[evolution-patches] Hi,

From: "Jukaku Mubeen" <jmubeen novell com>
To: <evolution-patches lists ximian com>
Cc: Veerapuram Varadhan <VVaradhan BLR BANGALORE novell com>
Subject: [evolution-patches] Hi,
Date: Fri, 22 Jul 2005 00:55:58 -0600
When i add several tasks/events, request them via
	
e_cal_get_changes, delete all of them and
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Hi, 
 
When i add several tasks/events, request them via 
e_cal_get_changes, delete all of them and request again using 
e_cal_get_changes the returned GList will contain more items than
deleted 
and the additional items look like random memory locations. 
 
Attached is patch against e-d-s to fix this bug. 
The bug was caused since you modified a hashtable during a call to
g_hash_table_foreach. 
You call e_xmlhash_foreach_key during 
e_cal_backend_file_compute_changes. Then the callback 
e_cal_backend_file_compute_changes_foreach_key removes entries. This 
works if only 1 is removed but leads to corruption when removing several

items. 
 
See the comments on 
http://developer.gnome.org/doc/API/2.0/glib/glib-Hash-Tables.html#g-hash-table-foreach

 
The correct solution is to provide a new e_xmlhash_foreach_key_remove 
function where it is safe to remove a key. The attached patch does this.

I suggest that you check the remaining code for similar errors. 
 
See
http://lists.ximian.com/archives/public/evolution-hackers/2005-March/005257.html
for details. 
 
Thanks 
Mubeen 


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<html>
  <head>
    <style type=3D"text/css">
      <!--
        body { margin-right: 4px; margin-bottom: 1px; margin-top: 4px; =
margin-left: 4px; font-variant: normal; line-height: normal }
      -->
    </style>
   =20
  </head>
  <body>
    <DIV>
      Hi&#44;
    </DIV>
    <DIV>&nbsp;</DIV>
    <DIV>
      When i add several tasks/events&#44; request them via=20
    </DIV>
    <DIV>
      e_cal_get_changes&#44; delete all of them and request again using=20
    </DIV>
    <DIV>
      e_cal_get_changes the returned GList will contain more items than =
deleted
    </DIV>
    <DIV>
      and the additional items look like random memory locations.
    </DIV>
    <DIV>&nbsp;</DIV>
    <DIV>
      Attached is patch against e-d-s to fix this bug.
    </DIV>
    <DIV>
      The bug was caused since you modified a hashtable during a call to =
g_hash_table_foreach.
    </DIV>
    <DIV>
      You call e_xmlhash_foreach_key during
    </DIV>
    <DIV>
      e_cal_backend_file_compute_changes. Then the callback
    </DIV>
    <DIV>
      e_cal_backend_file_compute_changes_foreach_key removes entries. This
    </DIV>
    <DIV>
      works if only 1 is removed but leads to corruption when removing =
several
    </DIV>
    <DIV>
      items.
    </DIV>
    <DIV>&nbsp;</DIV>
    <DIV>
      See the comments on
    </DIV>
    <DIV>
      http://developer.gnome.org/doc/API/2.0/glib/glib-Hash-Tables.html&#35=
;g-hash-table-foreach
    </DIV>
    <DIV>&nbsp;</DIV>
    <DIV>
      The correct solution is to provide a new e_xmlhash_foreach_key_remove=

    </DIV>
    <DIV>
      function where it is safe to remove a key. The attached patch does =
this.
    </DIV>
    <DIV>
      I suggest that you check the remaining code for similar errors.
    </DIV>
    <DIV>&nbsp;</DIV>
    <DIV>
      See <font color=3D"#0000ff"><a href=3D"http://lists.ximian.com/archiv=
es/public/evolution-hackers/2005-March/005257.html"><u><i>http://lists.ximi=
an.com/archives/public/evolution-hackers/2005-March/005257.html</i></u></a>=
</font>&nbsp;for details.
    </DIV>
    <DIV>&nbsp;</DIV>
    <DIV>
      Thanks
    </DIV>
    <DIV>
      Mubeen
    </DIV>
  </body>
</html>

