commit 28ae4adc44cf2fda2f8fac0b8ecaeb59f13645c4
author James Carter <jwcart2@gmail.com> Mon Aug 16 14:17:28 2021 -0400
committer James Carter <jwcart2@gmail.com> Thu Aug 19 11:08:59 2021 -0400
tree df412d23d19cef8fb5bfd3d3d26cce890ad7ef35
parent fb9ed092dacc21dfa3c7a3912af846a36250ac19

libsepol/cil: Report correct high-level language line numbers

CIL supports specifiying the original high-level language file and
line numbers when reporting errors. This is done through line marks
and is mostly used to report the original Refpolicy file and line
number for neverallow rules that have been converted to CIL.

As long as the line mark remain simple, everything works fine, but
the wrong line numbers will be reported with more complex nextings
of line marks.

Example:
;;* lms 100 file01.hll
(type t1a)
(allow t1a self (CLASS (PERM)))
;;* lmx 200 file02.hll
(type t2a)
(allow t2a self (CLASS (PERM)))
;;* lme
(type t1b)
(allow t1b self (CLASS (PERM)))
(allow bad1b self (CLASS (PERM))) ; file01.hll:101 (Should be 106)
;;* lme

The primary problem is that the tree nodes can only store one hll
line number. Instead a number is needed that can be used by any
number of stacked line mark sections. This number would increment
line a normal line number except when in lmx sections (that have
the same line number throughout the section because they represent
an expansion of a line -- like the expansion of a macro call. This
number can go backwards when exiting a lms section within a lmx
section, because line number will increase in the lms section, but
outside the lmx section, the line number did not advance.

This number is called the hll_offset and this is the value that is
now stored in tree nodes instead of the hll line number. To calculate
the hll line number for a rule, a search is made for an ancestor of
the node that is a line mark and the line number for a lms section
is the hll line number stored in the line mark, plus the hll offset
of the rule, minus the hll offset of the line mark node, minus one.
(hll_lineno + hll_offset_rule - hll_offset_lm - 1)

Signed-off-by: James Carter <jwcart2@gmail.com>