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_emplace_enlarge.c | 69 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 69 insertions(+) create mode 100644 malloc/dynarray_emplace_enlarge.c (limited to 'malloc/dynarray_emplace_enlarge.c') diff --git a/malloc/dynarray_emplace_enlarge.c b/malloc/dynarray_emplace_enlarge.c new file mode 100644 index 0000000..dfc7001 --- /dev/null +++ b/malloc/dynarray_emplace_enlarge.c @@ -0,0 +1,69 @@ +/* Increase the size of a dynamic array in preparation of an emplace operation. + 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_emplace_enlarge (struct dynarray_header *list, + void *scratch, size_t element_size) +{ + size_t new_allocated; + if (list->allocated == 0) + { + /* No scratch buffer provided. Choose a reasonable default + size. */ + if (element_size < 4) + new_allocated = 16; + if (element_size < 8) + new_allocated = 8; + else + new_allocated = 4; + } + else + /* Increase the allocated size, using an exponential growth + policy. */ + { + new_allocated = list->allocated + list->allocated / 2 + 1; + if (new_allocated <= list->allocated) + /* Overflow. */ + return false; + } + + size_t new_size; + if (check_mul_overflow_size_t (new_allocated, element_size, &new_size)) + return false; + void *new_array; + if (list->array == scratch) + { + /* The previous array was not heap-allocated. */ + new_array = malloc (new_size); + if (new_array != NULL && list->array != NULL) + memcpy (new_array, list->array, list->used * element_size); + } + else + new_array = realloc (list->array, new_size); + if (new_array == NULL) + return false; + list->array = new_array; + list->allocated = new_allocated; + return true; +} +libc_hidden_def (__libc_dynarray_emplace_enlarge) -- cgit v1.1