universalservice/examples/string/uns_string.c

/* Copyright (c) 2024, Peter McGoron
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1) Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2) Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <string.h>
#include "uns.h"
#include "uns_string.h"

enum {
	ALLEN_IND = 0,
	LEN_IND = 1,
	BYTES_IND = 2,
	NUMBER_OF_IND = 3
};

static size_t get_size_t(struct uns_gc *gc, struct uns_ctr *root, size_t i)
{
	size_t r;

	void *p = gc->record_get_ptr(root->p, i);
	memcpy(&r, p, sizeof(r));

	return r;
}

static void set_size_t(struct uns_gc *gc, struct uns_ctr *root, size_t i, size_t val)
{
	void *p = gc->record_get_ptr(root->p, i);
	memcpy(p, &val, sizeof(val));
}

#define set_allen(gc,root,val) set_size_t(gc, root, ALLEN_IND, val)
#define set_len(gc,root,val) set_size_t(gc, root, LEN_IND, val)

static size_t uns_string_allen(struct uns_gc *gc, struct uns_ctr *root)
{
	return get_size_t(gc, root, ALLEN_IND);
}

size_t uns_string_len(struct uns_gc *gc, struct uns_ctr *root)
{
	return get_size_t(gc, root, LEN_IND);
}

char *uns_string_ptr(struct uns_gc *gc, struct uns_ctr *root)
{
	return gc->record_get_ptr(root->p, BYTES_IND);
}

void uns_string_alloc(struct uns_gc *gc, struct uns_ctr *root, size_t start_len)
{
	unsigned char *p;
	root->p = gc->alloc_record(gc, NUMBER_OF_IND);

	/* The following is incorrect:
	 *   gc->record_set_ptr(root->p, ALLEN_IND, gc->alloc(gc, sizeof(size_t)));
	 * This is because gc->alloc() can cause a collection, invalidating root->p,
	 * but root->p may have already been put on the stack.
	 */

	p = gc->alloc(gc, sizeof(size_t));
	gc->record_set_ptr(root->p, ALLEN_IND, p);
	set_allen(gc, root, start_len);

	p = gc->alloc(gc, sizeof(size_t));
	gc->record_set_ptr(root->p, LEN_IND, p);
	set_len(gc, root, 0);

	p = gc->alloc(gc, start_len);
	gc->record_set_ptr(root->p, BYTES_IND, p);
}

void uns_string_resize(struct uns_gc *gc, struct uns_ctr *root, size_t newlen)
{
	struct uns_ctr tmp_new = {0};
	size_t old_len = uns_string_len(gc, root);

	/* The temporary string needs to be added to the roots list because
	 * there are multiple allocations that happen in the body of the string.
	 */
	uns_root_add(gc, &tmp_new);
	uns_string_alloc(gc, &tmp_new, newlen);

	if (newlen <= old_len)
		set_len(gc, &tmp_new, newlen);
	else
		set_len(gc, &tmp_new, old_len);

	memcpy(uns_string_ptr(gc, &tmp_new), uns_string_ptr(gc, root), uns_string_len(gc, root));
	root->p = tmp_new.p;
	uns_root_remove(gc, &tmp_new);
}

void uns_string_ensure(struct uns_gc *gc, struct uns_ctr *root, size_t extent)
{
	size_t used = uns_string_len(gc, root);
	size_t allen = uns_string_allen(gc, root);

	if (used + extent > allen)
		uns_string_resize(gc, root, used + extent);
}

void uns_string_append_bytes(struct uns_gc *gc, struct uns_ctr *to,
                            const void *from, size_t bytes)
{
	size_t len = uns_string_len(gc, to);
	uns_string_ensure(gc, to, bytes);
	memcpy(uns_string_ptr(gc, to) + len, from, bytes);
	set_len(gc, to, len + bytes);
}

void uns_string_append_char(struct uns_gc *gc, struct uns_ctr *root, char c)
{
	uns_string_append_bytes(gc, root, &c, 1);
}

char *uns_string_cstring(struct uns_gc *gc, struct uns_ctr *root)
{
	char *p;
	uns_string_ensure(gc, root, 1);

	p = uns_string_ptr(gc, root);
	p[uns_string_len(gc, root)] = 0;
	return p;
}