Ignore comments in ssh_config Include parsing

[remil1000]

When parsing Include directive in ssh_config files, comments on the same line as the directive are considered as files to be recursively processed. Best case the recursive max_depth=16 terminates this early, but on old versions it may lead to random reads or an infinite recursion, hanging the shell process

Example before/after:

A minimal ssh client config file

$ cat config 
Include foo bar .ssh/baz # do not include

The current sed expression

$ sed -ne 's/^[[:blank:]]*[Ii][Nn][Cc][Ll][Uu][Dd][Ee][[:blank:]]\(.*\)$/\1/p' config 
foo bar .ssh/baz # do not include

Proposed change to sed expression (ignore anything coming after a #)

$ sed -ne 's/^[[:blank:]]*[Ii][Nn][Cc][Ll][Uu][Dd][Ee][[:blank:]]\([^#]*\).*$/\1/p' config
foo bar .ssh/baz 

[scop]

Thanks!

In addition to the requested test suite update, please search for "conventional commits" in CONTRIBUTING.md for info how to format the commit message and modify it accordingly (+ force-push with it).

[akinomyoga]

Thanks for updating.

[akinomyoga]

So for example code

_comp_split hosts "$(command sed -ne 's/^[[:blank:]]*[Hh][Oo][Ss][Tt][[:blank:]=]\{1,\}\(.*\)$/\1/p' "${config[@]}")"; then

in block https://github.com/scop/bash-completion/blob/main/bash_completion#L2646-L2652 may need changes also to handle those inline comments

I agree. We want to apply the changes consistently for similar cases.

[akinomyoga]

I rebased it.

[akinomyoga]

I squashed commits.

A similar change for the Host directive discussed in the following places haven't been processed, but I think they can be processed in a separate PR:

#1199 (comment) by @remil1000

[...] also I realized we may be in murky waters at this inline/trailing comment support has only been gradually added to sshd_config then ssh_config around SSH version 8.5 (sshd_config - https://bugzilla.mindrot.org/attachment.cgi?id=3460 and ssh_config https://bugzilla.mindrot.org/show_bug.cgi?id=2320)

So for example code

_comp_split hosts "$(command sed -ne 's/^[[:blank:]]*[Hh][Oo][Ss][Tt][[:blank:]=]\{1,\}\(.*\)$/\1/p' "${config[@]}")"; then

in block https://github.com/scop/bash-completion/blob/main/bash_completion#L2646-L2652 may need changes also to handle those inline comments

#1199 (comment) by @remil1000

[...] if the included file would contain Host with_comment # to be ignored then this patch would also require to update the Host directive parsing sed expression (which I already tried) only to find out it breaks https://github.com/scop/bash-completion/blob/main/test/fixtures/_known_hosts/config#L9 Host = hus%%eth0 !negated #not-a-comment as until now fixtures considered inline comments as actual content to be parsed

This is precisely why I only patched the Include parsing expression and mentioned this future Host issue, because tests would fail one after the other