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73 lines
2.3 KiB
C
73 lines
2.3 KiB
C
/* Test that malloc uses mmap when sbrk or brk fails.
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Copyright (C) 2024-2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/* This test sets up an obstruction to ensure that brk/sbrk fails to
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grow the heap, then verifies that malloc uses mmap for allocations
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instead. */
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#include <unistd.h>
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#include <sys/mman.h>
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#include <stdlib.h>
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#include <libc-pointer-arith.h>
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#include <support/check.h>
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#include <stddef.h>
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#include <stdalign.h>
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#define LARGE_SIZE (10 * (1 << 20)) // 10 MB
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static long page_size;
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static int
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do_test (void)
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{
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/* Get current program break. */
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void *current_brk = sbrk (0);
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page_size = sysconf (_SC_PAGESIZE);
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/* Round up to the next page boundary. */
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void *next_page_boundary = PTR_ALIGN_UP (current_brk, page_size);
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/* Place a mapping using mmap at the next page boundary. */
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void *obstruction_addr
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= mmap (next_page_boundary, page_size, PROT_READ,
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MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
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/* Check if memory obstruction is set up correctly. */
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TEST_VERIFY_EXIT (obstruction_addr == next_page_boundary);
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/* Try to extend the heap beyond the obstruction using sbrk */
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int *ptr = sbrk (page_size);
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TEST_VERIFY_EXIT (ptr == (void *) -1);
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/* Attempt multiple small allocations using malloc. */
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for (size_t i = 0; i < page_size / alignof (max_align_t); i++)
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{
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TEST_VERIFY (malloc (alignof (max_align_t)));
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}
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/* Attempt to allocate a large block of memory using malloc. */
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TEST_VERIFY_EXIT (malloc (LARGE_SIZE) != NULL);
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/* Check if malloc changed current program break. */
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TEST_VERIFY_EXIT (current_brk == sbrk (0));
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return 0;
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}
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#include <support/test-driver.c>
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