hg-ssh: refactor to have main() method

Refactor hg-ssh to have a main() function instead of a bunch of
top-level statements.

contrib/hg-ssh

@@ -1,57 +1,63 b''
 #!/usr/bin/env python
 #
 # Copyright 2005-2007 by Intevation GmbH <[e-mail]>
 #
 # Author(s):
 # Thomas Arendsen Hein <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 """
 hg-ssh - a wrapper for ssh access to a limited set of mercurial repos
 
 To be used in ~/.ssh/authorized_keys with the "command" option, see sshd(8):
 command="hg-ssh path/to/repo1 /path/to/repo2 ~/repo3 ~user/repo4" ssh-dss ...
 (probably together with these other useful options:
  no-port-forwarding,no-X11-forwarding,no-agent-forwarding)
 
 This allows pull/push over ssh from/to the repositories given as arguments.
 
 If all your repositories are subdirectories of a common directory, you can
 allow shorter paths with:
 command="cd path/to/my/repositories && hg-ssh repo1 subdir/repo2"
 
 You can use pattern matching of your normal shell, e.g.:
 command="cd repos && hg-ssh user/thomas/* projects/{mercurial,foo}"
 """
 
 # enable importing on demand to reduce startup time
 from mercurial import demandimport; demandimport.enable()
 
 from mercurial import dispatch
 
 import sys, os, shlex
 
-cwd = os.getcwd()
-allowed_paths = [os.path.normpath(os.path.join(cwd, os.path.expanduser(path)))
-                 for path in sys.argv[1:]]
-orig_cmd = os.getenv('SSH_ORIGINAL_COMMAND', '?')
-try:
-    cmdargv = shlex.split(orig_cmd)
-except ValueError, e:
-    sys.stderr.write('Illegal command "%s": %s\n' % (orig_cmd, e))
-    sys.exit(255)
+def main():
+    cwd = os.getcwd()
+    allowed_paths = [os.path.normpath(os.path.join(cwd,
+                                                   os.path.expanduser(path)))
+                     for path in sys.argv[1:]]
+    orig_cmd = os.getenv('SSH_ORIGINAL_COMMAND', '?')
+    try:
+        cmdargv = shlex.split(orig_cmd)
+    except ValueError, e:
+        sys.stderr.write('Illegal command "%s": %s\n' % (orig_cmd, e))
+        sys.exit(255)
 
-if cmdargv[:2] == ['hg', '-R'] and cmdargv[3:] == ['serve', '--stdio']:
-    path = cmdargv[2]
-    repo = os.path.normpath(os.path.join(cwd, os.path.expanduser(path)))
-    if repo in allowed_paths:
-        dispatch.dispatch(dispatch.request(['-R', repo, 'serve', '--stdio']))
+    if cmdargv[:2] == ['hg', '-R'] and cmdargv[3:] == ['serve', '--stdio']:
+        path = cmdargv[2]
+        repo = os.path.normpath(os.path.join(cwd, os.path.expanduser(path)))
+        if repo in allowed_paths:
+            dispatch.dispatch(dispatch.request(['-R', repo,
+                                                'serve',
+                                                '--stdio']))
+        else:
+            sys.stderr.write('Illegal repository "%s"\n' % repo)
+            sys.exit(255)
     else:
-        sys.stderr.write('Illegal repository "%s"\n' % repo)
+        sys.stderr.write('Illegal command "%s"\n' % orig_cmd)
         sys.exit(255)
-else:
-    sys.stderr.write('Illegal command "%s"\n' % orig_cmd)
-    sys.exit(255)
 
+if __name__ == '__main__':
+    main()