[gnome-continuous-yocto/gnomeostree-3.28-rocko: 3915/8267] bitbake: prserv/serv: Tweak stdout manipulation to be stream safe

[Emmanuele Bassi <ebassi src gnome org>]

commit 9f6a1043f68580ed9604e750fd0f993f933bb66e
Author: Richard Purdie <richard purdie linuxfoundation org>
Date:   Wed Jan 4 23:23:52 2017 +0000

    bitbake: prserv/serv: Tweak stdout manipulation to be stream safe
    
    We've been seeing oe-selftest failures under puzzling circumstances. It
    turns out if you run oe-selftest on a machine with xmlrunner installed
    and have the recent tinfoil2 changes, the launching of PR server crashes
    leading to selftest hanging if using an autoloaded PR server.
    
    The reason is that xmlrunner uses an io.StringIO object as stdout/stderr
    instead of the usual io.TextIOWrapper and StringIO lacks a fileno() method.
    
    We have to deal with both cases and in the python way, we try and then seek
    forgivness if we see an AttributeError or UnSupportedOperation exception.
    Unfortunately we have to deal with both cases as we may be performing a
    traditiional double fork() from the commandline, or a larger python program.
    
    [YOCTO #10866]
    
    (Bitbake rev: 26243f04e3af652291d13e85c084057104fe155b)
    
    Signed-off-by: Richard Purdie <richard purdie linuxfoundation org>

 bitbake/lib/prserv/serv.py |   21 +++++++++++++++++----
 1 files changed, 17 insertions(+), 4 deletions(-)
---
diff --git a/bitbake/lib/prserv/serv.py b/bitbake/lib/prserv/serv.py
index 350b085..d9b602f 100644
--- a/bitbake/lib/prserv/serv.py
+++ b/bitbake/lib/prserv/serv.py
@@ -242,12 +242,25 @@ class PRServer(SimpleXMLRPCServer):
 
         sys.stdout.flush()
         sys.stderr.flush()
+
+        # We could be called from a python thread with io.StringIO as
+        # stdout/stderr or it could be 'real' unix fd forking where we need
+        # to physically close the fds to prevent the program launching us from
+        # potentially hanging on a pipe. Handle both cases.
         si = open('/dev/null', 'r')
+        try:
+            os.dup2(si.fileno(),sys.stdin.fileno())
+        except (AttributeError, io.UnsupportedOperation):
+            sys.stdin = si
         so = open(self.logfile, 'a+')
-        se = so
-        os.dup2(si.fileno(),sys.stdin.fileno())
-        os.dup2(so.fileno(),sys.stdout.fileno())
-        os.dup2(se.fileno(),sys.stderr.fileno())
+        try:
+            os.dup2(so.fileno(),sys.stdout.fileno())
+        except (AttributeError, io.UnsupportedOperation):
+            sys.stdout = so
+        try:
+            os.dup2(so.fileno(),sys.stderr.fileno())
+        except (AttributeError, io.UnsupportedOperation):
+            sys.stderr = so
 
         # Clear out all log handlers prior to the fork() to avoid calling
         # event handlers not part of the PRserver