> From: Riza Dindir <riza.din...@gmail.com> > Date: Sat, 7 Sep 2024 19:11:02 +0300 > Cc: 73...@debbugs.gnu.org > > I am new to the code base, and it was just a suggestion to check for the > ioctl call for any failures and take > precautions, maybe inform the user of the issue that the suspend-emacs > command did not run correctly. Since > the command was not printing out anything when called with 'M-: > (suspend-emacs "pwd")' I was not sure what > was happening.
I was asking for your user's expectations, not how to do that in the code. > For users that use the linux kernel 6.2+ the ioctl command does not work > correctly. When the STUFFSTRING is > passed to the suspend-emacs command, it does nothing. The problem with kernel > 6.2+ is that it requires > CAP_SYS_ADMIN capability > (https://www.man7.org/linux/man-pages/man2/TIOCSTI.2const.html). > > In the code at some point suspend-emacs command calls stuff_char, which uses > ioctl (code snippet below, from > https://git.savannah.gnu.org/cgit/emacs.git/tree/src/sysdep.c#n403). The > ioctl call fails. But in the code there is > no check for that, that might confuse people that use linux kernel 6.2+. I > wanted to use suspend-emacs with > "pwd" as the string (as shown in the example in the documentation in > https://www.gnu.org/software/emacs/manual/html_node/elisp/Suspending-Emacs.html). > But the "pwd" command > was not displaying anything. Because it was not being sent/stuffed to the > superior process. Does ioctl return -1 in that case? (I don't have access to a system where it fails, it works for me on GNU/Linux.) > Adding an error check would be one of the solutions. Assuming we can check that (see above), the question is what to do if we do detect a failure. > The other solution might be to add a piece of information to the > documentation for suspend-emacs, (and > maybe to the documentation string for suspend-emacs) regarding this problem. > So that people that use linux > kernel 6.2+ would be aware of this issue. That is already done, except that the documentation cannot be too specific regarding when and under what conditions it could happen.
