MFC r283471:

According to Linux man sigaltstack(3) shall return EINVAL if the ss
argument is not a null pointer, and the ss_flags member pointed to by ss
contains flags other than SS_DISABLE. However, in fact, Linux also
allows SS_ONSTACK flag which is simply ignored.

For buggy apps (at least mono) ignore other than SS_DISABLE
flags as a Linux do.

While here move MI part of sigaltstack code to the appropriate place.

1 files changed, 26 insertions, 0 deletions

diff --git a/sys/compat/linux/linux_signal.c b/sys/compat/linux/linux_signal.c
index 856d433..f60e731 100644
--- a/sys/compat/linux/linux_signal.c
+++ b/sys/compat/linux/linux_signal.c
@@ -754,6 +754,32 @@ siginfo_to_lsiginfo(const siginfo_t *si, l_siginfo_t *lsi, l_int sig)
 	}
 }
 
+int
+linux_to_bsd_sigaltstack(int lsa)
+{
+	int bsa = 0;
+
+	if (lsa & LINUX_SS_DISABLE)
+		bsa |= SS_DISABLE;
+	/*
+	 * Linux ignores SS_ONSTACK flag for ss
+	 * parameter while FreeBSD prohibits it.
+	 */
+	return (bsa);
+}
+
+int
+bsd_to_linux_sigaltstack(int bsa)
+{
+	int lsa = 0;
+
+	if (bsa & SS_DISABLE)
+		lsa |= LINUX_SS_DISABLE;
+	if (bsa & SS_ONSTACK)
+		lsa |= LINUX_SS_ONSTACK;
+	return (lsa);
+}
+
 void
 lsiginfo_to_ksiginfo(const l_siginfo_t *lsi, ksiginfo_t *ksi, int sig)
 {