On Mon, Mar 28, 2005 at 05:22:36PM +0000, Artem B. Bityuckiy wrote: > > I made the changes to deflate_decompr() because the old version doesn't > work properly for me. There are 2 changes. > > 1. I've added the following code: > > ------------------------------------------------------------------------ > if (slen > 2 && !(src[1] & PRESET_DICT) /* No preset dictionary */ > && ((src[0] & 0x0f) == Z_DEFLATED) /* Comp. method byte is OK */ > && !(((src[0] << 8) + src[1]) % 31)) { /* CMF*256 + FLG */ > stream->next_in += 2; > stream->avail_in -= 2; > } > ------------------------------------------------------------------------
The reason you need to add this is because the window bits that was used to produce the compressed data is positive while the window bits crypto/deflate is using to perform the decompression isn't. So what we should do here is turn window bits into a configurable parameter. Once you supply the correct window bits information, the above is then simply an optimisation. Rather than keeping the above optimisation, JFFS should simply do the compression with a negative window bits value. Of course to maintain backwards compatibility you'll need to do this as a new compression type. > 2. I've removed the "strange" (for me) uncompress sequence: > > ------------------------------------------------------------------------ > ret = zlib_inflate(stream, Z_SYNC_FLUSH); > /* > * Work around a bug in zlib, which sometimes wants to taste an extra > * byte when being used in the (undocumented) raw deflate mode. > * (From USAGI). > */ I believe this bit of code originally came from FreeS/WAN and was written by Svenning Sørensen. Maybe he or Yoshifuji-san can tell us why? Unless we're sure that zlib has been fixed we should leave it in. It should be a no-op if zlib has been fixed. So this probably isn't causing the breakage that you saw. Cheers, -- Visit Openswan at http://www.openswan.org/ Email: Herbert Xu ~{PmV>HI~} <[EMAIL PROTECTED]> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/