Add convert_to_persistent_dev method in Linux

This method replaces all non-persistent device appearances in fstab and
grub1 with UUIDs.

image_creator/os_type/linux.py

 from image_creator.os_type.unix import Unix
+import re
 
 
 class Linux(Unix):
-    pass
+    def __init__(self, rootdev, ghandler):
+        super(Linux, self).__init__(rootdev, ghandler)
+        self._uuid = dict()
+        self._persistent = re.compile('/dev/[hsv]d[a-z][1-9]*')
+
+    def is_persistent(self, dev):
+        return not self._persistent.match(dev)
+
+    def get_uuid(self, dev):
+        if dev in self._uuid:
+            return self._uuid[dev]
+
+        for attr in self.g.blkid(dev):
+            if attr[0] == 'UUID':
+                self._uuid[dev] = attr[1]
+                return attr[1]
+
+    def convert_to_persistent_dev(self):
+        # convert all devices in fstab to persistent
+        persistent_root = self._persistent_fstab()
+
+        # convert all devices in grub1 to persistent
+        self._persistent_grub1(persistent_root)
+
+    def _persistent_grub1(self, conf, new_root):
+        if self.g.is_file('/boot/grub/menu.lst'):
+            grub1 = '/boot/grub/menu.lst'
+        elif self.g.is_file('/etc/grub.conf'):
+            grub1 = '/etc/grub.conf'
+        else:
+            return
+
+        self.g.aug_init('/', 0)
+        try:
+            roots = self.g.aug_match('/files%s/title[*]/kernel/root' % grub1)
+            for root in roots:
+                dev = self.g.aug_get(root)
+                if not self.is_persistent(dev):
+                    # This is not always correct. Grub may contain root entries
+                    # for other systems, but we only support 1 OS per hard
+                    # disk, so this shouldn't harm.
+                    self.g.aug_set(root, new_root)
+        finally:
+            self.g.aug_save()
+            self.g.aug_close()
+
+    def _persistent_fstab(self):
+        mpoints = self.g.mountpoints()
+        if len(mpoints) == 0:
+            pass  # TODO: error handling
+
+        device_dict = dict([[mpoint, dev] for dev, mpoint in mpoints])
+
+        root_dev = None
+        new_fstab = ""
+        fstab = self.g.cat('/etc/fstab')
+        for line in fstab.splitlines():
+
+            line, dev, mpoint = self._convert_fstab_line(line, device_dict)
+            new_fstab += "%s\n" % line
+
+            if mpoint == '/':
+                root_dev = dev
+
+        self.g.write('/etc/fstab', new_fstab)
+        if root_dev is None:
+            pass  # TODO: error handling
+
+        return root_dev
+
+    def _convert_fstab_line(self, line, devices):
+        orig = line
+        line = line.split('#')[0].strip()
+        if len(line) == 0:
+            return orig, "", ""
+
+        entry = line.split()
+        if len(entry) != 6:
+            print "Warning: detected abnorman entry in fstab"
+            return orig, "", ""
+
+        dev = entry[0]
+        mpoint = entry[1]
+
+        if not self.is_persistent(dev):
+            if mpoint in devices:
+                dev = "UUID=%s" % self.get_uuid(devices[mpoint])
+                entry[0] = dev
+            else:
+                # comment out the entry
+                entry[0] = "#%s" % dev
+            return " ".join(entry), dev, mpoint
+
+        return orig, dev, mpoint
 
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