Switch libc from using _sig{procmask,action,suspend} symbols, which

are aliases for the syscall stubs and are plt-interposed, to the
libc-private aliases of internally interposed sigprocmask() etc.

Since e.g. _sigaction is not interposed by libthr, calling signal()
removes thr_sighandler() from the handler slot etc.  The result was
breaking signal semantic and rtld locking.

The added __libc_sigprocmask and other symbols are hidden, they are
not exported and cannot be called through PLT.  The setjmp/longjmp
functions for x86 were changed to use direct calls, and since
PIC_PROLOGUE only needed for functional PLT indirection on i386, it is
removed as well.

The PowerPC bug of calling the syscall directly in the setjmp/longjmp
implementation is kept as is.

Reported by:	Pete French <petefrench@ingresso.co.uk>
Tested by:	Michiel Boland <boland37@xs4all.nl>
Reviewed by:	jilles (previous version)
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week

1 files changed, 2 insertions, 4 deletions

diff --git a/lib/libc/gen/signal.c b/lib/libc/gen/signal.c
index ee96dcc..70e7f17 100644
--- a/lib/libc/gen/signal.c
+++ b/lib/libc/gen/signal.c
@@ -44,9 +44,7 @@ __FBSDID("$FreeBSD$");
 sigset_t _sigintr __hidden;	/* shared with siginterrupt */
 
 sig_t
-signal(s, a)
-	int s;
-	sig_t a;
+signal(int s, sig_t a)
 {
 	struct sigaction sa, osa;
 
@@ -55,7 +53,7 @@ signal(s, a)
 	sa.sa_flags = 0;
 	if (!sigismember(&_sigintr, s))
 		sa.sa_flags |= SA_RESTART;
-	if (_sigaction(s, &sa, &osa) < 0)
+	if (__libc_sigaction(s, &sa, &osa) < 0)
 		return (SIG_ERR);
 	return (osa.sa_handler);
 }