[PATCH] Secure newlib stdio functions against thread cancellation (was Re: newlib stdio and thread cancellation)

[Hans-Peter Nilsson]

On May 29 09:27, Corinna Vinschen wrote:
> 	  * libc/stdio/local.h (_newlib_flockfile_start): New macro to
> 	  secure stream related critical section against thread cancellation.
> 	  (_newlib_flockfile_exit): Ditto.
> 	  (_newlib_sfp_lock_end): Ditto.
> 	  (_newlib_sfp_lock_start): Ditto for the list of streams.
> 	  (_newlib_sfp_lock_exit): Ditto.
> 	  (_newlib_sfp_lock_end): Ditto.
> 	  Use aforementioned macros in place of _flockfile/_funlockfile
> 	  and __sfp_lock_acquire/__sfp_lock_release throughout the code.

Looks like a typo: no _newlib_sfp_lock_exit definition in the
#else arm below, but two _newlib_sfp_lock_end.

> Index: libc/stdio/local.h
> ===================================================================
> RCS file: /cvs/src/src/newlib/libc/stdio/local.h,v
> retrieving revision 1.31
> diff -u -p -r1.31 local.h
> --- libc/stdio/local.h  14 Jun 2011 03:56:05 -0000      1.31
> +++ libc/stdio/local.h  29 May 2012 17:18:38 -0000
> @@ -32,6 +32,70 @@
>  # include <io.h>
>  #endif
> 
> +#if !defined (__SINGLE_THREAD__) && defined (_POSIX_THREADS)

...

> +/* Exit from a stream list oriented critical section prematurely: */
> +# define _newlib_sfp_lock_exit() \
> +               __sfp_lock_release (); \
> +               pthread_setcancelstate (__oldcancel, &__oldcancel);
> +
> +/* End a stream list oriented critical section: */
> +# define _newlib_sfp_lock_end() \
> +               __sfp_lock_release (); \
> +               pthread_setcancelstate (__oldcancel, &__oldcancel); \
> +       }
> +
> +#else /* __SINGLE_THREAD__ || !_POSIX_THREADS */

...

> +# define _newlib_sfp_lock_end() \
> +               __sfp_lock_release ();
> +
> +# define _newlib_sfp_lock_end() \
> +               __sfp_lock_release (); \
> +       }
> +
> +#endif /* !__SINGLE_THREAD__ && _POSIX_THREADS */

This shows up in my gcc autotester when testing a newlib-update
candidate as follows:

/tmp/hpautotest-gcc47/gcc/newlib/libc/stdio/findfp.c:124:
undefined reference to `_newlib_sfp_lock_exit'
collect2: error: ld returned 1 exit status

Can you please fix?  Thanks.

brgds, H-P