[libcxx] [test] Quote env variables that are set with a shell "export" in ssh.py

This safeguards against cases if some of the env vars contain chars
that are problematic for shells, e.g. if called with --env "X=Y;Z".

(In cases of cross testing for windows, the PATH variable can end up
specified with semicolon separators - even if specifying a PATH when
cross testing in such differing environments might not make sense or
do anything - but this makes ssh.py not break on such a variable.)

Differential Revision: https://reviews.llvm.org/D99242

libcxx/utils/ssh.py

@@ -23,6 +23,12 @@ import sys
 import tarfile
 import tempfile
 
+try:
+   from shlex import quote as cmd_quote
+except ImportError:
+   # for Python 2 compatibility
+   from pipes import quote as cmd_quote
+
 def ssh(args, command):
     cmd = ['ssh', '-oBatchMode=yes']
     if args.extra_ssh_args is not None:
@@ -107,7 +113,7 @@ def main():
         commandLine = (pathOnRemote(x) if isTestExe(x) else x for x in commandLine)
         remoteCommands.append('cd {}'.format(tmp))
         if args.env:
-            remoteCommands.append('export {}'.format(' '.join(args.env)))
+            remoteCommands.append('export {}'.format(cmd_quote(' '.join(args.env))))
         remoteCommands.append(subprocess.list2cmdline(commandLine))
 
         # Finally, SSH to the remote host and execute all the commands.