[gnumeric] Fix crash on resaving LibreOffice created xlsx files with unauthored comments. [#642850]

[Andreas J. Guelzow <guelzow src gnome org>]

commit 91f8a58d3d93532248f67c0a9006f0b4975a1928
Author: Andreas J Guelzow <aguelzow pyrshep ca>
Date:   Mon Feb 21 22:25:36 2011 -0700

    Fix crash on resaving LibreOffice created xlsx files with unauthored comments. [#642850]
    
    2011-02-21  Andreas J. Guelzow <aguelzow pyrshep ca>
    
    	* xlsx-write.c (xlsx_write_comments): skip NULL author
    	(see glib bug #642944)

 NEWS                       |    2 ++
 plugins/excel/ChangeLog    |    5 +++++
 plugins/excel/xlsx-write.c |    7 +++++--
 3 files changed, 12 insertions(+), 2 deletions(-)
---
diff --git a/NEWS b/NEWS
index 0530eb7..661d5b9 100644
--- a/NEWS
+++ b/NEWS
@@ -7,6 +7,8 @@ Andreas:
 	* Minor histogram improvements.
 	* Fix import of LibreOffice created xlsx files using shared formulas. 
 	  [#642850]
+	* Fix crash on resaving LibreOffice created xlsx files with unauthored 
+	  comments. [#642850]
 
 Jean:
 	* Fix cursor position inside a cell edited in a zoomed sheet. [#641709]
diff --git a/plugins/excel/ChangeLog b/plugins/excel/ChangeLog
index cc77e7c..411ce3c 100644
--- a/plugins/excel/ChangeLog
+++ b/plugins/excel/ChangeLog
@@ -1,5 +1,10 @@
 2011-02-21  Andreas J. Guelzow <aguelzow pyrshep ca>
 
+	* xlsx-write.c (xlsx_write_comments): skip NULL author 
+	(see glib bug #642944)
+
+2011-02-21  Andreas J. Guelzow <aguelzow pyrshep ca>
+
 	* xlsx-read.c (xlsx_chart_dtd): add c:crossesAt
 	(xlsx_cell_expr_begin): don't ignore shared expressions with 
 	duplicate id
diff --git a/plugins/excel/xlsx-write.c b/plugins/excel/xlsx-write.c
index c589a72..129853e 100644
--- a/plugins/excel/xlsx-write.c
+++ b/plugins/excel/xlsx-write.c
@@ -1352,7 +1352,7 @@ xlsx_write_comments (XLSXWriteState *state, GsfOutput *sheet_part, GSList *objec
 	authors = g_hash_table_new (g_str_hash, g_str_equal);
 	for (ptr = objects; ptr; ptr = ptr->next) {
 		authorname = cell_comment_author_get (CELL_COMMENT (ptr->data));
-		if (!g_hash_table_lookup_extended (authors, authorname, NULL, NULL))
+		if (authorname != NULL && !g_hash_table_lookup_extended (authors, authorname, NULL, NULL))
 			g_hash_table_insert (authors, (gpointer) authorname, GUINT_TO_POINTER (author++));
 	}
 	/* save authors */
@@ -1365,7 +1365,10 @@ xlsx_write_comments (XLSXWriteState *state, GsfOutput *sheet_part, GSList *objec
 		gsf_xml_out_start_element (xml, "comment");
 		anchor = sheet_object_get_anchor (ptr->data);
 		gsf_xml_out_add_cstr_unchecked (xml, "ref", range_as_string (&anchor->cell_bound));
-		gsf_xml_out_add_uint (xml, "authorId", GPOINTER_TO_UINT (g_hash_table_lookup (authors, cell_comment_author_get (CELL_COMMENT (ptr->data)))));
+		authorname = cell_comment_author_get (CELL_COMMENT (ptr->data));
+		if (authorname != NULL)
+			gsf_xml_out_add_uint (xml, "authorId", 
+					      GPOINTER_TO_UINT (g_hash_table_lookup (authors, authorname)));
 		gsf_xml_out_start_element (xml, "text");
 		/* Save text as rich text */
 		g_object_get (ptr->data, "text", &name, "markup", &attrs, NULL);