1  /* Increase the size of a dynamic array.
       2     Copyright (C) 2017-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <dynarray.h>
      20  #include <errno.h>
      21  #include <intprops.h>
      22  #include <stdlib.h>
      23  #include <string.h>
      24  
      25  bool
      26  __libc_dynarray_resize (struct dynarray_header *list, size_t size,
      27                          void *scratch, size_t element_size)
      28  {
      29    /* The existing allocation provides sufficient room.  */
      30    if (size <= list->allocated)
      31      {
      32        list->used = size;
      33        return true;
      34      }
      35  
      36    /* Otherwise, use size as the new allocation size.  The caller is
      37       expected to provide the final size of the array, so there is no
      38       over-allocation here.  */
      39  
      40    size_t new_size_bytes;
      41    if (INT_MULTIPLY_WRAPV (size, element_size, &new_size_bytes))
      42      {
      43        /* Overflow.  */
      44        __set_errno (ENOMEM);
      45        return false;
      46      }
      47    void *new_array;
      48    if (list->array == scratch)
      49      {
      50        /* The previous array was not heap-allocated.  */
      51        new_array = malloc (new_size_bytes);
      52        if (new_array != NULL && list->array != NULL)
      53          memcpy (new_array, list->array, list->used * element_size);
      54      }
      55    else
      56      new_array = realloc (list->array, new_size_bytes);
      57    if (new_array == NULL)
      58      return false;
      59    list->array = new_array;
      60    list->allocated = size;
      61    list->used = size;
      62    return true;
      63  }
      64  libc_hidden_def (__libc_dynarray_resize)