From 61b4199fe43e94d6753290a62eb45363503e0deb Mon Sep 17 00:00:00 2001
From: Laurent Bercot <ska-skaware@skarnet.org>
Date: Mon, 5 Sep 2022 06:59:43 +0000
Subject:  Better NSIG detection and fix

 Incredibly enough, OpenBSD defines NSIG correctly, so our workaround
was not accurate.

Signed-off-by: Laurent Bercot <ska@appnovation.com>
---
 src/include/skalibs/nsig.h       | 20 ++++++++++++--------
 src/include/skalibs/skalibs.h    |  2 +-
 src/libstddjb/selfpipe_trapset.c |  1 -
 src/libstddjb/sig_catch.c        | 10 +++-------
 4 files changed, 16 insertions(+), 17 deletions(-)

diff --git a/src/include/skalibs/nsig.h b/src/include/skalibs/nsig.h
index 6dbddea..f6d0ee5 100644
--- a/src/include/skalibs/nsig.h
+++ b/src/include/skalibs/nsig.h
@@ -1,9 +1,8 @@
 /* ISC license. */
 
 /*
-   This header MUST be paired with skalibs/nonposix.h AND
-   skalibs/bsdsnowflake.h, both of which must be included
-   before system headers.
+   This header MUST be paired with skalibs/nonposix.h,
+   which must be included before system headers.
 */
 
 #ifndef SKALIBS_NSIG_H
@@ -18,17 +17,22 @@
 #  define NSIG (SIGMAX + 1)
 # elif defined(_SIGMAX)
 #  define NSIG(_SIGMAX + 1)
-# elif defined(SKALIBS_BSD_SUCKS)
-#  define NSIG 64
 # else
 #  define NSIG 65
 # endif
 #endif
 
-#ifdef SKALIBS_BSD_SUCKS
-# define SKALIBS_NSIG (NSIG+1)
-#else
+/*
+  Some systems (FreeBSD, Darwin) incorrectly define NSIG as 32
+  (their highest signal number) when it should be 33 (highest plus one).
+  OpenBSD gets this right so we can't use SKALIBS_BSD_SUCKS.
+  The heuristic we use is: if NSIG is a power of two, it's wrong.
+*/
+
+#if NSIG & (NSIG - 1)
 # define SKALIBS_NSIG NSIG
+#else
+# define SKALIBS_NSIG (NSIG+1)
 #endif
 
 #endif
diff --git a/src/include/skalibs/skalibs.h b/src/include/skalibs/skalibs.h
index 5e24fe2..c1eaf81 100644
--- a/src/include/skalibs/skalibs.h
+++ b/src/include/skalibs/skalibs.h
@@ -9,7 +9,7 @@
    - skalibs/sysdeps.h: system-dependent feature test macros
    - skalibs/nonposix.h: pre-system headers definitions for POSIX extensions
    - skalibs/bsdsnowflake.h: pre-system headers BSD-specific workarounds
-   - skalibs/nsig.h: SKALIBS_NSIG definition, requires nonposix+bsdsnowflake
+   - skalibs/nsig.h: SKALIBS_NSIG definition, requires nonposix
    - skalibs/posixishard.h: post-system headers workarounds for conformance failures
 */
 
diff --git a/src/libstddjb/selfpipe_trapset.c b/src/libstddjb/selfpipe_trapset.c
index 9559c07..3bb64d4 100644
--- a/src/libstddjb/selfpipe_trapset.c
+++ b/src/libstddjb/selfpipe_trapset.c
@@ -30,7 +30,6 @@ int selfpipe_trapset (sigset_t const *set)
 #else
 
 #include <skalibs/nonposix.h>
-#include <skalibs/bsdsnowflake.h>
 
 #include <errno.h>
 #include <signal.h>
diff --git a/src/libstddjb/sig_catch.c b/src/libstddjb/sig_catch.c
index a11e317..1c106a0 100644
--- a/src/libstddjb/sig_catch.c
+++ b/src/libstddjb/sig_catch.c
@@ -3,7 +3,6 @@
 /* MT-unsafe */
 
 #include <skalibs/nonposix.h>
-#include <skalibs/bsdsnowflake.h>
 
 #include <signal.h>
 #include <errno.h>
@@ -13,8 +12,8 @@
 #include <skalibs/nsig.h>
 
  /*
-   BSD fails sigaction() with EINVAL on non-catchable signals, whereas
-   every reasonable OS succeeds and simply ignores the signal handler.
+   We don't want to fail on non-catchable signals,
+   even if sigaction() does.
  */
 
 int sig_catch (int sig, sig_func_ref f)
@@ -22,8 +21,5 @@ int sig_catch (int sig, sig_func_ref f)
   struct sigaction action = { .sa_handler = f, .sa_flags = SA_RESTART | SA_NOCLDSTOP } ;
   sigfillset(&action.sa_mask) ;
   return sigaction(sig, &action, 0) >= 0
-#ifdef SKALIBS_BSD_SUCKS
- || (errno == EINVAL && sig >= 1 && sig <= NSIG)
-#endif
- ;
+   || (errno == EINVAL && sig >= 1 && sig < SKALIBS_NSIG) ;
 }
-- 
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