Implement _dl_catch_error, _dl_signal_error in libc.so [BZ #16628]

This change moves the main implementation of _dl_catch_error,
_dl_signal_error to libc.so, where TLS variables can be used
directly.  This removes a writable function pointer from the
rtld_global variable.

For use during initial relocation, minimal implementations of these
functions are provided in ld.so.  These are eventually interposed
by the libc.so implementations.  This is implemented by compiling
elf/dl-error-skeleton.c twice, via elf/dl-error.c and
elf/dl-error-minimal.c.

As a side effect of this change, the static version of dl-error.c
no longer includes support for the
_dl_signal_cerror/_dl_receive_error mechanism because it is only
used in ld.so.

1 files changed, 23 insertions, 0 deletions

diff --git a/elf/dl-error-minimal.c b/elf/dl-error-minimal.c
new file mode 100644
index 0000000000..d535d65877
--- /dev/null
+++ b/elf/dl-error-minimal.c
@@ -0,0 +1,23 @@
+/* Error handling for runtime dynamic linker, minimal version.
+   Copyright (C) 1995-2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* This version does lives in ld.so, does not use thread-local data
+   and supports _dl_signal_cerror and _dl_receive_error.  */
+
+#define DL_ERROR_BOOTSTRAP 1
+#include "dl-error-skeleton.c"