Allow for switching between git and svn

Depending on the kind of checkout, msfupdate should be smart about this.
This was first proposed by @corelanc0d3r I believe, but rejected because
it didn't seem to solve any immediate problem. Now, it does, as we are
ditching SVN Real Soon Now for performance reasons.

This change is minimal functionality and doesn't handle switching over
from one to the other.

msfupdate

@@ -9,12 +9,14 @@ while File.symlink?(msfbase)
 	msfbase = File.expand_path(File.readlink(msfbase), File.dirname(msfbase))
 end
 
+msfbase_dir = File.dirname(msfbase)
+
 @args = ARGV.dup
 
 # May be changed
 @configdir = File.expand_path(File.join(File.dirname(msfbase), "data", "svn"))
 
-Dir.chdir(File.dirname(msfbase))
+Dir.chdir(msfbase_dir)
 
 $stderr.puts "[*]"
 $stderr.puts "[*] Attempting to update the Metasploit Framework..."
@@ -26,16 +28,32 @@ if not (Process.uid == 0 or File.stat(msfbase).owned?)
 	$stderr.puts "Please run msfupdate as the same user who installed metasploit."
 end
 
+
+def is_git(msfbase_dir)
+	File.directory?(File.join(msfbase_dir, ".git"))
+end
+
+def is_svn
+	File.directory?(File.join(msfbase_dir, ".svn"))
+end
+
+# TODO
+def print_depreciation_warning
+
+end
+
+# Some of these args are meaningful for SVN, some for Git,
+# some for both. Fun times.
 @args.each_with_index do |arg,i|
 	case arg
-	# Handle the old wait/nowait argument behavior
+		# Handle the old wait/nowait argument behavior
 	when "wait", "nowait"
 		@wait_index = i
 		@actually_wait = (arg == "wait")
-	# An empty or absent config-dir means a default config-dir
+		# An empty or absent config-dir means a default config-dir
 	when "--config-dir"
 		@configdir_index = i
-	# A defined config dir means a defined config-dir
+		# A defined config dir means a defined config-dir
 	when /--config-dir=(.*)?/
 		# Spaces in the directory should be fine since this whole thing is passed
 		# as a single argument via the multi-arg syntax for system() below.
@@ -48,19 +66,49 @@ end
 @args[@wait_index] = nil      if @wait_index
 @args[@configdir_index] = nil if @configdir_index
 @args = @args.compact
-@args.push("--config-dir=#{@configdir}")
-@args.push("--non-interactive")
 
-res = system("svn", "cleanup")
-if res.nil?
-	$stderr.puts "[-] ERROR: Failed to run svn"
-	$stderr.puts ""
-	$stderr.puts "[-] If you used a binary installer, make sure you run the symlink in"
-	$stderr.puts "[-] /usr/local/bin instead of running this file directly (e.g.: ./msfupdate)"
-	$stderr.puts "[-] to ensure a proper environment."
-else
-	# Cleanup worked, go ahead and update
-	system("svn", "update", *@args)
+####### Since we're SVN, do it all this way #######
+if is_svn
+	print_depreciation_warning
+	@args.push("--config-dir=#{@configdir}")
+	@args.push("--non-interactive")
+
+	res = system("svn", "cleanup")
+	if res.nil?
+		$stderr.puts "[-] ERROR: Failed to run svn"
+		$stderr.puts ""
+		$stderr.puts "[-] If you used a binary installer, make sure you run the symlink in"
+		$stderr.puts "[-] /usr/local/bin instead of running this file directly (e.g.: ./msfupdate)"
+		$stderr.puts "[-] to ensure a proper environment."
+		exit 1
+	else
+		# Cleanup worked, go ahead and update
+		system("svn", "update", *@args)
+	end
+end
+
+####### Since we're Git, do it all that way #######
+if is_git
+	# Always lose any local changes, but not unchecked files
+	# TODO: Allow for git stash and git stash pop
+	res = system("git", "reset", "HEAD", "--hard")
+	if res.nil?
+		$stderr.puts "[-] ERROR: Failed to run git"
+		$stderr.puts ""
+		$stderr.puts "[-] If you used a binary installer, make sure you run the symlink in"
+		$stderr.puts "[-] /usr/local/bin instead of running this file directly (e.g.: ./msfupdate)"
+		$stderr.puts "[-] to ensure a proper environment."
+		exit 1
+	end
+
+	# TODO: Allow msfupdate to take a branch argument
+	system("git", "checkout", "master")
+	system("git", "fetch")
+	system("git", "merge", "origin/master")
+end
+
+unless is_svn || is_git
+	raise RuntimeError, "Cannot determine checkout type: `#{msfbase_dir}'"
 end
 
 if @actually_wait