sslh/gap.c

101 lines
2.3 KiB
C

/*
gap.c: gap, a simple, dynamically-growing array
of pointers that never shrinks
# Copyright (C) 2021 Yves Rutschle
#
# This program is free software; you can redistribute it
# and/or modify it under the terms of the GNU General Public
# License as published by the Free Software Foundation; either
# version 2 of the License, or (at your option) any later
# version.
#
# This program 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 General Public License for more
# details.
#
# The full text for the General Public License is here:
# http://www.gnu.org/licenses/gpl.html
*/
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "gap.h"
typedef struct gap_array {
int len; /* Number of elements in array */
void** array;
} gap_array;
/* Allocate one page-worth of elements */
static int gap_len_alloc(int elem_size)
{
return getpagesize() / elem_size;
}
/* Creates a new gap, all pointers are initialised at NULL */
gap_array* gap_init(void)
{
gap_array* gap = malloc(sizeof(*gap));
if (!gap) return NULL;
memset(gap, 0, sizeof(*gap));
int elem_size = sizeof(gap->array[0]);
gap->len = gap_len_alloc(elem_size);
gap->array = malloc(gap->len * elem_size);
if (!gap->array) return NULL;
for (int i = 0; i < gap->len; i++)
gap->array[i] = NULL;
return gap;
}
int gap_getlen(gap_array* gap)
{
return gap->len;
}
void* gap_get(gap_array* gap, int index)
{
int elem_size = sizeof(gap->array[0]);
return gap->array[index * elem_size];
}
static int gap_extend(gap_array* gap)
{
int elem_size = sizeof(gap->array[0]);
int new_length = gap->len + gap_len_alloc(elem_size);
void** new = realloc(gap->array, new_length * elem_size);
if (!new) return -1;
for (int i = gap->len; i < new_length; i++)
gap->array[i] = NULL;
return 0;
}
int gap_set(gap_array* gap, int index, void* ptr)
{
if (index > gap->len) {
int res = gap_extend(gap);
if (res == -1) return -1;
}
int elem_size = sizeof(gap->array[0]);
gap->array[index * elem_size] = ptr;
return 0;
}
void gap_destroy(gap_array* gap)
{
free(gap->array);
free(gap);
}