stdlib/tst-realpath.c

   1 /* Test to verify that realpath() doesn't cause false positives due
   2    to GCC attribute malloc.
   3
   4    Test failure exposes the presence of the attribute in the following
   5    declaration:
   6
   7    __attribute__ ((__malloc__ (free, 1))) char*
   8    realpath (const char *, char *);
   9
  10    Copyright (C) 2021-2022 Free Software Foundation, Inc.
  11    This file is part of the GNU C Library.
  12
  13    The GNU C Library is free software; you can redistribute it and/or
  14    modify it under the terms of the GNU Lesser General Public
  15    License as published by the Free Software Foundation; either
  16    version 2.1 of the License, or (at your option) any later version.
  17
  18    The GNU C Library is distributed in the hope that it will be useful,
  19    but WITHOUT ANY WARRANTY; without even the implied warranty of
  20    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  21    Lesser General Public License for more details.
  22
  23    You should have received a copy of the GNU Lesser General Public
  24    License along with the GNU C Library; if not, see
  25    <https://www.gnu.org/licenses/>.  */
  26
  27 #include <stdio.h>
  28 #include <stdlib.h>
  29 #include <malloc.h>
  30
  31 #if defined __GNUC__ && __GNUC__ >= 11
  32 /* Turn GCC -Wmismatched-dealloc warnings into errors to expose false
  33    positives.  */
  34 #  pragma GCC diagnostic push
  35 #  pragma GCC diagnostic error "-Wmismatched-dealloc"
  36
  37 /* Associate dealloc as the only deallocator suitable for pointers
  38    returned from alloc.
  39    GCC automatically disables inlining of allocator and deallocator
  40    functions marked with the argument form of attribute malloc but
  41    it doesn't hurt to disable it explicitly.  */
  42 __attribute  ((noipa)) void dealloc (void *);
  43 __attribute ((malloc (dealloc, 1))) char* alloc (void);
  44 #endif
  45
  46 void dealloc (void *p)
  47 {
  48   free (p);
  49 }
  50
  51 char* alloc (void)
  52 {
  53   return (char *)malloc (8);
  54 }
  55
  56 static int
  57 do_test (void)
  58 {
  59   char *resolved_path = alloc ();
  60   char *ret = realpath ("/", resolved_path);
  61   dealloc (ret);
  62
  63   resolved_path = alloc ();
  64   ret = realpath ("/", resolved_path);
  65   dealloc (resolved_path);
  66
  67   /* The following should emit a warning (but doesn't with GCC 11):
  68      resolved_path = alloc ();
  69      ret = realpath ("/", resolved_path);
  70      free (ret);   // expect -Wmismatched-dealloc
  71   */
  72
  73   return 0;
  74 }
  75
  76 #if defined __GNUC__ && __GNUC__ >= 11
  77 /* Restore -Wmismatched-dealloc setting.  */
  78 #  pragma GCC diagnostic pop
  79 #endif
  80
  81 #define TEST_FUNCTION do_test ()
  82 #include "../test-skeleton.c"