1 files changed, 26 insertions, 0 deletions

diff --git a/cli/internal/chrometracing/chrometracing_close.go b/cli/internal/chrometracing/chrometracing_close.go
new file mode 100644
index 0000000..1b3a7b9
--- /dev/null
+++ b/cli/internal/chrometracing/chrometracing_close.go
@@ -0,0 +1,26 @@
+package chrometracing
+
+// Close overwrites the trailing (,\n) with (]\n) and closes the trace file.
+// Close is implemented in a separate file to keep a separation between custom
+// code and upstream from github.com/google/chrometracing. Additionally, we can
+// enable linting for code we author, while leaving upstream code alone.
+func Close() error {
+	trace.fileMu.Lock()
+	defer trace.fileMu.Unlock()
+	// Seek backwards two bytes (,\n)
+	if _, err := trace.file.Seek(-2, 1); err != nil {
+		return err
+	}
+	// Write 1 byte, ']', leaving the trailing '\n' in place
+	if _, err := trace.file.Write([]byte{']'}); err != nil {
+		return err
+	}
+	// Force the filesystem to write to disk
+	if err := trace.file.Sync(); err != nil {
+		return err
+	}
+	if err := trace.file.Close(); err != nil {
+		return err
+	}
+	return nil
+}