Remove some asthelper APIs that haven't been used for some time.
They can be recovered from the git history if needed again.
One type assertion in the literals package is always true.
Embedded field objects are handled near the top of transformGo, so the
extra !obj.Embedded() check was always true. Remove it.
We always obfuscate standalone funcs now, so the obfuscatedTypesPackage
check is no longer necessary. This was necessary when we used to not
obfuscate func names when they were used in linkname directives.
The workaround for test package imports in obfuscatedTypesPackage I had
to add a few commits ago no longer seems to be necessary. This might be
thanks to the simplification with functions in the paragraph just above.
It's impossible to run garble without -trimpath nowadays, as we error
before the build even starts:
$ go build -toolexec=garble
go tool compile: exit status 1
cannot open shared file, this is most likely due to not running "garble [command]"
When run as "garble build", the trimpath flag is always set. So the
check in alterTrimpath never triggers anymore, and couldn't be tested.
Finally, simplify the handling of comment syntax in printFile, and add a
few TODOs for other code paths not covered by our existing tests.
Total code coverage is up from 90.3% to 91.0%.
In printFile, we print and re-parse the modified AST to be able to have
reliable position information.
The re-parsing step can fail if something goes very wrong, such as a bug
in -literals. It should generally not happen. However, in rare cases it
has happened, and it's confusing for the end user to see syntax errors
pointing at an existing file on disk, when the code doesn't align
- since we're on a modified copy.
To prevent such confusion, use an empty filename. Syntax errors will
still not be terribly helpful, but they should be extremely rare and
promptly fixed, so that's not a huge concern.
For that same reason, we can't really add a good test here. We could
perhaps add a test that forces garble to mess up the src slice in some
way, but that would be a weird test, and not particularly worth it.
Fixes#286.
Just two minor tweaks were necessary to get "go test" to pass on:
go version devel go1.17-a25c584629 Tue Apr 6 04:48:09 2021 +0000 linux/amd64
Re-enable the CI for it, too. The config needed changing since the
set-env and add-path commands now use special files instead, due to some
security issues uncovered last winter.
It's possible that CI on master could suddenly break, if Go master
changes in some substantial way that requires more tweaks. If that turns
out to be an issue pretty often, we could always pin a specific git repo
commit and update it every few weeks.
The regular obfuscation process simply modifies some simple nodes, such
as identifiers and strings. In those cases, we modify the nodes
in-place, meaning that their positions remain the same. This hasn't
caused any problems.
Literal obfuscation is trickier. Since we replace one expression with an
entirely different one, we use cursor.Replace. The new expression is
entirely made up on the spot, so it lacks position information.
This was causing problems. For example, in the added test input:
> garble -literals build
[stderr]
# test/main
dgcm4t6w.go:3: misplaced compiler directive
dgcm4t6w.go:4: misplaced compiler directive
dgcm4t6w.go:3: misplaced compiler directive
dgcm4t6w.go:6: misplaced compiler directive
dgcm4t6w.go:7: misplaced compiler directive
dgcm4t6w.go:3: misplaced compiler directive
dgcm4t6w.go:9: misplaced compiler directive
dgcm4t6w.go:3: misplaced compiler directive
dgcm4t6w.go:3: too many errors
The build errors are because we'd move the compiler directives, which
makes the compiler unhappy as they must be directly followed by a
function declaration.
The root cause there seems to be that, since the replacement nodes lack
position information, go/printer would try to estimate its printing
position by adding to the last known position. Since -literals adds
code, this would result in the printer position increasing rapidly, and
potentially printing directive comments earlier than needed.
For now, making the replacement nodes have the same position as the
original node seems to stop go/printer from making this mistake.
It's possible that this workaround won't be bulletproof forever, but it
works well for now, and I don't see a simpler workaround right now.
It would be possible to use fancier mechanisms like go/ast.CommentMap or
dave/dst, but those are a significant amount of added complexity as well.
Fixes#285.
Fix up a few TODOs, and simplify the way we handle comments.
We now add whitespace around inline /*line*/ directives, to ensure we
don't break programs. A test case is added too.
We now add line directives to call sites, not function declarations,
since those are what actually shows up in stack traces.
It's unclear if we care about any other lines inside functions at all.
This also fixes reversing with -literals, since that feature adds a
significant amount of code which shuffles line numbers around.
Finally, we extend the tests with types, methods, and anonymous
functions, and we make all of them work well.
Updates #5.
In particular, the positions within function declarations, including the
positions of call sites to other functions.
Note that this isn't well tested just yet, particularly not with other
features like -literals. We can extend the tests and code over time.
This gets us the core basics.
The issue will be closed once the feature is documented for users, in a
follow-up PR.
Updates #5.
First, rename line_obfuscator.go to position.go. We obfuscate filenames,
not just line numbers, and "obfuscator" is a bit redundant.
Second, use "/*line :x*/" comments rather than the "//line :x" form, as
the former allows us to insert them in any position without adding
unnecessary newlines. This will be important for changing the position
of call sites, which will be important for "garble reverse".
Third, do not rely on go/ast to remove and add comments. Since they are
free-floating, we can very easily end up with misplaced comments,
especially as the literal obfuscator heavily modifies the AST.
The new method prints and re-parses the file, to ensure all node
positions are consistent with a buffer, buf1. Then, we copy the contents
into a new buffer, buf2, while inserting the comments that we need.
The new method also modifies line numbers at the very end of obfuscating
a Go file, instead of at the very beginning. That's going to be more
robust long-term, as we will also obfuscate line numbers for any
additions or modifications to the AST.
Fourth, detachedDirectives is unnecessary, as we can accomplish the same
with two simple prefix matches.
Finally, this means we can stop using detachedComments entirely, as
printFile already inserts the comments we need.
For #5.
Daniel Martí