Messages in this thread | | | From | Andreas Schwab <> | Subject | Re: [PATCH] add strncmp to PowerPC | Date | Mon, 03 Mar 2008 11:10:27 +0100 |
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Gabriel Paubert <paubert@iram.es> writes:
> Now that I think a bit more about it, I believe that the C version is > incorrect: the clrldi/extsb dance takes a value between -255 and +255 > and collapses it into the -128 to 127 range, meaning that the return > value may be wrong if we rely on the sign of the result. So unless I > miss something, the problem is much more serious than just stupid code > (I had just a look at the libc version in C and characters are cast to > unsigned char before the comparison).
The latter is explicitly required by the C standard. Ie. even if your characters are signed they are always compared as unsigned by strcmp/strncmp/memcmp.
Andreas.
-- Andreas Schwab, SuSE Labs, schwab@suse.de SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany PGP key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different." -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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