feat: add xorg backend (#1)

* Xorg backend

* Xorg backend hotfix

* xorg.c: issues fixed; ukb.c: xorg backend added

* \t replacement

* ukb.c fromatting improved

* ukb.c typo fix

* fix: include order

---------

Co-authored-by: mrsobakin <68982655+mrsobakin@users.noreply.github.com>

src/backends/xorg.c

@@ -0,0 +1,124 @@
+#include <stdbool.h>
+#include <string.h>
+#include <X11/XKBlib.h>
+#include <X11/Xlib.h>
+
+#include "ukb.h"
+#include "../utils.h"
+
+
+static char current_layout[128] = {0};
+
+
+static Display *x_display = 0;
+
+static ukb_err_t update_current_layout() {
+    XkbStateRec xkb_state;
+    if (XkbGetState(x_display, XkbUseCoreKbd, &xkb_state) != Success) {
+        UKB_ERR("Failed to get keyboard state.");
+    }
+
+    XkbDescPtr desc_ptr = XkbGetKeyboard(x_display, XkbAllComponentsMask, XkbUseCoreKbd);
+    if (!desc_ptr) {
+        UKB_ERR("Failed to get keyboard description.");
+    }
+    if (!desc_ptr->names) {
+        UKB_ERR("Failed to get keyboard names.");
+    }
+
+    Status error_get_controls = XkbGetControls(x_display, XkbAllComponentsMask, desc_ptr);
+    if (error_get_controls != Success || !desc_ptr->ctrls) {
+        UKB_ERR("Failed to get keyboard controls.");
+    }
+
+    int num_groups = desc_ptr->ctrls->num_groups;
+    if (xkbState.group >= num_groups) {
+        UKB_ERR("Group index out of range.");
+    }
+
+    char *name_ptr = XGetAtomName(x_display, desc_ptr->names->groups[xkb_state.group]);
+    if (!name_ptr) {
+        UKB_ERR("Failed to get group name.");
+    }
+
+    if (strncmp(current_layout, name_ptr, sizeof(current_layout)) != 0) {
+        strncpy(current_layout, name_ptr, sizeof(current_layout) - 1);
+    }
+
+    XkbFreeKeyboard(desc_ptr, 0, True);
+    XFree(name_ptr);
+
+    UKB_OK();
+}
+
+static ukb_err_t xorg_wait_event() {
+    Bool bret = XkbSelectEventDetails(x_display, XkbUseCoreKbd, XkbStateNotify, XkbAllStateComponentsMask, XkbGroupStateMask);
+    if (!bret) {
+        UKB_ERR("XkbSelectEventDetails failed")
+    }
+
+    XEvent event;
+    int iret = XNextEvent(x_display, &event);
+    if (!iret) {
+        UKB_ERR("XNextEvent failed");
+    }
+
+    UKB_OK();
+}
+
+static ukb_err_t xorg_listen_loop(ukb_layout_cb_t cb) {
+    while(1) {
+        UKB_PROPAGATE(xorg_wait_event());
+        UKB_PROPAGATE(update_current_layout());
+        cb(current_layout);
+    }
+    UKB_OK();
+}
+
+static int xorg_open_display() {
+    int event_code;
+    int error_return;
+    int major = XkbMajorVersion;
+    int minor = XkbMinorVersion;
+    int reason_return;
+
+    x_display = XkbOpenDisplay(NULL, &event_code, &error_return, &major, &minor, &reason_return);
+    return reason_return;
+}
+
+/********************************* BACKEND ***********************************/
+
+static bool xorg_can_use(void) {
+    int reason_return = xorg_open_display();
+    XCloseDisplay(x_display);
+    return reason_return == XkbOD_Success;
+}
+
+static ukb_err_t xorg_listen(ukb_layout_cb_t cb) {
+    int reason_return = xorg_open_display();
+
+    switch (reason_return) {
+    case XkbOD_Success:
+        break;
+    case XkbOD_BadLibraryVersion:
+        UKB_ERR("Bad XKB library version.");
+    case XkbOD_ConnectionRefused:
+        UKB_ERR("Connection to X server refused.");
+    case XkbOD_BadServerVersion:
+        UKB_ERR("Bad X11 server version.");
+    case XkbOD_NonXkbServer:
+        UKB_ERR("XKB not present.");
+    default:
+        UKB_ERR("XKB refused to open the display.");
+    }
+
+    ukb_err_t err = xorg_listen_loop(cb);
+    XCloseDisplay(x_display);
+    return err;
+}
+
+const ukb_backend_t ukb_backend_xorg = {
+    .name = "xorg",
+    .can_use = xorg_can_use,
+    .listen = xorg_listen,
+};

src/ukb.c

@@ -12,7 +12,8 @@
 /********************************* BACKENDS **********************************/
 
 #define UKB_BACKENDS(M) \
-    M(ukb_backend_sway)
+    M(ukb_backend_sway) \
+    M(ukb_backend_xorg)
 
 /*****************************************************************************/