XFCE desktop components fail to start on kernels without close_range syscall

[lanmower]

Problem

On Oracle Linux and older kernels lacking the close_range syscall, XFCE session components (xfdesktop, xfwm4, xfce4-panel, xfsettingsd) fail to start. X server and Chromium work but desktop environment does not appear.

Root cause

• close_range syscall returns EPERM on older kernels
• XFCE components require D-Bus session bus
• LD_PRELOAD shim not inherited by XFCE session processes

Fix prompt

Fix XFCE startup on kernels without close_range syscall:

1. Create shim_close_range.c:
#define _GNU_SOURCE
#include <errno.h>
int close_range(unsigned int first, unsigned int last, int flags) {
    errno = 38;
    return -1;
}

2. In Dockerfile, compile shim and set system-wide:
RUN gcc -fPIC -shared shim_close_range.c -o /usr/local/lib/libshim_close_range.so
RUN echo 'LD_PRELOAD=/usr/local/lib/libshim_close_range.so' >> /etc/environment

3. In startup script, restart XFCE session with D-Bus:
pkill -u $USER xfce4-session || true
sudo -u $USER bash -c 'export LD_PRELOAD=/usr/local/lib/libshim_close_range.so; export DISPLAY=:1; eval $(dbus-launch --sh-syntax); xfce4-session &'

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