Use QMap in QProcessEnvironment so variables are sorted

The motivation for this change is to make it simple to pass a
correctly sorted environment block to Win32 CreateProcess(). It is
also nice in other contexts that the environment variables are
sorted. The change is made for all platforms. This keeps it simple and
the only ill effect is slightly slower lookups.

Concerning the environment block passed to Win32 CreateProcess:

The environment block that is passed to CreateProcess() must be sorted
case-insensitively and without regard to locale. See
 https://msdn.microsoft.com/en-us/library/windows/desktop/ms682009(v=vs.85).aspx

The need for sorting the environment block is also mentioned in the
CreateProcess() documentation, but with less details:
 https://msdn.microsoft.com/en-us/library/windows/desktop/ms682425(v=vs.85).aspx

Task-number: QTBUG-61315
Change-Id: Ie1edd443301de79cf5f699d45beab01b7c0f9de3
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 42 insertions, 0 deletions

diff --git a/tests/auto/corelib/io/qprocess/tst_qprocess.cpp b/tests/auto/corelib/io/qprocess/tst_qprocess.cpp
index 0783a65d8b..f4d6d5cb40 100644
--- a/tests/auto/corelib/io/qprocess/tst_qprocess.cpp
+++ b/tests/auto/corelib/io/qprocess/tst_qprocess.cpp
@@ -94,6 +94,7 @@ private slots:
     void setEnvironment();
     void setProcessEnvironment_data();
     void setProcessEnvironment();
+    void environmentIsSorted();
     void spaceInName();
     void setStandardInputFile();
     void setStandardOutputFile_data();
@@ -1733,6 +1734,47 @@ void tst_QProcess::setProcessEnvironment()
     }
 }
 
+void tst_QProcess::environmentIsSorted()
+{
+    QProcessEnvironment env;
+    env.insert(QLatin1String("a"), QLatin1String("foo_a"));
+    env.insert(QLatin1String("B"), QLatin1String("foo_B"));
+    env.insert(QLatin1String("c"), QLatin1String("foo_c"));
+    env.insert(QLatin1String("D"), QLatin1String("foo_D"));
+    env.insert(QLatin1String("e"), QLatin1String("foo_e"));
+    env.insert(QLatin1String("F"), QLatin1String("foo_F"));
+    env.insert(QLatin1String("Path"), QLatin1String("foo_Path"));
+    env.insert(QLatin1String("SystemRoot"), QLatin1String("foo_SystemRoot"));
+
+    const QStringList envlist = env.toStringList();
+
+#ifdef Q_OS_WIN32
+    // The environment block passed to CreateProcess "[Requires that] All strings in the
+    // environment block must be sorted alphabetically by name. The sort is case-insensitive,
+    // Unicode order, without regard to locale."
+    // https://msdn.microsoft.com/en-us/library/windows/desktop/ms682009(v=vs.85).aspx
+    // So on Windows we sort that way.
+    const QStringList expected = { QLatin1String("a=foo_a"),
+                                   QLatin1String("B=foo_B"),
+                                   QLatin1String("c=foo_c"),
+                                   QLatin1String("D=foo_D"),
+                                   QLatin1String("e=foo_e"),
+                                   QLatin1String("F=foo_F"),
+                                   QLatin1String("Path=foo_Path"),
+                                   QLatin1String("SystemRoot=foo_SystemRoot") };
+#else
+    const QStringList expected = { QLatin1String("B=foo_B"),
+                                   QLatin1String("D=foo_D"),
+                                   QLatin1String("F=foo_F"),
+                                   QLatin1String("Path=foo_Path"),
+                                   QLatin1String("SystemRoot=foo_SystemRoot"),
+                                   QLatin1String("a=foo_a"),
+                                   QLatin1String("c=foo_c"),
+                                   QLatin1String("e=foo_e") };
+#endif
+    QCOMPARE(envlist, expected);
+}
+
 void tst_QProcess::systemEnvironment()
 {
     QVERIFY(!QProcess::systemEnvironment().isEmpty());