On Thu, Nov 7, 2019 at 11:03 AM Emily Shaffer <emilyshaffer@xxxxxxxxxx> wrote:
>
> On Wed, Nov 06, 2019 at 09:59:38AM +0000, Heba Waly via GitGitGadget wrote:
> > From: Heba Waly <heba.waly@xxxxxxxxx>
> >
> > 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@xxxxxxxxx>
> > ---
> > 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?
Sure, no problem, I'll add the signals to the comment.
> > void sigchain_push_common(sigchain_fun f);
> > +
> > void sigchain_pop_common(void);
> >
> > #endif /* SIGCHAIN_H */
> > --
> > gitgitgadget
> >
>
> Otherwise this one looks fine for me.
>
> - Emily
