Zbigniew Jędrzejewski-Szmek
30927a2484
So far, we would allow certain control characters (NL sinceb4346b9a77, TAB since6294aa76d8), but not others. Having other control characters in environment variable *value* is expected and widely used, for various prompts like $LESS, $LESS_TERMCAP_*, and other similar variables. The typical environment exported by bash already contains a dozen or so such variables, so programs need to handle them. We handle then correctly too, for example in 'systemctl show-environment', since804ee07c13. But we would still disallow setting such variables by the user, in unit file Environment= and in set-environment/import-environment operations. This is unexpected and confusing and doesn't help with anything because such variables are present in the environment through other means. When printing such variables, 'show-environment' escapes all special characters, so variables with control characters are plainly visible. In other uses, e.g. 'cat -v' can be used in similar fashion. This would already need to be done to suppress color codes starting with \[. Note that we still forbid invalid utf-8 with this patch. (Control characters are valid, since they are valid 7-bit ascii.) I'm not sure if we should do that, but since people haven't been actually asking for invalid utf-8, and only for control characters, and invalid utf-8 causes other issues, I think it's OK to leave this unchanged. Fixes #4446, https://gitlab.gnome.org/GNOME/gnome-session/-/issues/45.
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