[libcalamares] Add a createTargetBasedirs()

- Used to ensure that the directories leading up to a given path
   exist. Implementation is incomplete and broken for now.
 - While here, avoid removing an empty pathname in removeTargetFile()
   (the empty pathname indicates a broken configuration).

src/libcalamares/utils/CalamaresUtilsSystem.cpp

@@ -338,7 +338,35 @@ System::removeTargetFile( const QString& path ) const
         cWarning() << "Will not remove non-absolute path" << path;
         return;
     }
-    QFile::remove( targetPath( path ) );
+    QString target = targetPath( path );
+    if ( !target.isEmpty() )
+    {
+        QFile::remove( target );
+    }
+    // If it was empty, a warning was already printed
+}
+
+int
+System::createTargetBasedirs(const QString& path) const
+{
+    if ( !isAbsolutePath( path ) )
+    {
+        cWarning() << "Will not create basedirs for non-absolute path" << path;
+        return -1;
+    }
+
+    QString target = targetPath( path );
+    if ( target.isEmpty() )
+    {
+        // If it was empty, a warning was already printed
+        return -1;
+    }
+
+    QString base( "/" );
+    QStringList parts = target.split( '/', QString::SplitBehavior::SkipEmptyParts );
+
+    cDebug() << parts;
+    return -1;
 }
 
 

src/libcalamares/utils/CalamaresUtilsSystem.h

@@ -255,6 +255,17 @@ public:
      */
     DLLEXPORT void removeTargetFile( const QString& path ) const;
 
+    /** @brief Ensure that the directories above @p path exist
+     *
+     * @param path a full pathname to a desired file.
+     *
+     * All the directory components before the last path component are
+     * created, as needed, with 0755 permissions. Returns the number
+     * of components that needed to be created; 0 if they all already
+     * existed, and < 0 on failure.
+     */
+    DLLEXPORT int createTargetBasedirs( const QString& path ) const;
+
     /**
      * @brief getTotalMemoryB returns the total main memory, in bytes.
      *