#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/objects.h>
#include <openssl/comp.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 = {
    NID_rle_compression,
    LN_rle_compression,
    NULL,
    NULL,
    rle_compress_block,
    rle_expand_block,
    NULL,
    NULL,
};

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)
{
    /* int i; */

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

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