Re: [PATCH v5 01/15] emul/vuart: introduce framework for UART emulators

[Jan Beulich <jbeulich@xxxxxxxx>]

On 29.08.2025 21:27, Stefano Stabellini wrote:
> On Thu, 28 Aug 2025, dmukhin@xxxxxxx wrote:
>> --- /dev/null
>> +++ b/xen/common/emul/vuart/vuart.c
>> @@ -0,0 +1,156 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/*
>> + * UART emulator framework.
>> + *
>> + * Copyright 2025 Ford Motor Company
>> + */
>> +
>> +#include <xen/err.h>
>> +#include <xen/sched.h>
>> +#include <xen/vuart.h>
>> +#include <xen/xvmalloc.h>
>> +
>> +#define for_each_emulator(e) \
>> +    for ( e = vuart_array_start; e < vuart_array_end; e++ )
>> +
>> +extern const struct vuart_emulator vuart_array_start[];
>> +extern const struct vuart_emulator vuart_array_end[];
>> +
>> +static const struct vuart_emulator *
>> +vuart_match_by_compatible(struct domain *d, const char *compat)
>> +{
>> +    const struct vuart_emulator *emulator;
>> +
>> +    if ( d->console.vuart )
>> +        return NULL;
>> +
>> +    for_each_emulator(emulator)
>> +        if ( emulator->compatible &&
>> +             !strncmp(emulator->compatible, compat,
>> +                      strlen(emulator->compatible)) )
> 
> strncmp will continue until the given count even if compat is shorter

Not really, one string having a nul char and the other not having one is a
difference, at which point comparison will stop. There would be a problem
if "compat" didn't point to a nul-terminated string, though (and I didn't
check that aspect, not the least because then "shorter" doesn't really
make much sense without a length passed in).

Jan