Re: [PATCH] Better handling for realpath() failures in windows_make_so() on Cygwin

[Pedro Alves <pedro@palves.net>]

On 2024-03-21 16:31, Orgad Shaneh wrote:
> On Thu, Mar 21, 2024 at 6:13 PM Pedro Alves <pedro@palves.net> wrote:
>>
>> On 2024-03-21 14:45, Jon Turney wrote:
>>> On 21/03/2024 06:53, Orgad Shaneh wrote:
>>>> From: Jon Turney <jon.turney@dronecode.org.uk>
>>>
>>> Not sure where this is coming from, but this doesn't seem to be my latest version of this patch.
>>>
>>>> Fix a memory leak which would occur in the case when the result of realpath() is
>>>> greater than or equal to SO_NAME_MAX_PATH_SIZE.
>>>>
>>>> Distinguish between realpath() failing (returning NULL), and returning a path
>>>> longer than SO_NAME_MAX_PATH_SIZE
>>>>
>>>> Warn rather than stopping with an error in those cases.
>>>
>>> This line in the patch commentary, and the title, refers to the part of the patch submitted [1], which is already applied as commit a0e9b53238c3033222c53b1654da535c0743ab6e.
>>>
>>> I separated that out because of the discussion starting at [2] ("Remove SO_NAME_PATH_SIZE instead"...)
>>>
>>> [1] https://sourceware.org/pipermail/gdb-patches/2020-January/164695.html
>>> [2] https://sourceware.org/pipermail/gdb-patches/2016-January/130435.html
> 
> I took it from MSYS2 patches, which were taken from cygwin patches,
> but apparently diverged (possibly my fault, in
> https://github.com/msys2/MSYS2-packages/pull/2475. Not sure why :))
> 
> Thanks for the references. I see that some of the work is already done
> (so_name, so_original_name and so->name are all std::strings), so it
> looks like there's not much left.

Indeed.  I actually thought the std::string conversion hadn't been merged yet.  Should
have checked.  :-)

So we can simplify this code already.  I sent a series to clean up things:

https://inbox.sourceware.org/gdb-patches/20240322190424.1231540-1-pedro@palves.net/T/

[PATCH 0/4] Down with SO_NAME_MAX_PATH_SIZE and windows_make_so spring cleaning
  [PATCH 1/4] Remove SO_NAME_MAX_PATH_SIZE limit from core solib code
  [PATCH 2/4] Simplify windows-nat.c:windows_make_so #ifdefery
  [PATCH 3/4] windows-nat: Remove SO_NAME_MAX_PATH_SIZE limit
  [PATCH 4/4] windows-nat: Use gdb_realpath

Thanks,
Pedro Alves

> 
>> Curiously, after upstreaming your _sigbe unwinder recently, I looked at upstreaming this patch (the version of the 2016 patch
>> in downstream cygwin gdb), but then this same thought of removing the limit hit me.  (at least I'm consistent over the
>> years, eh.)
>>
>> I then realized that Simon is working on a series that switches the solib path storage to a std::string, which will
>> let us easily not use SO_NAME_MAX_PATH_SIZE at all in the Windows code.  So I just dropped that patch from
>> my upstreaming queue...
> 
> Great! So I'll drop this patch.
>