This patch fixes SLiM so it really waits for the X server to be ready
before attempting to connect to it.  Indeed, the X server notices that
its parent process has a handler for SIGUSR1, and consequently sends it
SIGUSR1 when it's ready to accept connections.

The problem was that SLiM doesn't pay attention to SIGUSR1.  So in practice,
if X starts slowly, then SLiM gets ECONNREFUSED a couple of time on
/tmp/.X11-unix/X0, then goes on trying to connect to localhost:6000,
where nobody answers; eventually, it times out and tries again on
/tmp/.X11-unix/X0, and finally it shows up on the screen.

Patch by L. Courtès.

--- slim-1.3.6/app.cpp	2014-02-05 15:27:20.000000000 +0100
+++ slim-1.3.6/app.cpp	2014-02-09 22:42:04.000000000 +0100
@@ -119,7 +119,9 @@ void CatchSignal(int sig) {
 	exit(ERR_EXIT);
 }
 
+static volatile int got_sigusr1 = 0;
 void User1Signal(int sig) {
+	got_sigusr1 = 1;
 	signal(sig, User1Signal);
 }
 
@@ -884,6 +886,7 @@ int App::WaitForServer() {
 	int	ncycles	 = 120;
 	int	cycles;
 
+	while (!got_sigusr1);
 	for(cycles = 0; cycles < ncycles; cycles++) {
 		if((Dpy = XOpenDisplay(DisplayName))) {
 			XSetIOErrorHandler(xioerror);
7a08'>refs</a><a class='active' href='/guix/log/gnu/build/accounts.scm'>log</a><a href='/guix/tree/gnu/build/accounts.scm?id=f0752de257d5521f7cbe31a4c0f5114694747a08'>tree</a><a href='/guix/commit/gnu/build/accounts.scm?id=f0752de257d5521f7cbe31a4c0f5114694747a08'>commit</a><a href='/guix/diff/gnu/build/accounts.scm?id=f0752de257d5521f7cbe31a4c0f5114694747a08'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/build/accounts.scm'>
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<tr><td><span title='2023-10-12 18:53:06 +0200'>2023-10-12</span></td><td><a href='/guix/commit/gnu/build/accounts.scm?id=8b8ab17561cad10ce2b613ece8e8cdfba729fc1a'>accounts: Fix typo in comment.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/build/accounts.scm (passwd-&gt;shadow): Fix typo in comment.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2023-10-08 23:43:49 +0200'>2023-10-08</span></td><td><a href='/guix/commit/gnu/build/accounts.scm?id=002c5bec07e88c00d9d96209438728d0271f57da'>accounts: Ensure ‘last-change’ field of shadow entries is never zero.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/build/accounts.scm (passwd-&gt;shadow): Add ‘max’ call so NOW is
greater than or equal to 1.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-01-01 15:10:12 +0100'>2022-01-01</span></td><td><a href='/guix/commit/gnu/build/accounts.scm?id=671e6a81804f264ddcdd6fe7579644404da079b8'>system: Allow 'chfn' to change the user's full name.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes &lt;https://issues.guix.gnu.org/52539&gt;.
Reported by Jacob First &lt;jacob.first@member.fsf.org&gt;.

* gnu/build/accounts.scm (allocate-passwd): Add comment as to why
'real-name' is taken from PREVIOUS.  Add (not system?) to the
condition.
* gnu/system.scm (operating-system-etc-service) &lt;login.defs&gt;: Add
"CHFN_RESTRICT".
* gnu/system.scm (%setuid-programs): Add "chfn".
* gnu/system/pam.scm (base-pam-services): Add "chfn".
* doc/guix.texi (User Accounts): Document it.
</span></span></td><td>Ludovic Courtès</td></tr>