Created attachment 4510 [details]
patch that fixes fd leak

Any package build fails with
-------------
The stack trace of python calls that resulted in this exception/failure was:
File: 'exec_python_func() autogenerated', lineno: 2, function: <module>
     0001:
 *** 0002:extend_recipe_sysroot(d)
     0003:
File: 'DDD/meta/classes/staging.bbclass', lineno: 559, function: extend_recipe_sysroot
     0555:    bb.note("Installed into sysroot: %s" % str(msg_adding))
     0556:    bb.note("Skipping as already exists in sysroot: %s" % str(msg_exists))
     0557:
     0558:    for f in fixme:
 *** 0559:        staging_processfixme(fixme[f], f, recipesysroot, recipesysrootnative, d)
     0560:
     0561:    for p in postinsts:
     0562:        subprocess.check_output(p, shell=True, stderr=subprocess.STDOUT)
     0563:
File: 'DDD/meta/classes/staging.bbclass', lineno: 174, function: staging_processfixme
     0170:    for fixmevar in ['COMPONENTS_DIR', 'HOSTTOOLS_DIR', 'PKGDATA_DIR', 'PSEUDO_LOCALSTATEDIR', 'LOGFIFO']:
     0171:        fixme_path = d.getVar(fixmevar)
     0172:        cmd += " -e 's:FIXME_%s:%s:g'" % (fixmevar, fixme_path)
     0173:    bb.debug(2, cmd)
 *** 0174:    subprocess.check_output(cmd, shell=True, stderr=subprocess.STDOUT)
     0175:
     0176:
     0177:def staging_populate_sysroot_dir(targetsysroot, nativesysroot, native, d):
     0178:    import glob
File: '/usr/lib/python3.5/subprocess.py', lineno: 316, function: check_output
     0312:        # empty string. That is maintained here for backwards compatibility.
     0313:        kwargs['input'] = '' if kwargs.get('universal_newlines', False) else b''
     0314:
     0315:    return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
 *** 0316:               **kwargs).stdout
     0317:
     0318:
     0319:class CompletedProcess(object):
     0320:    """A process that has finished running.
File: '/usr/lib/python3.5/subprocess.py', lineno: 398, function: run
     0394:            raise
     0395:        retcode = process.poll()
     0396:        if check and retcode:
     0397:            raise CalledProcessError(retcode, process.args,
 *** 0398:                                     output=stdout, stderr=stderr)
     0399:    return CompletedProcess(process.args, retcode, stdout, stderr)
     0400:
     0401:
     0402:def list2cmdline(seq):
Exception: subprocess.CalledProcessError: Command 'sed -e 's:^[^/]*/:DDD/WWW/tmp/work/cortexa9hf-neon-poky-linux-gnueabi/perl/5.24.4-r0/recipe-sysroot-native/:g' DDD/WWW/tmp/sysroots-components/x86_64/rpm-native/fixmepath DDD/WWW/tmp/sysroots-components/x86_64/pkgconfig-native/fixmepath DDD/WWW/tmp/sysroots-components/x86_64/elfutils-native/fixmepath DDD/WWW/tmp/sysroots-components/x86_64/dbus-native/fixmepath DDD/WWW/tmp/sysroots-components/x86_64/python3-native/fixmepath DDD/WWW/tmp/sysroots-components/x86_64/openssl-native/fixmepath DDD/WWW/tmp/sysroots-components/x86_64/nspr-native/fixmepath DDD/WWW/tmp/sysroots-components/x86_64/e2fsprogs-native/fixmepath DDD/WWW/tmp/sysroots-components/x86_64/ncurses-native/fixmepath | xargs sed -i -e 's:FIXMESTAGINGDIRTARGET:DDD/WWW/tmp/work/cortexa9hf-neon-poky-linux-gnueabi/perl/5.24.4-r0/recipe-sysroot:g; s:FIXMESTAGINGDIRHOST:DDD/WWW/tmp/work/cortexa9hf-neon-poky-linux-gnueabi/perl/5.24.4-r0/recipe-sysroot-native:g' -e 's:FIXME_COMPONENTS_DIR:DDD/WWW/tmp/sysroots-components:g' -e 's:FIXME_HOSTTOOLS_DIR:DDD/WWW/tmp/hosttools:g' -e 's:FIXME_PSEUDO_LOCALSTATEDIR:DDD/WWW/tmp/work/cortexa9hf-neon-poky-linux-gnueabi/perl/5.24.4-r0/pseudo/:g' -e 's:FIXME_LOGFIFO:DDD/WWW/tmp/work/cortexa9hf-neon-poky-linux-gnueabi/perl/5.24.4-r0/temp/fifo.3940:g'' returned non-zero exit status 125

Subprocess output:
xargs: File descriptor 8 will leak; please report this as a bug, remembering to include a detailed description of the simplest way to reproduce this problem.
xargs: fdleak.c:396: complain_about_leaky_fds: Assertion `no_leaks' failed.
xargs: sed: terminated by signal 6
-------------

when building with enabled and redirected pseudo logging:
conf/local.conf:

FAKEROOTENV_append = " PSEUDO_DEBUG=7 PSEUDO_DEBUG_FILE=<>/pseudolog/pseudo_dbg.log"

I've tracked down this issue and found that file descriptor 8 belong to pseudo log file descriptor itself which is leaked when xargs performs exec.
So, with the attached patch I propose to add O_CLOEXEC flag to automatically close file descriptor on forking new process with fork/exec. 

NB
I set version to 2.6.1 but I am using the latest pseudo SRCREV in bbappend with 
SRCREV = "3fa7c853e0bcd6fe23f7524c2a3c9e3af90901c3"

thus it's applicable to master.