Date: Sun, 02 Feb 2020 16:42:07 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 243807] CURRENT libedit breaks emacs tramp-mode Message-ID: <bug-243807-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D243807 Bug ID: 243807 Summary: CURRENT libedit breaks emacs tramp-mode Product: Base System Version: CURRENT Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: misc Assignee: bugs@FreeBSD.org Reporter: jfc@mit.edu Emacs tramp-mode uses ssh to move data and commands back and forth to use a local emacs to edit remote files. It no longer works when the remote syste= m is running FreeBSD CURRENT. The problem is apparently caused by the new versi= on of libedit. Running 12.1 in a jail on CURRENT works, but copying in the CURRENT version of libedit reintroduced the problem. I suspect this will turn out to be undesirable behavior that is not strictly speaking a bug, but the current behavior is suboptimal for reasons other th= an breaking tramp mode. Emacs tramp mode opens an ssh connection to a remote machine. It doesn't w= ant to see input echoed back so it runs stty -inlcr -onlcr -echo kill '^U' erase '^H' This doesn't do anything useful if a shell is running in line editing mode (raw) instead of using the tty (cooked). So tramp falls back to a hack to detect echoed input. It sends "_echo" followed by a string of backspace characters. "_echo" is unlikely to appear in program output. Here is the next command after the initial stty: _echo^H^H^H^H^Hstty icanon erase ^H cols 32767_echo^H^H^H^H^H The groups of 5 ^H represent 5 backspace characters and the lone ^H in the middle is a two character sequence for stty. The terminal output from a 12.1 system is _echo^H ^H^H ^H^H ^H^H ^H^H ^Hstty icanon erase ^H cols 32767_echo^H ^H^H ^= H^H ^H^H ^H^H ^H #$=20 where again the middle ^H is a two character sequence and the others are control characters. There is a carriage return between the two lines. "#$ = " is the shell prompt set by tramp. The terminal output from a CURRENT system is _echo #$ _ech ^H #$ _ec ^H #$ _e ^H #$ _ ^H #$ ^Hstty icanon erase ^H cols 32767_echo #$ stty icanon erase ^H cols 32767_ech ^H #$ stty icanon erase ^H cols 32767_ec ^H #$ stty icanon erase ^H cols 32767_e ^H #$ stty icanon erase ^H cols 32767_ ^H #$ stty icanon erase ^H cols 32767 ^H #$=20 with carriage returns between lines. This does not make sense to emacs. (= And it is the suboptimial behavior I mentioned above, doing much more terminal output than necessary.) I tried both /bin/sh and /bin/csh as shells and tramp didn't work with eith= er.=20 I put set +V and set +E in my .profile thinking that would turn off line editing but there was no change. Probably the shell still takes raw input through libedit even if vi and emacs style editing are off. I browsed the large diff between 12 and head versions of libedit and didn't= see anything obvious. I don't have a NetBSD system to test on. (NetBSD is the source of libedit.) To reproduce run the emacs command M-x load-library tramp and try to open a file like /ssh:user@host:/path This should work when the remote host is 12.1 and hang if the remote host is CURRENT. --=20 You are receiving this mail because: You are the assignee for the bug.=
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