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.

1 files changed, 2 insertions, 18 deletions

diff --git a/src/signal/sigprocmask.c b/src/signal/sigprocmask.c
index a272c10d..3f003afb 100644
--- a/src/signal/sigprocmask.c
+++ b/src/signal/sigprocmask.c
@@ -4,27 +4,11 @@
 #include "libc.h"
 #include "pthread_impl.h"
 
-int __libc_sigprocmask(int how, const sigset_t *set, sigset_t *old)
+int sigprocmask(int how, const sigset_t *set, sigset_t *old)
 {
-	return syscall(SYS_rt_sigprocmask, how, set, old, 8);
-}
-
-int __sigprocmask(int how, const sigset_t *set, sigset_t *old)
-{
-	sigset_t tmp;
 	if (how > 2U) {
 		errno = EINVAL;
 		return -1;
 	}
-	/* Disallow blocking thread control signals */
-	if (set && how != SIG_UNBLOCK) {
-		tmp = *set;
-		set = &tmp;
-		sigdelset(&tmp, SIGCANCEL);
-		sigdelset(&tmp, SIGSYSCALL);
-		sigdelset(&tmp, SIGTIMER);
-	}
-	return __libc_sigprocmask(how, set, old);
+	return syscall(SYS_rt_sigprocmask, how, set, old, 8);
 }
-
-weak_alias(__sigprocmask, sigprocmask);