Re: [musl] [PATCH v1] string.h: Unconditionally expose C23 functions

["A. Wilcox" <AWilcox@Wilcox-Tech.com>]

On Jul 11, 2025, at 08:47, Alejandro Colomar <alx@kernel.org> wrote:
> 
> memccpy(3), strnlen(3), strdup(3), and strndup(3) are now specified by
> ISO C, since C23.
> 
> Link: <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3220.pdf>
> Signed-off-by: Alejandro Colomar <alx@kernel.org>
> ---
> include/string.h | 13 +++++--------
> 1 file changed, 5 insertions(+), 8 deletions(-)
> 
> diff --git a/include/string.h b/include/string.h
> index 83e2b946..723cfc42 100644
> --- a/include/string.h
> +++ b/include/string.h
> @@ -26,6 +26,7 @@ extern "C" {
> 
> void *memcpy (void *__restrict, const void *__restrict, size_t);
> void *memmove (void *, const void *, size_t);
> +void *memccpy (void *__restrict, const void *__restrict, int, size_t);
> void *memset (void *, int, size_t);
> int memcmp (const void *, const void *, size_t);
> void *memchr (const void *, int, size_t);
> @@ -36,6 +37,9 @@ char *strncpy (char *__restrict, const char *__restrict, size_t);
> char *strcat (char *__restrict, const char *__restrict);
> char *strncat (char *__restrict, const char *__restrict, size_t);
> 
> +char *strdup (const char *);
> +char *strndup (const char *, size_t);
> +
> int strcmp (const char *, const char *);
> int strncmp (const char *, const char *, size_t);
> 
> @@ -52,6 +56,7 @@ char *strstr (const char *, const char *);
> char *strtok (char *__restrict, const char *__restrict);
> 
> size_t strlen (const char *);
> +size_t strnlen (const char *, size_t);
> 
> char *strerror (int);
> 
> @@ -66,9 +71,6 @@ char *strtok_r (char *__restrict, const char *__restrict, char **__restrict);
> int strerror_r (int, char *, size_t);
> char *stpcpy(char *__restrict, const char *__restrict);
> char *stpncpy(char *__restrict, const char *__restrict, size_t);
> -size_t strnlen (const char *, size_t);
> -char *strdup (const char *);
> -char *strndup (const char *, size_t);
> char *strsignal(int);
> char *strerror_l (int, locale_t);
> int strcoll_l (const char *, const char *, locale_t);
> @@ -76,11 +78,6 @@ size_t strxfrm_l (char *__restrict, const char *__restrict, size_t, locale_t);
> void *memmem(const void *, size_t, const void *, size_t);
> #endif
> 
> -#if defined(_XOPEN_SOURCE) || defined(_GNU_SOURCE) \
> - || defined(_BSD_SOURCE)
> -void *memccpy (void *__restrict, const void *__restrict, int, size_t);
> -#endif
> -
> #if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
> char *strsep(char **, const char *);
> size_t strlcat (char *, const char *, size_t);
> -- 
> 2.50.0


These should not be unconditionally exposed because you can still build C99 or C11 code against musl.

We actually already had to patch something like this *away* (in https://cgit.adelielinux.org/musl/commit/?id=41735bdeff548ce44afe21aa21f1345047eb18e4) to ensure no namespace pollution.  Please don’t make it worse.  Add || __STDC_VERSION__ >= 202311L instead.

Best,
-Anna