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, 16 insertions, 19 deletions

diff --git a/src/corelib/io/qprocess_p.h b/src/corelib/io/qprocess_p.h
index b8820510b3..c5abf7b762 100644
--- a/src/corelib/io/qprocess_p.h
+++ b/src/corelib/io/qprocess_p.h
@@ -55,6 +55,7 @@
 #include "QtCore/qprocess.h"
 #include "QtCore/qstringlist.h"
 #include "QtCore/qhash.h"
+#include "QtCore/qmap.h"
 #include "QtCore/qshareddata.h"
 #include "private/qiodevice_p.h"
 
@@ -90,22 +91,19 @@ public:
     QProcEnvKey(const QProcEnvKey &other) : QString(other) {}
     bool operator==(const QProcEnvKey &other) const { return !compare(other, Qt::CaseInsensitive); }
 };
-inline uint qHash(const QProcEnvKey &key) { return qHash(key.toCaseFolded()); }
 
-typedef QString QProcEnvValue;
-#else
-class QProcEnvKey
+inline bool operator<(const QProcEnvKey &a, const QProcEnvKey &b)
 {
-public:
-    QProcEnvKey() : hash(0) {}
-    explicit QProcEnvKey(const QByteArray &other) : key(other), hash(qHash(key)) {}
-    QProcEnvKey(const QProcEnvKey &other) { *this = other; }
-    bool operator==(const QProcEnvKey &other) const { return key == other.key; }
+    // On windows use case-insensitive ordering because that is how Windows needs the environment
+    // block sorted (https://msdn.microsoft.com/en-us/library/windows/desktop/ms682009(v=vs.85).aspx)
+    return a.compare(b, Qt::CaseInsensitive) < 0;
+}
 
-    QByteArray key;
-    uint hash;
-};
-inline uint qHash(const QProcEnvKey &key) Q_DECL_NOTHROW { return key.hash; }
+Q_DECLARE_TYPEINFO(QProcEnvKey, Q_MOVABLE_TYPE);
+
+typedef QString QProcEnvValue;
+#else
+using QProcEnvKey = QByteArray;
 
 class QProcEnvValue
 {
@@ -138,7 +136,6 @@ public:
 };
 Q_DECLARE_TYPEINFO(QProcEnvValue, Q_MOVABLE_TYPE);
 #endif
-Q_DECLARE_TYPEINFO(QProcEnvKey, Q_MOVABLE_TYPE);
 
 class QProcessEnvironmentPrivate: public QSharedData
 {
@@ -161,13 +158,13 @@ public:
     inline Key prepareName(const QString &name) const
     {
         Key &ent = nameMap[name];
-        if (ent.key.isEmpty())
-            ent = Key(name.toLocal8Bit());
+        if (ent.isEmpty())
+            ent = name.toLocal8Bit();
         return ent;
     }
     inline QString nameToString(const Key &name) const
     {
-        const QString sname = QString::fromLocal8Bit(name.key);
+        const QString sname = QString::fromLocal8Bit(name);
         nameMap[sname] = name;
         return sname;
     }
@@ -206,8 +203,8 @@ public:
     }
 #endif
 
-    typedef QHash<Key, Value> Hash;
-    Hash vars;
+    using Map = QMap<Key, Value>;
+    Map vars;
 
 #ifdef Q_OS_UNIX
     typedef QHash<QString, Key> NameHash;