c_rle.c

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#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);
    }