sysdeps/x86/tst-ldbl-nonnormal-printf.c

   1 /* Test printf with x86-specific non-normal long double value.
   2    Copyright (C) 2020-2023 Free Software Foundation, Inc.
   3
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20 #include <stdio.h>
  21 #include <string.h>
  22 #include <support/check.h>
  23
  24 /* Fill the stack with non-zero values.  This makes a crash in
  25    snprintf more likely.  */
  26 static void __attribute__ ((noinline, noclone))
  27 fill_stack (void)
  28 {
  29   char buffer[65536];
  30   memset (buffer, 0xc0, sizeof (buffer));
  31   asm ("" ::: "memory");
  32 }
  33
  34 static int
  35 do_test (void)
  36 {
  37   fill_stack ();
  38
  39   long double value;
  40   memcpy (&value, "\x00\x04\x00\x00\x00\x00\x00\x00\x00\x04", 10);
  41
  42   char buf[30];
  43   int ret = snprintf (buf, sizeof (buf), "%Lg", value);
  44   TEST_COMPARE (ret, strlen (buf));
  45   TEST_COMPARE_STRING (buf, "nan");
  46   return 0;
  47 }
  48
  49 #include <support/test-driver.c>