/*      $OpenBSD: compress_gzip.c,v 1.13 2021/06/14 17:58:15 eric Exp $ */

/*
 * Copyright (c) 2012 Gilles Chehade <gilles@poolp.org>
 * Copyright (c) 2012 Charles Longeau <chl@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <stdlib.h>
#include <zlib.h>

#include "smtpd.h"

#define GZIP_BUFFER_SIZE        16384


static size_t   compress_gzip_chunk(void *, size_t, void *, size_t);
static size_t   uncompress_gzip_chunk(void *, size_t, void *, size_t);
static int      compress_gzip_file(FILE *, FILE *);
static int      uncompress_gzip_file(FILE *, FILE *);


struct compress_backend compress_gzip = {
        compress_gzip_chunk,
        uncompress_gzip_chunk,

        compress_gzip_file,
        uncompress_gzip_file,
};

static size_t
compress_gzip_chunk(void *ib, size_t ibsz, void *ob, size_t obsz)
{
        z_stream       *strm;
        size_t          ret = 0;

        if ((strm = calloc(1, sizeof *strm)) == NULL)
                return 0;

        strm->zalloc = Z_NULL;
        strm->zfree = Z_NULL;
        strm->opaque = Z_NULL;
        if (deflateInit2(strm, Z_DEFAULT_COMPRESSION, Z_DEFLATED,
                (15+16), 8, Z_DEFAULT_STRATEGY) != Z_OK)
                goto end;

        strm->avail_in  = ibsz;
        strm->next_in   = (unsigned char *)ib;
        strm->avail_out = obsz;
        strm->next_out  = (unsigned char *)ob;
        if (deflate(strm, Z_FINISH) != Z_STREAM_END)
                goto end;

        ret = strm->total_out;

end:
        deflateEnd(strm);
        free(strm);
        return ret;
}


static size_t
uncompress_gzip_chunk(void *ib, size_t ibsz, void *ob, size_t obsz)
{
        z_stream       *strm;
        size_t          ret = 0;

        if ((strm = calloc(1, sizeof *strm)) == NULL)
                return 0;

        strm->zalloc   = Z_NULL;
        strm->zfree    = Z_NULL;
        strm->opaque   = Z_NULL;
        strm->avail_in = 0;
        strm->next_in  = Z_NULL;

        if (inflateInit2(strm, (15+16)) != Z_OK)
                goto end;

        strm->avail_in  = ibsz;
        strm->next_in   = (unsigned char *)ib;
        strm->avail_out = obsz;
        strm->next_out  = (unsigned char *)ob;

        if (inflate(strm, Z_FINISH) != Z_STREAM_END)
                goto end;

        ret = strm->total_out;

end:
        deflateEnd(strm);
        free(strm);
        return ret;
}


static int
compress_gzip_file(FILE *in, FILE *out)
{
        gzFile  gzf;
        char  ibuf[GZIP_BUFFER_SIZE];
        int  r;
        int  ret = 0;

        if (in == NULL || out == NULL)
                return (0);

        gzf = gzdopen(fileno(out), "wb");
        if (gzf == NULL)
                return (0);

        while ((r = fread(ibuf, 1, GZIP_BUFFER_SIZE, in)) != 0) {
                if (gzwrite(gzf, ibuf, r) != r)
                        goto end;
        }
        if (!feof(in))
                goto end;

        ret = 1;

end:
        gzclose(gzf);
        return (ret);
}


static int
uncompress_gzip_file(FILE *in, FILE *out)
{
        gzFile  gzf;
        char  obuf[GZIP_BUFFER_SIZE];
        int  r;
        int  ret = 0;

        if (in == NULL || out == NULL)
                return (0);

        gzf = gzdopen(fileno(in), "r");
        if (gzf == NULL)
                return (0);

        while ((r = gzread(gzf, obuf, sizeof(obuf))) > 0) {
                if  (fwrite(obuf, r, 1, out) != 1)
                        goto end;
        }
        if (!gzeof(gzf))
                goto end;

        ret = 1;

end:
        gzclose(gzf);
        return (ret);
}