pkg/host: rework host feature detection/setup

Currently host feature detection/setup code is spread
across platform-independent fuzzer code, pkg/host, pkg/ipc
and executor.
Move this all into pkg/host and show readable info
about features on manager start.

Fixes #46

1 files changed, 79 insertions, 0 deletions

diff --git a/pkg/host/host.go b/pkg/host/host.go
index c8f786e5a..d4f4d71a8 100644
--- a/pkg/host/host.go
+++ b/pkg/host/host.go
@@ -26,3 +26,82 @@ func DetectSupportedSyscalls(target *prog.Target, sandbox string) (
 	}
 	return supported, unsupported, nil
 }
+
+const (
+	FeatureCoverage = iota
+	FeatureComparisons
+	FeatureSandboxSetuid
+	FeatureSandboxNamespace
+	FeatureFaultInjection
+	FeatureLeakChecking
+	FeatureNetworkInjection
+	numFeatures
+)
+
+type Feature struct {
+	Name    string
+	Enabled bool
+	Reason  string
+}
+
+type Features [numFeatures]Feature
+
+var checkFeature [numFeatures]func() string
+var setupFeature [numFeatures]func() error
+var callbFeature [numFeatures]func()
+
+func unconditionallyEnabled() string { return "" }
+
+// Check detects features supported on the host.
+// Empty string for a feature means the feature is supported,
+// otherwise the string contains the reason why the feature is not supported.
+func Check() (*Features, error) {
+	const unsupported = "support is not implemented in syzkaller"
+	res := &Features{
+		FeatureCoverage:         {Name: "code coverage", Reason: unsupported},
+		FeatureComparisons:      {Name: "comparison tracing", Reason: unsupported},
+		FeatureSandboxSetuid:    {Name: "setuid sandbox", Reason: unsupported},
+		FeatureSandboxNamespace: {Name: "namespace sandbox", Reason: unsupported},
+		FeatureFaultInjection:   {Name: "fault injection", Reason: unsupported},
+		FeatureLeakChecking:     {Name: "leak checking", Reason: unsupported},
+		FeatureNetworkInjection: {Name: "net packed injection", Reason: unsupported},
+	}
+	for n, check := range checkFeature {
+		if check == nil {
+			continue
+		}
+		if reason := check(); reason == "" {
+			res[n].Enabled = true
+			res[n].Reason = "enabled"
+		} else {
+			res[n].Reason = reason
+		}
+	}
+	return res, nil
+}
+
+// Setup enables and does any one-time setup for the requested features on the host.
+// Note: this can be called multiple times and must be idempotent.
+func Setup(features *Features) (func(), error) {
+	var callback func()
+	for n, setup := range setupFeature {
+		if setup == nil || !features[n].Enabled {
+			continue
+		}
+		if err := setup(); err != nil {
+			return nil, err
+		}
+		cb := callbFeature[n]
+		if cb != nil {
+			prev := callback
+			callback = func() {
+				cb()
+				if prev != nil {
+					prev()
+				}
+			}
+
+		}
+	}
+	return callback, nil
+}