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--- calendar/backends/file/e-cal-backend-file.c	2005-07-21 18:24:47.255439795 +0530
+++ ../evolution-data-server.new/calendar/backends/file/e-cal-backend-file.c	2005-07-21 18:25:28.372232186 +0530
@@ -1477,7 +1477,7 @@
 	EXmlHash *ehash;
 } ECalBackendFileComputeChangesData;
 
-static void
+static gboolean
 e_cal_backend_file_compute_changes_foreach_key (const char *key, gpointer value, gpointer data)
 {
 	ECalBackendFileComputeChangesData *be_data = data;
@@ -1494,8 +1494,9 @@
 		e_cal_component_set_uid (comp, key);
 		be_data->deletes = g_list_prepend (be_data->deletes, e_cal_component_get_as_string (comp));
 
-		e_xmlhash_remove (be_data->ehash, key);
+		return TRUE;
  	}
+	return FALSE;
 }
 
 static ECalBackendSyncStatus
@@ -1555,7 +1556,7 @@
 	be_data.deletes = NULL;
 	be_data.ehash = ehash;
 	
-	e_xmlhash_foreach_key (ehash, (EXmlHashFunc)e_cal_backend_file_compute_changes_foreach_key, &be_data);
+	e_xmlhash_foreach_key_remove (ehash, (EXmlHashRemoveFunc)e_cal_backend_file_compute_changes_foreach_key, &be_data);
 	
 	*deletes = be_data.deletes;
 
--- libedataserver/e-xml-hash-utils.c	2005-07-21 18:24:47.256439669 +0530
+++ ../evolution-data-server.new/libedataserver/e-xml-hash-utils.c	2005-07-20 17:03:08.000000000 +0530
@@ -319,6 +319,32 @@
 	g_hash_table_foreach (hash->objects, foreach_hash_func, &data);
 }
 
+typedef struct {
+	EXmlHashRemoveFunc func;
+	gpointer user_data;
+} foreach_data_remove_t;
+
+static gboolean
+foreach_hash_remove_func (gpointer  key, gpointer value, gpointer user_data)
+{
+	foreach_data_remove_t *data = (foreach_data_remove_t *) user_data;
+
+	return data->func ((const char *) key, (const char *) value, data->user_data);
+}
+
+void
+e_xmlhash_foreach_key_remove (EXmlHash *hash, EXmlHashRemoveFunc func, gpointer user_data)
+{
+	foreach_data_remove_t data;
+
+	g_return_if_fail (hash != NULL);
+	g_return_if_fail (func != NULL);
+
+	data.func = func;
+	data.user_data = user_data;
+	g_hash_table_foreach_remove (hash->objects, foreach_hash_remove_func, &data);
+}
+
 /**
  * e_xmlhash_write:
  * @hash: The #EXmlHash to write.
--- libedataserver/e-xml-hash-utils.h	2005-07-21 18:24:47.257439542 +0530
+++ ../evolution-data-server.new/libedataserver/e-xml-hash-utils.h	2005-07-21 18:31:04.460638126 +0530
@@ -58,6 +58,7 @@
 } EXmlHashStatus;
 
 typedef void (* EXmlHashFunc) (const char *key, const char *value, gpointer user_data);
+typedef gboolean (* EXmlHashRemoveFunc) (const char *key, const char *value, gpointer user_data);
 
 typedef struct EXmlHash EXmlHash;
 
@@ -76,6 +77,10 @@
 				      EXmlHashFunc  func,
 				      gpointer      user_data);
 
+void           e_xmlhash_foreach_key_remove (EXmlHash     *hash,
+				      EXmlHashRemoveFunc  func,
+				      gpointer      user_data);
+
 void           e_xmlhash_write       (EXmlHash     *hash);
 void           e_xmlhash_destroy     (EXmlHash     *hash);
 

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Follow-Ups:
- Re: [evolution-patches] Hi,
  - From: Jeffrey Stedfast
- Re: [evolution-patches] Hi,
  - From: Not Zed
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