libio/tst-sprintf-ub.c

   1 /* Test the sprintf (buf, "%s", buf) does not override buf.
   2    Copyright (C) 2019-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <stdarg.h>
  20 #include <stdio.h>
  21 #include <string.h>
  22
  23 #include <support/check.h>
  24
  25 enum
  26 {
  27   FUNCTION_FIRST,
  28   FUNCTION_SPRINTF = FUNCTION_FIRST,
  29   FUNCTION_SNPRINF,
  30   FUNCTION_VSPRINTF,
  31   FUNCTION_VSNPRINTF,
  32   FUNCTION_LAST
  33 };
  34
  35 static void
  36 do_one_test (int function, char *buf, ...)
  37 {
  38   va_list args;
  39   char *arg;
  40
  41   /* Expected results for fortified and non-fortified sprintf.  */
  42 #if defined _FORTIFY_SOURCE && _FORTIFY_SOURCE > 1
  43   const char *expected = "CD";
  44 #else
  45   const char *expected = "ABCD";
  46 #endif
  47
  48   va_start (args, buf);
  49   arg = va_arg (args, char *);
  50   va_end (args);
  51
  52   switch (function)
  53     {
  54       /* The regular sprintf and vsprintf functions do not override the
  55          destination buffer, even if source and destination overlap.  */
  56       case FUNCTION_SPRINTF:
  57         sprintf (buf, "%sCD", buf);
  58         TEST_COMPARE_STRING (buf, expected);
  59         break;
  60       case FUNCTION_VSPRINTF:
  61         va_start (args, buf);
  62         vsprintf (arg, "%sCD", args);
  63         TEST_COMPARE_STRING (arg, expected);
  64         va_end (args);
  65         break;
  66       /* On the other hand, snprint and vsnprint override overlapping
  67          source and destination buffers.  */
  68       case FUNCTION_SNPRINF:
  69         snprintf (buf, 3, "%sCD", buf);
  70         TEST_COMPARE_STRING (buf, "CD");
  71         break;
  72       case FUNCTION_VSNPRINTF:
  73         va_start (args, buf);
  74         vsnprintf (arg, 3, "%sCD", args);
  75         TEST_COMPARE_STRING (arg, "CD");
  76         va_end (args);
  77         break;
  78       default:
  79         support_record_failure ();
  80     }
  81 }
  82
  83 static int
  84 do_test (void)
  85 {
  86   char buf[8];
  87   int i;
  88
  89   /* For each function in the enum do:
  90        - reset the buffer to the initial state "AB";
  91        - call the function with buffer as source and destination;
  92        - check for the desired behavior.  */
  93   for (i = FUNCTION_FIRST; i < FUNCTION_LAST; i++)
  94     {
  95       strncpy (buf, "AB", 3);
  96       do_one_test (i, buf, buf);
  97     }
  98
  99   return 0;
 100 }
 101
 102 #include <support/test-driver.c>