Re: patch: make the size of errbuf configurable

["Z. Gilboa" <zg7s@eservices.virginia.edu>]

On 05/19/2013 05:03 PM, Rich Felker wrote:
> On Sun, May 19, 2013 at 04:12:58PM -0400, Z. Gilboa wrote:
>> Greetings,
>>
>> When a shared library that resides in a deeply nested folder
>> contains unresolved (long-named, mangled) symbols, the displayed
>> name of the library and/or symbol might get truncated.  The attached
>> patch makes the size of errbuf (ldso/dynlink.c) configurable
>> (--with-ld-errbuf-size), while yet leaving the default size of 128
>> unaffected.
> If at some point we do have build configurations, I'd want it to be
> more structured, and for the user-visible names not to reflect
> internal variable names, but something more meaningful to users.
>
> With that said, in this case I think a different solution is called
> for, mainly because having configurability for such small details is
> setting a precedent that, if followed, could lead to hundreds of
> trivial configurable knobs and the same testability nightmare that
> plagues uClibc.
>
> My preference is that either long pathnames should be truncated in a
> reasonable way (keep in mind that the message is *not* parsable by the
> caller; the only way it can be used is presenting it to the user)
certainly; the initial motivation was log-file processing.

> or
> larger buffers should be dynamically allocated. The only reason I did
> not go the dynamic-allocation path to begin with was to make it so
> non-thread-safe usage of dlerror yields (at worst) corrupted messages
> rather than crashes. This can also be achieved with dynamic allocation
> (as long as the old too-short buffer is never freed), but it's more
> complex.

In my understanding, the current approach of having a fixed buffer size 
is by far the superior one.  And I also see your point about keeping the 
number of configurable options to a minimum.   With this in mind, here 
are some alternatives:

1) remove the change from _configure_, but keep the change in 
_dynlink.c_ intact, which would allow developers to control the buffer 
size via CFLAGS.  Add a note to the documentation (and configure's 
--help) about the option to do so.

2) discard the patch altogether, but add a list of "strategic code 
locations" to the documentation...

Any thoughts?


>
> I'd welcome input on which approach users would prefer.
>
> Rich