Fix a crash on checking NVIDIA driver version with incorrect X11 DISPLAY

Check if the display was valid (non-null Display pointer) before
querying NVCTRL X11 extension.

Bug: 840249
Change-Id: I299f87e2eb150d56649dd71c7becbe8f8abf7841
Reviewed-on: https://chromium-review.googlesource.com/c/1392906
Reviewed-by: Geoff Lang <[email protected]>
Reviewed-by: Corentin Wallez <[email protected]>
Commit-Queue: Geoff Lang <[email protected]>

Author: kkinnunen

src/gpu_info_util/SystemInfo_x11.cpp

@@ -30,7 +30,7 @@ bool GetNvidiaDriverVersionWithXNVCtrl(std::string *version)
 
     Display *display = XOpenDisplay(nullptr);
 
-    if (XNVCTRLQueryExtension(display, &eventBase, &errorBase))
+    if (display && XNVCTRLQueryExtension(display, &eventBase, &errorBase))
     {
         int screenCount = ScreenCount(display);
         for (int screen = 0; screen < screenCount; ++screen)

src/tests/util_tests/PrintSystemInfoTest.cpp

@@ -12,6 +12,7 @@
 #include <iostream>
 
 #include "common/platform.h"
+#include "common/system_utils.h"
 #include "gpu_info_util/SystemInfo.h"
 
 using namespace angle;
@@ -99,4 +100,31 @@ TEST(PrintSystemInfoTest, Print)
 #endif
 }
 
+TEST(PrintSystemInfoTest, GetSystemInfoNoCrashOnInvalidDisplay)
+{
+#if defined(SYSTEM_INFO_IMPLEMENTED) && defined(ANGLE_USE_X11)
+    const char kX11DisplayEnvVar[] = "DISPLAY";
+    const char kInvalidDisplay[]   = "124:";
+    std::string previous_display   = GetEnvironmentVar(kX11DisplayEnvVar);
+    SetEnvironmentVar(kX11DisplayEnvVar, kInvalidDisplay);
+    SystemInfo info;
+
+    // This should not crash.
+    GetSystemInfo(&info);
+
+    if (previous_display.empty())
+    {
+        UnsetEnvironmentVar(kX11DisplayEnvVar);
+    }
+    else
+    {
+        SetEnvironmentVar(kX11DisplayEnvVar, previous_display.c_str());
+    }
+#elif defined(SYSTEM_INFO_IMPLEMENTED)
+    std::cerr << "GetSystemInfo not implemented, skipping" << std::endl;
+#else
+    std::cerr << "GetSystemInfo X11 test not applicable, skipping" << std::endl;
+#endif
+}
+
 }  // anonymous namespace