Some of these stubs were quite slow to evaluate. It's possible they
could be optimised, but it seems pointless as long as we don't have
call-context-sensitive virtual dispatch in the C++ library.
These two elements weren't cached, which meant that local data flow was
recalculated in every query that used data flow. They are also cached in
the Java version of `DataFlowUtil.qll`.
This commits also adds a test that uses `getParameter`. The new tests
demonstrate that support for array-to-pointer decay works, but we get
data flow to the array rather than its contents.
This accessor may not be forward-compatible with an IR-based version,
and it's unclear whether it has any use. The `VariableAccess` remains in
the `TDefinitionByReferenceNode` constructor since it's used to
implement `getType`.
The configuration in `DefaultOptions.qll` assumed that a call to any
top-level function named `error` would exit the program. This is not
true.
The assumption was probably about `error(3)`, which is a GNU extension.
It only exits if its first argument it not 0. Furthermore, projects such
as openssh may define their own function named `error` with different
behaviour. Because the GNU `error` function is non-standard, it's
perfectly fine to shadow it with a project-specific definition.
This change removes two FPs from `PointlessComparison.qll` on
https://github.com/openssh/openssh-portable.
A PR check was failing because this query was enabled on LGTM but had no
qhelp. I'm removing the `@precision` for now to take it off LGTM, and
then we can add it back when it has qhelp, tests, and change note.
Thanks to Sam Lanning (@samlanning) and Robert Marsh for taking the time to help
to make it possible. In fact, it was Robert Marsh who effectively
wrote the query and figured out that __builtin_alloca should be
used to also take functions like strdupa into account. I just
filled out the metadata :-)
Before this change, all the cached predicates in `IRGuards.qll` were in
separate cached stages, resulting in recomputation of most of the
library for each stage. This change groups the cached predicates in two
cached classes. A better grouping may be possible, but this grouping was
easy to do and seems to solve the problem.
Before this change, the `IRGuards` library accounted for five cached
stages when using the `RangeAnalysis` library. After this change, it
only accounts for one.
This new query is not written because it's the most interesting query we
could write but because it's an IR-based query whose results are easy to
verify.
