Backport the implementation of gtk_list_store_iter_is_valid from gtk+-3.

Index: gtk+-2.24.33/gtk/gtkliststore.c
===================================================================
--- gtk+-2.24.33.orig/gtk/gtkliststore.c
+++ gtk+-2.24.33/gtk/gtkliststore.c
@@ -1195,16 +1195,31 @@ gboolean
 gtk_list_store_iter_is_valid (GtkListStore *list_store,
                               GtkTreeIter  *iter)
 {
+  GSequenceIter *seq_iter;
+
   g_return_val_if_fail (GTK_IS_LIST_STORE (list_store), FALSE);
   g_return_val_if_fail (iter != NULL, FALSE);
 
-  if (!VALID_ITER (iter, list_store))
-    return FALSE;
+  /* can't use VALID_ITER() here, because iter might point
+   * to random memory.
+   *
+   * We MUST NOT dereference it.
+   */
 
-  if (g_sequence_iter_get_sequence (iter->user_data) != list_store->seq)
+  if (iter == NULL ||
+      iter->user_data == NULL ||
+      list_store->stamp != iter->stamp)
     return FALSE;
 
-  return TRUE;
+  for (seq_iter = g_sequence_get_begin_iter (list_store->seq);
+       !g_sequence_iter_is_end (seq_iter);
+       seq_iter = g_sequence_iter_next (seq_iter))
+    {
+      if (seq_iter == iter->user_data)
+        return TRUE;
+    }
+
+  return FALSE;
 }
 
 static gboolean real_gtk_list_store_row_draggable (GtkTreeDragSource *drag_source,
2abe12d53eb5d853f26e7d95bff3'>tree</a><a href='/guix/commit/gnu/installer/record.scm?id=ab280fd55d1e2abe12d53eb5d853f26e7d95bff3'>commit</a><a href='/guix/diff/gnu/installer/record.scm?id=ab280fd55d1e2abe12d53eb5d853f26e7d95bff3'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/installer/record.scm'>
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<div class='path'>path: <a href='/guix/log/?id=ab280fd55d1e2abe12d53eb5d853f26e7d95bff3'>root</a>/<a href='/guix/log/gnu?id=ab280fd55d1e2abe12d53eb5d853f26e7d95bff3'>gnu</a>/<a href='/guix/log/gnu/installer?id=ab280fd55d1e2abe12d53eb5d853f26e7d95bff3'>installer</a>/<a href='/guix/log/gnu/installer/record.scm?id=ab280fd55d1e2abe12d53eb5d853f26e7d95bff3'>record.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/installer/record.scm?id=ab280fd55d1e2abe12d53eb5d853f26e7d95bff3&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2022-11-15 12:16:43 +0100'>2022-11-15</span></td><td><a href='/guix/commit/gnu/installer/record.scm?id=514fedbf3966b7fbab31a6c63b4210ec8b5b0c9a'>installer: Report known-unsupported PCI devices.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/hardware.scm: New file.
* gnu/local.mk (INSTALLER_MODULES): Add it.
* po/guix/POTFILES.in: Add it.
* gnu/installer.scm (installer-steps): Pass #:pci-database to the
'welcome' step procedure.
* gnu/installer/newt.scm (welcome-page): Add #:pci-database and pass it
to 'run-welcome-page'.
* gnu/installer/newt/welcome.scm (check-hardware-support): Add #:pci-database.
Enumerate unsupported PCI devices and run an error page when unsupported
devices are found.
(run-welcome-page): Add #:pci-database and pass it to
'check-hardware-support' and to the recursive call.
* gnu/installer/record.scm (&lt;installer&gt;)[welcome-page]: Adjust comment.
* doc/guix.texi (Hardware Considerations): Mention it.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-02-02 16:46:44 +0100'>2022-02-02</span></td><td><a href='/guix/commit/gnu/installer/record.scm?id=ad55ccf9b18000144a4e0f28a0f9e57132f94edc'>installer: Make dump archive creation optional and selective.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer.scm (installer-program): Let the installer customize
the dump archive.
* gnu/installer/dump.scm (prepare-dump, make-dump): Split make-dump in
prepare-dump, which copies the files necessary for the dump, and
make-dump which creates the archive.
* gnu/installer/record.scm (installer): Add report-page field.  Change
documented return value of exit-error.
* gnu/installer/newt.scm (exit-error): Change arguments to be a string
containing the error.  Let the user choose between exiting and
initiating a dump.
(report-page): Add new variable.
* gnu/installer/newt/page.scm (run-dump-page): New variable.
* gnu/installer/newt/dump.scm: Delete it.

Signed-off-by: Mathieu Othacehe &lt;othacehe@gnu.org&gt;
</span></span></td><td>Josselin Poiret</td></tr>
<tr><td><span title='2022-02-02 16:46:43 +0100'>2022-02-02</span></td><td><a href='/guix/commit/gnu/installer/record.scm?id=408427a36c6545115068d5f06de2ea21407374c6'>installer: Add installer-specific run command process.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/record.scm (installer)[run-command]: Add field.
* gnu/installer/utils.scm (run-command-in-installer): Add parameter.
* gnu/installer.scm (installer-program): Parameterize
run-command-in-installer with current installer's run-command.
* gnu/installer/newt.scm (newt-run-command): New variable.
(newt-installer): Use it.

Signed-off-by: Mathieu Othacehe &lt;othacehe@gnu.org&gt;
</span></span></td><td>Josselin Poiret</td></tr>
<tr><td><span title='2022-02-02 16:46:42 +0100'>2022-02-02</span></td><td><a href='/guix/commit/gnu/installer/record.scm?id=0d37a5df7e709cadca97cfbbf9c680dfe54b8302'>installer: Add crash dump upload support.</a><span class='msg-avail'>...<span class='msg-tooltip'>Suggested-by: Josselin Poiret &lt;dev@jpoiret.xyz&gt;

* gnu/installer/dump.scm: New file.
* gnu/installer/newt/dump.scm: New file.
* gnu/local.mk (INSTALLER_MODULES): Add them.
* gnu/installer/record.scm (&lt;installer&gt;)[dump-page]: New field.
* gnu/installer/steps.scm (%current-result): New variable.
(run-installer-steps): Update it.
* gnu/installer.scm (installer-program): Add tar and gip to the installer
path. Add guile-webutils and gnutls to the Guile extensions. Generate and send
the crash dump report.
* gnu/installer/newt.scm (exit-error): Add a report argument. Display the
report id.
(dump-page): New procedure.
(newt-installer): Update it.
</span></span></td><td>Mathieu Othacehe</td></tr>