2 files changed, 12 insertions, 1 deletions
diff --git a/test/util/pty_util.cc b/test/util/pty_util.cc
index c0fd9a095..c01f916aa 100644
--- a/test/util/pty_util.cc
+++ b/test/util/pty_util.cc
@@ -24,6 +24,14 @@ namespace gvisor {
 namespace testing {
 
 PosixErrorOr<FileDescriptor> OpenSlave(const FileDescriptor& master) {
+  PosixErrorOr<int> n = SlaveID(master);
+  if (!n.ok()) {
+    return PosixErrorOr<FileDescriptor>(n.error());
+  }
+  return Open(absl::StrCat("/dev/pts/", n.ValueOrDie()), O_RDWR | O_NONBLOCK);
+}
+
+PosixErrorOr<int> SlaveID(const FileDescriptor& master) {
   // Get pty index.
   int n;
   int ret = ioctl(master.get(), TIOCGPTN, &n);
@@ -38,7 +46,7 @@ PosixErrorOr<FileDescriptor> OpenSlave(const FileDescriptor& master) {
     return PosixError(errno, "ioctl(TIOSPTLCK) failed");
   }
 
-  return Open(absl::StrCat("/dev/pts/", n), O_RDWR | O_NONBLOCK);
+  return n;
 }
 
 }  // namespace testing
diff --git a/test/util/pty_util.h b/test/util/pty_util.h
index 367b14f15..0722da379 100644
--- a/test/util/pty_util.h
+++ b/test/util/pty_util.h
@@ -24,6 +24,9 @@ namespace testing {
 // Opens the slave end of the passed master as R/W and nonblocking.
 PosixErrorOr<FileDescriptor> OpenSlave(const FileDescriptor& master);
 
+// Get the number of the slave end of the master.
+PosixErrorOr<int> SlaveID(const FileDescriptor& master);
+
 }  // namespace testing
 }  // namespace gvisor