In 90fa325da7, the obfuscation logic was changed to use hashes for
exported names, but incremental names starting at just one letter for
unexported names. Presumably, this was done for the sake of binary size.
I argue that this is not a good idea for the default mode for a number
of reasons:
1) It makes reversing of stack traces nearly impossible for unexported
names, since replacing an obfuscated name "c" with "originalName"
would trigger too many false positives by matching single characters.
2) Exported and unexported names aren't different. We need to know how
names were obfuscated at a later time in both cases, thanks to use
cases like -ldflags=-X. Using short names for one but not the other
doesn't make a lot of sense, and makes the logic inconsistent.
3) Shaving off three bytes for unexported names doesn't seem like a huge
deal for the default mode, when we already have -tiny to optimize for
size.
This saves us a bit of work, but most importantly, simplifies the
obfuscation state as we no longer need to carry privateNameMap between
the compile and link stages.
name old time/op new time/op delta
Build-8 153ms ± 2% 150ms ± 2% ~ (p=0.065 n=6+6)
name old bin-B new bin-B delta
Build-8 7.09M ± 0% 7.08M ± 0% -0.24% (p=0.002 n=6+6)
name old sys-time/op new sys-time/op delta
Build-8 296ms ± 5% 277ms ± 6% -6.50% (p=0.026 n=6+6)
name old user-time/op new user-time/op delta
Build-8 562ms ± 1% 558ms ± 3% ~ (p=0.329 n=5+6)
Note that I do not oppose using short names for both exported and
unexported names in the future for -tiny, since reversing of stack
traces will by design not work there. The code can be resurrected from
the git history if we want to improve -tiny that way in the future, as
we'd need to store state in header files again.
Another major cleanup we can do here is to no longer use the
garbledImports map. From a look at obfuscateImports, we hash a package's
import path with its action ID, much like exported names, so we can
simply re-do that hashing for the linker's -X flag.
garbledImports does have some logic to handle duplicate package names,
but it's worth noting that should not affect package paths, as they are
always unique. That area of code could probably do with some
simplification in the future, too.
While at it, make hashWith panic if either parameter is empty.
obfuscateImports was hashing the main package path without a salt due to
a bug, so we want to catch those in the future.
Finally, make some tiny spacing and typo tweaks to the README.
testscript already included magic to also account for commands in the
total code coverage. That does not happen with plain tests, since those
only include coverage from the main test process.
The main problem was that, before, indirectly executed commands did not
properly save their coverage profile anywhere for testscript to collect
it at the end. In other words, we only collected coverage from direct
garble executions like "garble -help", but not indirect ones like "go
build -toolexec=garble".
$ go test -coverprofile=cover.out
PASS
coverage: 3.6% of statements
total coverage: 16.6% of statements
ok mvdan.cc/garble 6.453s
After the delicate changes to testscript, any direct or indirect
executions of commands all go through $PATH and properly count towards
the total coverage:
$ go test -coverprofile=cover.out
PASS
coverage: 3.6% of statements
total coverage: 90.5% of statements
ok mvdan.cc/garble 33.258s
Note that we can also get rid of our code to set up $PATH, since
testscript now does it for us.
goversion.txt needed minor tweaks, since we no longer set up $WORK/.bin.
Finally, note that we disable the reuse of $GOCACHE when collecting
coverage information. This is to do "full builds", as otherwise the
cached package builds would result in lower coverage.
Fixes#35.
Previously garble heavily used env vars to share data between processes.
This also makes it easy to share complex data between processes.
The complexity of main.go is considerably reduced.
In Go 1.15, if a dependency is required but not listed in go.mod/go.sum,
it's resolved and added automatically.
This is changing in 1.16. From that release, one will have to explicitly
update the mod files via 'go mod tidy' or 'go get'.
To get ahead of the curve, start using -mod=readonly to get the same
behavior in 1.15, and fix all existing tests.
The only tests that failed were imports.txt and syntax.txt, the only
ones to require other modules. But since we're here, let's add the 'go'
line to all go.mod files as well.
As per the discussion in https://github.com/golang/go/issues/41145, it
turns out that we don't need special support for build caching in
-toolexec. We can simply modify the behavior of "[...]/compile -V=full"
and "[...]/link -V=full" so that they include garble's own version and
options in the printed build ID.
The part of the build ID that matters is the last, since it's the
"content ID" which is used to work out whether there is a need to redo
the action (build) or not. Since cmd/go parses the last word in the
output as "buildID=...", we simply add "+garble buildID=_/_/_/${hash}".
The slashes let us imitate a full binary build ID, but we assume that
the other components such as the action ID are not necessary, since the
only reader here is cmd/go and it only consumes the content ID.
The reported content ID includes the tool's original content ID,
garble's own content ID from the built binary, and the garble options
which modify how we obfuscate code. If any of the three changes, we
should use a different build cache key. GOPRIVATE also affects caching,
since a different GOPRIVATE value means that we might have to garble a
different set of packages.
Include tests, which mainly check that 'garble build -v' prints package
lines when we expect to always need to rebuild packages, and that it
prints nothing when we should be reusing the build cache even when the
built binary is missing.
After this change, 'go test' on Go 1.15.2 stabilizes at about 8s on my
machine, whereas it used to be at around 25s before.
This shouldn't break often, so it doesn't need to be covered by 'go test
-short'. Moreover, it's still a relatively expensive step, since we end
up reaching package compilation.
basic.txt just builds main.go without a module. Similarly, we leave
imports.txt without a GOPRIVATE, to test the 'go list -m' fallback.
For all other tests, explicitly set GOPRIVATE, to avoid two exec calls -
both 'go env GOPRIVATE' as well as 'go list -m'. Each of those calls
takes in the order of 10ms, so saving ~26 exec calls should easily add
to 200-300ms saved from 'go test -short'.
Fixes #2.
Line numbers are now obfuscated, via `//line` comments.
Filenames are now obfuscated via `//line` comments, instead of changing the actual filename.
New flag `-tiny` to reduce the binary size, at the cost of reversibility.
This requires a bit of extra magic to replace one constant in
runtime/internal/sys, but that was simple enough given that we can reuse
a lot of the code to parse the files and write them to a temporary dir.
We can also drop the -X flags, as runtime.buildVersion is based on the
constant that we replace here.
Fixes#44, again.
Since we introduced $GARBLE_DIR, we stopped recommending the use of
toolexec directly. It's still possible to set up the right flags and env
vars, but that will be a moving target.
In particular, string obfuscation in #16 will require using $GARBLE_DIR
in more scenarios. A work-in-progress patch for string obfuscation
triggered this test script to start failing for the reason above.
While at it, we don't care about what the second build contains, since
we already compare it with the previous build.
The problem with the "grep" built-in command is that it prints the
entire data if there is an error. We don't want megabytes of binary
output for a test.
Daniel Martí
lu4p
pagran