[libcxx] [test] Run `chmod +x` on executables when testing via SSH

[broadwaylamb]

Summary

When running libc++ tests on a remote machine via SSH, we can encounter
a 'Permission denied' error.

Fix this with plain old 'chmod +x <executable>'.

[broadwaylamb]

Execute chmod +x without creating a separate connection

[ldionne]

libcxx/utils/libcxx/test/executor.py

139

Do I understand correctly: the problem is that files are created on Windows and then scp'd to Linux, but there is no executable bit set on Windows so the files arrive on Linux as not executable?

142

You're assuming that we have chmod on the system, but what if we're instead remotely executing binaries compiled on Linux for Windows (not sure that's even a thing, but you get the point)?

[ldionne]

Requesting changes so it shows up properly in my review queue.

[broadwaylamb]

libcxx/utils/libcxx/test/executor.py

139

Yes, exactly.

142

In D68275 I made Executor depend on the target info object, so we can ask if the target system is not Windows, and only then set the executable bit.

But if there are better solutions, I'm ready to investigate them.

[broadwaylamb]

libcxx/utils/libcxx/test/executor.py

147–149

Found a bug in this line: in the _execute_command_remote method we actually prepend the env command to set the execution environment. However, because of this patch, the env command is only applied to chmod.

I'm going to send a fix.

[broadwaylamb]

Use export instead of env for setting execution environment in SSHExecutor.

This is safe, because the exported environment can't outlive the SSH session, which itself is alive only within the _execute_command_remote method.

[ldionne]

LGTM with the requested change.

libcxx/utils/libcxx/test/executor.py

203

This seems clearer to me:

if export_cmd:
  remote_cmd = ' '.join(export_cmd) + ' && ' + remote_cmd

[broadwaylamb]

Use a simpler condition syntax in executor.py

[broadwaylamb]

@ldionne if everything is good, can we land this?

libcxx/utils/libcxx/test/executor.py

203

Oh. Of course. Updated accordingly.

libcxx/utils/libcxx/test/executor.py

def run(self, exe_path, cmd=None, work_dir='.', file_deps=None, env=None):
             srcs = [exe_path]
             dsts = [target_exe_path]
             if file_deps is not None:
                 dev_paths = [os.path.join(target_cwd, os.path.basename(f))
                              for f in file_deps]
                 srcs.extend(file_deps)
                 dsts.extend(dev_paths)
             self.copy_in(srcs, dsts)
+
+            # When testing executables that were cross-compiled on Windows for
+            # Linux, we may need to explicitly set the execution permission to
+            # avoid the 'Permission denied' error:
+            chmod_cmd = ['chmod', '+x', target_exe_path]
+
             # TODO(jroelofs): capture the copy_in and delete_remote commands,
             # and conjugate them with '&&'s around the first tuple element
             # returned here:
-            return self._execute_command_remote(cmd, target_cwd, env)
+            return self._execute_command_remote(chmod_cmd + ['&&'] + cmd,
+                                                target_cwd,
+                                                env)
         finally:
             if target_cwd:
                 self.delete_remote(target_cwd)
 
     def _execute_command_remote(self, cmd, remote_work_dir='.', env=None):
         raise NotImplementedError()
 
 
def _copy_in_file(self, src, dst):
         remote = self.user_prefix + remote
         cmd = [scp, '-p', src, remote + ':' + dst]
         self.local_run(cmd)
 
     def _execute_command_remote(self, cmd, remote_work_dir='.', env=None):
         remote = self.user_prefix + self.host
         ssh_cmd = [self.ssh_command, '-oBatchMode=yes', remote]
         if env:
-            env_cmd = ['env'] + ['%s="%s"' % (k, v) for k, v in env.items()]
+            export_cmd = \
+                ['export'] + ['"%s"="%s"' % (k, v) for k, v in env.items()]
         else:
-            env_cmd = []
-        remote_cmd = ' '.join(env_cmd + cmd)
+            export_cmd = []
+
+        remote_cmd = ' '.join(cmd)
+        if export_cmd:
+            remote_cmd = ' '.join(export_cmd) + ' && ' + remote_cmd
         if remote_work_dir != '.':
             remote_cmd = 'cd ' + remote_work_dir + ' && ' + remote_cmd
         out, err, rc = self.local_run(ssh_cmd + [remote_cmd])
         return (remote_cmd, out, err, rc)