[gnumeric] Fix BIFF7 export of comments.

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

commit 1bdb115fe42a8525072fc91b25b48ba66c50108a
Author: Morten Welinder <terra gnome org>
Date:   Sat Feb 22 13:06:09 2014 -0700

    Fix BIFF7 export of comments.

 NEWS                           |    1 +
 plugins/excel/ChangeLog        |    6 ++
 plugins/excel/ms-excel-write.c |  103 ++++++++++++++++++++++++++++++---------
 3 files changed, 86 insertions(+), 24 deletions(-)
---
diff --git a/NEWS b/NEWS
index 248310d..1109220 100644
--- a/NEWS
+++ b/NEWS
@@ -27,6 +27,7 @@ Morten:
        * Fix xls export of long strings in formulas.
        * Fix xls import of cells with long string results.
        * Fix xls export of long strings in various places.
+       * Fix BIFF7 export of comments.
 
 --------------------------------------------------------------------------
 Gnumeric 1.12.11
diff --git a/plugins/excel/ChangeLog b/plugins/excel/ChangeLog
index c66394c..9d65fcd 100644
--- a/plugins/excel/ChangeLog
+++ b/plugins/excel/ChangeLog
@@ -1,3 +1,9 @@
+2014-02-22  Morten Welinder  <terra gnome org>
+
+       * ms-excel-write.c (excel_convert_string): New function.
+       (excel_write_comments_biff7): Avoid infinite loop when a comment
+       contains characters that cannot be represented in the codepage.
+
 2014-02-21  Morten Welinder  <terra gnome org>
 
        * ms-excel-read.c (excel_read_FORMULA): Try to handle missing
diff --git a/plugins/excel/ms-excel-write.c b/plugins/excel/ms-excel-write.c
index 51561b8..d70e1d2 100644
--- a/plugins/excel/ms-excel-write.c
+++ b/plugins/excel/ms-excel-write.c
@@ -284,6 +284,69 @@ excel_strlen (guint8 const *str, size_t *bytes)
        return i;
 }
 
+static gpointer
+excel_convert_string (BiffPut *bp, const char *txt, size_t *out_bytes)
+{
+       GError *err = NULL;
+       size_t bytes_read;
+       GString *accum;
+       gpointer res;
+
+       res = g_convert_with_iconv
+               (txt, -1,
+                bp->convert,
+                &bytes_read, out_bytes,
+                &err);
+       if (res)
+               return res;
+
+       if (!g_error_matches (err, G_CONVERT_ERROR, G_CONVERT_ERROR_ILLEGAL_SEQUENCE)) {
+               g_error_free (err);
+               g_printerr ("Unexpected conversion error for string\n");
+               *out_bytes = 0;
+               return g_strdup ("");
+       }
+
+       /*
+        * Invalid character.  Be crude: convert the sequence before,
+        * add a fallback character, and finally convert the sequence
+        * after.
+        */
+       accum = g_string_new (NULL);
+
+       res = g_convert_with_iconv
+               (txt, bytes_read,
+                bp->convert,
+                NULL, out_bytes,
+                NULL);
+       if (res) {
+               g_string_append_len (accum, res, *out_bytes);
+               g_free (res);
+       }
+
+       res = g_convert_with_iconv
+               ("?", -1,
+                bp->convert,
+                NULL, out_bytes,
+                NULL);
+       if (res) {
+               g_string_append_len (accum, res, *out_bytes);
+               g_free (res);
+       }
+
+       res = excel_convert_string (bp,
+                                   g_utf8_next_char (txt + bytes_read),
+                                   out_bytes);
+       if (res) {
+               g_string_append_len (accum, res, *out_bytes);
+               g_free (res);
+       }
+
+       *out_bytes = accum->len;
+       return g_string_free (accum, FALSE);
+}
+
+
 static guint32
 string_maxlen[4] = {
        /* STR_ONE_BYTE_LENGTH */  G_MAXUINT8,
@@ -3391,40 +3454,32 @@ excel_write_comments_biff7 (BiffPut *bp, ExcelWriteSheet *esheet)
 
        for (l = esheet->comments; l; l = l->next) {
                GnmComment const *cc = l->data;
-               guint8 data[6];
                GnmRange const *pos = sheet_object_get_range (SHEET_OBJECT (cc));
-               char const  *in = cell_comment_text_get (cc);
-               size_t in_bytes, out_bytes;
-               unsigned len = excel_strlen (in, &in_bytes);
-               char *buf;
+               char const *in = cell_comment_text_get (cc);
+               size_t out_bytes, o;
+               gpointer convstr;
 
                g_return_if_fail (in != NULL);
                g_return_if_fail (pos != NULL);
 
-               ms_biff_put_var_next (bp, BIFF_NOTE);
-               GSF_LE_SET_GUINT16 (data + 0, pos->start.row);
-               GSF_LE_SET_GUINT16 (data + 2, pos->start.col);
-               GSF_LE_SET_GUINT16 (data + 4, len);
-               ms_biff_put_var_write (bp, data, 6);
-
-repeat:
-               buf = bp->buf;
-               out_bytes = MAX_BIFF_NOTE_CHUNK; /* bp::buf is always at least this big */
-               g_iconv (bp->convert, (char **)&in, &in_bytes, &buf, &out_bytes);
-               if (in_bytes > 0) {
-                       ms_biff_put_var_write (bp, bp->buf, MAX_BIFF_NOTE_CHUNK);
-                       ms_biff_put_commit (bp);
+               gsf_mem_dump (in, strlen (in));
+               convstr = excel_convert_string (bp, in, &out_bytes);
+               gsf_mem_dump (convstr, out_bytes);
+
+               for (o = 0; o < out_bytes; o += MAX_BIFF_NOTE_CHUNK) {
+                       guint8 data[6];
+                       size_t this_len = MIN (MAX_BIFF_NOTE_CHUNK, out_bytes - o);
 
                        ms_biff_put_var_next (bp, BIFF_NOTE);
-                       GSF_LE_SET_GUINT16 (data + 0, 0xffff);
-                       GSF_LE_SET_GUINT16 (data + 2, 0);
-                       GSF_LE_SET_GUINT16 (data + 4, MIN (MAX_BIFF_NOTE_CHUNK, in_bytes));
+                       GSF_LE_SET_GUINT16 (data + 0, o ? 0xffff : pos->start.row);
+                       GSF_LE_SET_GUINT16 (data + 2, o ? 0      : pos->start.col);
+                       GSF_LE_SET_GUINT16 (data + 4, o ? this_len : out_bytes);
                        ms_biff_put_var_write (bp, data, 6);
-                       goto repeat;
-               } else {
-                       ms_biff_put_var_write (bp, bp->buf, MAX_BIFF_NOTE_CHUNK);
+
+                       ms_biff_put_var_write (bp, (char *)convstr + o, this_len);
                        ms_biff_put_commit (bp);
                }
+               g_free (convstr);
        }
 }