From 7dc71b1ff87913cba31a26f081b65d85b429186f Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Wed, 5 Oct 2016 16:37:23 +0300
Subject: Fix redirection of process stdout to stderr in POSIX implementation

---
 butl/process.cxx | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

(limited to 'butl/process.cxx')

diff --git a/butl/process.cxx b/butl/process.cxx
index 38948a1..64366ba 100644
--- a/butl/process.cxx
+++ b/butl/process.cxx
@@ -332,11 +332,27 @@ namespace butl
       if (in != STDIN_FILENO)
         duplicate (STDIN_FILENO, in, out_fd);
 
-      if (out != STDOUT_FILENO)
-        duplicate (STDOUT_FILENO, out, in_ofd);
+      // If stdout is redirected to stderr (out == 2) we need to duplicate it
+      // after duplicating stderr to pickup the proper fd. Otherwise keep the
+      // "natual" order of duplicate() calls, so if stderr is redirected to
+      // stdout it picks up the proper fd as well.
+      //
+      if (out == STDERR_FILENO)
+      {
+        if (err != STDERR_FILENO)
+          duplicate (STDERR_FILENO, err, in_efd);
 
-      if (err != STDERR_FILENO)
-        duplicate (STDERR_FILENO, err, in_efd);
+        if (out != STDOUT_FILENO)
+          duplicate (STDOUT_FILENO, out, in_ofd);
+      }
+      else
+      {
+        if (out != STDOUT_FILENO)
+          duplicate (STDOUT_FILENO, out, in_ofd);
+
+        if (err != STDERR_FILENO)
+          duplicate (STDERR_FILENO, err, in_efd);
+      }
 
       // Change current working directory if requested.
       //
-- 
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