Fix encoding of _NET_DESKTOP_NAMES

This commit fixes the encoding of _NET_DESKTOP_NAMES to match the
specification[1]:

    … The names of all virtual desktops. This is a list
      of NULL-terminated strings in UTF-8 encoding …

We use Xutf8TextListToTextProperty to transform a list of strings
(NULL-terminated) into one XTextProperty which is lacking the last
NULL-Termination … at least that is what observation tells us and what
is written in the documentation of that function[2]:

    … A final terminating null byte is stored at the end of
      the value field of text_prop_return but is not included
      in the nitems member.

As a result, the way *fluxbox* is storing desktop names and the way
other WMs are storing them and how other tools like pagers etc are
expecting the content to be formated is slightly off.

This commit addresses that issue by adding one more "artificial" desktop
name and thus producing the desired content for _NET_DESKTOP_NAMES.

[1]: https://specifications.freedesktop.org/wm-spec/wm-spec-1.4.html#idm46439038971488
[2]: https://www.x.org/releases/X11R7.5/doc/man/man3/Xutf8TextListToTextProperty.3.html

1 files changed, 13 insertions, 7 deletions

diff --git a/src/Ewmh.cc b/src/Ewmh.cc
index 03a824f..e12a792 100644
--- a/src/Ewmh.cc
+++ b/src/Ewmh.cc
@@ -821,32 +821,38 @@ void Ewmh::updateWorkspaceNames(BScreen &screen) {
     const BScreen::WorkspaceNames &workspacenames = screen.getWorkspaceNames();
     const size_t number_of_desks = workspacenames.size();
 
-    const char** names = new const char*[number_of_desks];
+    /* the SPEC states "NULL-terminated strings". This implies, that also the
+     * last element actually gets proper NULL-termination after being treated
+     * by Xutf8TextListToTextProperty. Xutf8TextListToTextProperty removes
+     * the NULL from the last name and thus it is missing when reading the
+     * _NET_DESKTOP_NAMES property. This might confuse other WMs, pagers etc.
+     * thus, an artifical "empty" name is added at the end of the regular
+     * names list which is then properly encoded by Xutf8TextListToTextProperty
+     * and everyone is happy
+     */
+    const char* names[number_of_desks+1];
 
     for (size_t i = 0; i < number_of_desks; i++) {
         names[i] = workspacenames[i].c_str();
     }
+    names[number_of_desks] = NULL;
 
 #ifdef X_HAVE_UTF8_STRING
     int code = Xutf8TextListToTextProperty(FbTk::App::instance()->display(),
-                                const_cast<char**>(names), number_of_desks, XUTF8StringStyle, &text);
+                                const_cast<char**>(names), number_of_desks+1, XUTF8StringStyle, &text);
     if (code != XNoMemory && code != XLocaleNotSupported) {
         XSetTextProperty(FbTk::App::instance()->display(),
                          screen.rootWindow().window(),
                          &text, m_net->desktop_names);
-
         XFree(text.value);
     }
-
 #else
-    if (XStringListToTextProperty(names, number_of_desks, &text)) {
+    if (XStringListToTextProperty(names, number_of_desks+1, &text)) {
         XSetTextProperty(FbTk::App::instance()->display(), screen.rootWindow().window(),
                 &text, m_net->desktop_names);
         XFree(text.value);
     }
 #endif
-
-    delete[] names;
 }
 
 void Ewmh::updateCurrentWorkspace(BScreen &screen) {