Re: Fixes bug in strlower_libc_sb()

Hi Hackers,

While reviewing Jeff's patch [1], I found this bug in strlower_libc_sb():

```

static size_t

strlower_libc_sb(char *dest, size_t destsize, const char *src, ssize_t srclen,

pg_locale_t locale)

{

if (srclen < 0)

srclen = strlen(src);

if (srclen + 1 <= destsize)

{

locale_t loc = locale->lt;

char   *p;

if (srclen + 1 > destsize)  <== This check will never be true

return srclen;

```

So I removed the useless check in the patch.

I also noticed strlower_libc_sb’s behavior is different from unicode_strlower(), where the function comment says:

```

* Result string is stored in dst, truncating if larger than dstsize. If
* dstsize is greater than the result length, dst will be NUL-terminated;
* otherwise not.

```

And Jeff’s new code in [1] matches the description. The behavior is like trying the best to copy as many chars as possible, if not enough space in dest, then NULL-terminator can be omitted. But the current behavior of strlower_libc_sb that only copies data to dest when dest has enough space for src and NULL-terminator.

So I updated strlower_libc_sb(), strtitle_libc_sb() and strupper_libc_sb() to comply with the behavior in this patch as well. “Make check” passed from my side, so the patch doesn't seem to break anything.

[1] https://www.postgresql.org/message-id/450ceb6260cad30d7afdf155d991a9caafee7c0d.camel%40j-davis.com