btrfs-progs/common/array.c
David Sterba a5d95a73f9 btrfs-progs: add an extensible pointer array struct
API for extensible array of pointers for covenience. A simple wrapper
around a (void *) array with length.

Signed-off-by: David Sterba <dsterba@suse.com>
2023-08-28 17:24:24 +02:00

100 lines
2.5 KiB
C

/*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* 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.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#define _GNU_SOURCE 1
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "common/array.h"
/*
* Extensible array of pointers. Length is the number of user defined pointers,
* capacity is the whole allocated size. Pointers are potentially unstable after
* an append operation. Array initialized to all zeros is valid and can be extended.
*/
static const int alloc_increment = 32;
/* Initialize new array, preallocate @capacity elemennts. */
int array_init(struct array *arr, unsigned int capacity)
{
void *tmp;
arr->data = NULL;
arr->length = 0;
arr->capacity = capacity;
if (arr->capacity == 0)
arr->capacity = alloc_increment;
tmp = calloc(arr->capacity, sizeof(void *));
if (!tmp)
return -1;
arr->data = tmp;
return 0;
}
/* Free internal data array. */
void array_free(struct array *arr)
{
free(arr->data);
arr->length = 0;
arr->capacity = 0;
arr->data = NULL;
}
/* Free all elements up to length. */
void array_free_elements(struct array *arr)
{
unsigned int i;
for (i = 0; i < arr->length; i++) {
free(arr->data[i]);
arr->data[i] = NULL;
}
arr->length = 0;
}
/* Reset all elements to NULL up to capacity. */
void array_clear(struct array *arr)
{
for (unsigned int i = 0; i < arr->capacity; i++)
arr->data[i] = NULL;
}
/* Use the whole capacity for elements. */
void array_use_capacity(struct array *arr)
{
arr->length = arr->capacity;
}
/* Append a new element (increas length), extend the array if needed. */
int array_append(struct array *arr, void *element)
{
if (arr->length == arr->capacity) {
void **tmp;
tmp = realloc(arr->data, (arr->capacity + alloc_increment) * sizeof(void *));
if (!tmp)
return -1;
arr->data = tmp;
memset(&arr->data[arr->capacity], 0, alloc_increment * sizeof(void *));
arr->capacity += alloc_increment;
}
arr->data[arr->length] = element;
arr->length++;
return 0;
}