bruce Evans wrote: > Author: bde > Date: Fri Mar 29 15:57:08 2019 > New Revision: 345696 > URL: https://svnweb.freebsd.org/changeset/base/345696 > > Log: > Fix endless loops for handling SIGBUS and SIGSEGV. > > r80270 has the usual wrong fix for unsafe signal handling -- just set > a flag and return to let an event loop check the flag and do safe > handling. This never works for signals like SIGBUS and SIGSEGV that > repeat and works poorly for others unless the application has an event > loop designed to support this. > > For these signals, clean up unsafely as before, except for arranging that > nested signals are fatal and forcing a nested signal if the cleanup doesn't > cause one. > > Modified: > head/lib/libvgl/main.c > > Modified: head/lib/libvgl/main.c > ============================================================================== > --- head/lib/libvgl/main.c Fri Mar 29 15:20:48 2019 (r345695) > +++ head/lib/libvgl/main.c Fri Mar 29 15:57:08 2019 (r345696) > @@ -31,9 +31,9 @@ > #include <sys/cdefs.h> > __FBSDID("$FreeBSD$"); > > +#include <signal.h> > #include <stdio.h> > #include <sys/types.h> > -#include <sys/signal.h> > #include <sys/file.h> > #include <sys/ioctl.h> > #include <sys/mman.h> > @@ -107,14 +107,22 @@ struct vt_mode smode; > } > > static void > -VGLAbort(int arg __unused) > +VGLAbort(int arg) > { > + sigset_t mask; > + > VGLAbortPending = 1; > signal(SIGINT, SIG_IGN); > signal(SIGTERM, SIG_IGN); > - signal(SIGSEGV, SIG_IGN); > - signal(SIGBUS, SIG_IGN); > signal(SIGUSR2, SIG_IGN); > + if (arg == SIGBUS || arg == SIGSEGV) { > + signal(arg, SIG_DFL); > + sigemptyset(&mask); > + sigaddset(&mask, arg); > + sigprocmask(SIG_UNBLOCK, &mask, NULL); > + VGLEnd(); > + kill(getpid(), arg); This of course misses the siginfo information from the real fault. Why SIGBUS/SIGSEGV are caught at all ? > + } > } > > static void
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