[PATCH] Fix build if __GLIBC_PREREQ is not defined

[Jörg Krause]

On Wed, 2018-03-07 at 21:13 +0100, Jörg Krause wrote:
> Hi all,
> 
> On Fri, 2018-03-02 at 08:03 +0100, Jörg Krause wrote:
> > __GLIBC_PREREQ is specific to glibc so it should be checked if it is
> > defined or not.
> > 
> > Fixes build error with musl:
> > '''
> > ../include/bsd/stdlib.h:70:66: error: missing binary operator before token "("
> >  #if defined(_GNU_SOURCE) && defined(__GLIBC__) && !__GLIBC_PREREQ(2, 26)
> > '''
> > 
> > Signed-off-by: Jörg Krause <joerg.krause at embedded.rocks>
> > ---
> >  include/bsd/stdlib.h | 4 +++-
> >  include/bsd/string.h | 4 +++-
> >  2 files changed, 6 insertions(+), 2 deletions(-)
> > 
> > diff --git a/include/bsd/stdlib.h b/include/bsd/stdlib.h
> > index ebc9638..6cd7943 100644
> > --- a/include/bsd/stdlib.h
> > +++ b/include/bsd/stdlib.h
> > @@ -67,9 +67,11 @@ int sradixsort(const unsigned char **base, int nmemb,
> >                 const unsigned char *table, unsigned endbyte);
> >  
> >  void *reallocf(void *ptr, size_t size);
> > -#if defined(_GNU_SOURCE) && defined(__GLIBC__) && !__GLIBC_PREREQ(2, 26)
> > +#if defined(_GNU_SOURCE) && defined(__GLIBC__) && defined(__GLIBC_PREREQ)
> > +#if !__GLIBC_PREREQ(2, 26)
> >  void *reallocarray(void *ptr, size_t nmemb, size_t size);
> >  #endif
> > +#endif
> >  
> >  long long strtonum(const char *nptr, long long minval, long long maxval,
> >                     const char **errstr);
> > diff --git a/include/bsd/string.h b/include/bsd/string.h
> > index 6798bf6..50542ee 100644
> > --- a/include/bsd/string.h
> > +++ b/include/bsd/string.h
> > @@ -42,9 +42,11 @@ size_t strlcat(char *dst, const char *src, size_t siz);
> >  char *strnstr(const char *str, const char *find, size_t str_len);
> >  void strmode(mode_t mode, char *str);
> >  
> > -#if defined(_GNU_SOURCE) && defined(__GLIBC__) && !__GLIBC_PREREQ(2, 25)
> > +#if defined(_GNU_SOURCE) && defined(__GLIBC__) && defined(__GLIBC_PREREQ)
> > +#if !__GLIBC_PREREQ(2, 25)
> >  void explicit_bzero(void *buf, size_t len);
> >  #endif
> > +#endif
> >  __END_DECLS
> >  
> >  #endif
> 
> I've noticed that this patch allows building with musl, but produces
> warnings because of implicit function declarations.
> 
> An improved version of the patch could be for example:
> 
> '''
> #if defined(__GLIBC__) && defined(__GLIBC_PREREQ)
> #if __GLIBC_PREREQ(2, 25)
> #define HAVE_EXPLICIT_BZERO
> #endif
> #endif
> 
> __BEGIN_DECLS
> [...]
> 
> #if defined(_GNU_SOURCE) && !defined(HAVE_EXPLICIT_BZERO)
> void explicit_bzero(void *buf, size_t len);
> #endif
> __END_DECLS
> '''AC_CHECK_FUNCS
> 
> Would do you think?

At second thought adding explicit_bzero and reallocarray to
AC_CHECK_FUNCS is much more convenient, right?

Best regards,
Jörg Krause