[msitools] Prevent null pointer dereference in memset

[Marc-Andre Lureau <malureau src gnome org>]

commit 56738e0440e1617a90b6b76e1b6eb355601a268a
Author: Stephen Kitt <steve sk2 org>
Date:   Sun Nov 30 17:49:00 2014 +0000

    Prevent null pointer dereference in memset
    
    This is copied from Wine's deb274226783ab886bdb44876944e156757efe2b
    msi: Prevent call to memset with a null pointer in get_tablecolumns function.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=740901

 libmsi/table.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/libmsi/table.c b/libmsi/table.c
index 895d5e0..5c207e3 100644
--- a/libmsi/table.c
+++ b/libmsi/table.c
@@ -669,7 +669,7 @@ static unsigned get_tablecolumns( LibmsiDatabase *db, const char *szTableName, L
     /* Note: _Columns table doesn't have non-persistent data */
 
     /* if maxcount is non-zero, assume it's exactly right for this table */
-    memset( colinfo, 0, maxcount * sizeof(*colinfo) );
+    if (colinfo) memset( colinfo, 0, maxcount * sizeof(*colinfo) );
     count = table->row_count;
     for (i = 0; i < count; i++)
     {
@@ -682,7 +682,7 @@ static unsigned get_tablecolumns( LibmsiDatabase *db, const char *szTableName, L
             /* check the column number is in range */
             if (col < 1 || col > maxcount)
             {
-                g_critical("column %d out of range\n", col);
+                g_critical("column %d out of range (maxcount: %d)\n", col, maxcount);
                 continue;
             }
             /* check if this column was already set */