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>

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)

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);
+}

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)

elf/Makefile

@@ -1283,6 +1283,7 @@ $(objpfx)dl-allobjs.os: $(all-rtld-routines:%=$(objpfx)%.os)
 rtld-stubbed-symbols = \
   __GI___pthread_disable_asynccancel \
   __GI___pthread_enable_asynccancel \
+  __libc_assert_fail \
   __pthread_disable_asynccancel \
   __pthread_enable_asynccancel \
   calloc \

include/assert.h

@@ -20,8 +20,14 @@ extern void __assert_fail_base (const char *fmt, const char *assertion,
 				const char *function)
      __THROW  __attribute__ ((__noreturn__)) attribute_hidden;
 
-# if IS_IN (libc) || (IS_IN (rtld) && !defined NO_RTLD_HIDDEN)
-hidden_proto (__assert_fail)
-hidden_proto (__assert_perror_fail)
+rtld_hidden_proto (__assert_fail)
+rtld_hidden_proto (__assert_perror_fail)
+libc_hidden_proto (__assert_perror_fail)
+
+
+# if IS_IN (libc)
+/* Redirect to the internal version which does not use stderr.  */
+extern _Noreturn __typeof (__assert_fail) __libc_assert_fail attribute_hidden;
+#  define __assert_fail __libc_assert_fail
 # endif
 #endif

malloc/malloc.c

@@ -288,22 +288,6 @@
 #define MALLOC_DEBUG 0
 #endif
 
-#if IS_IN (libc)
-#ifndef NDEBUG
-# define __assert_fail(assertion, file, line, function)			\
-	 __malloc_assert(assertion, file, line, function)
-
-_Noreturn static void
-__malloc_assert (const char *assertion, const char *file, unsigned int line,
-		 const char *function)
-{
-  __libc_message ("Fatal glibc error: malloc assertion failure in %s: %s\n",
-		  function, assertion);
-  __builtin_unreachable ();
-}
-#endif
-#endif
-
 #if USE_TCACHE
 /* We want 64 entries.  This is an arbitrary limit, which tunables can reduce.  */
 # define TCACHE_MAX_BINS		64

stdlib/tst-bz20544.c

@@ -78,7 +78,7 @@ test_bz20544_cxa_at_quick_exit (void *closure)
 static void
 test_one_fn (void (*test_fn) (void *))
 {
-  const char expected_error[] = "Assertion `func != NULL' failed.\n";
+  const char expected_error[] = "assertion failed: func != NULL\n";
   struct support_capture_subprocess result;
   result = support_capture_subprocess (test_fn, NULL);
   support_capture_subprocess_check (&result, "bz20544", -SIGABRT,