Horton

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Commits

  1. Remove a useless length check.

  1. Fixes bug in strlower_libc_sb()

    Chao Li <li.evan.chao@gmail.com> — 2025-11-25T03:03:50Z

    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


Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/

  2. Re: Fixes bug in strlower_libc_sb()

    Chao Li <li.evan.chao@gmail.com> — 2025-11-25T05:50:42Z

    On Tue, Nov 25, 2025 at 11:03 AM Chao Li <li.evan.chao@gmail.com> wrote:

> 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
>
>

I thought over and splitted the patch into two commits:

0001 - Fixes the obvious bug by simply deleting the useless length check.
0002 - Updates strlower_lic_sb, strtitle_lic_sb, strupper_lic_sb to comply
with unicode_strlower's truncation behavior

Best regards,
Chao Li (Evan)
---------------------
HighGo Software Co., Ltd.
https://www.highgo.com/

  3. Re: Fixes bug in strlower_libc_sb()

    Bertrand Drouvot <bertranddrouvot.pg@gmail.com> — 2025-11-26T16:15:01Z

    Hi,

On Tue, Nov 25, 2025 at 01:50:42PM +0800, Chao Li wrote:
> On Tue, Nov 25, 2025 at 11:03 AM Chao Li <li.evan.chao@gmail.com> wrote:
> 
> > 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);

Nice catch!

FWIW this thread gave me the idea to create a coccinelle script to detect dead
branches [1]. It reports 4 more that are false positives, so I don't think there
is more dead branches in the code tree.

[1]: https://github.com/bdrouvot/coccinelle_on_pg/blob/main/misc/dead_branches.cocci

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com