[PATCH 08 of 10] Switch cmd to use popen2() instead of popen()

[jgoerzen at complete.org]

# HG changeset patch
# User John Goerzen <jgoerzen at complete.org>
# Date 1173038767 21600
# Node ID 7ade700f8b5da237accfa2ce81daf71a0e41cb3d
# Parent  820de3cbb48bf52b869e164363d6c95fc7c56f2a
Switch cmd to use popen2() instead of popen()
Now it is possible to avoid shell escaping bugs when passing usernames and
similar info to commands

diff --git a/contrib/darcs2hg.py b/contrib/darcs2hg.py
--- a/contrib/darcs2hg.py
+++ b/contrib/darcs2hg.py
@@ -42,16 +42,21 @@ USAGE = """\
 #
 # ------------------------------------------------------------------------------
 
-def cmd(text, path=None, silent=False):
+def cmd(cmd, path=None, silent=False):
 	"""Executes a command, in the given directory (if any), and returns the
-	command result as a string."""
+	command result as a string.  Command may be a string (which will be
+        passed to the shell) or a sequence (which will not be passed through
+        a shell), as handled by os.popen2().  The command's stdin will
+        be closed immediately upon starting."""
 	cwd = None
 	if path:
 		path = os.path.abspath(path)
 		cwd  = os.getcwd()
 		os.chdir(path)
-	if not silent: print "> ", text
-	res = os.popen(text).read()
+	if not silent: print "> ", cmd
+        fds = os.popen2(cmd)
+        fds[0].close()
+        res = fds[1].read()
 	if path:
 		os.chdir(cwd)
 	return res