Re: [PATCH 2/2] tests/vhost-user-bridge.c: Fix const qualifier build errors with recent glibc

["Cédric Le Goater" <clg@redhat.com>]

On 12/13/25 01:17, Yodel Eldar wrote:
> 
> On 12/12/2025 17:33, Yodel Eldar wrote:
>> Hi, Cédric!
>>
>> On 10/12/2025 12:13, Cédric Le Goater wrote:
>>> A recent change in glibc 2.42.9000 [1] changes the return type of
>>> strstr() and other string functions to be 'const char *' when the
>>> input is a 'const char *'. This breaks the build in :
>>>
>>> ../tests/vhost-user-bridge.c: In function ‘vubr_parse_host_port’:
>>> ../tests/vhost-user-bridge.c:749:15: error: initialization discards ‘const’ qualifier from pointer target type [-Werror=discarded-qualifiers]
>>>    749 |     char *p = strchr(buf, ':');
>>>        |               ^~~~~~
>>>
>>> Fix this by using the glib g_strsplit() routine instead of strdup().
>>>
>>> [1] https://sourceware.org/git/? p=glibc.git;a=commit;h=cd748a63ab1a7ae846175c532a3daab341c62690
>>>
>>> Suggested-by: Peter Maydell <peter.maydell@linaro.org>
>>> Signed-off-by: Cédric Le Goater <clg@redhat.com>
>>> ---
>>>   tests/vhost-user-bridge.c | 10 ++++------
>>>   1 file changed, 4 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/tests/vhost-user-bridge.c b/tests/vhost-user-bridge.c
>>> index a5c711b1de8e9c164dd1614f4329b8e3c05d0402..ce4c3426d3938a0b54195f3e95bb1f1c3c4ae823 100644
>>> --- a/tests/vhost-user-bridge.c
>>> +++ b/tests/vhost-user-bridge.c
>>> @@ -746,14 +746,12 @@ vubr_run(VubrDev *dev)
>>>   static int
>>>   vubr_parse_host_port(const char **host, const char **port, const char *buf)
>>>   {
>>> -    char *p = strchr(buf, ':');
>>> -
>>> -    if (!p) {
>>> +    g_auto(GStrv) tokens = g_strsplit(buf, ":", 2);
>>> +    if (!tokens[0] || !tokens[1]) {
>>>           return -1;
>>>       }
>>> -    *p = '\0';
>>> -    *host = strdup(buf);
>>> -    *port = strdup(p + 1);
>>> +    *host = g_steal_pointer(&tokens[0]);
>>> +    *port = g_steal_pointer(&tokens[1]);
>>>       return 0;
>>>   }
>>
>> Thanks for addressing this before the glibc change is widely propagated
>> among distros.
>>
>> Acked-by: Yodel Eldar <yodel.eldar@yodel.dev>
>> Tested-by: Yodel Eldar <yodel.eldar@yodel.dev>
>>
>> For testing, I built and installed glibc (76 commits ahead of cd748a63a)
>> in an x86_64 Linux container and built vhost-user-bridge on top of that.
>> Ran it with:
>>
>> ./build/tests/vhost-user-bridge -H
>>
>> qemu-system-x86_64 \
>>      -enable-kvm -m 4G \
>>      -object memory-backend-ram,id=mem0,size=4G,share=on \
>>      -numa node,memdev=mem0 -mem-prealloc \
>>      -chardev socket,id=char0,path=/tmp/vubr.sock \
>>      -netdev type=vhost-user,id=net0,chardev=char0,vhostforce=on \
>>      -device virtio-net-pci,netdev=net0 \
>>      -drive file=linux.qcow2
>>
>> and visually inspected the logged traffic.
>>
>> Thanks,
>> Yodel
>>
> 
> P.S. To build vhost-user-bridge, I had to modify util/log.c as in
> the PULL submission "<20251209200537.84097-9-philmd@linaro.org>".
> 
> For completion, the commands used:
> 
> ../configure --enable-tools --enable-vhost-user --disable-system \
>    --disable-user
> 
> ninja tests/vhost-user-bridge
> 
> Yodel
> 


Thanks Yodel,

My plan is to send a small PR as soon as QEMU 10.2 is out and ask
Michael T. to include the changes in the stable branches.

C.