path: root/malloc/tst-mallocstate.c

/* Emulate Emacs heap dumping to test malloc_set_state.
   Copyright (C) 2001-2025 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 <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <libc-symbols.h>
#include <shlib-compat.h>
#include <support/check.h>
#include <support/support.h>
#include <support/test-driver.h>

#include "malloc.h"

/* Make the compatibility symbols availabile to this test case.  */
void *malloc_get_state (void);
compat_symbol_reference (libc, malloc_get_state, malloc_get_state, GLIBC_2_0);
int malloc_set_state (void *);
compat_symbol_reference (libc, malloc_set_state, malloc_set_state, GLIBC_2_0);

/* Maximum object size in the fake heap.  */
enum { max_size = 64 };

/* Allocation actions.  These are randomized actions executed on the
   dumped heap (see allocation_tasks below).  They are interspersed
   with operations on the new heap (see heap_activity).  */
enum allocation_action
  {
    action_free,                /* Dumped and freed.  */
    action_realloc,             /* Dumped and realloc'ed.  */
    action_realloc_same,        /* Dumped and realloc'ed, same size.  */
    action_realloc_smaller,     /* Dumped and realloc'ed, shrunk.  */
    action_count
  };

/* Dumped heap.  Initialize it, so that the object is placed into the
   .data section, for increased realism.  The size is an upper bound;
   we use about half of the space.  */
static size_t dumped_heap[action_count * max_size * max_size
                          / sizeof (size_t)] = {1};

/* Next free space in the dumped heap.  Also top of the heap at the
   end of the initialization procedure.  */
static size_t *next_heap_chunk;

/* Copied from malloc.c and hooks.c.  The version is deliberately
   lower than the final version of malloc_set_state.  */
# define NBINS 128
# define MALLOC_STATE_MAGIC   0x444c4541l
# define MALLOC_STATE_VERSION (0 * 0x100l + 4l)
static struct
{
  long magic;
  long version;
  void *av[NBINS * 2 + 2];
  char *sbrk_base;
  int sbrked_mem_bytes;
  unsigned long trim_threshold;
  unsigned long top_pad;
  unsigned int n_mmaps_max;
  unsigned long mmap_threshold;
  int check_action;
  unsigned long max_sbrked_mem;
  unsigned long max_total_mem;
  unsigned int n_mmaps;
  unsigned int max_n_mmaps;
  unsigned long mmapped_mem;
  unsigned long max_mmapped_mem;
  int using_malloc_checking;
  unsigned long max_fast;
  unsigned long arena_test;
  unsigned long arena_max;
  unsigned long narenas;
} save_state =
  {
    .magic = MALLOC_STATE_MAGIC,
    .version = MALLOC_STATE_VERSION,
  };

/* Allocate a blob in the fake heap.  */
static void *
dumped_heap_alloc (size_t length)
{
  /* malloc needs three state bits in the size field, so the minimum
     alignment is 8 even on 32-bit architectures.  malloc_set_state
     should be compatible with such heaps even if it currently
     provides more alignment to applications.  */
  enum
  {
    heap_alignment = 8,
    heap_alignment_mask = heap_alignment - 1
  };
  _Static_assert (sizeof (size_t) <= heap_alignment,
                  "size_t compatible with heap alignment");

  /* Need at least this many bytes for metadata and application
     data. */
  size_t chunk_size = sizeof (size_t) + length;
  /* Round up the allocation size to the heap alignment.  */
  chunk_size += heap_alignment_mask;
  chunk_size &= ~heap_alignment_mask;
  TEST_VERIFY_EXIT ((chunk_size & 3) == 0);
  if (next_heap_chunk == NULL)
    /* Initialize the top of the heap.  Add one word of zero padding,
       to match existing practice.  */
    {
      dumped_heap[0] = 0;
      next_heap_chunk = dumped_heap + 1;
    }
  else
    /* The previous chunk is allocated. */
    chunk_size |= 1;
  *next_heap_chunk = chunk_size;

  /* User data starts after the chunk header.  */
  void *result = next_heap_chunk + 1;
  next_heap_chunk += chunk_size / sizeof (size_t);

  /* Mark the previous chunk as used.   */
  *next_heap_chunk = 1;
  return result;
}

/* Global seed variable for the random number generator.  */
static unsigned long long global_seed;

/* Simple random number generator.  The numbers are in the range from
   0 to UINT_MAX (inclusive).  */
static unsigned int
rand_next (unsigned long long *seed)
{
  /* Linear congruential generated as used for MMIX.  */
  *seed = *seed * 6364136223846793005ULL + 1442695040888963407ULL;
  return *seed >> 32;
}

/* Fill LENGTH bytes at BUFFER with random contents, as determined by
   SEED.  */
static void
randomize_buffer (unsigned char *buffer, size_t length,
                  unsigned long long seed)
{
  for (size_t i = 0; i <