From 91b6eb1140eda6bab324821ee3785e5d0ca155b8 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Fri, 2 Jun 2017 11:59:28 +0200 Subject: Add internal facility for dynamic array handling This is intended as a type-safe alternative to obstacks and hand-written realloc constructs. The implementation avoids writing function pointers to the heap. --- malloc/dynarray_resize.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 59 insertions(+) create mode 100644 malloc/dynarray_resize.c (limited to 'malloc/dynarray_resize.c') diff --git a/malloc/dynarray_resize.c b/malloc/dynarray_resize.c new file mode 100644 index 0000000000..e6dc9fbc68 --- /dev/null +++ b/malloc/dynarray_resize.c @@ -0,0 +1,59 @@ +/* Increase the size of a dynamic array. + Copyright (C) 2017 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 + . */ + +#include +#include +#include +#include + +bool +__libc_dynarray_resize (struct dynarray_header *list, size_t size, + void *scratch, size_t element_size) +{ + /* The existing allocation provides sufficient room. */ + if (size <= list->allocated) + { + list->used = size; + return true; + } + + /* Otherwise, use size as the new allocation size. The caller is + expected to provide the final size of the array, so there is no + over-allocation here. */ + + size_t new_size_bytes; + if (check_mul_overflow_size_t (size, element_size, &new_size_bytes)) + return false; + void *new_array; + if (list->array == scratch) + { + /* The previous array was not heap-allocated. */ + new_array = malloc (new_size_bytes); + if (new_array != NULL && list->array != NULL) + memcpy (new_array, list->array, list->used * element_size); + } + else + new_array = realloc (list->array, new_size_bytes); + if (new_array == NULL) + return false; + list->array = new_array; + list->allocated = size; + list->used = size; + return true; +} +libc_hidden_def (__libc_dynarray_resize) -- cgit v1.2.3