[libgsf] msole: first attempt at writing non-ascii properties.

[Morten Welinder <mortenw src gnome org>]

commit 6ac8154c729e149b998fcef48ceafc7834898076
Author: Morten Welinder <terra gnome org>
Date:   Fri Feb 25 20:21:24 2022 -0500

    msole: first attempt at writing non-ascii properties.
    
    We guess a codepage for strings instead of just using 1252.
    If anything doesn't convert to 1252, we switch to -535 which,
    apparently, means UTF-8.

 gsf/gsf-msole-utils.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 97 insertions(+), 1 deletion(-)
---
diff --git a/gsf/gsf-msole-utils.c b/gsf/gsf-msole-utils.c
index 6978b685..1c224ce7 100644
--- a/gsf/gsf-msole-utils.c
+++ b/gsf/gsf-msole-utils.c
@@ -1694,6 +1694,91 @@ cb_count_props (char const *name, GsfDocProp *prop, WritePropState *state)
        }
 }
 
+static void
+guess_codepage_string (WritePropState *state, const char *str)
+{
+       const char *p;
+       gboolean is_ascii;
+       gsize bytes_written;
+       char *cstr;
+
+       if (state->codepage)
+               return;
+
+       if (!str)
+               return;
+
+       // Don't bother with ascii strings
+       is_ascii = TRUE;
+       for (p = str; *p && is_ascii; p++)
+               is_ascii = (*p & 0x80) == 0;
+       if (is_ascii)
+               return;
+
+       cstr = g_convert_with_iconv (str, strlen (str), state->iconv_handle,
+                                    NULL, &bytes_written, NULL);
+       if (cstr) {
+               g_free (cstr);
+               return;
+       }
+
+       // Conversion failed.  Switch to UTF-8
+       state->codepage = -535;
+}
+
+static void
+guess_codepage_prop (WritePropState *state, const char *name, GValue const *value)
+{
+       GsfMSOleMetaDataPropMap const *map =
+               (name != NULL) ? msole_gsf_name_to_prop (name) : NULL;
+       GsfMSOleVariantType type;
+
+       type = gvalue_to_msole_vt (value, map);
+
+       if (type & VT_VECTOR) {
+               GArray *vector = gsf_value_get_docprop_array (value);
+               unsigned i, n = vector->len;
+               for (i = 0; i < n; i++)
+                       guess_codepage_prop (state, NULL, &g_array_index (vector, GValue, i));
+               return;
+       }
+
+       switch (type) {
+       case VT_LPSTR:
+               guess_codepage_string (state, g_value_get_string (value));
+               return;
+       default:
+               // Don't care.
+               return;
+       }
+}
+
+static void
+guess_codepage (WritePropState *state, gboolean user)
+{
+       GSList   *ptr   = user ? state->user.props : state->builtin.props;
+       unsigned  count = user ? state->user.count : state->builtin.count;
+       unsigned i = 0;
+
+       if (i < count) {
+               // Codepage
+               i++;
+       }
+
+       if (user && i < count) {
+               // Dictionary
+               i++;
+       }
+
+       for (; ptr != NULL && i < count ; ptr = ptr->next, i++) {
+               GsfDocProp const *prop = ptr->data;
+               const char *name = gsf_doc_prop_get_name (prop);
+               guess_codepage_string (state, name);
+               guess_codepage_prop (state, name, gsf_doc_prop_get_val (prop));
+       }
+}
+
+
 /**
  * gsf_doc_meta_data_write_to_msole:
  * @out: #GsfOutput
@@ -1720,8 +1805,9 @@ gsf_doc_meta_data_write_to_msole (GsfDocMetaData const *meta_data,
        gboolean        success = FALSE;
        guint8          buf [4];
        WritePropState  state;
+       const int default_codepage = 1252;
 
-       state.codepage          = 1252;
+       state.codepage          = 0;
        state.iconv_handle      = (GIConv)-1;
        state.char_size         = 1;
        state.out               = out;
@@ -1736,6 +1822,16 @@ gsf_doc_meta_data_write_to_msole (GsfDocMetaData const *meta_data,
        d (g_print ("Done\n"
                    "================================\n"););
 
+       state.iconv_handle = gsf_msole_iconv_open_codepage_for_export (default_codepage);
+       if (state.codepage == 0) {
+               guess_codepage (&state, FALSE);
+               if (state.dict)
+                       guess_codepage (&state, TRUE);
+               if (state.codepage == 0)
+                       state.codepage = default_codepage;
+       }
+       gsf_iconv_close (state.iconv_handle);
+
        state.iconv_handle = gsf_msole_iconv_open_codepage_for_export (state.codepage);
        state.char_size = msole_codepage_char_size (state.codepage);