From aed607fa413622b314ac82a827682dae2487418a Mon Sep 17 00:00:00 2001
From: Eric Wong <e@yhbt.net>
Date: Sat, 2 Apr 2011 14:57:20 -0700
Subject: [PATCH] clobber errno before syscalls for BasicSocket#read

We don't want old errnos being leftover and affecting
the error check for EOF
---
 ext/socket_dontwait/socket_dontwait_ext.c |  5 ++++-
 test/test_socket_dontwait.rb              | 35 +++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/ext/socket_dontwait/socket_dontwait_ext.c b/ext/socket_dontwait/socket_dontwait_ext.c
index 2a261a3..7598596 100644
--- a/ext/socket_dontwait/socket_dontwait_ext.c
+++ b/ext/socket_dontwait/socket_dontwait_ext.c
@@ -164,8 +164,10 @@ static VALUE readpartial(int argc, VALUE *argv, VALUE io)
 static VALUE recv_all(void *arg)
 {
 	struct io_args *a = arg;
-	long n = (long)recv(a->fd, a->ptr, a->len, MSG_WAITALL);
+	long n;
 
+	errno = 0;
+	n = (long)recv(a->fd, a->ptr, a->len, MSG_WAITALL);
 	if (n >= 0) {
 		a->ptr += n;
 		a->len -= n;
@@ -231,6 +233,7 @@ static VALUE xread(int argc, VALUE *argv, VALUE io)
 		return a.buf;
 
 	/* try to read as much as possible without blocking */
+	errno = 0;
 	do
 		n = (long)recv(a.fd, a.ptr, a.len, MSG_DONTWAIT);
 	while (n > 0 && (a.ptr += n) && (a.len -= n) > 0);
diff --git a/test/test_socket_dontwait.rb b/test/test_socket_dontwait.rb
index e8c18db..82d8f79 100644
--- a/test/test_socket_dontwait.rb
+++ b/test/test_socket_dontwait.rb
@@ -20,6 +20,9 @@ ORIGINAL_SOCKET = ENV['ORIGINAL_SOCKET'].to_i != 0
 require(ORIGINAL_SOCKET ? 'socket' : 'socket_dontwait')
 
 class TestSocketDontwait < Test::Unit::TestCase
+  BS = ENV['bs'] ? ENV['bs'].to_i : 16384
+  COUNT = ENV['count'] ? ENV['count'].to_i : 100000
+
   def setup
     @rd, @wr = UNIXSocket.pair
   end
@@ -265,4 +268,36 @@ class TestSocketDontwait < Test::Unit::TestCase
     assert_nothing_raised { @wr.sync = false }
     assert @wr.sync
   end unless ORIGINAL_SOCKET
+
+  def read_loop(io)
+    rbuf = ""
+    bs = BS
+    n = bs * COUNT
+    while io.read(bs, rbuf)
+      n -= rbuf.size
+    end
+    0 == n
+  end
+
+  def write_loop(io)
+    buf = " " * BS
+    n = 0
+    COUNT.times do
+      n += io.write buf
+    end
+    io.close
+    n == COUNT * BS
+  end
+
+  def test_read_write_loop_fork
+    pid = fork do
+      @wr.close
+      exit read_loop(@rd)
+    end
+    @rd.close
+    rv = write_loop(@wr)
+    assert rv
+    _, status = Process.waitpid2(pid)
+    assert status.success?
+  end
 end
-- 
2.11.4.GIT