Vulkan: Prepend layer path to VK_LAYER_PATH

src/common/system_utils.cpp

+//
+// Copyright 2018 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+
+// system_utils.cpp: Implementation of common functions
+
+#include "system_utils.h"
+
+namespace angle
+{
+
+bool PrependPathToEnvironmentVar(const char *variableName, const char *path)
+{
+    std::string oldValue = GetEnvironmentVar(variableName);
+    const char *newValue = nullptr;
+    std::string buf;
+    if (oldValue.empty())
+    {
+        newValue = path;
+    }
+    else
+    {
+        buf = path;
+        buf += GetPathSeparator();
+        buf += oldValue;
+        newValue = buf.c_str();
+    }
+    return SetEnvironmentVar(variableName, newValue);
+}
+
+}  // namespace angle

src/common/system_utils.h

@@ -21,6 +21,9 @@ const char *GetSharedLibraryExtension();
 Optional<std::string> GetCWD();
 bool SetCWD(const char *dirName);
 bool SetEnvironmentVar(const char *variableName, const char *value);
+std::string GetEnvironmentVar(const char *variableName);
+const char *GetPathSeparator();
+bool PrependPathToEnvironmentVar(const char *variableName, const char *path);
 
 }  // namespace angle
 

src/common/system_utils_linux.cpp

@@ -86,4 +86,15 @@ bool SetEnvironmentVar(const char *variableName, const char *value)
     return (setenv(variableName, value, 1) == 0);
 }
 
+std::string GetEnvironmentVar(const char *variableName)
+{
+    const char *value = getenv(variableName);
+    return (value == nullptr ? std::string() : std::string(value));
+}
+
+const char *GetPathSeparator()
+{
+    return ":";
+}
+
 }  // namespace angle

src/common/system_utils_mac.cpp

@@ -91,4 +91,15 @@ bool SetEnvironmentVar(const char *variableName, const char *value)
     return (setenv(variableName, value, 1) == 0);
 }
 
+std::string GetEnvironmentVar(const char *variableName)
+{
+    const char *value = getenv(variableName);
+    return (value == nullptr ? std::string() : std::string(value));
+}
+
+const char *GetPathSeparator()
+{
+    return ":";
+}
+
 }  // namespace angle

src/common/system_utils_win.cpp

@@ -76,4 +76,24 @@ bool SetEnvironmentVar(const char *variableName, const char *value)
     return (SetEnvironmentVariableA(variableName, value) == TRUE);
 }
 
+std::string GetEnvironmentVar(const char *variableName)
+{
+    std::array<char, MAX_PATH> oldValue;
+    DWORD result =
+        GetEnvironmentVariableA(variableName, oldValue.data(), static_cast<DWORD>(oldValue.size()));
+    if (result == 0)
+    {
+        return std::string();
+    }
+    else
+    {
+        return std::string(oldValue.data());
+    }
+}
+
+const char *GetPathSeparator()
+{
+    return ";";
+}
+
 }  // namespace angle

src/libANGLE/renderer/vulkan/RendererVk.cpp

@@ -122,7 +122,7 @@ class ScopedVkLoaderEnvironment : angle::NonCopyable
         // Override environment variable to use the ANGLE layers.
         if (mEnableValidationLayers)
         {
-            if (!angle::SetEnvironmentVar(g_VkLoaderLayersPathEnv, ANGLE_VK_LAYERS_DIR))
+            if (!angle::PrependPathToEnvironmentVar(g_VkLoaderLayersPathEnv, ANGLE_VK_LAYERS_DIR))
             {
                 ERR() << "Error setting environment for Vulkan layers init.";
                 mEnableValidationLayers = false;

src/libGLESv2.gypi

@@ -27,6 +27,8 @@
             'common/platform.h',
             'common/string_utils.cpp',
             'common/string_utils.h',
+            'common/system_utils.cpp',
+            'common/system_utils.h',
             'common/third_party/base/anglebase/base_export.h',
             'common/third_party/base/anglebase/containers/mru_cache.h',
             'common/third_party/base/anglebase/logging.h',