[partition] Add convenience methods to FstabEntry

- Add something like a constructor
 - Add validity checking

src/modules/partition/core/OsproberEntry.h

@@ -1,6 +1,7 @@
 /* === This file is part of Calamares - <https://github.com/calamares> ===
  *
  *   Copyright 2014-2016, Teo Mrnjavac <teo@kde.org>
+ *   Copyright 2018, Adriaan de Groot <groot@kde.org>
  *
  *   Calamares is free software: you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -29,6 +30,18 @@ struct FstabEntry
     QString options;
     int dump;
     int pass;
+
+    /// Does this entry make sense and is it complete?
+    bool isValid() const; // implemented in Partutils.cpp
+
+    /** @brief Create an entry from a live of /etc/fstab
+     *
+     * Splits the given string (which ought to follow the format
+     * of /etc/fstab) and returns a corresponding Fstab entry.
+     * If the string isn't valid (e.g. comment-line, or broken
+     * fstab entry) then the entry that is returned is invalid.
+     */
+    FstabEntry fromEtcFstab( const QString& ); // implemented in Partutils.cpp
 };
 
 typedef QList< FstabEntry > FstabEntryList;

src/modules/partition/core/PartUtils.cpp

@@ -372,3 +372,31 @@ isEfiBootable( const Partition* candidate )
 }
 
 }  // nmamespace PartUtils
+
+/* Implementation of methods for FstabEntry, from OsproberEntry.h */
+
+bool
+FstabEntry::isValid() const
+{
+    return !partitionNode.isEmpty() && !mountPoint.isEmpty() && !fsType.isEmpty();
+}
+
+FstabEntry
+FstabEntry::fromEtcFstab( const QString& rawLine )
+{
+    QString line = rawLine.simplified();
+    if ( line.startsWith( '#' ) )
+        return FstabEntry{ QString(), QString(), QString(), QString(), 0, 0 };
+
+    QStringList splitLine = line.split( ' ' );
+    if ( splitLine.length() != 6 )
+        return FstabEntry{ QString(), QString(), QString(), QString(), 0, 0 };
+
+    return FstabEntry{ splitLine.at( 0 ), // path, or UUID, or LABEL, etc.
+                       splitLine.at( 1 ), // mount point
+                       splitLine.at( 2 ), // fs type
+                       splitLine.at( 3 ), // options
+                       splitLine.at( 4 ).toInt(), //dump
+                       splitLine.at( 5 ).toInt()  //pass
+                       };
+ }