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

[Yodel Eldar <yodel.eldar@yodel.dev>]

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