From 0bd8cb742eadf45969133c13ebc5252b5234ef92 Mon Sep 17 00:00:00 2001
From: Eric Wong <normalperson@yhbt.net>
Date: Fri, 10 Apr 2009 13:52:46 -0700
Subject: Restore unlinked UNIX sockets on SIGHUP

Sockets may be unintentionally unlinked on the filesystem.
When reloading our config, ensure that the socket exists
on the filesystem.  If not, close the listener (since it's
unusable by outside apps) and reopen it.
---
 lib/unicorn.rb         | 17 +++++++++++++----
 test/exec/test_exec.rb | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/lib/unicorn.rb b/lib/unicorn.rb
index 02419e7..2883bc2 100644
--- a/lib/unicorn.rb
+++ b/lib/unicorn.rb
@@ -105,16 +105,25 @@ module Unicorn
     # replaces current listener set with +listeners+.  This will
     # close the socket if it will not exist in the new listener set
     def listeners=(listeners)
-      cur_names = listener_names
+      cur_names, dead_names = [], []
+      listener_names.each do |name|
+        if "/" == name[0..0]
+          # mark unlinked sockets as dead so we can rebind them
+          (File.socket?(name) ? cur_names : dead_names) << name
+        else
+          cur_names << name
+        end
+      end
       set_names = listener_names(listeners)
-      dead_names = cur_names - set_names
+      dead_names += cur_names - set_names
+      dead_names.uniq!
 
       @listeners.delete_if do |io|
         if dead_names.include?(sock_name(io))
           @io_purgatory.delete_if do |pio|
-            pio.fileno == io.fileno && (pio.close rescue nil).nil?
+            pio.fileno == io.fileno && (pio.close rescue nil).nil? # true
           end
-          (io.close rescue nil).nil?
+          (io.close rescue nil).nil? # true
         else
           false
         end
diff --git a/test/exec/test_exec.rb b/test/exec/test_exec.rb
index 336dc53..ec00fac 100644
--- a/test/exec/test_exec.rb
+++ b/test/exec/test_exec.rb
@@ -439,6 +439,38 @@ end
     reexec_basic_test(pid, pid_file)
   end
 
+  def test_socket_unlinked_restore
+    results = nil
+    sock = Tempfile.new('unicorn_test_sock')
+    sock_path = sock.path
+    sock.close!
+    ucfg = Tempfile.new('unicorn_test_config')
+    ucfg.syswrite("listen \"#{sock_path}\"\n")
+
+    File.open("config.ru", "wb") { |fp| fp.syswrite(HI) }
+    pid = xfork { redirect_test_io { exec($unicorn_bin, "-c#{ucfg.path}") } }
+    wait_for_file(sock_path)
+    assert File.socket?(sock_path)
+    assert_nothing_raised do
+      sock = UNIXSocket.new(sock_path)
+      sock.syswrite("GET / HTTP/1.0\r\n\r\n")
+      results = sock.sysread(4096)
+    end
+    assert_equal String, results.class
+    assert_nothing_raised do
+      File.unlink(sock_path)
+      Process.kill(:HUP, pid)
+    end
+    wait_for_file(sock_path)
+    assert File.socket?(sock_path)
+    assert_nothing_raised do
+      sock = UNIXSocket.new(sock_path)
+      sock.syswrite("GET / HTTP/1.0\r\n\r\n")
+      results = sock.sysread(4096)
+    end
+    assert_equal String, results.class
+  end
+
   def test_unicorn_config_file
     pid_file = "#{@tmpdir}/test.pid"
     sock = Tempfile.new('unicorn_test_sock')
-- 
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