[msitools] libmsi: don't crash on invalid string conversion

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

commit e02b155b332df452a9df86984e11eb8a1772aa86
Author: Marc-André Lureau <marcandre lureau gmail com>
Date:   Fri Nov 8 14:13:39 2013 +0100

    libmsi: don't crash on invalid string conversion
    
    SSIA, TODO: check if "forcecodepage" is used correctly.
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1027256

 libmsi/string.c |   13 ++++++++++---
 1 files changed, 10 insertions(+), 3 deletions(-)
---
diff --git a/libmsi/string.c b/libmsi/string.c
index 9514d46..0dfa003 100644
--- a/libmsi/string.c
+++ b/libmsi/string.c
@@ -200,6 +200,8 @@ static void insert_string_sorted( string_table *st, unsigned string_id )
 
 static void set_st_entry( string_table *st, unsigned n, char *str, uint16_t refcount, enum StringPersistence 
persistence )
 {
+    g_return_if_fail(str != NULL);
+
     if (persistence == StringPersistent)
     {
         st->strings[n].persistent_refcount = refcount;
@@ -253,6 +255,7 @@ static int msi_addstring( string_table *st, unsigned n, const char *data, int le
     size_t sz;
     int codepage;
     GIConv cpconv;
+    GError *err = NULL;
 
     if( !data )
         return 0;
@@ -288,10 +291,14 @@ static int msi_addstring( string_table *st, unsigned n, const char *data, int le
     /* allocate a new string */
     codepage = st->codepage ? st->codepage : gsf_msole_iconv_win_codepage();
     cpconv = gsf_msole_iconv_open_for_import(codepage);
-    str = g_convert_with_iconv(data, len, cpconv, NULL, &sz, NULL);
+    str = g_convert_with_iconv(data, len, cpconv, NULL, &sz, &err);
     g_iconv_close(cpconv);
-
-    set_st_entry( st, n, str, refcount, persistence );
+    if (err) {
+        g_warning("iconv failed: %s", err->message);
+        g_clear_error(&err);
+    } else {
+        set_st_entry( st, n, str, refcount, persistence);
+    }
 
     return n;
 }