[libgsf] ole2: fix seek error check

[Morten Welinder <mortenw src gnome org>]

commit a46106a428f78055d8e7d12d8728284dcc02285e
Author: Morten Welinder <terra gnome org>
Date:   Mon Jul 6 13:28:58 2015 -0400

    ole2: fix seek error check

 ChangeLog              |    5 +++++
 gsf/gsf-infile-msole.c |   27 +++++++++++++++++++--------
 2 files changed, 24 insertions(+), 8 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 0b56cf8..92d8ba4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2015-07-06  Morten Welinder  <terra gnome org>
+
+       * gsf/gsf-infile-msole.c (ole_init_info): Add debug code.
+       (gsf_infile_msole_new_child): Fix error check from seek.
+
 2015-07-02  Morten Welinder  <terra gnome org>
 
        * gsf/gsf-msole-utils.c (msole_prop_parse): Exit loop if no
diff --git a/gsf/gsf-infile-msole.c b/gsf/gsf-infile-msole.c
index 06cbb03..400e0bb 100644
--- a/gsf/gsf-infile-msole.c
+++ b/gsf/gsf-infile-msole.c
@@ -492,7 +492,7 @@ ole_init_info (GsfInfileMSOle *ole, GError **err)
        guint8 const *header, *tmp;
        guint32 *metabat = NULL;
        MSOleInfo *info;
-       guint32 bb_shift, sb_shift, num_bat, num_metabat, last, dirent_start;
+       guint32 bb_shift, sb_shift, num_bat, num_sbat, num_metabat, threshold, last, dirent_start;
        guint32 metabat_block, *ptr;
        gboolean fail;
 
@@ -509,10 +509,22 @@ ole_init_info (GsfInfileMSOle *ole, GError **err)
        bb_shift      = GSF_LE_GET_GUINT16 (header + OLE_HEADER_BB_SHIFT);
        sb_shift      = GSF_LE_GET_GUINT16 (header + OLE_HEADER_SB_SHIFT);
        num_bat       = GSF_LE_GET_GUINT32 (header + OLE_HEADER_NUM_BAT);
+       num_sbat      = GSF_LE_GET_GUINT32 (header + OLE_HEADER_NUM_SBAT);
+       threshold     = GSF_LE_GET_GUINT32 (header + OLE_HEADER_THRESHOLD);
        dirent_start  = GSF_LE_GET_GUINT32 (header + OLE_HEADER_DIRENT_START);
         metabat_block = GSF_LE_GET_GUINT32 (header + OLE_HEADER_METABAT_BLOCK);
        num_metabat   = GSF_LE_GET_GUINT32 (header + OLE_HEADER_NUM_METABAT);
 
+       if (gsf_debug_flag ("OLE2")) {
+               g_printerr ("bb_shift=%d (size=%d)\n", bb_shift, 1 << bb_shift);
+               g_printerr ("sb_shift=%d (size=%d)\n", sb_shift, 1 << sb_shift);
+               g_printerr ("num_bat=%d (0x%08x)\n", num_bat, num_bat);
+               g_printerr ("num_sbat=%d (0x%08x)\n", num_sbat, num_sbat);
+               g_printerr ("threshold=%d (0x%08x)\n", threshold, threshold);
+               g_printerr ("dirent_start=0x%08x\n", dirent_start);
+               g_printerr ("num_metabat=%d (0x%08x)\n", num_metabat, num_metabat);
+       }
+
        /* Some sanity checks
         * 1) There should always be at least 1 BAT block
         * 2) It makes no sense to have a block larger than 2^31 for now.
@@ -536,9 +548,9 @@ ole_init_info (GsfInfileMSOle *ole, GError **err)
        info->sb.shift       = sb_shift;
        info->sb.size        = 1 << info->sb.shift;
        info->sb.filter      = info->sb.size - 1;
-       info->threshold      = GSF_LE_GET_GUINT32 (header + OLE_HEADER_THRESHOLD);
+       info->threshold      = threshold;
         info->sbat_start     = GSF_LE_GET_GUINT32 (header + OLE_HEADER_SBAT_START);
-        info->num_sbat       = GSF_LE_GET_GUINT32 (header + OLE_HEADER_NUM_SBAT);
+       info->num_sbat       = num_sbat;
        info->max_block      = (gsf_input_size (ole->input) - OLE_HEADER_SIZE + info->bb.size -1) / 
info->bb.size;
        info->sb_file        = NULL;
 
@@ -817,7 +829,6 @@ gsf_infile_msole_new_child (GsfInfileMSOle *parent,
        if (dirent->use_sb) {
                unsigned int i;
                int remaining;
-               guint8 const *data;
 
                g_return_val_if_fail (sb_file != NULL, NULL);
 
@@ -826,10 +837,10 @@ gsf_infile_msole_new_child (GsfInfileMSOle *parent,
 
                for (i = 0 ; remaining > 0 && i < child->bat.num_blocks; i++, remaining -= info->sb.size)
                        if (gsf_input_seek (GSF_INPUT (sb_file),
-                                           (gsf_off_t)(child->bat.block [i] << info->sb.shift), G_SEEK_SET) 
< 0 ||
-                           (data = gsf_input_read (GSF_INPUT (sb_file),
-                                                   MIN (remaining, (int)info->sb.size),
-                                                   child->stream.buf + (i << info->sb.shift))) == NULL) {
+                                           (gsf_off_t)(child->bat.block [i] << info->sb.shift), G_SEEK_SET) 
||
+                           !gsf_input_read (GSF_INPUT (sb_file),
+                                            MIN (remaining, (int)info->sb.size),
+                                            child->stream.buf + (i << info->sb.shift))) {
 
                                g_warning ("failure reading block %d for '%s'", i, dirent->name);
                                if (err) *err = g_error_new