From 6eeb0d3c513e7739bfdf7e63a7850a6d3b798da1 Mon Sep 17 00:00:00 2001
From: Kyle Machulis <kyle@nonpolynomial.com>
Date: Tue, 19 Nov 2013 12:52:37 -0800
Subject: [PATCH] Bug 937496 - Check if libudev already loaded before trying to
 load symbols from it; r=ted

---
 hal/linux/udev.h | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/hal/linux/udev.h b/hal/linux/udev.h
index 049b20357ea..9c29c2905bf 100644
--- a/hal/linux/udev.h
+++ b/hal/linux/udev.h
@@ -30,13 +30,27 @@ class udev_lib {
     // symbols this code relies on, per:
     // https://lists.fedoraproject.org/pipermail/devel/2012-June/168227.html
     const char* lib_names[] = {"libudev.so.0", "libudev.so.1"};
+    // Check whether a library is already loaded so we don't load two
+    // conflicting libs.
     for (unsigned i = 0; i < ArrayLength(lib_names); i++) {
-      lib = dlopen(lib_names[i], RTLD_LAZY | RTLD_GLOBAL);
-      if (lib)
+      lib = dlopen(lib_names[i], RTLD_NOLOAD | RTLD_LAZY | RTLD_GLOBAL);
+      if (lib) {
         break;
+      }
     }
-    if (lib && LoadSymbols())
+    // If nothing loads the first time through, it means no version of libudev
+    // was already loaded.
+    if (!lib) {
+      for (unsigned i = 0; i < ArrayLength(lib_names); i++) {
+        lib = dlopen(lib_names[i], RTLD_LAZY | RTLD_GLOBAL);
+        if (lib) {
+          break;
+        }
+      }
+    }
+    if (lib && LoadSymbols()) {
       udev = udev_new();
+    }
   }
 
   ~udev_lib() {