Logging: Let user configure rules via QT_LOGGING_RULES

Check also for rules set in an environment variable QT_LOGGING_RULES.
This makes it even more convenient to set rules e.g. for just one run of an
application, without having to create a logging configuration file. It
is also more in place with the current way we enable/disable debugging
of parts of Qt via environment variables.

Change-Id: I4d05976f2b6c12bca472552ffa22345475cd01de
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>
Reviewed-by: Tomasz Olszak <olszak.tomasz@gmail.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/src/corelib/io/qloggingregistry.cpp b/src/corelib/io/qloggingregistry.cpp
index 6e195d29cb..23f1ffbd16 100644
--- a/src/corelib/io/qloggingregistry.cpp
+++ b/src/corelib/io/qloggingregistry.cpp
@@ -248,7 +248,7 @@ static bool qtLoggingDebug()
 /*!
     \internal
     Initializes the rules database by loading
-    .config/QtProject/qtlogging.ini and $QT_LOGGING_CONF.
+    $QT_LOGGING_CONF, $QT_LOGGING_RULES, and .config/QtProject/qtlogging.ini.
  */
 void QLoggingRegistry::init()
 {
@@ -266,6 +266,14 @@ void QLoggingRegistry::init()
             envRules = parser.rules();
         }
     }
+    const QByteArray rulesSrc = qgetenv("QT_LOGGING_RULES");
+    if (!rulesSrc.isEmpty()) {
+         QTextStream stream(rulesSrc);
+         QLoggingSettingsParser parser;
+         parser.setSection(QStringLiteral("Rules"));
+         parser.setContent(stream);
+         envRules += parser.rules();
+    }
 
     // get rules from qt configuration
     QString envPath = QStandardPaths::locate(QStandardPaths::GenericConfigLocation,