[libgsf] ole: fix problem with error handling when writing.

[Morten Welinder <mortenw src gnome org>]

commit ba3cee59b33f46c0512f675d5f876793be9c1467
Author: Morten Welinder <terra gnome org>
Date:   Wed May 11 18:01:12 2022 -0400

    ole: fix problem with error handling when writing.
    
    Things could get into a really bad state and cause a loop.

 NEWS                    |  3 +++
 gsf/gsf-outfile-msole.c | 65 +++++++++++++++++++++++++++++++++----------------
 2 files changed, 47 insertions(+), 21 deletions(-)
---
diff --git a/NEWS b/NEWS
index 82afb07a..cb831484 100644
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,8 @@
 libgsf 1.14.50
 
+Morten:
+       * Fix error handling problem when writing ole files.  [#27]
+
 --------------------------------------------------------------------------
 libgsf 1.14.49
 
diff --git a/gsf/gsf-outfile-msole.c b/gsf/gsf-outfile-msole.c
index 6490e740..266151dc 100644
--- a/gsf/gsf-outfile-msole.c
+++ b/gsf/gsf-outfile-msole.c
@@ -300,9 +300,9 @@ ole_pad_bat_unused (GsfOutfileMSOle *ole, unsigned residual)
                (ole_bytes_left_in_block (ole) / BAT_INDEX_SIZE) - residual);
 }
 
-/* write the metadata (dirents, small block, xbats) and close the sink */
+/* write the metadata (dirents, small block, xbats) */
 static gboolean
-gsf_outfile_msole_close_root (GsfOutfileMSOle *ole)
+gsf_outfile_msole_write_directory (GsfOutfileMSOle *ole)
 {
        GsfOutfile *tmp;
        guint8  buf [OLE_HEADER_SIZE];
@@ -454,22 +454,29 @@ gsf_outfile_msole_close_root (GsfOutfileMSOle *ole)
         */
        num_bat = 0;
        num_xbat = 0;
-recalc_bat_bat :
-       i = ((ole->sink->cur_size
-             + BAT_INDEX_SIZE * (num_bat + num_xbat)
-             - OLE_HEADER_SIZE - 1) >> ole->bb.shift) + 1;
-       i -= bat_start;
-       if (num_bat != i) {
-               num_bat = i;
-               goto recalc_bat_bat;
-       }
-       i = 0;
-       if (num_bat > OLE_HEADER_METABAT_SIZE)
-               i = 1 + ((num_bat - OLE_HEADER_METABAT_SIZE - 1)
-                        / metabat_size);
-       if (num_xbat != i) {
-               num_xbat = i;
-               goto recalc_bat_bat;
+       while (gsf_output_error (ole->sink) == NULL) {
+               // If we have an error, then the actual size as reported
+               // by _tell and ->cur_size may be out of sync.  We don't
+               // want to loop forever here.
+
+               unsigned i = ((ole->sink->cur_size
+                     + BAT_INDEX_SIZE * (num_bat + num_xbat)
+                     - OLE_HEADER_SIZE - 1) >> ole->bb.shift) + 1;
+               i -= bat_start;
+               if (num_bat != i) {
+                       num_bat = i;
+                       continue;
+               }
+               i = 0;
+               if (num_bat > OLE_HEADER_METABAT_SIZE)
+                       i = 1 + ((num_bat - OLE_HEADER_METABAT_SIZE - 1)
+                                / metabat_size);
+               if (num_xbat != i) {
+                       num_xbat = i;
+                       continue;
+               }
+
+               break;
        }
 
        ole_write_const (ole->sink, BAT_MAGIC_BAT, num_bat);
@@ -541,16 +548,32 @@ recalc_bat_bat :
        g_ptr_array_free (elem, TRUE);
        ole->content.dir.root_order = NULL;
 
-       return gsf_output_close (ole->sink);
+       return TRUE;
 }
 
+static void
+gsf_outfile_msole_hoist_error (GsfOutfileMSOle *ole)
+{
+       GsfOutput *oole = GSF_OUTPUT (ole);
+       if (gsf_output_error (oole) == NULL &&
+           gsf_output_error (ole->sink)) {
+               oole->err = g_error_copy (ole->sink->err);
+       }
+}
+
+
 static gboolean
 gsf_outfile_msole_close (GsfOutput *output)
 {
        GsfOutfileMSOle *ole = (GsfOutfileMSOle *)output;
 
-       if (gsf_output_container (output) == NULL)      /* The root dir */
-               return gsf_outfile_msole_close_root (ole);
+       if (gsf_output_container (output) == NULL) {    /* The root dir */
+               gboolean ok = gsf_outfile_msole_write_directory (ole);
+               gsf_outfile_msole_hoist_error (ole);
+               if (!gsf_output_close (ole->sink))
+                       ok = FALSE;
+               return ok;
+       }
 
        if (ole->type == MSOLE_BIG_BLOCK) {
                gsf_outfile_msole_seek (output, 0, G_SEEK_END);