From 43aa565f14442fd4d63aec1df41c0357605db5fa Mon Sep 17 00:00:00 2001
From: Francis Tsui <ftsui@google.com>
Date: Tue, 22 Oct 2024 13:35:51 -0700
Subject: [PATCH] Fix GetOsDeviceName returns string with trailing \0.

PiperOrigin-RevId: 688673080
---
 internal/platform/implementation/windows/BUILD    |  1 +
 .../implementation/windows/device_info.cc         | 15 ++++++++++-----
 .../implementation/windows/device_info_test.cc    |  9 +++++++--
 3 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/internal/platform/implementation/windows/BUILD b/internal/platform/implementation/windows/BUILD
index 5ebadaf8..1639b12f 100644
--- a/internal/platform/implementation/windows/BUILD
+++ b/internal/platform/implementation/windows/BUILD
@@ -53,6 +53,7 @@ cc_library(
         "//internal/platform:logging",
         "//internal/platform:uuid",
         "//internal/platform/implementation:types",
+        "//internal/platform/implementation/windows:string_utils",
         "//internal/platform/implementation/windows/generated:types",
         "@com_google_absl//absl/base:core_headers",
         "@com_google_absl//absl/container:flat_hash_map",
diff --git a/internal/platform/implementation/windows/device_info.cc b/internal/platform/implementation/windows/device_info.cc
index 236ce63b..cdb51c7b 100644
--- a/internal/platform/implementation/windows/device_info.cc
+++ b/internal/platform/implementation/windows/device_info.cc
@@ -28,6 +28,7 @@
 #include "internal/base/files.h"
 #include "internal/platform/implementation/device_info.h"
 #include "internal/platform/implementation/windows/generated/winrt/base.h"
+#include "internal/platform/implementation/windows/string_utils.h"
 #include "internal/platform/logging.h"
 #include "winrt/Windows.Foundation.Collections.h"
 #include "winrt/Windows.Foundation.h"
@@ -43,6 +44,8 @@ using UserType = winrt::Windows::System::UserType;
 using UserAuthenticationStatus =
     winrt::Windows::System::UserAuthenticationStatus;
 
+using ::nearby::windows::string_utils::WideStringToString;
+
 template <typename T>
 using IVectorView = winrt::Windows::Foundation::Collections::IVectorView<T>;
 
@@ -57,18 +60,20 @@ std::optional<std::string> DeviceInfo::GetOsDeviceName() const {
   DWORD size = 0;
 
   // Get length of the computer name.
-  if (!GetComputerNameExW(ComputerNameDnsHostname, nullptr, &size)) {
+  if (GetComputerNameExW(ComputerNameDnsHostname, nullptr, &size) == 0) {
     if (GetLastError() != ERROR_MORE_DATA) {
       LOG(ERROR) << ": Failed to get device name size, error:"
                  << GetLastError();
       return std::nullopt;
     }
   }
-
   std::wstring device_name(size, L' ');
-  if (GetComputerNameExW(ComputerNameDnsHostname, device_name.data(), &size)) {
-    winrt::hstring device_name_str(device_name);
-    return winrt::to_string(device_name_str);
+  if (GetComputerNameExW(ComputerNameDnsHostname, device_name.data(), &size) !=
+      0) {
+    // On input size includes null termination.
+    // On output size excludes null termination.
+    device_name.resize(size);
+    return WideStringToString(device_name);
   }
 
   LOG(ERROR) << ": Failed to get device name, error:" << GetLastError();
diff --git a/internal/platform/implementation/windows/device_info_test.cc b/internal/platform/implementation/windows/device_info_test.cc
index 59f344c4..0fa23b26 100644
--- a/internal/platform/implementation/windows/device_info_test.cc
+++ b/internal/platform/implementation/windows/device_info_test.cc
@@ -14,6 +14,8 @@
 
 #include "internal/platform/implementation/windows/device_info.h"
 
+#include <cstring>
+#include <string>
 
 #include "gtest/gtest.h"
 #include "internal/platform/implementation/device_info.h"
@@ -22,8 +24,11 @@ namespace nearby {
 namespace windows {
 namespace {
 
-TEST(DeviceInfo, DISABLED_GetComputerName) {
-  EXPECT_TRUE(DeviceInfo().GetOsDeviceName().has_value());
+TEST(DeviceInfo, GetComputerName) {
+  ASSERT_TRUE(DeviceInfo().GetOsDeviceName().has_value());
+  std::string device_name = DeviceInfo().GetOsDeviceName().value();
+  // Makes sure device_name does not include terminating null character.
+  EXPECT_EQ(device_name.size(), std::strlen(device_name.data()));
 }
 
 TEST(DeviceInfo, DISABLED_GetDeviceType) {