Re: [PATCH xserver] os: don't re-remove an already removed fd

[Keith Packard]

Peter Hutterer <peter.hutte...@who-t.net> writes:

> that's the plan for the driver, but for now the current behaviour is a
> change to what used to work. And it's a bit confusing too -
> xf86AddEnabledDevice() takes a pInfo, not just an fd. So it looks like it
> works on a per-device level and we should emulate that behaviour as best as
> we can. Right now you can pass two different pInfos in and then you get to
> bet whether you remove the same device twice or not.

I went and looked at the previous version of xf86AddEnabledDevice, and
it supports multiple calls with the same fd by replacing the callback
and args. We can do the same thing with InputThreadRegisterDev and make
it actually compatible with the old API. Seems like a more sane plan
than having duplicate fds in the input device list, only one of which
actually gets used.


From 0ed596f16bde0f6df151db657c11973c457f4eb4 Mon Sep 17 00:00:00 2001
From: Keith Packard <kei...@keithp.com>
Date: Thu, 11 Aug 2016 12:34:54 -0700
Subject: [PATCH xserver] os: Allow re-registering fd with
 InputThreadRegisterDev

Calling InputThreadRegisterDev twice with the same fd should replace
the existing function and args instead of creating a new entry with
the same fd.

Signed-off-by: Keith Packard <kei...@keithp.com>
---
 os/inputthread.c | 36 +++++++++++++++++++++++++-----------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/os/inputthread.c b/os/inputthread.c
index cb3af06..1cd1c2a 100644
--- a/os/inputthread.c
+++ b/os/inputthread.c
@@ -188,24 +188,38 @@ InputThreadRegisterDev(int fd,
                        NotifyFdProcPtr readInputProc,
                        void *readInputArgs)
 {
-    InputThreadDevice *dev;
+    InputThreadDevice *dev, *old;
 
     if (!inputThreadInfo)
         return SetNotifyFd(fd, readInputProc, X_NOTIFY_READ, readInputArgs);
 
-    dev = calloc(1, sizeof(InputThreadDevice));
-    if (dev == NULL) {
-        DebugF("input-thread: could not register device\n");
-        return 0;
+    input_lock();
+
+    dev = NULL;
+    xorg_list_for_each_entry(old, &inputThreadInfo->devs, node) {
+        if (old->fd == fd) {
+            dev = old;
+            break;
+        }
     }
 
-    dev->fd = fd;
-    dev->readInputProc = readInputProc;
-    dev->readInputArgs = readInputArgs;
-    dev->state = device_state_added;
+    if (dev) {
+        dev->readInputProc = readInputProc;
+        dev->readInputArgs = readInputArgs;
+    } else {
+        dev = calloc(1, sizeof(InputThreadDevice));
+        if (dev == NULL) {
+            DebugF("input-thread: could not register device\n");
+            input_unlock();
+            return 0;
+        }
 
-    input_lock();
-    xorg_list_append(&dev->node, &inputThreadInfo->devs);
+        dev->fd = fd;
+        dev->readInputProc = readInputProc;
+        dev->readInputArgs = readInputArgs;
+        dev->state = device_state_added;
+        xorg_list_append(&dev->node, &inputThreadInfo->devs);
+    }
 
     inputThreadInfo->changed = TRUE;
 
-- 
2.8.1


-- 
-keith

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