Remove empty entries in elog lookup meta data

A journal entry is produced for failure to find empty string meta data
for elogs due to an empty string entry within the generated elog lookup
source. This empty string is due to error yamls that do not contain any
meta data entry of their own and only inherit from another error yaml.

An example of the journal entry for the empty string meta data that is
removed with this fix::

    CODE_LINE=76
    CODE_FUNC=helper_log
    _SYSTEMD_SLICE=system.slice
    CODE_FILE=../git/phosphor-logging/log.hpp
    MESSAGE=Failed to find metadata
    TRANSACTION_ID=4016514682
    META_FIELD=
    SYSLOG_IDENTIFIER=phosphor-log-manager
    _PID=181
    _COMM=phosphor-log-ma
    _EXE=/usr/bin/phosphor-log-manager

Tested:
    Built image and verified empty string entry no longer generated on
errors without meta data but inherit meta data from other error yaml

Change-Id: I3c8745acd86173873827cd59eb6e8d4f687b0e1b
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>

1 files changed, 9 insertions, 7 deletions

diff --git a/tools/phosphor-logging/templates/elog-lookup-template.mako.cpp b/tools/phosphor-logging/templates/elog-lookup-template.mako.cpp
index e29b7a9..c9361d8 100644
--- a/tools/phosphor-logging/templates/elog-lookup-template.mako.cpp
+++ b/tools/phosphor-logging/templates/elog-lookup-template.mako.cpp
@@ -16,18 +16,20 @@ namespace logging
 const std::map<std::string,std::vector<std::string>> g_errMetaMap = {
     % for name in errors:
 <%
+    meta_string = ""
     meta_list = []
-    if(name in meta):
+    if(name in meta and meta[name]):
         meta_list = meta[name]
-    meta_string = '\",\"'.join(meta_list)
+        meta_string = '\",\"'.join(meta_list)
 
     parent = parents[name]
     while parent:
-        tmpparent = parent.split('.')
-        ## Name is the last item
-        parent_name = tmpparent[-1]
-        parent_meta_short = '\",\"'.join(meta[parent])
-        meta_string = meta_string + "\",\"" + parent_meta_short
+        if (parent in meta and meta[parent]):
+            parent_meta_short = '\",\"'.join(meta[parent])
+            if (meta_string):
+                meta_string = meta_string + "\",\"" + parent_meta_short
+            else:
+                meta_string = parent_meta_short
         parent = parents[parent]
     if ("example.xyz.openbmc_project" not in name):
         index = name.rfind('.')