assert: Do not use stderr in libc-internal assert

Redirect internal assertion failures to __libc_assert_fail, based on
based on __libc_message, which writes directly to STDERR_FILENO
and calls abort.  Also disable message translation and reword the
error message slightly (adjusting stdlib/tst-bz20544 accordingly).

As a result of these changes, malloc no longer needs its own
redefinition of __assert_fail.

__libc_assert_fail needs to be stubbed out during rtld dependency
analysis because the rtld rebuilds turn __libc_assert_fail into
__assert_fail, which is unconditionally provided by elf/dl-minimal.c.

This change is not possible for the public assert macro and its
__assert_fail function because POSIX requires that the diagnostic
is written to stderr.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

3 files changed, 39 insertions, 2 deletions

diff --git a/assert/Makefile b/assert/Makefile
index f7cf8e9..c905845 100644
--- a/assert/Makefile
+++ b/assert/Makefile
@@ -24,7 +24,12 @@ include ../Makeconfig
 
 headers	:= assert.h
 
-routines := assert assert-perr __assert
+routines := \
+  __assert \
+  __libc_assert_fail \
+  assert \
+  assert-perr \
+  # routines
 tests := test-assert test-assert-perr tst-assert-c++ tst-assert-g++
 
 ifeq ($(have-cxx-thread_local),yes)
diff --git a/assert/__libc_assert_fail.c b/assert/__libc_assert_fail.c
new file mode 100644
index 0000000..149d5fe
--- /dev/null
+++ b/assert/__libc_assert_fail.c
@@ -0,0 +1,33 @@
+/* libc-internal assert that calls __libc_message.
+   Copyright (C) 2022 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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <_itoa.h>
+#include <array_length.h>
+#include <intprops.h>
+#include <stdio.h>
+
+void
+__libc_assert_fail (const char *assertion, const char *file, unsigned int line,
+                    const char *function)
+{
+  char linebuf[INT_BUFSIZE_BOUND (unsigned int)];
+  array_end (linebuf)[-1] = '\0';
+  char *linestr = _itoa_word (line, array_end (linebuf) - 1, 10, 0);
+  __libc_message ("Fatal glibc error: %s:%s (%s): assertion failed: %s\n",
+                  file, linestr, function, assertion);
+}
diff --git a/assert/assert.c b/assert/assert.c
index 133a183..564ae28 100644
--- a/assert/assert.c
+++ b/assert/assert.c
@@ -101,4 +101,3 @@ __assert_fail (const char *assertion, const char *file, unsigned int line,
   __assert_fail_base (_("%s%s%s:%u: %s%sAssertion `%s' failed.\n%n"),
 		      assertion, file, line, function);
 }
-hidden_def(__assert_fail)