xcb: add xcb_init(): checks the x server + extensions, and caches atoms

xcb.c

@@ -1,9 +1,113 @@
 #include "xcb.h"
 
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <assert.h>
 
+#include <xcb/xcb.h>
+#include <xcb/randr.h>
+#include <xcb/render.h>
+
+xcb_atom_t UTF8_STRING;
+xcb_atom_t _NET_WM_PID;
+xcb_atom_t _NET_WM_WINDOW_TYPE;
+xcb_atom_t _NET_WM_WINDOW_TYPE_DOCK;
+xcb_atom_t _NET_WM_STATE;
+xcb_atom_t _NET_WM_STATE_ABOVE;
+xcb_atom_t _NET_WM_STATE_STICKY;
+xcb_atom_t _NET_WM_DESKTOP;
+xcb_atom_t _NET_WM_STRUT;
+xcb_atom_t _NET_WM_STRUT_PARTIAL;
+xcb_atom_t _NET_ACTIVE_WINDOW;
+xcb_atom_t _NET_CURRENT_DESKTOP;
+xcb_atom_t _NET_WM_VISIBLE_NAME;
+xcb_atom_t _NET_WM_NAME;
+
+bool
+xcb_init(void)
+{
+    xcb_connection_t *conn = xcb_connect(NULL, NULL);
+    assert(conn != NULL);
+
+    const xcb_setup_t *setup = xcb_get_setup(conn);
+
+    /* Vendor string */
+    int length = xcb_setup_vendor_length(setup);
+    char *vendor = malloc(length + 1);
+    memcpy(vendor, xcb_setup_vendor(setup), length);
+    vendor[length] = '\0';
+
+    /* Vendor release number */
+    unsigned release = setup->release_number;
+    unsigned major = release / 10000000; release %= 10000000;
+    unsigned minor = release / 100000; release %= 100000;
+    unsigned patch = release / 1000;
+
+    printf("%s %u.%u.%u (protocol: %u.%u)\n", vendor,
+           major, minor, patch,
+           setup->protocol_major_version,
+           setup->protocol_minor_version);
+    free(vendor);
+
+    const xcb_query_extension_reply_t *randr =
+        xcb_get_extension_data(conn, &xcb_randr_id);
+    assert(randr->present);
+
+    const xcb_query_extension_reply_t *render =
+        xcb_get_extension_data(conn, &xcb_render_id);
+    assert(render->present);
+
+    xcb_randr_query_version_cookie_t randr_cookie =
+        xcb_randr_query_version(conn, XCB_RANDR_MAJOR_VERSION,
+                                XCB_RANDR_MINOR_VERSION);
+    xcb_render_query_version_cookie_t render_cookie =
+        xcb_render_query_version(conn, XCB_RENDER_MAJOR_VERSION,
+                                 XCB_RENDER_MINOR_VERSION);
+
+    xcb_generic_error_t *e;
+    xcb_randr_query_version_reply_t *randr_version =
+        xcb_randr_query_version_reply(conn, randr_cookie, &e);
+    assert(e == NULL);
+
+    xcb_render_query_version_reply_t *render_version =
+        xcb_render_query_version_reply(conn, render_cookie, &e);
+    assert(e == NULL);
+
+    xcb_flush(conn);
+
+    printf("  RANDR: %u.%u\n"
+           "  RENDER: %u.%u\n",
+           randr_version->major_version,
+           randr_version->minor_version,
+           render_version->major_version,
+           render_version->minor_version);
+
+    free(randr_version);
+    free(render_version);
+
+    /* Cache atoms */
+    UTF8_STRING = get_atom(conn, "UTF8_STRING");
+    _NET_WM_PID = get_atom(conn, "_NET_WM_PID");
+    _NET_WM_WINDOW_TYPE = get_atom(conn,  "_NET_WM_WINDOW_TYPE");
+    _NET_WM_WINDOW_TYPE_DOCK = get_atom(conn, "_NET_WM_WINDOW_TYPE_DOCK");
+    _NET_WM_STATE = get_atom(conn, "_NET_WM_STATE");
+    _NET_WM_STATE_ABOVE = get_atom(conn, "_NET_WM_STATE_ABOVE");
+    _NET_WM_STATE_STICKY = get_atom(conn, "_NET_WM_STATE_STICKY");
+    _NET_WM_DESKTOP = get_atom(conn, "_NET_WM_DESKTOP");
+    _NET_WM_STRUT = get_atom(conn, "_NET_WM_STRUT");
+    _NET_WM_STRUT_PARTIAL = get_atom(conn, "_NET_WM_STRUT_PARTIAL");
+    _NET_ACTIVE_WINDOW = get_atom(conn, "_NET_ACTIVE_WINDOW");
+    _NET_CURRENT_DESKTOP = get_atom(conn, "_NET_CURRENT_DESKTOP");
+    _NET_WM_VISIBLE_NAME = get_atom(conn, "_NET_WM_VISIBLE_NAME");
+    _NET_WM_NAME = get_atom(conn, "_NET_WM_NAME");
+    _NET_WM_PID = get_atom(conn, "_NET_WM_PID");
+
+    xcb_disconnect(conn);
+
+    return true;
+}
+
 xcb_atom_t
 get_atom(xcb_connection_t *conn, const char *name)
 {