From f6d4a7d27a094861a3a9c112d3818d27dab4cd0f Mon Sep 17 00:00:00 2001
From: Adam McClenaghan <adam@mcclenaghan.co.uk>
Date: Wed, 23 Apr 2025 21:01:10 +0100
Subject: [PATCH] Perf: skip license scanner injection (#3796)

* (perf): allow library users to skip default scanner injection

Signed-off-by: Adam McClenaghan <adam@mcclenaghan.co.uk>

* (perf): remove prints

Signed-off-by: Adam McClenaghan <adam@mcclenaghan.co.uk>

* perf: move to cataloging licenses.go

Signed-off-by: adammcclenaghan <adam.mcclenaghan@upwind.io>

* perf: Simplify to expose a SetContextLicenseScanner func

Signed-off-by: adammcclenaghan <adam.mcclenaghan@upwind.io>

---------

Signed-off-by: Adam McClenaghan <adam@mcclenaghan.co.uk>
Signed-off-by: adammcclenaghan <adam.mcclenaghan@upwind.io>
---
 internal/licenses/context.go      | 11 ++++++--
 internal/licenses/context_test.go | 47 +++++++++++++++++++++++++++++++
 syft/create_sbom.go               | 15 +++++++---
 3 files changed, 67 insertions(+), 6 deletions(-)
 create mode 100644 internal/licenses/context_test.go

diff --git a/internal/licenses/context.go b/internal/licenses/context.go
index 9d735a8a3..91301cc20 100644
--- a/internal/licenses/context.go
+++ b/internal/licenses/context.go
@@ -6,12 +6,19 @@ import (
 
 type licenseScannerKey struct{}
 
+var ctxKey = licenseScannerKey{}
+
 func SetContextLicenseScanner(ctx context.Context, s Scanner) context.Context {
-	return context.WithValue(ctx, licenseScannerKey{}, s)
+	return context.WithValue(ctx, ctxKey, s)
+}
+
+func IsContextLicenseScannerSet(ctx context.Context) bool {
+	_, ok := ctx.Value(ctxKey).(Scanner)
+	return ok
 }
 
 func ContextLicenseScanner(ctx context.Context) (Scanner, error) {
-	if s, ok := ctx.Value(licenseScannerKey{}).(Scanner); ok {
+	if s, ok := ctx.Value(ctxKey).(Scanner); ok {
 		return s, nil
 	}
 	return NewDefaultScanner()
diff --git a/internal/licenses/context_test.go b/internal/licenses/context_test.go
new file mode 100644
index 000000000..822be2fa4
--- /dev/null
+++ b/internal/licenses/context_test.go
@@ -0,0 +1,47 @@
+package licenses
+
+import (
+	"context"
+	"github.com/stretchr/testify/require"
+	"testing"
+)
+
+func TestSetContextLicenseScanner(t *testing.T) {
+	scanner := testScanner(true)
+	ctx := context.Background()
+	ctx = SetContextLicenseScanner(ctx, scanner)
+
+	val := ctx.Value(ctxKey)
+	require.NotNil(t, val)
+	s, ok := val.(Scanner)
+	require.True(t, ok)
+	require.Equal(t, scanner, s)
+}
+
+func TestIsContextLicenseScannerSet(t *testing.T) {
+	scanner := testScanner(true)
+	ctx := context.Background()
+	require.False(t, IsContextLicenseScannerSet(ctx))
+
+	ctx = SetContextLicenseScanner(ctx, scanner)
+	require.True(t, IsContextLicenseScannerSet(ctx))
+}
+
+func TestContextLicenseScanner(t *testing.T) {
+	t.Run("with scanner", func(t *testing.T) {
+		scanner := testScanner(true)
+		ctx := SetContextLicenseScanner(context.Background(), scanner)
+		s, err := ContextLicenseScanner(ctx)
+		if err != nil || s != scanner {
+			t.Fatal("expected scanner from context")
+		}
+	})
+
+	t.Run("without scanner", func(t *testing.T) {
+		ctx := context.Background()
+		s, err := ContextLicenseScanner(ctx)
+		if err != nil || s == nil {
+			t.Fatal("expected default scanner")
+		}
+	})
+}
diff --git a/syft/create_sbom.go b/syft/create_sbom.go
index aec9fdcae..68605d564 100644
--- a/syft/create_sbom.go
+++ b/syft/create_sbom.go
@@ -96,14 +96,21 @@ func setupContext(ctx context.Context, cfg *CreateSBOMConfig) (context.Context,
 	ctx = setContextExecutors(ctx, cfg)
 
 	// configure license scanner
-	return setContextLicenseScanner(ctx, cfg)
+	// skip injecting a license scanner if one already set on context
+	if licenses.IsContextLicenseScannerSet(ctx) {
+		return ctx, nil
+	}
+
+	return SetContextLicenseScanner(ctx, cfg.Licenses)
 }
 
-func setContextLicenseScanner(ctx context.Context, cfg *CreateSBOMConfig) (context.Context, error) {
+// SetContextLicenseScanner creates and sets a license scanner
+// on the provided context using the provided license config.
+func SetContextLicenseScanner(ctx context.Context, cfg cataloging.LicenseConfig) (context.Context, error) {
 	// inject a single license scanner and content config for all package cataloging tasks into context
 	licenseScanner, err := licenses.NewDefaultScanner(
-		licenses.WithIncludeLicenseContent(cfg.Licenses.IncludeUnkownLicenseContent),
-		licenses.WithCoverage(cfg.Licenses.Coverage),
+		licenses.WithIncludeLicenseContent(cfg.IncludeUnkownLicenseContent),
+		licenses.WithCoverage(cfg.Coverage),
 	)
 	if err != nil {
 		return nil, fmt.Errorf("could not build licenseScanner for cataloging: %w", err)