[RFC v1 1/1] string: Add streq(), memeq(), wcseq(), wmemeq()

[Adhemerval Zanella Netto]

On 30/08/25 15:47, Alejandro Colomar wrote:
> Hi,
> 
> On Sat, Aug 30, 2025 at 08:46:10AM +0200, Alejandro Colomar wrote:
>> These inline functions serve the most common use case of the comparison
>> functions: test for equality.  It avoids the reversed return value that
>> confuses programmers.  Using these APIs will result in more readable
>> code, which in the end means safer code.
> 
> I've built a glibc with these inline functions, and one with these
> implemented as macros.  The one with macros results in a smaller binary,
> so I guess I should implement them as macros.  Also, that removes the
> issue about bool/_Bool.
> 
> 
> Have a lovely night!
> Alex
> 
>>
>> Signed-off-by: Alejandro Colomar <alx@kernel.org>

Hi Alejandro,

I am aware this is a RFC, but this patch triggered some CI issues [1], where
some old standard modes do not support '_Bool'.

This is not a complete review, I am still not sure about these new functions.

[1] https://www.delorie.com/trybots/32bit/51346/ 

>> ---
>>  string/string.h | 21 +++++++++++++++++++++
>>  wcsmbs/wchar.h  | 31 +++++++++++++++++++++++++++++++
>>  2 files changed, 52 insertions(+)
>>
>> diff --git a/string/string.h b/string/string.h
>> index df4d489556..7618c209dd 100644
>> --- a/string/string.h
>> +++ b/string/string.h
>> @@ -80,6 +80,16 @@ extern int memcmp (const void *__s1, const void *__s2, size_t __n)
>>  extern int __memcmpeq (const void *__s1, const void *__s2, size_t __n)
>>       __THROW __attribute_pure__ __nonnull ((1, 2));
>>  .
>> +#ifdef __USE_GNU
>> +/* Compare N bytes of M1 and M2 for equality.  */
>> +__attribute_pure__ __nonnull ((1, 2))
>> +static inline _Bool
>> +memeq (const void *__m1, const void *__m2, size_t __n)
>> +{
>> +  return __memcmpeq(__m1, __m2, __n) == 0;
>> +}
>> +#endif
>> +
>>  /* Search N bytes of S for C.  */
>>  #ifdef __CORRECT_ISO_CPP_STRING_H_PROTO
>>  extern "C++"
>> @@ -155,6 +165,17 @@ extern char *strncat (char *__restrict __dest, const char *__restrict __src,
>>  /* Compare S1 and S2.  */
>>  extern int strcmp (const char *__s1, const char *__s2)
>>       __THROW __attribute_pure__ __nonnull ((1, 2));
>> +
>> +#ifdef __USE_GNU
>> +/* Compare S1 and S2 for equality.  */
>> +__attribute_pure__ __nonnull ((1, 2))
>> +static inline _Bool
>> +streq (const char *__s1, const char *__s2)
>> +{
>> +  return strcmp(__s1, __s2) == 0;
>> +}
>> +#endif
>> +
>>  /* Compare N characters of S1 and S2.  */
>>  extern int strncmp (const char *__s1, const char *__s2, size_t __n)
>>       __THROW __attribute_pure__ __nonnull ((1, 2));
>> diff --git a/wcsmbs/wchar.h b/wcsmbs/wchar.h
>> index b31ca2d241..fe8899867f 100644
>> --- a/wcsmbs/wchar.h
>> +++ b/wcsmbs/wchar.h
>> @@ -129,6 +129,22 @@ extern wchar_t *wcsncat (wchar_t *__restrict __dest,
>>  /* Compare S1 and S2.  */
>>  extern int wcscmp (const wchar_t *__s1, const wchar_t *__s2)
>>       __THROW __attribute_pure__ __nonnull ((1, 2));
>> +
>> +#ifdef __USE_GNU
>> +/* Compare S1 and S2 for equality.  */
>> +__attribute_pure__ __nonnull ((1, 2))
>> +static inline
>> +# ifdef __cplusplus
>> +bool
>> +# else
>> +_Bool
>> +# endif
>> +wcseq (const wchar_t *__s1, const wchar_t *__s2)
>> +{
>> +  return wcscmp(__s1, __s2) == 0;
>> +}
>> +#endif
>> +
>>  /* Compare N wide-characters of S1 and S2.  */
>>  extern int wcsncmp (const wchar_t *__s1, const wchar_t *__s2, size_t __n)
>>       __THROW __attribute_pure__ __nonnull ((1, 2));
>> @@ -283,6 +299,21 @@ extern wchar_t *wmemchr (const wchar_t *__s, wchar_t __c, size_t __n)
>>  extern int wmemcmp (const wchar_t *__s1, const wchar_t *__s2, size_t __n)
>>       __THROW __attribute_pure__;
>>  
>> +#ifdef __USE_GNU
>> +/* Compare N wide characters of M1 and M2 for equality.  */
>> +__attribute_pure__ __nonnull ((1, 2))
>> +static inline
>> +# ifdef __cplusplus
>> +bool
>> +# else
>> +_Bool
>> +# endif
>> +wmemeq (const wchar_t *__m1, const wchar_t *__m2, size_t __n)
>> +{
>> +  return wmemcmp(__m1, __m2, __n) == 0;
>> +}
>> +#endif
>> +
>>  /* Copy N wide characters of SRC to DEST.  */
>>  extern wchar_t *wmemcpy (wchar_t *__restrict __s1,
>>  			 const wchar_t *__restrict __s2, size_t __n) __THROW;
>> -- 
>> 2.50.1
>>
>