Re: [PATCH 2/2] Make CONTEXT available to signal handlers

[Corinna Vinschen <corinna-cygwin at cygwin dot com>]

On Mar 30 18:32, Jon TURNEY wrote:
> +typedef struct ucontext {
> +	mcontext_t	uc_mcontext;
> +} ucontext_t;

I liked that better as before.  Keep in mind that changing, improving
user-space provided structures practically always requires to add
code to account for old and for newly built applications, the ones
which only know the old struct layout, and the new ones knowning the
new layout.

Therefore we should define ucontext_t in a way which does not require
to change it later.  Looking at the Linux definition:

  typedef struct ucontext
  {
    unsigned long int uc_flags;
    struct ucontext *uc_link;
    stack_t uc_stack;
    mcontext_t uc_mcontext;
    __sigset_t uc_sigmask;
    struct _libc_fpstate __fpregs_mem;
  } ucontext_t;

We won't have __fpregs_mem, ever, since it's part of uc_mcontext (see
the comments in sys/ucontext.h) so this can be dropped.  But everything
else we can and should provide.  uc_link might come in handy as well at
one point, who knows?  Just set it to NULL for now.


Thanks,
Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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