overhaul implementation-internal signal protections
the new approach relies on the fact that the only ways to create
sigset_t objects without invoking UB are to use the sig*set()
functions, or from the masks returned by sigprocmask, sigaction, etc.
or in the ucontext_t argument to a signal handler. thus, as long as
sigfillset and sigaddset avoid adding the "protected" signals, there
is no way the application will ever obtain a sigset_t including these
bits, and thus no need to add the overhead of checking/clearing them
when sigprocmask or sigaction is called.
note that the old code actually *failed* to remove the bits from
sa_mask when sigaction was called.
the new implementations are also significantly smaller, simpler, and
faster due to ignoring the useless "GNU HURD signals" 65-1024, which
are not used and, if there's any sanity in the world, never will be
used.
diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c
index 0d2c17b..6545539 100644
--- a/src/thread/pthread_create.c
+++ b/src/thread/pthread_create.c
@@ -34,7 +34,7 @@
if (!n) exit(0);
if (self->detached && self->map_base) {
- __syscall(SYS_rt_sigprocmask, SIG_BLOCK, (long)(uint64_t[1]){-1},0,8);
+ __syscall(SYS_rt_sigprocmask, SIG_BLOCK, (uint64_t[]){-1},0,8);
__unmapself(self->map_base, self->map_size);
}
@@ -44,12 +44,8 @@
static int start(void *p)
{
struct pthread *self = p;
- if (self->unblock_cancel) {
- sigset_t set;
- sigemptyset(&set);
- sigaddset(&set, SIGCANCEL);
- __libc_sigprocmask(SIG_UNBLOCK, &set, 0);
- }
+ if (self->unblock_cancel)
+ __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, &SIGPT_SET, 0, 8);
pthread_exit(self->start(self->start_arg));
return 0;
}
@@ -72,11 +68,7 @@
if (!self) return ENOSYS;
if (!libc.threaded) {
- sigset_t set;
- sigemptyset(&set);
- sigaddset(&set, SIGSYSCALL);
- sigaddset(&set, SIGCANCEL);
- __libc_sigprocmask(SIG_UNBLOCK, &set, 0);
+ __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, &SIGPT_SET, 0, 8);
libc.threaded = 1;
}