[musl] libc-test contribution

[musl] libc-test contribution

[Ward, Ryan C]

Hello,

I would like to start contributing some test cases to libc-test. I have 
started with testing some simple recent regressions (e.g. a test for
the recent fix commit 947b4574), and am aiming to start filling in
missing functional test coverage. Am I able to submit the test
directly to this mailing list, and are there any other immediate 
areas of libc-test that need implementation?

Kind regards,
Ryan

Re: [musl] libc-test contribution

[Szabolcs Nagy]

* Ward, Ryan C <ryan.c.ward3@boeing.com> [2024-08-16 01:06:55 +0000]:
> Hello,
> 
> I would like to start contributing some test cases to libc-test. I have 
> started with testing some simple recent regressions (e.g. a test for
> the recent fix commit 947b4574), and am aiming to start filling in
> missing functional test coverage. Am I able to submit the test
> directly to this mailing list, and are there any other immediate 
> areas of libc-test that need implementation?

this list is fine

there are many areas missing
but they need test infrastucture
eg networking tests depending on
/etc/resolv.conf need to run in
a separate mount namespace.

adding selfcontained regression
tests should be fine

> 
> Kind regards,
> Ryan

Re: [musl] libc-test contribution

[Rich Felker]

On Fri, Aug 16, 2024 at 09:35:38AM +0200, Szabolcs Nagy wrote:
> * Ward, Ryan C <ryan.c.ward3@boeing.com> [2024-08-16 01:06:55 +0000]:
> > Hello,
> > 
> > I would like to start contributing some test cases to libc-test. I have 
> > started with testing some simple recent regressions (e.g. a test for
> > the recent fix commit 947b4574), and am aiming to start filling in
> > missing functional test coverage. Am I able to submit the test
> > directly to this mailing list, and are there any other immediate 
> > areas of libc-test that need implementation?
> 
> this list is fine
> 
> there are many areas missing
> but they need test infrastucture
> eg networking tests depending on
> /etc/resolv.conf need to run in
> a separate mount namespace.

I could try writing a helper module to do this. Basically it would
just unshare into a new user+mount+network namespace and, if
/etc/resolv.conf exists, bind-mount an empty file over it. Then you
can bind port 53 and it will intercept all queries, and you don't have
to worry about anything going out to the real network or having
network-dependent behaviors.

Rich

Re: [musl] libc-test contribution

[Rich Felker]

On Fri, Aug 16, 2024 at 11:57:29AM -0400, Rich Felker wrote:
> On Fri, Aug 16, 2024 at 09:35:38AM +0200, Szabolcs Nagy wrote:
> > * Ward, Ryan C <ryan.c.ward3@boeing.com> [2024-08-16 01:06:55 +0000]:
> > > Hello,
> > > 
> > > I would like to start contributing some test cases to libc-test. I have 
> > > started with testing some simple recent regressions (e.g. a test for
> > > the recent fix commit 947b4574), and am aiming to start filling in
> > > missing functional test coverage. Am I able to submit the test
> > > directly to this mailing list, and are there any other immediate 
> > > areas of libc-test that need implementation?
> > 
> > this list is fine
> > 
> > there are many areas missing
> > but they need test infrastucture
> > eg networking tests depending on
> > /etc/resolv.conf need to run in
> > a separate mount namespace.
> 
> I could try writing a helper module to do this. Basically it would
> just unshare into a new user+mount+network namespace and, if
> /etc/resolv.conf exists, bind-mount an empty file over it. Then you
> can bind port 53 and it will intercept all queries, and you don't have
> to worry about anything going out to the real network or having
> network-dependent behaviors.

Something like this:

#define _GNU_SOURCE
#include <stdio.h>
#include <unistd.h>
#include <sched.h>
#include <sys/mount.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <netinet/in.h>

int enter_dns_test_ns()
{
	if (unshare(CLONE_NEWUSER|CLONE_NEWNS|CLONE_NEWNET) < 0)
		return -1;
	int s = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
	if (s < 0) return -1;
	struct ifreq ifr = {
		.ifr_name = "lo",
		.ifr_addr = (union { struct sockaddr_in sin; struct sockaddr sa; }){{
			.sin_family = AF_INET,
			.sin_port = 0,
			.sin_addr = htonl(0x7f000001),
			}}.sa,
	};
	if (ioctl(s, SIOCSIFADDR, &ifr) < 0)
		return -1;
	if (ioctl(s, SIOCGIFFLAGS, &ifr) < 0)
		return -1;
	ifr.ifr_flags |= IFF_UP;
	if (ioctl(s, SIOCSIFFLAGS, &ifr) < 0)
		return -1;
	char tmp[] = "/tmp/emptyXXXXXX";
	int fd = mkostemp(tmp, O_CLOEXEC);
	if (fd < 0) return -1;
	int r = mount(tmp, "/etc/resolv.conf", 0, MS_BIND, 0);
	unlink(tmp);
	return r;
}