On Thu, Jul 18, 2013 at 11:29:57PM +0200, Geert Uytterhoeven wrote: > On Thu, Jul 18, 2013 at 11:18 PM, Sergey Senozhatsky > <sergey.senozhat...@gmail.com> wrote: > > On (07/12/13 12:48), Sergey Senozhatsky wrote: > >> On (07/12/13 11:28), Yann Collet wrote: > >> > The reference implementation, hosted at :� > >> > [1]https://code.google.com/p/lz4/ > >> > only proposes char* (signed) types as part of the interface contract. > >> > I would recommend to keep it that way, to remain consistent. > >> > Regards > >> > >> Crypto lz4 accepts u8 * for both compression and decompression: > >> > >> lz4_compress_crypto(struct crypto_tfm *tfm, const u8 *src, > >> unsigned int slen, u8 *dst, unsigned int *dlen) > >> > >> lz4_decompress_crypto(struct crypto_tfm *tfm, const u8 *src, > >> unsigned int slen, u8 *dst, unsigned int *dlen) > >> > >> > >> Internally LZ4 may cast unsigned char* to signed char*, the same way you > >> already do with compression: > >> > >> int lz4_compress(const unsigned char *src, size_t src_len, > >> unsigned char *dst, size_t *dst_len, void *wrkmem) > >> > >> calls: > >> lz4_compressctx(void *ctx, > >> const char *source, char *dest, > >> int isize, int maxoutputsize) > >> > > > > > > + lib/decompress_unlz4.c > > STATIC int INIT decompress(unsigned char *buf, int in_len, > > int(*fill)(void*, unsigned int), > > int(*flush)(void*, unsigned int), > > unsigned char *output, > > int *posp, > > void(*error)(char *x) > > > >> > >> At the moment API is a bit misaligned: unsiged char* for compression and > >> signed char* for > >> decompression. > >> > >> > >> My 'real word' use case is, suppose: > >> > >> struct foo { > >> [..] > >> int (*compress)(const unsigned char *src, size_t src_len, > >> unsigned char *dst, size_t *dst_len, void > >> *wrkmem); > >> int (*decompress)(const unsigned char *src, size_t src_len, > >> unsigned char *dst, size_t *dst_len); > >> }; > >> > >> > >> and (for example) module also provides sysfs attribute, so user can switch > >> select > >> LZO or LZ4 compressions depending of his needs: > >> > >> ->compress = lzo1x_1_compress; > >> ->decompress = lzo1x_decompress_safe; > >> > >> to > >> ->compress = lz4_compress; > >> ->decompress = lz4_decompress_unknownoutputsize; > >> > >> > >> the last one produces unneccessary compilation warning. > >> > > > > did you guys have a chance to review the patch? it does not change > > implementation/internals, just decompression exported symbols. > > IMHO, all these memory buffers should be of type "(const) void *", cfr. > e.g. read(2) and memcpy(3). > > This avoids casts in the callers.
How about using "const unsigned char *" for the exported symbols in the patch? It is OK unless the patch changes the internal implementation. Thanks, Kyungsik -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
