QML: Sanitize reading environment variables.

Where possible, use qEnvironmentVariableIsSet()/
qEnvironmentVariableIsEmpty() instead of checking on the
return value of qgetenv().
Where the value is required, add a check using one of
qEnvironmentVariableIsSet()/Empty().

Change-Id: Ia8b7534e6f5165bd8a6b4e63ccc139c42dd03056
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/src/qml/qml/qqmlglobal_p.h b/src/qml/qml/qqmlglobal_p.h
index b7212648ab..23cfc24e7a 100644
--- a/src/qml/qml/qqmlglobal_p.h
+++ b/src/qml/qml/qqmlglobal_p.h
@@ -59,10 +59,12 @@ QT_BEGIN_NAMESPACE
     { \
         static enum { Yes, No, Unknown } status = Unknown; \
         if (status == Unknown) { \
-            QByteArray v = qgetenv(#var); \
-            bool value = !v.isEmpty() && v != "0" && v != "false"; \
-            if (value) status = Yes; \
-            else status = No; \
+            status = No; \
+            if (Q_UNLIKELY(!qEnvironmentVariableIsEmpty(#var))) { \
+                const QByteArray v = qgetenv(#var); \
+                if (v != "0" && v != "false") \
+                    status = Yes; \
+            } \
         } \
         return status == Yes; \
     }