From 9614d5113526ba82bc8522b0b1c9a119e45932d3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sa=C3=BAl=20Ibarra=20Corretg=C3=A9?= <saghul@gmail.com>
Date: Thu, 27 Dec 2012 23:15:40 +0100
Subject: [PATCH] unix: reset errno when using sendfile emulation

A common way to check if a uv_fs_t request failed is to check that
req->errorno != 0.

With uv_fs_sendfile(), when the sendfile() syscall fails, req->errorno is set
to (for example) ENOTSOCK, even when the emulation code path succeeds.

Zero errno before the call to uv__fs_sendfile_emul() to prevent that from
happening.
---
 src/unix/fs.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/unix/fs.c b/src/unix/fs.c
index 6c6faf53..f01c83b4 100644
--- a/src/unix/fs.c
+++ b/src/unix/fs.c
@@ -381,6 +381,7 @@ static ssize_t uv__fs_sendfile(uv_fs_t* req) {
         errno == EIO ||
         errno == ENOTSOCK ||
         errno == EXDEV) {
+      errno = 0;
       return uv__fs_sendfile_emul(req);
     }
 
@@ -412,6 +413,7 @@ static ssize_t uv__fs_sendfile(uv_fs_t* req) {
         errno == EIO ||
         errno == ENOTSOCK ||
         errno == EXDEV) {
+      errno = 0;
       return uv__fs_sendfile_emul(req);
     }