Preserve comments and format generated whitespace in fstab

lib/linux_admin/fstab.rb

@@ -13,57 +13,95 @@ class FSTabEntry < LinuxAdmin
     attr_accessor :mount_options
     attr_accessor :dumpable
     attr_accessor :fsck_order
+    attr_accessor :comment
 
     def initialize(args = {})
       @device        = args[:device]
       @mount_point   = args[:mount_point]
       @fs_type       = args[:fs_type]
       @mount_options = args[:mount_options]
-      @dumpable      = args[:dumpable]
-      @fsck_order    = args[:fsck_order]
+      @dumpable      = args[:dumpable].to_i unless args[:dumpable].nil?
+      @fsck_order    = args[:fsck_order].to_i unless args[:fsck_order].nil?
+      @comment       = args[:comment]
     end
 
     def self.from_line(fstab_line)
-      columns = fstab_line.chomp.split
+      columns, comment = fstab_line.split('#')
+      comment = "##{comment}" unless comment.blank?
+      columns = columns.chomp.split
+
       FSTabEntry.new :device        => columns[0],
                      :mount_point   => columns[1],
                      :fs_type       => columns[2],
                      :mount_options => columns[3],
-                     :dumpable      => columns[4].to_i,
-                     :fsck_order    => columns[5].to_i
-
+                     :dumpable      => columns[4],
+                     :fsck_order    => columns[5],
+                     :comment       => comment
+    end
+
+    def has_content?
+      !self.columns.first.nil?
+    end
+
+    def columns
+      [self.device, self.mount_point, self.fs_type,
+       self.mount_options, self.dumpable, self.fsck_order, self.comment]
+    end
+
+    def column_lengths
+      self.columns.collect { |c| c ? c.size : 0 }
+    end
+
+    def formatted_columns(max_lengths)
+      self.columns.collect.
+        with_index { |col, i| col.to_s.rjust(max_lengths[i]) }.join(" ")
     end
   end
 
   class FSTab < LinuxAdmin
     include Singleton
 
     attr_accessor :entries
+    attr_accessor :maximum_column_lengths
 
     def initialize
       refresh
     end
 
     def write!
       content = ''
+      comment_index = 0
       @entries.each do |entry|
-        content += "#{entry.device} #{entry.mount_point} #{entry.fs_type} #{entry.mount_options} #{entry.dumpable} #{entry.fsck_order}\n"
+        if entry.has_content?
+          content << entry.formatted_columns(@maximum_column_lengths) << "\n"
+        else
+          content << "#{entry.comment}"
+        end
       end
+
       File.write('/etc/fstab', content)
       self
     end
 
     private
 
     def read
-      File.read('/etc/fstab').lines.find_all {|line| !line.blank? && !line.strip.starts_with?("#")}
+      File.read('/etc/fstab').lines
     end
 
     def refresh
-      @entries = 
-        read.collect { |line|
-          FSTabEntry.from_line line
-        }
+      @entries  = []
+      @maximum_column_lengths = Array.new(7, 0) # # of columns
+      read.each do |line|
+        entry = FSTabEntry.from_line(line)
+        @entries << entry
+
+        lengths = entry.column_lengths
+        lengths.each_index do |i|
+          @maximum_column_lengths[i] =
+            lengths[i] if lengths[i] > @maximum_column_lengths[i]
+        end
+      end
     end
   end
 end

spec/fstab_spec.rb

@@ -7,41 +7,47 @@
     Singleton.send :__init__, LinuxAdmin::FSTab
   end
 
-  it "newline, single spaces, tab" do
+  it "has newline, single spaces, tab" do
     fstab = <<eos
 
 
 
 eos
     File.should_receive(:read).with('/etc/fstab').and_return(fstab)
-    LinuxAdmin::FSTab.instance.entries.size.should == 0
+    LinuxAdmin::FSTab.instance.entries.size.should == 3
+    LinuxAdmin::FSTab.instance.entries.any? { |e| e.has_content? }.should be_false
   end
 
   it "creates FSTabEntry for each line in fstab" do
     fstab = <<eos
 # Comment, indented comment, comment with device information
   # /dev/sda1 / ext4  defaults  1 1
 # /dev/sda1 / ext4  defaults  1 1
+
 /dev/sda1 / ext4  defaults  1 1
 /dev/sda2 swap  swap  defaults  0 0
 eos
     File.should_receive(:read).with('/etc/fstab').and_return(fstab)
     entries = LinuxAdmin::FSTab.instance.entries
-    entries.size.should == 2
+    entries.size.should == 6
 
-    entries[0].device.should == '/dev/sda1'
-    entries[0].mount_point.should == '/'
-    entries[0].fs_type.should == 'ext4'
-    entries[0].mount_options.should == 'defaults'
-    entries[0].dumpable.should == 1
-    entries[0].fsck_order.should == 1
+    entries[0].comment.should == "# Comment, indented comment, comment with device information\n"
+    entries[1].comment.should == "# /dev/sda1 / ext4  defaults  1 1\n"
+    entries[2].comment.should == "# /dev/sda1 / ext4  defaults  1 1\n"
+    entries[3].comment.should == nil
+    entries[4].device.should == '/dev/sda1'
+    entries[4].mount_point.should == '/'
+    entries[4].fs_type.should == 'ext4'
+    entries[4].mount_options.should == 'defaults'
+    entries[4].dumpable.should == 1
+    entries[4].fsck_order.should == 1
 
-    entries[1].device.should == '/dev/sda2'
-    entries[1].mount_point.should == 'swap'
-    entries[1].fs_type.should == 'swap'
-    entries[1].mount_options.should == 'defaults'
-    entries[1].dumpable.should == 0
-    entries[1].fsck_order.should == 0
+    entries[5].device.should == '/dev/sda2'
+    entries[5].mount_point.should == 'swap'
+    entries[5].fs_type.should == 'swap'
+    entries[5].mount_options.should == 'defaults'
+    entries[5].dumpable.should == 0
+    entries[5].fsck_order.should == 0
   end
 
   describe "#write!" do
@@ -54,10 +60,12 @@
       entry.mount_options = 'defaults'
       entry.dumpable      = 1
       entry.fsck_order    = 1
+      entry.comment = "# more"
       LinuxAdmin::FSTab.any_instance.stub(:refresh) # don't read /etc/fstab
-      LinuxAdmin::FSTab.instance.entries = [entry]
+      LinuxAdmin::FSTab.instance.maximum_column_lengths = [9, 1, 4, 8, 1, 1, 1]
+      LinuxAdmin::FSTab.instance.entries  = [entry]
 
-      File.should_receive(:write).with('/etc/fstab', "/dev/sda1 / ext4 defaults 1 1\n")
+      File.should_receive(:write).with('/etc/fstab', "/dev/sda1 / ext4 defaults 1 1 # more\n")
       LinuxAdmin::FSTab.instance.write!
     end
   end