mirror of git://sourceware.org/git/glibc.git
120 lines
4.1 KiB
C
120 lines
4.1 KiB
C
/* Test that free preserves errno.
|
|
Copyright (C) 2020-2025 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 <errno.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <unistd.h>
|
|
#include <fcntl.h>
|
|
#include <stdint.h>
|
|
#include <string.h>
|
|
#include <stdio.h>
|
|
#include <sys/mman.h>
|
|
#include <support/check.h>
|
|
#include <support/support.h>
|
|
#include <support/temp_file.h>
|
|
|
|
/* The __attribute__ ((weak)) prevents a GCC optimization. Without
|
|
it, GCC would "know" that errno is unchanged by calling free (ptr),
|
|
when ptr was the result of a malloc call in the same function. */
|
|
int __attribute__ ((weak))
|
|
get_errno (void)
|
|
{
|
|
return errno;
|
|
}
|
|
|
|
static int
|
|
do_test (void)
|
|
{
|
|
/* Check that free() preserves errno. */
|
|
{
|
|
errno = 1789; /* Liberté, égalité, fraternité. */
|
|
free (NULL);
|
|
TEST_VERIFY (get_errno () == 1789);
|
|
}
|
|
{ /* Large memory allocations, to force mmap. */
|
|
enum { N = 2 };
|
|
void * volatile ptrs[N];
|
|
size_t i;
|
|
for (i = 0; i < N; i++)
|
|
ptrs[i] = xmalloc (5318153);
|
|
for (i = 0; i < N; i++)
|
|
{
|
|
errno = 1789;
|
|
free (ptrs[i]);
|
|
TEST_VERIFY (get_errno () == 1789);
|
|
}
|
|
}
|
|
|
|
/* Test a less common code path.
|
|
When malloc() is based on mmap(), free() can sometimes call munmap().
|
|
munmap() usually succeeds, but fails in a particular situation: when
|
|
- it has to unmap the middle part of a VMA, and
|
|
- the number of VMAs of a process is limited and the limit is
|
|
already reached.
|
|
On Linux, the default VMA count limit is 65536 although many systems
|
|
might override this. For this test, irrespective of the system, we
|
|
try to create up to 65536 mappings in order to attempt to hit the
|
|
limit. */
|
|
{
|
|
/* We expect the kernel to coalesce the VMAs for these large mallocs
|
|
(which will be mmap'd by malloc due to their size). */
|
|
size_t big_size = 0x3000000;
|
|
void * volatile block1 = xmalloc (big_size - 100);
|
|
void * volatile block2 = xmalloc (big_size - 100);
|
|
void * volatile block3 = xmalloc (big_size - 100);
|
|
|
|
/* If block2 lands between block1 and block3, we can continue the test
|
|
since it depends on being able to free block2 to cause an munmap
|
|
failure. */
|
|
if (((block2 > block1) && (block2 > block3))
|
|
|| ((block2 < block1) && (block2 < block3)))
|
|
printf
|
|
("warning: block2 was not allocated between block1 and block3\n");
|
|
|
|
/* We will map this fd repeatedly to consume VMA mappings. */
|
|
int fd = create_temp_file ("tst-free-errno", NULL);
|
|
if (fd < 0)
|
|
FAIL_EXIT1 ("cannot create temporary file for mmap'ing");
|
|
|
|
/* Now add as many mappings as we can.
|
|
Stop at 65536, in order not to crash the machine (in case the
|
|
limit has been increased by the system administrator). */
|
|
size_t pagesize = getpagesize ();
|
|
for (int i = 0; i < 65536; i++)
|
|
if (mmap (NULL, pagesize, PROT_READ, MAP_FILE | MAP_PRIVATE,
|
|
fd, 0)
|
|
== MAP_FAILED)
|
|
break;
|
|
/* Now the number of VMAs of this process has hopefully attained
|
|
its limit. */
|
|
|
|
errno = 1789;
|
|
/* This call to free() is supposed to call munmap, which should
|
|
fail because the fragmentation of a bigger coalesced VMA will
|
|
lead to an increase in the number of VMAs which we already
|
|
maxed out. */
|
|
free (block2);
|
|
TEST_VERIFY (get_errno () == 1789);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
#include <support/test-driver.c>
|