qmake: require a drive in a DOS path for it to be absolute

For Q_OS_WIN, a path is only truly absolute if it includes a drive
letter; merely starting with a slash is not enough.  (We can't support
UNC paths, so don't even try: qmake runs various commands in the
source directory using CMD.exe, which doesn't support UNC as PWD.)
This requires, when resolving a path relative to a root, transcribing
the root's drive to such not-quite-absolute paths.

Changed QMakeGlobals, $$absolute_path() and $$relative_path() to now
use IoUtils::resolvePath() rather than delegating to QDir's absolute
path method, since that doesn't correctly recognize the need for a
drive letter (and qmake did run into problems with some paths, from
splitPathList and a failing test, as a result).

Change-Id: I2bfc13c1bfbe1ae09997274622ea55cb3de31b43
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
(cherry picked from qtbase/e86f3c018833141776db2d15772ba53995656eac)
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/shared/proparser/ioutils.cpp

@@ -64,21 +64,22 @@ IoUtils::FileType IoUtils::fileType(const QString &fileName)
 
 bool IoUtils::isRelativePath(const QString &path)
 {
-    if (path.startsWith(QLatin1Char('/')))
-        return false;
 #ifdef QMAKE_BUILTIN_PRFS
     if (path.startsWith(QLatin1String(":/")))
         return false;
 #endif
 #ifdef Q_OS_WIN
-    if (path.startsWith(QLatin1Char('\\')))
+    // Unlike QFileInfo, this considers only paths with both a drive prefix and
-        return false;
+    // a subsequent (back-)slash absolute:
-    // Unlike QFileInfo, this won't accept a relative path with a drive letter.
-    // Such paths result in a royal mess anyway ...
     if (path.length() >= 3 && path.at(1) == QLatin1Char(':') && path.at(0).isLetter()
-        && (path.at(2) == QLatin1Char('/') || path.at(2) == QLatin1Char('\\')))
+        && (path.at(2) == QLatin1Char('/') || path.at(2) == QLatin1Char('\\'))) {
         return false;
-#endif
+    }
+    // (... unless, of course, they're UNC, which qmake fails on anyway)
+#else
+    if (path.startsWith(QLatin1Char('/')))
+        return false;
+#endif // Q_OS_WIN
     return true;
 }
 
@@ -98,6 +99,12 @@ QString IoUtils::resolvePath(const QString &baseDir, const QString &fileName)
         return QString();
     if (isAbsolutePath(fileName))
         return QDir::cleanPath(fileName);
+#ifdef Q_OS_WIN // Add drive to otherwise-absolute path:
+    if (fileName.at(0).unicode() == '/' || fileName.at(0).unicode() == '\\') {
+        Q_ASSERT(isAbsolutePath(baseDir));
+        return QDir::cleanPath(baseDir.left(2) + fileName);
+    }
+#endif // Q_OS_WIN
     return QDir::cleanPath(baseDir + QLatin1Char('/') + fileName);
 }
 

src/shared/proparser/qmakebuiltins.cpp

@@ -1174,9 +1174,9 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateBuiltinExpand(
         if (args.count() > 2) {
             evalError(fL1S("absolute_path(path[, base]) requires one or two arguments."));
         } else {
-            QString rstr = QDir::cleanPath(
+            QString arg = args.at(0).toQString(m_tmp1);
-                    QDir(args.count() > 1 ? args.at(1).toQString(m_tmp2) : currentDirectory())
+            QString baseDir = args.count() > 1 ? args.at(1).toQString(m_tmp2) : currentDirectory();
-                    .absoluteFilePath(args.at(0).toQString(m_tmp1)));
+            QString rstr = arg.isEmpty() ? baseDir : IoUtils::resolvePath(baseDir, arg);
             ret << (rstr.isSharedWith(m_tmp1)
                         ? args.at(0)
                         : args.count() > 1 && rstr.isSharedWith(m_tmp2)
@@ -1188,9 +1188,10 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateBuiltinExpand(
         if (args.count() > 2) {
             evalError(fL1S("relative_path(path[, base]) requires one or two arguments."));
         } else {
-            QDir baseDir(args.count() > 1 ? args.at(1).toQString(m_tmp2) : currentDirectory());
+            QString arg = args.at(0).toQString(m_tmp1);
-            QString rstr = baseDir.relativeFilePath(baseDir.absoluteFilePath(
+            QString baseDir = args.count() > 1 ? args.at(1).toQString(m_tmp2) : currentDirectory();
-                                args.at(0).toQString(m_tmp1)));
+            QString absArg = arg.isEmpty() ? baseDir : IoUtils::resolvePath(baseDir, arg);
+            QString rstr = QDir(baseDir).relativeFilePath(absArg);
             ret << (rstr.isSharedWith(m_tmp1) ? args.at(0) : ProString(rstr).setSource(args.at(0)));
         }
         break;

src/shared/proparser/qmakeglobals.cpp

@@ -65,6 +65,7 @@
 #endif
 
 QT_BEGIN_NAMESPACE
+using namespace QMakeInternal; // for IoUtils
 
 #define fL1S(s) QString::fromLatin1(s)
 
@@ -93,9 +94,9 @@ QString QMakeGlobals::cleanSpec(QMakeCmdLineParserState &state, const QString &s
 {
     QString ret = QDir::cleanPath(spec);
     if (ret.contains(QLatin1Char('/'))) {
-        QString absRet = QDir(state.pwd).absoluteFilePath(ret);
+        QString absRet = IoUtils::resolvePath(state.pwd, ret);
         if (QFile::exists(absRet))
-            ret = QDir::cleanPath(absRet);
+            ret = absRet;
     }
     return ret;
 }
@@ -123,10 +124,10 @@ QMakeGlobals::ArgumentReturn QMakeGlobals::addCommandLineArguments(
             user_template_prefix = arg;
             break;
         case ArgCache:
-            cachefile = args[*pos] = QDir::cleanPath(QDir(state.pwd).absoluteFilePath(arg));
+            cachefile = args[*pos] = IoUtils::resolvePath(state.pwd, arg);
             break;
         case ArgQtConf:
-            qtconf = args[*pos] = QDir::cleanPath(QDir(state.pwd).absoluteFilePath(arg));
+            qtconf = args[*pos] = IoUtils::resolvePath(state.pwd, arg);
             break;
         default:
             if (arg.startsWith(QLatin1Char('-'))) {
@@ -256,11 +257,11 @@ QStringList QMakeGlobals::splitPathList(const QString &val) const
 {
     QStringList ret;
     if (!val.isEmpty()) {
-        QDir bdir;
+        QString cwd(QDir::currentPath());
         const QStringList vals = val.split(dirlist_sep);
         ret.reserve(vals.length());
         for (const QString &it : vals)
-            ret << QDir::cleanPath(bdir.absoluteFilePath(it));
+            ret << IoUtils::resolvePath(cwd, it);
     }
     return ret;
 }
@@ -315,7 +316,7 @@ bool QMakeGlobals::initProperties()
         return false;
     data = proc.readAll();
 #else
-    if (FILE *proc = QT_POPEN(QString(QMakeInternal::IoUtils::shellQuote(qmake_abslocation)
+    if (FILE *proc = QT_POPEN(QString(IoUtils::shellQuote(qmake_abslocation)
                                       + QLatin1String(" -query")).toLocal8Bit(), QT_POPEN_READ)) {
         char buff[1024];
         while (!feof(proc))