1 files changed, 34 insertions, 0 deletions
diff --git a/go/tools/gopackagesdriver/build_context.go b/go/tools/gopackagesdriver/build_context.go
new file mode 100644
index 00000000..dac786b9
--- /dev/null
+++ b/go/tools/gopackagesdriver/build_context.go
@@ -0,0 +1,34 @@
+package main
+
+import (
+	"go/build"
+	"path/filepath"
+	"strings"
+)
+
+var buildContext = makeBuildContext()
+
+func makeBuildContext() *build.Context {
+	bctx := build.Default
+	bctx.BuildTags = strings.Split(getenvDefault("GOTAGS", ""), ",")
+
+	return &bctx
+}
+
+func filterSourceFilesForTags(files []string) []string {
+	ret := make([]string, 0, len(files))
+
+	for _, f := range files {
+		dir, filename := filepath.Split(f)
+		ext := filepath.Ext(f)
+
+		match, _ := buildContext.MatchFile(dir, filename)
+		// MatchFile filters out anything without a file extension. In the
+		// case of CompiledGoFiles (in particular gco processed files from
+		// the cache), we want them.
+		if match || ext == "" {
+			ret = append(ret, f)
+		}
+	}
+	return ret
+}