add test coverage for cgo

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

syft/file/cataloger/executable/elf_test.go

@@ -7,6 +7,7 @@ import (
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
@@ -265,6 +266,38 @@ func Test_elfGoToolchainDetection(t *testing.T) {
 	}
 }
 
+func Test_elfCgoToolchainDetection(t *testing.T) {
+	readerForFixture := func(t *testing.T, fixture string) unionreader.UnionReader {
+		t.Helper()
+		f, err := os.Open(filepath.Join("test-fixtures/golang", fixture))
+		require.NoError(t, err)
+		return f
+	}
+
+	t.Run("cgo binary has both go and c toolchains", func(t *testing.T) {
+		reader := readerForFixture(t, "bin/hello_linux_cgo")
+		f, err := elf.NewFile(reader)
+		require.NoError(t, err)
+
+		toolchains := elfToolchains(reader, f)
+
+		// versions are dynamic based on Docker image, so we ignore them in comparison
+		want := []file.Toolchain{
+			{Name: "go", Kind: file.ToolchainKindCompiler},
+			{Name: "gcc", Kind: file.ToolchainKindCompiler},
+		}
+
+		if d := cmp.Diff(want, toolchains, cmpopts.IgnoreFields(file.Toolchain{}, "Version")); d != "" {
+			t.Errorf("elfToolchains() mismatch (-want +got):\n%s", d)
+		}
+
+		// verify versions are populated
+		for _, tc := range toolchains {
+			assert.NotEmpty(t, tc.Version, "expected version to be set for %s toolchain", tc.Name)
+		}
+	})
+}
+
 func Test_elfGoSymbolCapture(t *testing.T) {
 	readerForFixture := func(t *testing.T, fixture string) unionreader.UnionReader {
 		t.Helper()

syft/file/cataloger/executable/test-fixtures/golang/Dockerfile

@@ -5,10 +5,14 @@ WORKDIR /app
 COPY go.mod go.sum ./
 RUN go mod download
 
-COPY main.go ./
+COPY main.go cgo_main.go ./
 
+# pure Go builds (no CGO)
 RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o /hello_linux .
 
 RUN CGO_ENABLED=0 GOOS=darwin GOARCH=amd64 go build -o /hello_mac .
 
 RUN CGO_ENABLED=0 GOOS=windows GOARCH=amd64 go build -o /hello.exe .
+
+# CGO-enabled build (Linux only, uses gcc)
+RUN CGO_ENABLED=1 GOOS=linux GOARCH=amd64 go build -o /hello_linux_cgo ./cgo_main.go

syft/file/cataloger/executable/test-fixtures/golang/Makefile

@@ -19,12 +19,12 @@ tools-check:
 
 tools:
 	@(docker inspect $(TOOL_IMAGE) > /dev/null && make tools-check) || \
-		(docker build -t $(TOOL_IMAGE) . && sha256sum Dockerfile > Dockerfile.sha256)
+		(docker build --platform=linux/amd64 -t $(TOOL_IMAGE) . && sha256sum Dockerfile > Dockerfile.sha256)
 
 build: tools
 	@mkdir -p $(BIN)
 	docker run -i -v $(shell pwd)/$(BIN):/out $(TOOL_IMAGE) sh -c \
-		"cp /hello_linux /hello_mac /hello.exe /out/"
+		"cp /hello_linux /hello_mac /hello.exe /hello_linux_cgo /out/"
 
 debug:
 	docker run -it --rm -v $(shell pwd):/mount -w /mount $(TOOL_IMAGE) sh

syft/file/cataloger/executable/test-fixtures/golang/cgo_main.go

@@ -0,0 +1,18 @@
+package main
+
+/*
+#include <string.h>
+#include <stdio.h>
+
+int get_length(const char* s) {
+    return strlen(s);
+}
+*/
+import "C"
+import "fmt"
+
+func main() {
+	msg := C.CString("Hello from CGO!")
+	length := C.get_length(msg)
+	fmt.Printf("String length: %d\n", int(length))
+}