Fix known issues which blow up the process after dlopen("libthr.so")

(or loading a dso linked to libthr.so into process which was not
linked against threading library).

MFC r276630:
Remove interposing, fix malloc, reinstall signal handlers wrappers on
libthr load.

MFC r276681:
Avoid calling internal libc function through PLT or accessing data
though GOT.

MFC r277032:
Reduce the size of the interposing table and amount of
cancellation-handling code in the libthr.

MFC note:
r276646 ("do not erronously export 'openat' symbol from rtld") is not
applicable to stable/10 yet, since PATHFDS support was not merged.

1 files changed, 10 insertions, 3 deletions

diff --git a/lib/libc/compat-43/creat.c b/lib/libc/compat-43/creat.c
index fc3be06..4545482 100644
--- a/lib/libc/compat-43/creat.c
+++ b/lib/libc/compat-43/creat.c
@@ -36,11 +36,18 @@ __FBSDID("$FreeBSD$");
 #include "namespace.h"
 #include <fcntl.h>
 #include "un-namespace.h"
+#include "libc_private.h"
 
+__weak_reference(__creat, creat);
+__weak_reference(__creat, _creat);
+
+#pragma weak creat
 int
 __creat(const char *path, mode_t mode)
 {
-	return(_open(path, O_WRONLY|O_CREAT|O_TRUNC, mode));
+
+	return (((int (*)(int, const char *, int, ...))
+	    __libc_interposing[INTERPOS_openat])(AT_FDCWD, path, O_WRONLY |
+	    O_CREAT | O_TRUNC, mode));
 }
-__weak_reference(__creat, creat);
-__weak_reference(__creat, _creat);
+