Re: [PATCH] log: Fix result of strstr to 'const char *'

["Cédric Le Goater" <clg@redhat.com>]

On 12/9/25 16:07, Peter Maydell wrote:
> On Tue, 9 Dec 2025 at 15:04, Cédric Le Goater <clg@redhat.com> wrote:
>>
>> Assigning the result of strstr() to a 'char *' is unsafe since
>> strstr() returns a pointer into the original string which is a
>> read-only 'const char *' string. Newer compilers
> 
> Which ones? Or does this depend on how the libc headers have
> marked up the strstr() prototype?

Right. This is a new issue and I am not sure why.

It's showing on :

  gcc version 15.2.1 20251111 (Red Hat 15.2.1-4) (GCC)
  glibc-devel-2.42.9000-14.fc44.x86_64

and <string.h> doesn't seem to have change. Both strstr() prototypes
are available.

Let me check.

C.


> 
>> now complain when the
>> result of strstr() is not a 'const char *' :
>>
>> ../util/log.c:208:24: error: initialization discards ‘const’ qualifier from pointer target type [-Werror=discarded-qualifiers]
>>    208 |         char *pidstr = strstr(filename, "%");
>>        |                        ^~~~~~
>>
>> Fix that.
>>
>> Signed-off-by: Cédric Le Goater <clg@redhat.com>
>> ---
>>   util/log.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/util/log.c b/util/log.c
>> index 41f78ce86b2522b8b7072c8b76d8e18603142db6..c44d66b5ce78338cf1b2cd26b7503cb94d4570cb 100644
>> --- a/util/log.c
>> +++ b/util/log.c
>> @@ -203,7 +203,7 @@ static ValidFilenameTemplateResult
>>   valid_filename_template(const char *filename, bool per_thread, Error **errp)
>>   {
>>       if (filename) {
>> -        char *pidstr = strstr(filename, "%");
>> +        const char *pidstr = strstr(filename, "%");
>>
>>           if (pidstr) {
>>               /* We only accept one %d, no other format strings */
>> --
> 
> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
> 
> thanks
> -- PMM
>