Re: [PATCH] eblopenback: Warn when unable to find ebl backend

[Ben Gamari <ben at smart-cactus dot org>]

Josh Stone <jistone@redhat.com> writes:

> On 11/25/2015 04:45 AM, Ben Gamari wrote:
>> This could have easily saved me three hours.
>> ---
>>  libebl/eblopenbackend.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>> 
>> diff --git a/libebl/eblopenbackend.c b/libebl/eblopenbackend.c
>> index b301400..662842d 100644
>> --- a/libebl/eblopenbackend.c
>> +++ b/libebl/eblopenbackend.c
>> @@ -376,7 +376,8 @@ openbackend (Elf *elf, const char *emulation, GElf_Half machine)
>>  	result->dlhandle = NULL;
>>  	result->elf = elf;
>>  	result->name = machines[cnt].prefix;
>> -	fill_defaults (result);
>> +        fill_defaults (result);
>> +        fprintf(stderr, "ebl_openbackend: Failed to find backend DSO to handle machine.\n");
>>  
>>  	return result;
>>        }
>
> It's not really kosher for a library to dump on stderr.  No other part
> of elfutils does this AFAICS.  Maybe some other location needs to return
> better errors from not having the ebl->dlhandle?
>
I can see the argument here. That being said, as a user of libdw I can
attest that the debug output really could be improved. As things stand it's
a nightmare trying to figure out precisely where things go off the
rails, typically requiring one to literally single-step through the
library in GDB until you are lucky enough to spot the error. I would
really appreciate some systematic debug output, even if one needs to
set a special LIBDW_DEBUG environment variable or some such to see it.

Would a patch introducing the infrastructure necessary for debug output
(and a rebased version of this patch) be acceptable?

> (Also, watch your tab changes.)

Indeed, I've fixed my editor.

Thanks,

- Ben

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