Re: [PATCH] retry opening startup files on EINTR

[Chet Ramey]

On 2/20/24 4:35 AM, Grisha Levit wrote:
> On Mon, Feb 19, 2024 at 5:10 PM Chet Ramey <chet.ramey@case.edu> wrote:
> > On 2/7/24 1:33 AM, Grisha Levit wrote:
> > > I have some dotfiles symlinked to storage backed by a macOS File
> > > Provider extension (e.g. Dropbox):
> > >
> > >       $ realpath ~/.bash_profile
> > >       /Users/levit/Library/CloudStorage/Dropbox/profile/.bash_profile
> > >
> > > This normally works fine, except when my terminal emulator (tested
> > > both Terminal.app and iTerm) restores sessions after being restarted
> > > -- opening the startup file fails in about half of the restored
> > > sessions, which ends up looking like:
> > >
> > >       [Restored Feb 7, 2024 at 00:11:37]
> > >       Last login: Wed Feb  7 00:11:37 on ttys008
> > >       Restored session: Wed Feb  7 00:11:27 EST 2024
> > >       -bash: /Users/levit/.bash_profile: Interrupted system call
> > >       mbp:~ levit$
> > >
> > > If I remove ~/.bash_profile, and make ~/.inputrc and ~/.bash_history
> > > similar symlinks, I see the same issue with loading them (without an
> > > error message).
> > >
> > > I'm not sure what the underlying cause is here, but maybe it would be
> > > appropriate to retry open(2) calls for these files if they fail with
> > > EINTR?
> >
> > What's the underlying signal here? I hope it's not SIGINT.
>
> Looks like it's a SIGWINCH getting sent -- so the Dropbox thing is only
> relevant in that it makes the open(2) take a while.
>
> Reproducible more easily on Linux with:
>
>      strace -e openat -e inject=openat:signal=SIGWINCH:error=EINTR:when=1 \
>          -P ~/.bashrc ./bash -i <&-

Well, depending on when the terminal emulator sends the SIGWINCH, this is
probably a bug in Dropbox or the File Provider code. Bash installs its
SIGWINCH handler with SA_RESTART, and the default disposition is to
discard, so even if a SIGWINCH arrives before bash installs its handler it
should not interrupt open().

I suppose we'll have to work around it.

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/