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Re: strnlen, strict ansi, newlib vs glibc


On Sat, 2014-09-13 at 14:57 +0200, Luca Barbato wrote:

> On 14/08/14 17:27, Joel Sherrill wrote:
> > Hi
> > 
> > I have some native C++ code that I developed on CentOS and it
> > has no warnings. Someone moved it to Cygwin and reported warnings
> > for strnlen() not being prototyped. I investigated and the program did
> > include string.h. I tried RTEMS tools and got the same as Cygwin
> > since we have the same string.h from newlib.
> > 
> > Investigating this, it appears that strnlen() is protected by
> > __STRICT_ANSI__ on newlib and  __USE_XOPEN2K8 on Linux.
> > 
> > Command: g++ -Wall -std=c++0x -c strtest.cc
> > 
> > This program is enough to reproduce the issue:
> > 
> >     #include <string.h>
> > 
> >     // size_t strnlen( const char *, size_t );
> > 
> >     size_t f( const char *str )
> >     {
> >       return strnlen( str, 1000 );
> >     }
> > 
> > 
> > What do you all think?
> > 
> 
> Might be nice to add the support for _DEFAULT_SOURCE with the semantic
> of not filter what is on by default notwithstanding the defines -std
> might set.
> 
> It seems supported by glibc and musl so might be good to do as well.
> 
> lu
> 

Hello Joel and Luca,

I think that the current guard in newlib/libc/include/string.h:119

#if !defined(__STRICT_ANSI__) || __XSI_VISIBLE >= 500

should be simply replaced by the amended one

#if !defined(__STRICT_ANSI__) || __POSIX_VISIBLE >= 200809 || __XSI_VISIBLE >= 700

to fix this issue.


Best regards,

Thomas Uhle


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