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
pagran