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

2 files changed, 6 insertions, 4 deletions

diff --git a/lib/libc/db/btree/bt_open.c b/lib/libc/db/btree/bt_open.c
index 94ba014..051fc28 100644
--- a/lib/libc/db/btree/bt_open.c
+++ b/lib/libc/db/btree/bt_open.c
@@ -57,6 +57,7 @@ __FBSDID("$FreeBSD$");
 #include <string.h>
 #include <unistd.h>
 #include "un-namespace.h"
+#include "libc_private.h"
 
 #include <db.h>
 #include "btree.h"
@@ -401,10 +402,10 @@ tmp(void)
 	}
 
 	(void)sigfillset(&set);
-	(void)_sigprocmask(SIG_BLOCK, &set, &oset);
+	(void)__libc_sigprocmask(SIG_BLOCK, &set, &oset);
 	if ((fd = mkostemp(path, O_CLOEXEC)) != -1)
 		(void)unlink(path);
-	(void)_sigprocmask(SIG_SETMASK, &oset, NULL);
+	(void)__libc_sigprocmask(SIG_SETMASK, &oset, NULL);
 	return(fd);
 }
 
diff --git a/lib/libc/db/hash/hash_page.c b/lib/libc/db/hash/hash_page.c
index d319d98..8040419 100644
--- a/lib/libc/db/hash/hash_page.c
+++ b/lib/libc/db/hash/hash_page.c
@@ -66,6 +66,7 @@ __FBSDID("$FreeBSD$");
 #include <assert.h>
 #endif
 #include "un-namespace.h"
+#include "libc_private.h"
 
 #include <db.h>
 #include "hash.h"
@@ -861,10 +862,10 @@ open_temp(HTAB *hashp)
 
 	/* Block signals; make sure file goes away at process exit. */
 	(void)sigfillset(&set);
-	(void)_sigprocmask(SIG_BLOCK, &set, &oset);
+	(void)__libc_sigprocmask(SIG_BLOCK, &set, &oset);
 	if ((hashp->fp = mkostemp(path, O_CLOEXEC)) != -1)
 		(void)unlink(path);
-	(void)_sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL);
+	(void)__libc_sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL);
 	return (hashp->fp != -1 ? 0 : -1);
 }