tcgetpgrp

Andy Koppe andy.koppe@gmail.com
Thu Oct 8 06:34:00 GMT 2009


I'm having trouble with this change:

        * fhandler_termios.cc (fhandler_termios::tcgetpgrp): Only return
        valid pgid if tty is controlling tty.  Set errno to ENOTTY and
        return -1 otherwise.

Mintty uses the following call to create its pty:

  openpty (&parent_fd, &child_fd, 0, 0, winp)

It then forks a child process which calls login_tty(child_fd) and
execs the shell or other command. Meanwhile, the parent mintty process
retains the child_fd, so that it can find out what the current
foreground process of the pty is, using tcgetpgrp(child_fd).
/proc/<id>/cwd then allows it to find the current working directory of
the foreground process.

This is used for a new feature in mintty-0.5: Ctrl+clicking on a file
to open it via cygstart, whereby the current working directory of the
foreground process is needed for relative paths. This worked fine up
to 1.7.0-62, but due to the change above it no longer works on
cygwin-cvs.

Is it really necessary to restrict tcgetpgrp() in that way? Is there
any other way to find the current foreground process of a terminal?

Andy



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