Feature request: able to gracefully end readline() from another thread about editline HOT 8 CLOSED

Thanks. Closing. BTW I've updated the sample code above to handle interruption during searching.

from editline.

We have the new alternate interface, for event loops, bc7fc7e, which may be of interest to you.

There is also the option of using a different rl_getc_function. Editline defaults to use the local rl_getc() fucntion which uses read(), which is wrapped in a do-while(EINTR)-loop to handle aborted syscalls due to signals. So if you like you could do another implementation of that and install a signal handler in the thread (to prevent the thread from dying), upon return from readline() the TTY will be restored by el_deprep().

Maybe GNU Readline has some other API or method for this, but at this point I haven't looked into that.

from editline.

Thanks. I'll take a look. I was trying to modify rl_getc() just now.

from editline.

I added a reference implementation for the alternate API in examples/excallback.c. Having everything in the same thread/process is sometimes the preferred way to go. In particular if you use libev or some other neat event loop instead of rolling your own (as the example does).

from editline.

If I'm correct, current implementation of rl_getc() ignores SIGINT directly, thus I need a new implementation anyway, even if I go for the alternate API approach. Created PR #29 for this.

The links you provided in #28 is useful for this discussion:

• Signals handling: http://www.delorie.com/gnu/docs/readline/rlman_43.html
• Example of alternate API: https://stackoverflow.com/a/27662212

from editline.

You're almost correct. The rl_getc() implementation ignores any signal by checking for EINTR and restarting the syscall. This is common practice in UNIX.

from editline.

FWIW, my implementation of rl_getc() looks like:

static int interrupted = false;
static int interruptible_getc(void)
{
   int r;
   char c;

   if (interrupted)
      return EOF;

   r = read(0, &c, 1); // read from stdin, will return -1 when interrupted by a signal

   if (r == -1 && errno == EINTR)
      interrupted = true;

   return r == 1 ? c : EOF;
}

seems work for me.

EDIT: updated the code to make it work when got interrupted when searching

from editline.

Yup, that definitely looks like it should work for you. You may want to keep a list of which signals your application handles and add a check in interruptible_getc() to make sure you only return EOF when there is SIGINT and not another signal ...

... so maybe we can close this issue now?

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