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/* Test that malloc uses mmap when sbrk or brk fails.
Copyright (C) 2024 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/>. */
/* This test sets up an obstruction to ensure that brk/sbrk fails to
grow the heap, then verifies that malloc uses mmap for allocations
instead. */
#include <unistd.h>
#include <sys/mman.h>
#include <stdlib.h>
#include <libc-pointer-arith.h>
#include <support/check.h>
#include <stddef.h>
#include <stdalign.h>
#define LARGE_SIZE (10 * (1 << 20)) // 10 MB
static long page_size;
static int
do_test (void)
{
/* Get current program break. */
void *current_brk = sbrk (0);
page_size = sysconf (_SC_PAGESIZE);
/* Round up to the next page boundary. */
void *next_page_boundary = PTR_ALIGN_UP (current_brk, page_size);
/* Place a mapping using mmap at the next page boundary. */
void *obstruction_addr
= mmap (next_page_boundary, page_size, PROT_READ,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
/* Check if memory obstruction is set up correctly. */
TEST_VERIFY_EXIT (obstruction_addr == next_page_boundary);
/* Try to extend the heap beyond the obstruction using sbrk */
int *ptr = sbrk (page_size);
TEST_VERIFY_EXIT (ptr == (void *) -1);
/* Attempt multiple small allocations using malloc. */
for (size_t i = 0; i < page_size / alignof (max_align_t); i++)
{
TEST_VERIFY (malloc (alignof (max_align_t)));
}
/* Attempt to allocate a large block of memory using malloc. */
TEST_VERIFY_EXIT (malloc (LARGE_SIZE) != NULL);
/* Check if malloc changed current program break. */
TEST_VERIFY_EXIT (current_brk == sbrk (0));
return 0;
}
#include <support/test-driver.c>
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