[tracker-miners] extract/msoffice-xml: Treat zero-length strings as unset properties

[Sam Thursfield <sthursfield src gnome org>]

commit a1e766cd12610b10617a334489e8d117be337019
Author: Sam Thursfield <sam thursfield codethink co uk>
Date:   Thu Sep 28 18:40:32 2017 +0100

    extract/msoffice-xml: Treat zero-length strings as unset properties
    
    The MS Office extractor has been producing stuff like this:
    
        <file:///home/sam/Downloads/spreadsheet.xls> nie:comment "" ;
          nie:contentLastModified "2016-06-13T14:19:50Z" ;
          nie:contentCreated "2016-05-14T10:17:05Z" ;
          nie:plainTextContent "..." ;
          nie:subject "" ;
          a nfo:PaginatedTextDocument ;
          nie:title "" .
    
    This breaks queries which use COALESCE to do things like this:
    
        SELECT COALESCE(?nie_title, ?filename) as ?title
    
    If ?nie_title is unset then ?title will be set to the contents of
    ?filename; but if ?nie_title is present and set to an empty string then
    ?title will set to that empty string, which is not at all useful.
    
    The extractor will now ignore zero-length strings. Rather than
    using strlen() (which has to search to the end of the string)
    we just check if the first byte is 0.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=788298

 src/tracker-extract/tracker-extract-msoffice-xml.c |   22 ++++++++++----------
 1 files changed, 11 insertions(+), 11 deletions(-)
---
diff --git a/src/tracker-extract/tracker-extract-msoffice-xml.c 
b/src/tracker-extract/tracker-extract-msoffice-xml.c
index 1c6516c..b45667e 100644
--- a/src/tracker-extract/tracker-extract-msoffice-xml.c
+++ b/src/tracker-extract/tracker-extract-msoffice-xml.c
@@ -434,7 +434,7 @@ msoffice_xml_metadata_parse (GMarkupParseContext  *context,
                if (info->has_title) {
                        g_warning ("Avoiding additional title (%s) in MsOffice XML document '%s'",
                                   text, info->uri);
-               } else {
+               } else if (text[0] != '\0') {
                        info->has_title = TRUE;
                        tracker_resource_set_string (info->metadata, "nie:title", text);
                }
@@ -444,7 +444,7 @@ msoffice_xml_metadata_parse (GMarkupParseContext  *context,
                if (info->has_subject) {
                        g_warning ("Avoiding additional subject (%s) in MsOffice XML document '%s'",
                                   text, info->uri);
-               } else {
+               } else if (text[0] != '\0') {
                        info->has_subject = TRUE;
                        tracker_resource_set_string (info->metadata, "nie:subject", text);
                }
@@ -454,7 +454,7 @@ msoffice_xml_metadata_parse (GMarkupParseContext  *context,
                if (info->has_publisher) {
                        g_warning ("Avoiding additional publisher (%s) in MsOffice XML document '%s'",
                                   text, info->uri);
-               } else {
+               } else if (text[0] != '\0') {
                        TrackerResource *publisher = tracker_extract_new_contact (text);
 
                        info->has_publisher = TRUE;
@@ -468,7 +468,7 @@ msoffice_xml_metadata_parse (GMarkupParseContext  *context,
                if (info->has_comment) {
                        g_warning ("Avoiding additional comment (%s) in MsOffice XML document '%s'",
                                   text, info->uri);
-               } else {
+               } else if (text[0] != '\0') {
                        info->has_comment = TRUE;
                        tracker_resource_set_string (info->metadata, "nie:comment", text);
                }
@@ -478,7 +478,7 @@ msoffice_xml_metadata_parse (GMarkupParseContext  *context,
                if (info->has_content_created) {
                        g_warning ("Avoiding additional creation time (%s) in MsOffice XML document '%s'",
                                   text, info->uri);
-               } else {
+               } else if (text[0] != '\0') {
                        gchar *date;
 
                        date = tracker_date_guess (text);
@@ -497,7 +497,7 @@ msoffice_xml_metadata_parse (GMarkupParseContext  *context,
                if (info->has_generator) {
                        g_warning ("Avoiding additional generator (%s) in MsOffice XML document '%s'",
                                   text, info->uri);
-               } else {
+               } else if (text[0] != '\0') {
                        info->has_generator = TRUE;
                        tracker_resource_set_string (info->metadata, "nie:generator", text);
                }
@@ -514,7 +514,7 @@ msoffice_xml_metadata_parse (GMarkupParseContext  *context,
                if (info->has_content_last_modified) {
                        g_warning ("Avoiding additional last modification time (%s) in MsOffice XML document 
'%s'",
                                   text, info->uri);
-               } else {
+               } else if (text[0] != '\0') {
                        gchar *date;
 
                        date = tracker_date_guess (text);
@@ -533,7 +533,7 @@ msoffice_xml_metadata_parse (GMarkupParseContext  *context,
                if (info->has_page_count) {
                        g_warning ("Avoiding additional page count (%s) in MsOffice XML document '%s'",
                                   text, info->uri);
-               } else {
+               } else if (text[0] != '\0') {
                        info->has_page_count = TRUE;
                        tracker_resource_set_string (info->metadata, "nfo:pageCount", text);
                }
@@ -543,7 +543,7 @@ msoffice_xml_metadata_parse (GMarkupParseContext  *context,
                if (info->has_char_count) {
                        g_warning ("Avoiding additional character count (%s) in MsOffice XML document '%s'",
                                   text, info->uri);
-               } else {
+               } else if (text[0] != '\0') {
                        info->has_char_count = TRUE;
                        tracker_resource_set_string (info->metadata, "nfo:characterCount", text);
                }
@@ -553,7 +553,7 @@ msoffice_xml_metadata_parse (GMarkupParseContext  *context,
                if (info->has_word_count) {
                        g_warning ("Avoiding additional word count (%s) in MsOffice XML document '%s'",
                                   text, info->uri);
-               } else {
+               } else if (text[0] != '\0') {
                        info->has_word_count = TRUE;
                        tracker_resource_set_string (info->metadata, "nfo:wordCount", text);
                }
@@ -563,7 +563,7 @@ msoffice_xml_metadata_parse (GMarkupParseContext  *context,
                if (info->has_line_count) {
                        g_warning ("Avoiding additional line count (%s) in MsOffice XML document '%s'",
                                   text, info->uri);
-               } else {
+               } else if (text[0] != '\0') {
                        info->has_line_count = TRUE;
                        tracker_resource_set_string (info->metadata, "nfo:lineCount", text);
                }