debug: Add fortify wprintf tests

Similar to other printf-like ones.  It requires to be in a different
process so we can change the orientation of stdout.

Checked on aarch64, armhf, x86_64, and i686.

debug/Makefile

@@ -180,6 +180,7 @@ CPPFLAGS-tst-realpath-chk.c += $(no-fortify-source),-D_FORTIFY_SOURCE=2
 CPPFLAGS-tst-chk-cancel.c += $(no-fortify-source),-D_FORTIFY_SOURCE=2
 CFLAGS-tst-sprintf-fortify-rdonly.c += $(no-fortify-source),-D_FORTIFY_SOURCE=2
 CFLAGS-tst-fortify-syslog.c += $(no-fortify-source),-D_FORTIFY_SOURCE=2
+CFLAGS-tst-fortify-wide.c += $(no-fortify-source),-D_FORTIFY_SOURCE=2
 
 # _FORTIFY_SOURCE tests.
 # Auto-generate tests for _FORTIFY_SOURCE for different levels, compilers and
@@ -283,6 +284,7 @@ tests = \
   tst-backtrace4 \
   tst-backtrace5 \
   tst-backtrace6 \
+  tst-fortify-wide \
   tst-longjmp_chk \
   tst-longjmp_chk2 \
   tst-realpath-chk \

debug/tst-fortify-wide.c

@@ -0,0 +1,104 @@
+/* Fortify check for wprintf.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+   Copyright The GNU Toolchain Authors.
+   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 <setjmp.h>
+#include <stdio.h>
+#include <wchar.h>
+#include <unistd.h>
+
+#include <support/support.h>
+
+static volatile int chk_fail_ok;
+static volatile int ret;
+static jmp_buf chk_fail_buf;
+
+static void
+handler (int sig)
+{
+  if (chk_fail_ok)
+    {
+      chk_fail_ok = 0;
+      longjmp (chk_fail_buf, 1);
+    }
+  else
+    _exit (127);
+}
+
+static const wchar_t *wstr3 = L"%ls%n%ls%n";
+static const wchar_t *wstr4 = L"Hello, ";
+static const wchar_t *wstr5 = L"World!\n";
+static wchar_t wbuf2[20] = L"%ls";
+
+#define WFAIL \
+  do { wprintf (L"Failure on line %d\n", __LINE__); ret = 1; } while (0)
+#define CHK_FAIL_START \
+  chk_fail_ok = 1;				\
+  if (! setjmp (chk_fail_buf))			\
+    {
+#define CHK_FAIL_END \
+      chk_fail_ok = 0;				\
+      WFAIL;					\
+    }
+
+static int
+do_test (void)
+{
+  set_fortify_handler (handler);
+
+  int n1, n2;
+
+  int orientation = fwide (stdout, 1);
+  if (orientation <= 0)
+    WFAIL;
+
+  /* Constant literals passed directly are always ok
+     (even with warnings about possible bugs from GCC).  */
+  if (wprintf (L"%ls%n%ls%n", wstr4, &n1, wstr5, &n2) != 14
+      || n1 != 7 || n2 != 14)
+    WFAIL;
+
+  /* In this case the format string is not known at compile time,
+     but resides in read-only memory, so is ok.  */
+  if (wprintf (wstr3, wstr4, &n1, wstr5, &n2) != 14
+      || n1 != 7 || n2 != 14)
+    WFAIL;
+
+  wcpcpy (&wbuf2[3], L"%n%ls%n");
+  /* When the format string is writable and contains %n,
+     with -D_FORTIFY_SOURCE=2 it causes __chk_fail.  */
+  CHK_FAIL_START
+  if (wprintf (wbuf2, wstr4, &n1, wstr5, &n1) != 14)
+    WFAIL;
+  CHK_FAIL_END
+
+  /* But if there is no %n, even writable format string
+     should work.  */
+  wbuf2[8] = L'\0';
+  if (wprintf (&wbuf2[5], wstr5) != 7)
+    WFAIL;
+
+  /* Check whether missing N$ formats are detected.  */
+  CHK_FAIL_START
+  wprintf (L"%3$d\n", 1, 2, 3, 4);
+  CHK_FAIL_END
+
+  return ret;
+}
+
+#include <support/test-driver.c>