Subversion Repositories planix.SVN

#include <u.h>
#include <libc.h>
#include <flate.h>
#include "zlib.h"

typedef struct ZRead    ZRead;

struct ZRead
{
        ulong   adler;
        void    *rr;
        int     (*r)(void*, void*, int);
};

static int
zlread(void *vzr, void *buf, int n)
{
        ZRead *zr;

        zr = vzr;
        n = (*zr->r)(zr->rr, buf, n);
        if(n <= 0)
                return n;
        zr->adler = adler32(zr->adler, buf, n);
        return n;
}

int
deflatezlib(void *wr, int (*w)(void*, void*, int), void *rr, int (*r)(void*, void*, int), int level, int debug)
{
        ZRead zr;
        uchar buf[4];
        int ok;

        buf[0] = ZlibDeflate | ZlibWin32k;

        /* bogus zlib encoding of compression level */
        buf[1] = ((level > 2) + (level > 5) + (level > 8)) << 6;

        /* header check field */
        buf[1] |= 31 - ((buf[0] << 8) | buf[1]) % 31;
        if((*w)(wr, buf, 2) != 2)
                return FlateOutputFail;

        zr.rr = rr;
        zr.r = r;
        zr.adler = 1;
        ok = deflate(wr, w, &zr, zlread, level, debug);
        if(ok != FlateOk)
                return ok;

        buf[0] = zr.adler >> 24;
        buf[1] = zr.adler >> 16;
        buf[2] = zr.adler >> 8;
        buf[3] = zr.adler;
        if((*w)(wr, buf, 4) != 4)
                return FlateOutputFail;

        return FlateOk;
}