On 5/1/10 11:31 AM, Joerg Schilling wrote:
> OK, let's see.... here is the code:
[...]
> #include <schily/standard.h>
> #include <schily/unistd.h>
> #include <schily/schily.h>
>
> #ifndef HAVE_STRNLEN
>
> EXPORT size_t
> strnlen(s, len)
> register const char *s;
> register size_t len;
The above will need to be rewritten to conform with the style used in
the current OpenSolaris libc. That means:
- none of this "schily" stuff
- remove "register"
- remove the unneeded ifndef
- remove "EXPORT"
- use ANSI C not K&R function declaration
- prefer to use good variable names if possible; "s" isn't.
- prefer to use only needed headers; probably <sys/types.h>
and <string.h>.
- code is incomplete; need updates to header files, Makefiles,
packaging, and library control files (mapfiles).
> if (++len == 0) { /* unsigned overflow */
> while (len-- > 0 && *rs++ != '\0')
> ;
> if (len == 0)
> return (rs - s);
> return (--rs - s);
That case doesn't appear to work. If len is (size_t)~0, then ++len will
set len to 0 (unsigned overflow), making the first "if" statement true.
The "while" statement's first clause will check len>0 using len's value
before the post-decrement, and then post-decrement len back to ~0. It
will immediately terminate because 0>0 is false.
Len now isn't 0 due to the post-decrement, so the "if" statement is
false. We get to the return, and pre-decrement rs, and then return a
value of -1 casted to (size_t), which is not the right answer.
'strnlen("foo",~0)' should return 3, but it instead returns ~0.
I suspect that what may have been wanted was "--len > 0" in the while
statement, but then that makes the first "if" statement unnecessary.
It may be easier just to make "len == 0" a single special case on entry:
if (len == 0)
return (0);
while (*rs++ != '\0' && --len > 0)
;
if (len == 0)
return (rs - s);
else
return ((rs - s) - 1);
--
James Carlson 42.703N 71.076W <[email protected]>
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