[PATCH] Handle -displayfd and an explicit display number sensibly

[Jon TURNEY]

On 24/03/2014 19:56, Kristian Høgsberg wrote:
> On Wed, Mar 19, 2014 at 7:26 AM, Jon TURNEY wrote:
>> Handle -displayfd and an explicit display number sensibly, e.g. use the
>> explicitly specified display number, and write it to the displayfd
> 
> I  don't think the two options were meant to be used together, but I
> can see how that would be useful.  Non-signal based ready notification
> while letting the parent process pick the display is useful for
> Xwayland as well.

Well, in the alternative, the X server could exit with an error if -displayfd
and an explicit display number are used, but this seems more useful.

> The parent process creates the fd in our process environment and could
> pick 0 as the display fd.  Let's initialize to -1 which is never a
> valid fd.

A very good point.  Amended patch to account for this attached.


-------------- next part --------------
From 68382c191dfb8d285960c464bcb4fc934566ef34 Mon Sep 17 00:00:00 2001
From: Jon TURNEY <jon.turney at dronecode.org.uk>
Date: Mon, 11 Mar 2013 14:34:32 +0000
Subject: [PATCH] Handle -displayfd and an explicit display number sensibly

Handle -displayfd and an explicit display number sensibly, e.g. use the
explicitly specified display number, and write it to the displayfd

v2: displayfd might be 0, so use -1 as invalid value

Signed-off-by: Jon TURNEY <jon.turney at dronecode.org.uk>
---
 dix/globals.c    |  3 ++-
 include/opaque.h |  1 +
 os/connection.c  | 11 +++++------
 os/utils.c       |  2 +-
 4 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/dix/globals.c b/dix/globals.c
index 9738e9c..eaa2afe 100644
--- a/dix/globals.c
+++ b/dix/globals.c
@@ -127,7 +127,8 @@ int defaultColorVisualClass = -1;
 int monitorResolution = 0;
 
 const char *display;
-int displayfd;
+int displayfd = -1;
+Bool explicit_display = FALSE;
 char *ConnectionInfo;
 
 CARD32 TimeOutValue = DEFAULT_TIMEOUT * MILLI_PER_SECOND;
diff --git a/include/opaque.h b/include/opaque.h
index 73d40c3..0d917b0 100644
--- a/include/opaque.h
+++ b/include/opaque.h
@@ -51,6 +51,7 @@ extern _X_EXPORT int defaultScreenSaverBlanking;
 extern _X_EXPORT int defaultScreenSaverAllowExposures;
 extern _X_EXPORT const char *display;
 extern _X_EXPORT int displayfd;
+extern _X_EXPORT Bool explicit_display;
 
 extern _X_EXPORT int defaultBackingStore;
 extern _X_EXPORT Bool disableBackingStore;
diff --git a/os/connection.c b/os/connection.c
index ddf4f0a..7bc2d94 100644
--- a/os/connection.c
+++ b/os/connection.c
@@ -351,8 +351,8 @@ void
 NotifyParentProcess(void)
 {
 #if !defined(WIN32)
-    if (dynamic_display[0]) {
-        write(displayfd, dynamic_display, strlen(dynamic_display));
+    if (displayfd >= 0) {
+        write(displayfd, display, strlen(display));
         write(displayfd, "\n", 1);
         close(displayfd);
     }
@@ -404,15 +404,14 @@ CreateWellKnownSockets(void)
     FD_ZERO(&WellKnownConnections);
 
     /* display is initialized to "0" by main(). It is then set to the display
-     * number if specified on the command line, or to NULL when the -displayfd
-     * option is used. */
-    if (display) {
+     * number if specified on the command line. */
+    if ((displayfd < 0) || explicit_display) {
         if (TryCreateSocket(atoi(display), &partial) &&
             ListenTransCount >= 1)
             if (!PartialNetwork && partial)
                 FatalError ("Failed to establish all listening sockets");
     }
-    else { /* -displayfd */
+    else { /* -displayfd and no explicit display number */
         Bool found = 0;
         for (i = 0; i < 65535 - X_TCP_PORT; i++) {
             if (TryCreateSocket(i, &partial) && !partial) {
diff --git a/os/utils.c b/os/utils.c
index 497779b..8ea6e7a 100644
--- a/os/utils.c
+++ b/os/utils.c
@@ -666,6 +666,7 @@ ProcessCommandLine(int argc, char *argv[])
         else if (argv[i][0] == ':') {
             /* initialize display */
             display = argv[i];
+            explicit_display = TRUE;
             display++;
             if (!VerifyDisplayName(display)) {
                 ErrorF("Bad display name: %s\n", display);
@@ -736,7 +737,6 @@ ProcessCommandLine(int argc, char *argv[])
         else if (strcmp(argv[i], "-displayfd") == 0) {
             if (++i < argc) {
                 displayfd = atoi(argv[i]);
-                display = NULL;
 #ifdef LOCK_SERVER
                 nolock = TRUE;
 #endif
-- 
1.8.3.4