ephyr: set screen size & origin from host X server output's CRTC geometry

If a given output is passed via new -output option, Xephyr will query
host X server for its info. If the following conditions are met:

 a. RandR extension is enabled in host X server;
 b. supported RandR version in host X server is 1.2 or newer;
 c. the given output name is valid;
 d. the given output is connected;

then Xephyr will get output's CRTC geometry and use it to set its own
screen size and origin. It's just like starting Xephyr in fullscreen mode,
but restricted to the given output's CRTC geometry (fake "Zaphod mode").

This is the main feature needed for Xephyr-based single-card multiseat
setups where we don't have separate screens to start Xephyr in fullscreen
mode safely.

Signed-off-by: Laércio de Sousa <laerciosousa@sme-mogidascruzes.sp.gov.br>
Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Keith Packard <keithp@keithp.com>

6 files changed, 175 insertions, 8 deletions

diff --git a/configure.ac b/configure.ac
index f3d9654a4..cba7d24ea 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2364,7 +2364,7 @@ if test "$KDRIVE" = yes; then
        AC_DEFINE(KDRIVE_MOUSE, 1, [Enable KDrive mouse driver])
     fi
 
-    XEPHYR_REQUIRED_LIBS="xau xdmcp xcb xcb-shape xcb-aux xcb-image xcb-icccm xcb-shm xcb-keysyms"
+    XEPHYR_REQUIRED_LIBS="xau xdmcp xcb xcb-shape xcb-aux xcb-image xcb-icccm xcb-shm xcb-keysyms xcb-randr"
     if test "x$XV" = xyes; then
         XEPHYR_REQUIRED_LIBS="$XEPHYR_REQUIRED_LIBS xcb-xv"
     fi
diff --git a/hw/kdrive/ephyr/ephyr.c b/hw/kdrive/ephyr/ephyr.c
index b039c683f..85d419376 100644
--- a/hw/kdrive/ephyr/ephyr.c
+++ b/hw/kdrive/ephyr/ephyr.c
@@ -111,13 +111,16 @@ Bool
 ephyrScreenInitialize(KdScreenInfo *screen)
 {
     EphyrScrPriv *scrpriv = screen->driver;
+    int x = 0, y = 0;
     int width = 640, height = 480;
     CARD32 redMask, greenMask, blueMask;
 
-    if (hostx_want_screen_size(screen, &width, &height)
+    if (hostx_want_screen_geometry(screen, &width, &height, &x, &y)
         || !screen->width || !screen->height) {
         screen->width = width;
         screen->height = height;
+        screen->x = x;
+        screen->y = y;
     }
 
     if (EphyrWantGrayScale)
diff --git a/hw/kdrive/ephyr/ephyr.h b/hw/kdrive/ephyr/ephyr.h
index 5c4936bb2..4e753f158 100644
--- a/hw/kdrive/ephyr/ephyr.h
+++ b/hw/kdrive/ephyr/ephyr.h
@@ -74,8 +74,10 @@ typedef struct _ephyrScrPriv {
     xcb_window_t peer_win;            /* Used for GL; should be at most one */
     xcb_image_t *ximg;
     Bool win_explicit_position;
+    int win_x, win_y;
     int win_width, win_height;
     int server_depth;
+    const char *output;         /* Set via -output option */
     unsigned char *fb_data;     /* only used when host bpp != server bpp */
     xcb_shm_segment_info_t shminfo;
 
diff --git a/hw/kdrive/ephyr/ephyrinit.c b/hw/kdrive/ephyr/ephyrinit.c
index e04c8dc88..38acc52a6 100644
--- a/hw/kdrive/ephyr/ephyrinit.c
+++ b/hw/kdrive/ephyr/ephyrinit.c
@@ -47,6 +47,8 @@ extern KdPointerDriver LinuxEvdevMouseDriver;
 extern KdKeyboardDriver LinuxEvdevKeyboardDriver;
 #endif
 
