http_server: detect disk-full when writing PID file

While unlikely, it's possible for write(2) to return a truncated
value or ENOSPC error if the device is full when writing a tiny
PID file.

As optimism has no place in engineering, use IO#write instead of
IO#syswrite since the former will retry on truncation and raise
a exception on ENOSPC.

1 files changed, 2 insertions, 1 deletions

diff --git a/lib/unicorn/http_server.rb b/lib/unicorn/http_server.rb
index 21f2a05..3416808 100644
--- a/lib/unicorn/http_server.rb
+++ b/lib/unicorn/http_server.rb
@@ -187,7 +187,8 @@ class Unicorn::HttpServer
       rescue Errno::EEXIST
         retry
       end
-      fp.syswrite("#$$\n")
+      fp.sync = true
+      fp.write("#$$\n")
       File.rename(fp.path, path)
       fp.close
     end