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Old 10-23-2017, 10:20 AM   #1
hazel
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After updating glibc on Crux, some programs stopped resolving dns


The problem has corrected itself now but I'd like an explanation. The affected programs were firefox and claws. links still worked normally and I could ping the affected websites and pop3 servers by name, so basic dns resolution was working. Can anybody tell me what causes this sort of behaviour?

I am using FF to post this and everything now appears to be normal.
 
Old 10-23-2017, 12:39 PM   #2
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Let me try an explanation:

The linux (or unix) toolchain consists of Libc (in linux, glibc); Kernel headers: gcc or other compiler.

The libs you are operating with are different from the libs that programs were compiled against, and linux is abopuit asw friendly to that as an indecent assault. It is better not to upgrade glibc except in upgrading the distro.
 
Old 10-24-2017, 07:40 AM   #3
hazel
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If a distro provides updates to particular packages, then I use them. I assume that the devs know what they are doing. I've updated libc in Debian a few times and never had any problems. Besides, ping and links were built against the old libc too, and they still worked. Also claws-mail was already running when I started the update, which means it should have remained linked to the old libc and should not have been affected. And you haven't explained why everything now works normally!
 
Old 10-26-2017, 11:57 AM   #4
hazel
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Just out of interest, some other Crux users had resolution problems after that glibc update. Apparently they are due to incompatibility between the new glibc and glib, requiring the latter to be rebuilt. That's why only some programs were affected; I'm pretty sure from my LFS work that neither ping nor links uses glib. I can't remember now if a glib rebuild was included in that particular general update, but if it was, that would explain why the problem proved temporary in my case.

You can read the correspondence in the Crux mailing list at https://lists.crux.nu/pipermail/crux...er/thread.html.

PS: just checked. glib was rebuilt.

Last edited by hazel; 10-26-2017 at 12:21 PM.
 
Old 10-27-2017, 04:50 AM   #5
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You can surely tell if glib is involved if you get sa list of it's libs. Just run ldd on an affected executable and an unaffected one.
 
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Old 10-27-2017, 06:40 AM   #6
hazel
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Quote:
Originally Posted by business_kid View Post
You can surely tell if glib is involved if you get sa list of it's libs. Just run ldd on an affected executable and an unaffected one.
Good thinking! Neither ping nor links uses glib, but claws-mail does. Firefox doesn't link to glib directly (it actually has very few direct library links) but xulrunner (libxul) does. So the case is made.

That particular Crux update started with glibc and then did glibc-32. The glib update that cured the problem came towards the end. I can confirm that it was a rebuild, not a new version.
 
Old 10-28-2017, 04:12 AM   #7
business_kid
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I've had pain here before. It's this problem: For any lib, ldconfig puts 3 entries

1. Lib.so --> Lib.so.1.2.3
2. Lib.so.1 --> Lib.so.1.2.3
3. Lib.so.1.2.3

The third is the lib, and the first two are symlinks. Programs use 1. or 2. to refer to the lib, but they can be version sensitive. They also mask whether the lib is 32 bit or 64 bit.
 
  


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