BUG #13594: pg_ctl.exe redirects stderr to Windows Events Log if stderr is redirected to pipe

The following bug has been logged on the website:

Bug reference:      13594
Logged by:          Egon Kocjan
Email address:      ekocjan@gmail.com
PostgreSQL version: 9.5alpha2
Operating system:   Windows 8.1
Description:

Hello

Context:

I run PostgreSQL as a part of a larger software package, pg_ctl is used to
control PostgreSQL. I capture all subprocess stderr logs to make a complete
report.

Problem:

On Windows (but not Unix!), PostgreSQL (any version) pg_ctl stops writing
into stderr if stderr is not a character device. As a result, it's not
possible to capture stderr of pg_ctl when using CreateProcess and
STARTUPINFO.hStdError. It might be possible to create a workaround with a
console buffer, but I think it's quite ugly:
http://www.codeproject.com/Articles/16163/Real-Time-Console-Output-Redirection

Solution:

Fix pg_ctl to write into stderr, if stderr is available and not just a
character device. Possibly, add a flag to force stderr. I don't have the big
picture, but this is the quick solution that I use right now:

diff -ur postgresql-9.3.6.orig\src\bin\pg_ctl\pg_ctl.c
postgresql-9.3.6\src\bin\pg_ctl\pg_ctl.c
--- postgresql-9.3.6.orig\src\bin\pg_ctl\pg_ctl.c    Mon Feb 02 22:43:50 2015
+++ postgresql-9.3.6\src\bin\pg_ctl\pg_ctl.c    Fri Aug 28 08:21:01 2015
@@ -215,7 +215,7 @@
      * On Win32, we print to stderr if running on a console, or write to
      * eventlog if running as a service
      */
-    if (!isatty(fileno(stderr)))    /* Running as a service */
+    if (getenv("PG_CTL_STDERR") == NULL && !isatty(fileno(stderr)))    /* Running
as a service */
     {
         char        errbuf[2048];        /* Arbitrary size? */


Then in my main process: _putenv("PG_CTL_STDERR=1")

I also noticed, that write_stderr() in src/backend/utils/error/elog.c uses a
different check (not isatty):

if (pgwin32_is_service())    /* Running as a service */

Thank you