/* $OpenBSD: c_rle.c,v 1.9 2022/01/09 23:50:10 tb Exp $ */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/objects.h>
#include <openssl/comp.h>

#include "comp_local.h"

static int rle_compress_block(COMP_CTX *ctx, unsigned char *out,
    unsigned int olen, unsigned char *in, unsigned int ilen);
static int rle_expand_block(COMP_CTX *ctx, unsigned char *out,
    unsigned int olen, unsigned char *in, unsigned int ilen);

static COMP_METHOD rle_method = {
	.type = NID_rle_compression,
	.name = LN_rle_compression,
	.compress = rle_compress_block,
	.expand = rle_expand_block
};

COMP_METHOD *
COMP_rle(void)
{
	return (&rle_method);
}

static int
rle_compress_block(COMP_CTX *ctx, unsigned char *out, unsigned int olen,
    unsigned char *in, unsigned int ilen)
{

	if (ilen == 0 || olen < (ilen - 1)) {
		return (-1);
	}

	*(out++) = 0;
	memcpy(out, in, ilen);
	return (ilen + 1);
}

static int
rle_expand_block(COMP_CTX *ctx, unsigned char *out, unsigned int olen,
    unsigned char *in, unsigned int ilen)
{
	int i;

	if (olen < (ilen - 1)) {
		return (-1);
	}

	i= *(in++);
	if (i == 0) {
		memcpy(out, in, ilen - 1);
	}
	return (ilen - 1);
}