tree_append_json: Allow strings that are not valid UTF8

Fixes #3156.

I couldn't reproduce the problem in a "natural" way so I cheated:
1. Start i3 with gdb
2. Set breakpoing on tree_restore
3. Run, open window, i3-msg restart
5. Open the file in *path with a hex editor
6. Edit the "name" field of the window and insert bytes that are not
valid UTF8
7. Continue

After parsing fails, all nodes including croot are incomplete, meaning
they have to be deleted. We can't recover in any reasonable way so we
have to allow non-UTF8 characters to avoid this situation altogether.

diff --git a/src/load_layout.c b/src/load_layout.c
index 5f391ad727ed0da3f3811da91030d87293a813e8..d2ad4e87c9665c7173ea09086c484b2df3811dba 100644 (file)
--- a/src/load_layout.c
+++ b/src/load_layout.c
@@ -611,6 +611,10 @@ void tree_append_json(Con *con, const char *buf, const size_t len, char **errorm
     yajl_config(hand, yajl_allow_comments, true);
     /* Allow multiple values, i.e. multiple nodes to attach */
     yajl_config(hand, yajl_allow_multiple_values, true);
+    /* Allow strings that are not valid UTF8. Could be possible if a container
+     * name contains such characters. If yajl stops parsing because of this, an
+     * in-place restart could fail: see #3156. */
+    yajl_config(hand, yajl_dont_validate_strings, true);
     json_node = con;
     to_focus = NULL;
     incomplete = 0;