Allow runsc to generate coverage reports.

Add a coverage-report flag that will cause the sandbox to generate a coverage
report (with suffix .cov) in the debug log directory upon exiting. For the
report to be generated, runsc must have been built with the following Bazel
flags: `--collect_code_coverage --instrumentation_filter=...`.

With coverage reports, we should be able to aggregate results across all tests
to surface code coverage statistics for the project as a whole.

The report is simply a text file with each line representing a covered block
as `file:start_line.start_col,end_line.end_col`. Note that this is similar to
the format of coverage reports generated with `go test -coverprofile`,
although we omit the count and number of statements, which are not useful for
us.

Some simple ways of getting coverage reports:

bazel test <some_test> --collect_code_coverage \
  --instrumentation_filter=//pkg/...

bazel build //runsc --collect_code_coverage \
  --instrumentation_filter=//pkg/...
runsc -coverage-report=dir/ <other_flags> do ...

PiperOrigin-RevId: 368952911

1 files changed, 4 insertions, 2 deletions

diff --git a/runsc/cmd/symbolize.go b/runsc/cmd/symbolize.go
index fc0c69358..0fa4bfda1 100644
--- a/runsc/cmd/symbolize.go
+++ b/runsc/cmd/symbolize.go
@@ -65,13 +65,15 @@ func (c *Symbolize) Execute(_ context.Context, f *flag.FlagSet, args ...interfac
 		f.Usage()
 		return subcommands.ExitUsageError
 	}
-	if !coverage.KcovAvailable() {
+	if !coverage.Available() {
 		return Errorf("symbolize can only be used when coverage is available.")
 	}
 	coverage.InitCoverageData()
 
 	if c.dumpAll {
-		coverage.WriteAllBlocks(os.Stdout)
+		if err := coverage.WriteAllBlocks(os.Stdout); err != nil {
+			return Errorf("Failed to write out blocks: %v", err)
+		}
 		return subcommands.ExitSuccess
 	}