ShellDriver: put_key_file: write keys in chunks of 100 chars

Because of limits to the number of characters allowed on the command line,
break up the writing public ssh keys into 100 character chunks.

fixes labgrid-project#1627

Signed-off-by: Perry Melange <[email protected]>

Author: pmelange

labgrid/driver/shelldriver.py

@@ -213,6 +213,12 @@ def _inject_run(self):
         )
         self.console.expect(self.prompt)
 
+    def _write_key(self, keyline, dest):
+        for i in range(0, len(keyline), 100):
+            part = keyline[i:i+100]
+            self._run_check(f'echo -n "{part}" >> {dest}')
+        self._run_check(f'echo "" >> {dest}')
+
     @step(args=['keyfile_path', 'dest_authorized_keys'])
     def _put_ssh_key(self, keyfile_path, dest_authorized_keys):
         dest_authorized_keys_dir = os.path.dirname(dest_authorized_keys)
@@ -255,7 +261,7 @@ def _put_ssh_key(self, keyfile_path, dest_authorized_keys):
 
         if test_write == 0 and read_keys == 0:
             self.logger.debug("Key not on target and writeable, concatenating...")
-            self._run_check(f"""echo "{keyline}" >> {dest_authorized_keys}""")
+            self._write_key(keyline, dest_authorized_keys)
             self._run_check("rm ~/.test")
             return
 
@@ -267,14 +273,14 @@ def _put_ssh_key(self, keyfile_path, dest_authorized_keys):
                 self._run(f"""mkdir -p {dest_authorized_keys_dir}""")
             self._run_check(f"""chmod 700 {dest_authorized_keys_dir}""")
             self.logger.debug(f"""Creating {dest_authorized_keys}""")
-            self._run_check(f"""echo "{keyline}" > {dest_authorized_keys}""")
+            self._write_key(keylinei, dest_authorized_keys)
             self._run_check("rm ~/.test")
             return
 
         self.logger.debug("Key not on target and not writeable, using bind mount...")
         self._run_check('mkdir -m 700 /tmp/labgrid-ssh/')
         self._run(f"""cp -a {dest_authorized_keys_dir}/* /tmp/labgrid-ssh/""")
-        self._run_check(f"""echo "{keyline}" >> /tmp/labgrid-ssh/authorized_keys""")
+        self._write_key(keyline, "/tmp/labgrid-ssh/authorized_keys")
         self._run_check('chmod 600 /tmp/labgrid-ssh/authorized_keys')
         out, err, exitcode = self._run(f"""mount --bind /tmp/labgrid-ssh/ {dest_authorized_keys_dir}""")
         if exitcode != 0: