1 files changed, 82 insertions, 14 deletions
diff --git a/cloudinit/distros/helpers.py b/cloudinit/distros/helpers.py
index 251d5051..916935eb 100644
--- a/cloudinit/distros/helpers.py
+++ b/cloudinit/distros/helpers.py
@@ -23,6 +23,87 @@ from StringIO import StringIO
 from cloudinit import util
 
 
+def _chop_comment(text, comment_chars):
+    comment_locations = [text.find(c) for c in comment_chars]
+    comment_locations = [c for c in comment_locations if c != -1]
+    if not comment_locations:
+        return (text, '')
+    min_comment = min(comment_locations)
+    before_comment = text[0:min_comment]
+    comment = text[min_comment:]
+    return (before_comment, comment)
+
+
+# See: man hosts
+# or http://unixhelp.ed.ac.uk/CGI/man-cgi?hosts
+class HostsConf(object):
+    def __init__(self, text):
+        self._text = text
+        self._contents = None
+
+    def parse(self):
+        if self._contents is None:
+            self._contents = self._parse(self._text)
+
+    def get_entry(self, ip):
+        self.parse()
+        options = []
+        for (line_type, components) in self._contents:
+            if line_type == 'option':
+                (pieces, _tail) = components
+                if len(pieces) and pieces[0] == ip:
+                    options.append(pieces[1:])
+        return options
+
+    def del_entries(self, ip):
+        self.parse()
+        n_entries = []
+        for (line_type, components) in self._contents:
+            if line_type != 'option':
+                n_entries.append((line_type, components))
+                continue
+            else:
+                (pieces, _tail) = components
+                if len(pieces) and pieces[0] == ip:
+                    pass
+                elif len(pieces):
+                    n_entries.append((line_type, list(components)))
+        self._contents = n_entries
+
+    def add_entry(self, ip, canonical_hostname, *aliases):
+        self.parse()
+        self._contents.append(('option',
+                              ([ip, canonical_hostname] + list(aliases), '')))
+
+    def _parse(self, contents):
+        entries = []
+        for line in contents.splitlines():
+            if not len(line.strip()):
+                entries.append(('blank', [line]))
+                continue
+            (head, tail) = _chop_comment(line.strip(), '#')
+            if not len(head):
+                entries.append(('all_comment', [line]))
+                continue
+            entries.append(('option', [head.split(None), tail]))
+        return entries
+
+    def __str__(self):
+        self.parse()
+        contents = StringIO()
+        for (line_type, components) in self._contents:
+            if line_type == 'blank':
+                contents.write("%s\n")
+            elif line_type == 'all_comment':
+                contents.write("%s\n" % (components[0]))
+            elif line_type == 'option':
+                (pieces, tail) = components
+                pieces = [str(p) for p in pieces]
+                pieces = "\t".join(pieces)
+                contents.write("%s%s\n" % (pieces, tail))
+        return contents.getvalue()
+
+
 # See: man resolv.conf
 class ResolvConf(object):
     def __init__(self, text):
@@ -151,20 +232,7 @@ class ResolvConf(object):
             if not sline:
                 entries.append(('blank', [line]))
                 continue
-            comment_s_loc = sline.find(";")
-            comment_h_loc = sline.find("#")
-            comment_loc = -1
-            if comment_s_loc != -1 and comment_h_loc != -1:
-                comment_loc = min(comment_h_loc, comment_s_loc)
-            elif comment_s_loc != -1:
-                comment_loc = comment_s_loc
-            elif comment_h_loc != -1:
-                comment_loc = comment_h_loc
-            head = line
-            tail = None
-            if comment_loc != -1:
-                head = line[:comment_loc]
-                tail = line[comment_loc:]
+            (head, tail) = _chop_comment(line, ';#')
             if not len(head.strip()):
                 entries.append(('all_comment', [line]))
                 continue