+void processScreenOrOutputArg(const char *screen_size, const char *output, char *parent_id);
+void processOutputArg(const char *output, char *parent_id);
 void processScreenArg(const char *screen_size, char *parent_id);
 
 void
@@ -134,6 +136,7 @@ ddxUseMsg(void)
     ErrorF("-parent <XID>        Use existing window as Xephyr root win\n");
     ErrorF("-sw-cursor           Render cursors in software in Xephyr\n");
     ErrorF("-fullscreen          Attempt to run Xephyr fullscreen\n");
+    ErrorF("-output <NAME>       Attempt to run Xephyr fullscreen (restricted to given output geometry)\n");
     ErrorF("-grayscale           Simulate 8bit grayscale\n");
     ErrorF("-resizeable          Make Xephyr windows resizeable\n");
 #ifdef GLAMOR
@@ -154,7 +157,7 @@ ddxUseMsg(void)
 }
 
 void
-processScreenArg(const char *screen_size, char *parent_id)
+processScreenOrOutputArg(const char *screen_size, const char *output, char *parent_id)
 {
     KdCardInfo *card;
 
@@ -178,13 +181,25 @@ processScreenArg(const char *screen_size, char *parent_id)
 
         use_geometry = (strchr(screen_size, '+') != NULL);
         EPHYR_DBG("screen number:%d\n", screen->mynum);
-        hostx_add_screen(screen, p_id, screen->mynum, use_geometry);
+        hostx_add_screen(screen, p_id, screen->mynum, use_geometry, output);
     }
     else {
         ErrorF("No matching card found!\n");
     }
 }
 
+void
+processScreenArg(const char *screen_size, char *parent_id)
+{
+    processScreenOrOutputArg(screen_size, NULL, parent_id);
+}
+
+void
+processOutputArg(const char *output, char *parent_id)
+{
+    processScreenOrOutputArg("100x100+0+0", output, parent_id);
+}
+
 int
 ddxProcessArgument(int argc, char **argv, int i)
 {
@@ -226,6 +241,15 @@ ddxProcessArgument(int argc, char **argv, int i)
         UseMsg();
         exit(1);
     }
+    else if (!strcmp(argv[i], "-output")) {
+        if (i + 1 < argc) {
+            processOutputArg(argv[i + 1], NULL);
+            return 2;
+        }
+
+        UseMsg();
+        exit(1);
+    }
     else if (!strcmp(argv[i], "-sw-cursor")) {
         hostx_use_sw_cursor();
         return 1;
diff --git a/hw/kdrive/ephyr/hostx.c b/hw/kdrive/ephyr/hostx.c
index 92a8ada96..2161ad550 100644
--- a/hw/kdrive/ephyr/hostx.c
+++ b/hw/kdrive/ephyr/hostx.c
@@ -51,6 +51,7 @@
 #include <xcb/xcb_image.h>
 #include <xcb/shape.h>
 #include <xcb/xcb_keysyms.h>
+#include <xcb/randr.h>
 #ifdef XF86DRI
 #include <xcb/xf86dri.h>
 #include <xcb/glx.h>
@@ -104,12 +105,15 @@ static void
 #define host_depth_matches_server(_vars) (HostX.depth == (_vars)->server_depth)
 
 int
-hostx_want_screen_size(KdScreenInfo *screen, int *width, int *height)
+hostx_want_screen_geometry(KdScreenInfo *screen, int *width, int *height, int *x, int *y)
 {
     EphyrScrPriv *scrpriv = screen->driver;
 
     if (scrpriv && (scrpriv->win_pre_existing != None ||
+                    scrpriv->output != NULL ||
                     HostX.use_fullscreen == TRUE)) {
+        *x = scrpriv->win_x;
+        *y = scrpriv->win_y;
         *width = scrpriv->win_width;
         *height = scrpriv->win_height;
         return 1;
@@ -119,7 +123,7 @@ hostx_want_screen_size(KdScreenInfo *screen, int *width, int *height)
 }
 
