[Slackbuilds-users] tangogps slackbuild doesn't work

B Watson yalhcru at gmail.com
Sun Jul 31 21:39:04 UTC 2011

On 7/31/11, Donald Allen <donaldcallen at gmail.com> wrote:

> If you google for 'libcurl "error 6" segfault', you get hits involving all
> sorts of applications that apparently use curl. Try it. This looks to me
> like a bug in libcurl. So unless you are feeling better, stay in bed. This
> appears to be someone else's problem.

This sounds really similar to the issue with uget that I dealt with a
while back.

If it's the same issue, it can be fixed by adding

curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1);

somewhere in the bit of code that sets the other curl options.

The issue is actually documented in the curl API docs: if curl is
built with threads but without c-ares support (like the one shipped
with slackware), the default DNS timeout handling (which uses signals,
presumably SIGALRM) is unsafe.

Adding to the confusion is that (at least in the case of uget) this
didn't actually hurt anything on slackware 13.1, but it does on 13.37.

I dunno if you can consider this a bug in curl or not: it's documented,
but if I were a curl dev, I'd want to fix it (by having CURLOPT_NOSIGNAL
default to 1 when curl is built without c-ares). Application code can
set CURLOPT_NOSIGNAL, but I don't know how hard it is for a configure
script or makefile to detect whether curl was built with c-ares, and I
don't know what happens if you set CURLOPT_NOSIGNAL when using a libcurl
with c-ares support.

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