bugfixes to JSON junk filter, added unit/integration tests to exercise (#17834)

lib/ansible/module_utils/json_utils.py

@@ -0,0 +1,75 @@
+# This code is part of Ansible, but is an independent component.
+# This particular file snippet, and this file snippet only, is BSD licensed.
+# Modules you write using this snippet, which is embedded dynamically by Ansible
+# still belong to the author of the module, and may assign their own license
+# to the complete work.
+#
+# Redistribution and use in source and binary forms, with or without modification,
+# are permitted provided that the following conditions are met:
+#
+#    * Redistributions of source code must retain the above copyright
+#      notice, this list of conditions and the following disclaimer.
+#    * Redistributions in binary form must reproduce the above copyright notice,
+#      this list of conditions and the following disclaimer in the documentation
+#      and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+# IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
+# USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+
+try:
+    import json
+except ImportError:
+    import simplejson as json
+
+# NB: a copy of this function exists in ../../modules/core/async_wrapper.py. Ensure any
+# changes are propagated there.
+def _filter_non_json_lines(data):
+    '''
+    Used to filter unrelated output around module JSON output, like messages from
+    tcagetattr, or where dropbear spews MOTD on every single command (which is nuts).
+
+    Filters leading lines before first line-starting occurrence of '{' or '[', and filter all
+    trailing lines after matching close character (working from the bottom of output).
+    '''
+    warnings = []
+
+    # Filter initial junk
+    lines = data.splitlines()
+
+    for start, line in enumerate(lines):
+        line = line.strip()
+        if line.startswith(u'{'):
+            endchar = u'}'
+            break
+        elif line.startswith(u'['):
+            endchar = u']'
+            break
+    else:
+        raise ValueError('No start of json char found')
+
+    # Filter trailing junk
+    lines = lines[start:]
+
+    for reverse_end_offset, line in enumerate(reversed(lines)):
+        if line.strip().endswith(endchar):
+            break
+    else:
+        raise ValueError('No end of json char found')
+
+    if reverse_end_offset > 0:
+        # Trailing junk is uncommon and can point to things the user might
+        # want to change.  So print a warning if we find any
+        trailing_junk = lines[len(lines) - reverse_end_offset:]
+        warnings.append('Module invocation had junk after the JSON data: %s' % '\n'.join(trailing_junk))
+
+    lines = lines[:(len(lines) - reverse_end_offset)]
+
+    return ('\n'.join(lines), warnings)