 void
-hostx_add_screen(KdScreenInfo *screen, unsigned long win_id, int screen_num, Bool use_geometry)
+hostx_add_screen(KdScreenInfo *screen, unsigned long win_id, int screen_num, Bool use_geometry, const char *output)
 {
     EphyrScrPriv *scrpriv = screen->driver;
     int index = HostX.n_screens;
@@ -132,6 +136,7 @@ hostx_add_screen(KdScreenInfo *screen, unsigned long win_id, int screen_num, Boo
     scrpriv->screen = screen;
     scrpriv->win_pre_existing = win_id;
     scrpriv->win_explicit_position = use_geometry;
+    scrpriv->output = output;
 }
 
 void
@@ -211,6 +216,119 @@ hostx_want_preexisting_window(KdScreenInfo *screen)
 }
 
 void
+hostx_get_output_geometry(const char *output,
+                          int *x, int *y,
+                          int *width, int *height)
+{
+    int i, name_len = 0, output_found = FALSE;
+    char *name = NULL;
+    xcb_generic_error_t *error;
+    xcb_randr_query_version_cookie_t version_c;
+    xcb_randr_query_version_reply_t *version_r;
+    xcb_randr_get_screen_resources_cookie_t screen_resources_c;
+    xcb_randr_get_screen_resources_reply_t *screen_resources_r;
+    xcb_randr_output_t *randr_outputs;
+    xcb_randr_get_output_info_cookie_t output_info_c;
+    xcb_randr_get_output_info_reply_t *output_info_r;
+    xcb_randr_get_crtc_info_cookie_t crtc_info_c;
+    xcb_randr_get_crtc_info_reply_t *crtc_info_r;
+
+    /* First of all, check for extension */
+    if (!xcb_get_extension_data(HostX.conn, &xcb_randr_id)->present)
+    {
+        fprintf(stderr, "\nHost X server does not support RANDR extension (or it's disabled).\n");
+        exit(1);
+    }
+
+    /* Check RandR version */
+    version_c = xcb_randr_query_version(HostX.conn, 1, 2);
+    version_r = xcb_randr_query_version_reply(HostX.conn,
+                                              version_c,
+                                              &error);
+
+    if (error != NULL || version_r == NULL)
+    {
+        fprintf(stderr, "\nFailed to get RandR version supported by host X server.\n");
+        exit(1);
+    }
+    else if (version_r->major_version < 1 || version_r->minor_version < 2)
+    {
+        free(version_r);
+        fprintf(stderr, "\nHost X server doesn't support RandR 1.2, needed for -output usage.\n");
+        exit(1);
+    }
+
+    free(version_r);
+
+    /* Get list of outputs from screen resources */
+    screen_resources_c = xcb_randr_get_screen_resources(HostX.conn,
+                                                        HostX.winroot);
+    screen_resources_r = xcb_randr_get_screen_resources_reply(HostX.conn,
+                                                              screen_resources_c,
+                                                              NULL);
+    randr_outputs = xcb_randr_get_screen_resources_outputs(screen_resources_r);
+
+    for (i = 0; !output_found && i < screen_resources_r->num_outputs; i++)
+    {
+        /* Get info on the output */
+        output_info_c = xcb_randr_get_output_info(HostX.conn,
+                                                  randr_outputs[i],
+                                                  XCB_CURRENT_TIME);
+        output_info_r = xcb_randr_get_output_info_reply(HostX.conn,
+                                                        output_info_c,
+                                                        NULL);
+
+        /* Get output name */
+        name_len = xcb_randr_get_output_info_name_length(output_info_r);
+        name = malloc(name_len + 1);
+        strncpy(name, (char*)xcb_randr_get_output_info_name(output_info_r), name_len);
+        name[name_len] = '\0';
+
+        if (!strcmp(name, output))
+        {
+            output_found = TRUE;
+
+            /* Check if output is connected */
+            if (output_info_r->crtc == XCB_NONE)
+            {
+                free(name);
+                free(output_info_r);
+                free(screen_resources_r);
+                fprintf(stderr, "\nOutput %s is currently disabled (or not connected).\n", output);
+                exit(1);
+            }
+
+            /* Get CRTC from output info */
+            crtc_info_c = xcb_randr_get_crtc_info(HostX.conn,
+                                                  output_info_r->crtc,
+                                                  XCB_CURRENT_TIME);
+            crtc_info_r = xcb_randr_get_crtc_info_reply(HostX.conn,
+                                                        crtc_info_c,
+                                                        NULL);
+
+            /* Get CRTC geometry */
+            *x = crtc_info_r->x;
+            *y = crtc_info_r->y;
+            *width = crtc_info_r->width;
+            *height = crtc_info_r->height;
+
+            free(crtc_info_r);
+        }
+
+        free(name);
+        free(output_info_r);
+    }
+
+    free(screen_resources_r);
+
+    if (!output_found)
+    {
+        fprintf(stderr, "\nOutput %s not available in host X server.\n", output);
+        exit(1);
+    }
+}
+
+void
 hostx_use_fullscreen(void)
 {
     HostX.use_fullscreen = TRUE;
@@ -359,6 +477,8 @@ hostx_init(void)
         scrpriv->win = xcb_generate_id(HostX.conn);
         scrpriv->server_depth = HostX.depth;
         scrpriv->ximg = NULL;
+        scrpriv->win_x = 0;
+        scrpriv->win_y = 0;
 
