[Xcb] [PATCH:xwininfo 2/2] Print more detailed error messages when xcb_connect fails

[Alan Coopersmith]

Signed-off-by: Alan Coopersmith <alan.coopersmith at oracle.com>
---
 dsimple.c |   21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

A little bit nicer for users, and gives us a way to test the connection error 
reporting code.

Verified all 4 possible error codes are reported as expected:

% sh -c 'ulimit -d 50 ; ./xwininfo -root -display :0'
./xwininfo: error: Failed to allocate memory in xcb_connect
% ./xwininfo -root -display sdfgkjng
./xwininfo: error: unable to parse display name "sdfgkjng"
% ./xwininfo -root -display :0.100
./xwininfo: error: invalid screen 100 in display ":0.100"
% ./xwininfo -root -display :100
./xwininfo: error: unable to open display ":100"

diff --git a/dsimple.c b/dsimple.c
index 51fb231..6432e13 100644
--- a/dsimple.c
+++ b/dsimple.c
@@ -108,13 +108,26 @@ void Setup_Display_And_Screen (
     xcb_connection_t **dpy,	/* MODIFIED */
     xcb_screen_t **screen)	/* MODIFIED */
 {
-    int screen_number, i;
+    int screen_number, i, err;
 
     /* Open Display */
     *dpy = xcb_connect (display_name, &screen_number);
-    if (xcb_connection_has_error (*dpy)) {
-	Fatal_Error ("unable to open display \"%s\"",
-		     Get_Display_Name(display_name) );
+    if ((err = xcb_connection_has_error (*dpy)) != 0) {
+        switch (err) {
+        case XCB_CONN_CLOSED_MEM_INSUFFICIENT:
+            Fatal_Error ("Failed to allocate memory in xcb_connect");
+        case XCB_CONN_CLOSED_PARSE_ERR:
+            Fatal_Error ("unable to parse display name \"%s\"",
+                         Get_Display_Name(display_name) );
+#ifdef XCB_CONN_CLOSED_INVALID_SCREEN
+        case XCB_CONN_CLOSED_INVALID_SCREEN:
+            Fatal_Error ("invalid screen %d in display \"%s\"",
+                         screen_number, Get_Display_Name(display_name));
+#endif
+        default:
+            Fatal_Error ("unable to open display \"%s\"",
+                         Get_Display_Name(display_name) );
+        }
     }
 
     if (screen) {
-- 
1.7.9.2