/etc/resolv.conf caching bug fixed in glibc

/etc/resolv.conf caching bug fixed in glibc

[Jack O'Connor]

Glibc just released version 2.26, with the following note under "major
new features":

> The GNU C Library will now detect when /etc/resolv.conf has been modified and reload the changed configuration.

That refers to this bug: https://sourceware.org/bugzilla/show_bug.cgi?id=984

And this patch:
https://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=aef16cc8a4c670036d45590877d411a97f01e0cd;hp=a1c4eb8794e789b5055d7ceb13b2b3231abf5e26

I had hit this bug in the past
(https://github.com/golang/go/issues/21083), and I was eyeballing
other libc implementations to see if they might have the same problem.
It looks like Newlib might? But this was my first time looking at the
source, and I wanted to ask the experts :)

- Jack

Re: /etc/resolv.conf caching bug fixed in glibc

[Sebastian Huber]

Hello Jack,

On 03/08/17 17:33, Jack O'Connor wrote:
> Glibc just released version 2.26, with the following note under "major
> new features":
>
>> The GNU C Library will now detect when /etc/resolv.conf has been modified and reload the changed configuration.

Newlib has no networks stack included. It is usually provided by the 
operating systems that use Newlib. On RTEMS for example we use the 
FreeBSD network stack. The FreeBSD resolver checks the 
"/etc/resolv.conf" at most every two seconds (configurable). See

https://github.com/freebsd/freebsd/blob/master/lib/libc/resolv/res_state.c#L67

-- 
Sebastian Huber, embedded brains GmbH

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