         if (scrpriv->win_pre_existing != XCB_WINDOW_NONE) {
             xcb_get_geometry_reply_t *prewin_geom;
@@ -416,6 +536,17 @@ hostx_init(void)
 
                 hostx_set_fullscreen_hint();
             }
+            else if (scrpriv->output) {
+                hostx_get_output_geometry(scrpriv->output,
+                                          &scrpriv->win_x,
+                                          &scrpriv->win_y,
+                                          &scrpriv->win_width,
+                                          &scrpriv->win_height);
+
+                HostX.use_fullscreen = TRUE;
+                hostx_set_fullscreen_hint();
+            }
+
 
             tmpstr = getenv("RESOURCE_NAME");
             if (tmpstr && (!ephyrResNameFromCmd))
@@ -759,6 +890,8 @@ hostx_screen_init(KdScreenInfo *screen,
 
     scrpriv->win_width = width;
     scrpriv->win_height = height;
+    scrpriv->win_x = x;
+    scrpriv->win_y = y;
 
 #ifdef GLAMOR
     if (ephyr_glamor) {
diff --git a/hw/kdrive/ephyr/hostx.h b/hw/kdrive/ephyr/hostx.h
index c554ca370..80894c8c0 100644
--- a/hw/kdrive/ephyr/hostx.h
+++ b/hw/kdrive/ephyr/hostx.h
@@ -74,7 +74,7 @@ typedef struct {
 } EphyrRect;
 
 int
-hostx_want_screen_size(KdScreenInfo *screen, int *width, int *height);
+hostx_want_screen_geometry(KdScreenInfo *screen, int *width, int *height, int *x, int *y);
 
 int
  hostx_want_host_cursor(void);
@@ -83,6 +83,11 @@ void
  hostx_use_sw_cursor(void);
 
 void
+ hostx_get_output_geometry(const char *output,
+                           int *x, int *y,
+                           int *width, int *height);
+
+void
  hostx_use_fullscreen(void);
 
 int
@@ -107,7 +112,7 @@ int
  hostx_init(void);
 
 void
-hostx_add_screen(KdScreenInfo *screen, unsigned long win_id, int screen_num, Bool use_geometry);
+hostx_add_screen(KdScreenInfo *screen, unsigned long win_id, int screen_num, Bool use_geometry, const char *output);
 
 void
  hostx_set_display_name(char *name);