fix one last edge case regarding PATH, allows simpler config.

setusercontext resets PATH (which we want). but then it becomes
impossible to access the old PATH. save a copy in case we need it later.
bug report from espie.

always reset the "su" variables, which is more consistent and predictable.
ok martijn millert

redo the environment inheritance to not inherit. it was intended to make
life easier, but it can be surprising or even unsafe. instead, reset just
about everything to the target user's values.
ok deraadt martijn
Thanks to Sander Bos in particular for pointing out some nasty edge cases.

prepenv can take a const rule

use static in the right places to seperate modules better
ok tedu

rename variable for consistency

revise environment handling.
Add a setenv keyword for manipulating the environment. keepenv now means
only retain everything. (for one release, the old use of keepenv will still
work.)
Allow setting variables to new or existing values, and also removing vars
when keepenv is used.
ok djm martijn tb

Move the RB_ code from doas.h to env.c, and limit the environment interface to a
simple prepenv function.

OK tedu@

the environment handling code was showing its age. just because environ
is a char** array doesn't mean we must exclusively operate on such.
convert to a red-black tree, manipulate as desired, then flatten to array.
potentially overkill for the current operations, but reading the tea leaves
i see that more manipulations are desired.
ok tb
(and some thought provoking disagreement from martijn)

setusercontext resets PATH (which we want). but then it becomes
impossible to access the old PATH. save a copy in case we need it later.
bug report from espie.

always reset the "su" variables, which is more consistent and predictable.
ok martijn millert

redo the environment inheritance to not inherit. it was intended to make
life easier, but it can be surprising or even unsafe. instead, reset just
about everything to the target user's values.
ok deraadt martijn
Thanks to Sander Bos in particular for pointing out some nasty edge cases.

prepenv can take a const rule

use static in the right places to seperate modules better
ok tedu

rename variable for consistency

revise environment handling.
Add a setenv keyword for manipulating the environment. keepenv now means
only retain everything. (for one release, the old use of keepenv will still
work.)
Allow setting variables to new or existing values, and also removing vars
when keepenv is used.
ok djm martijn tb

Move the RB_ code from doas.h to env.c, and limit the environment interface to a
simple prepenv function.

OK tedu@

the environment handling code was showing its age. just because environ
is a char** array doesn't mean we must exclusively operate on such.
convert to a red-black tree, manipulate as desired, then flatten to array.
potentially overkill for the current operations, but reading the tea leaves
i see that more manipulations are desired.
ok tb
(and some thought provoking disagreement from martijn)

redo the environment inheritance to not inherit. it was intended to make
life easier, but it can be surprising or even unsafe. instead, reset just
about everything to the target user's values.
ok deraadt martijn
Thanks to Sander Bos in particular for pointing out some nasty edge cases.

prepenv can take a const rule

use static in the right places to seperate modules better
ok tedu

rename variable for consistency

revise environment handling.
Add a setenv keyword for manipulating the environment. keepenv now means
only retain everything. (for one release, the old use of keepenv will still
work.)
Allow setting variables to new or existing values, and also removing vars
when keepenv is used.
ok djm martijn tb

Move the RB_ code from doas.h to env.c, and limit the environment interface to a
simple prepenv function.

OK tedu@

the environment handling code was showing its age. just because environ
is a char** array doesn't mean we must exclusively operate on such.
convert to a red-black tree, manipulate as desired, then flatten to array.
potentially overkill for the current operations, but reading the tea leaves
i see that more manipulations are desired.
ok tb
(and some thought provoking disagreement from martijn)

prepenv can take a const rule

use static in the right places to seperate modules better
ok tedu

rename variable for consistency

revise environment handling.
Add a setenv keyword for manipulating the environment. keepenv now means
only retain everything. (for one release, the old use of keepenv will still
work.)
Allow setting variables to new or existing values, and also removing vars
when keepenv is used.
ok djm martijn tb

Move the RB_ code from doas.h to env.c, and limit the environment interface to a
simple prepenv function.

OK tedu@

the environment handling code was showing its age. just because environ
is a char** array doesn't mean we must exclusively operate on such.
convert to a red-black tree, manipulate as desired, then flatten to array.
potentially overkill for the current operations, but reading the tea leaves
i see that more manipulations are desired.
ok tb
(and some thought provoking disagreement from martijn)