Re: [PATCH v2 11/20] sigchain: move doc to sigchain.h

>
> On Wed, Nov 06, 2019 at 09:59:38AM +0000, Heba Waly via GitGitGadget wrote:
> > From: Heba Waly <heba.waly@gmail.com>
> >
> > Move the documentation from Documentation/technical/api-sigchain.txt
> > to sigchain.h as it's easier for the developers to find the usage
> > information beside the code instead of looking for it in another doc file.
> >
> > Also documentation/technical/api-sigchain.txt is removed because the
> > information it has is now redundant and it'll be hard to keep it up to
> > date and synchronized with the documentation in the header file.
> >
> > Signed-off-by: Heba Waly <heba.waly@gmail.com>
> > ---
> >  Documentation/technical/api-sigchain.txt | 41 -----------------------
> >  sigchain.h                               | 42 ++++++++++++++++++++++++
> >  2 files changed, 42 insertions(+), 41 deletions(-)
> >  delete mode 100644 Documentation/technical/api-sigchain.txt
> >
> > diff --git a/Documentation/technical/api-sigchain.txt b/Documentation/technical/api-sigchain.txt
> > deleted file mode 100644
> > index 9e1189ef01..0000000000
> > --- a/Documentation/technical/api-sigchain.txt
> > +++ /dev/null
> > @@ -1,41 +0,0 @@
> > -sigchain API
> > -============
> > -
> > -Code often wants to set a signal handler to clean up temporary files or
> > -other work-in-progress when we die unexpectedly. For multiple pieces of
> > -code to do this without conflicting, each piece of code must remember
> > -the old value of the handler and restore it either when:
> > -
> > -  1. The work-in-progress is finished, and the handler is no longer
> > -     necessary. The handler should revert to the original behavior
> > -     (either another handler, SIG_DFL, or SIG_IGN).
> > -
> > -  2. The signal is received. We should then do our cleanup, then chain
> > -     to the next handler (or die if it is SIG_DFL).
> > -
> > -Sigchain is a tiny library for keeping a stack of handlers. Your handler
> > -and installation code should look something like:
> > -
> > -------------------------------------------
> > -  void clean_foo_on_signal(int sig)
> > -  {
> > -       clean_foo();
> > -       sigchain_pop(sig);
> > -       raise(sig);
> > -  }
> > -
> > -  void other_func()
> > -  {
> > -       sigchain_push_common(clean_foo_on_signal);
> > -       mess_up_foo();
> > -       clean_foo();
> > -  }
> > -------------------------------------------
> > -
> > -Handlers are given the typedef of sigchain_fun. This is the same type
> > -that is given to signal() or sigaction(). It is perfectly reasonable to
> > -push SIG_DFL or SIG_IGN onto the stack.
> > -
> > -You can sigchain_push and sigchain_pop individual signals. For
> > -convenience, sigchain_push_common will push the handler onto the stack
> > -for many common signals.
> > diff --git a/sigchain.h b/sigchain.h
> > index 138b20f54b..a990f18cf6 100644
> > --- a/sigchain.h
> > +++ b/sigchain.h
> > @@ -1,12 +1,54 @@
> >  #ifndef SIGCHAIN_H
> >  #define SIGCHAIN_H
> >
> > +/**
> > + * Code often wants to set a signal handler to clean up temporary files or
> > + * other work-in-progress when we die unexpectedly. For multiple pieces of
> > + * code to do this without conflicting, each piece of code must remember
> > + * the old value of the handler and restore it either when:
> > + *
> > + *   1. The work-in-progress is finished, and the handler is no longer
> > + *      necessary. The handler should revert to the original behavior
> > + *      (either another handler, SIG_DFL, or SIG_IGN).
> > + *
> > + *   2. The signal is received. We should then do our cleanup, then chain
> > + *      to the next handler (or die if it is SIG_DFL).
> > + *
> > + * Sigchain is a tiny library for keeping a stack of handlers. Your handler
> > + * and installation code should look something like:
> > + *
> > + * ------------------------------------------
> > + *   void clean_foo_on_signal(int sig)
> > + *   {
> > + *     clean_foo();
> > + *     sigchain_pop(sig);
> > + *     raise(sig);
> > + *   }
> > + *
> > + *   void other_func()
> > + *   {
> > + *     sigchain_push_common(clean_foo_on_signal);
> > + *     mess_up_foo();
> > + *     clean_foo();
> > + *   }
> > + * ------------------------------------------
> > + *
> > + */
> > +
> > +/**
> > + * Handlers are given the typedef of sigchain_fun. This is the same type
> > + * that is given to signal() or sigaction(). It is perfectly reasonable to
> > + * push SIG_DFL or SIG_IGN onto the stack.
> > + */
> >  typedef void (*sigchain_fun)(int);
> >
> > +/* You can sigchain_push and sigchain_pop individual signals. */
> >  int sigchain_push(int sig, sigchain_fun f);
> >  int sigchain_pop(int sig);
> >
> > +/* push the handler onto the stack for many common signals. */
> It was lacking in the original doc too, but I want to know which common
> signals it pushes for. Is it too much work for you to peek in the
> implementation and let us know?

> >  void sigchain_push_common(sigchain_fun f);
> > +
> >  void sigchain_pop_common(void);
> >
> >  #endif /* SIGCHAIN_H */
> > --
> > gitgitgadget
> >
>
> Otherwise this one looks fine for me.
>
>  - Emily