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-rw-r--r--lib/malloc/dynarray_emplace_enlarge.c77
1 files changed, 77 insertions, 0 deletions
diff --git a/lib/malloc/dynarray_emplace_enlarge.c b/lib/malloc/dynarray_emplace_enlarge.c
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+++ b/lib/malloc/dynarray_emplace_enlarge.c
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+/* Increase the size of a dynamic array in preparation of an emplace operation.
+ Copyright (C) 2017-2022 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/>. */
+
+#ifndef _LIBC
+# include <libc-config.h>
+#endif
+
+#include <dynarray.h>
+#include <errno.h>
+#include <intprops.h>
+#include <stdlib.h>
+#include <string.h>
+
+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;
+ else 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. */
+ __set_errno (ENOMEM);
+ return false;
+ }
+ }
+
+ size_t new_size;
+ if (INT_MULTIPLY_WRAPV (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)