fix: a desktop Plasma makes after the layout has run gets the classroom's wallpaper
Tiny Pebbles came through the 0.2.2 upgrade on Plasma's own purple wallpaper: its desktop was containment 10, made after the layout had run (most likely the television arriving after a night-time reboot), with no wallpaper configured. The look and feel's fallback could not catch it, because it named a file and Plasma only accepts a wallpaper package there. The fallback is now the EkklesiaClassroom package, whose one image links to the classroom's picture. classroom-desktop-wallpaper, run before every plasmashell start, writes the picture into every desktop containment the file already has: found by plugin, never by number; panels and everything else byte for byte; a file that is already right not written at all. Co-Authored-By: Claude Opus 5.5 <[email protected]>
This commit is contained in:
ekklesia
co-authored by
Claude Opus 5.5
Claude Opus 5.5
parent
530f6f6563
commit
7b4ac39cd2
Executable
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#!/usr/bin/env python3
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"""Put the classroom's wallpaper on every desktop the shell has.
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Tiny Pebbles came up after the 0.2.2 -> 0.2.6.4 upgrade on Plasma's own
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purple wallpaper, with the right panel and the right package installed.
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Its desktop was containment 10, with no Wallpaper group at all:
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[Containments][10]
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plugin=org.kde.plasma.folder
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wallpaperplugin=org.kde.image
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[Containments][10][General]
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positions={"1920x1080":[]}
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The layout script writes the wallpaper, but only onto the desktops that
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exist while it runs. Plasma makes a desktop for every screen, and every
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activity, that appears afterwards — and it makes them without the layout.
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0.2.2's updater rebooted at three in the morning with the television
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switched off at the set, so the layout ran with no screen and no desktop
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at all, and the desktop Plasma made when the television came on was
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bare. Reproduced in the lab through a new activity, which takes the same
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path through the shell: containment 11, the same four lines, Plasma's
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wallpaper.
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Two things now close that. The look and feel's default wallpaper is a
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real wallpaper package, so a desktop Plasma makes on its own comes up
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with the classroom's picture — that is the fix, and it needs nothing to
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run. And this, which writes the picture into every desktop the file
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already has, so that the configuration says what the screen shows.
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WHICH CONTAINMENT IS THE DESKTOP is answered by what it is, never by its
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number: a top-level containment whose plugin is one of Plasma's desktop
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containments. Tiny Pebbles' desktop was 10 and River Kids' is 1, and the
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panel's number is whatever was free when it was built.
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ONLY THE DESKTOPS ARE TOUCHED. Every panel, applet and line that is not a
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desktop's wallpaper is written back byte for byte, and a file that is
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already right is not written at all.
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WHEN IT RUNS. Before plasmashell starts, as the shell's own ExecStartPre,
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because the shell owns this file: editing it underneath a live shell was
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measured to destroy the panel. That is every start — a login, a reboot,
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and the restart after a crash — and at a login it usually finds nothing,
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because classroom-desktop-reset has just removed the file for the layout
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to rebuild. Run by hand, it refuses while the shell is running and says
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how to apply it. Live D-Bus scripting is not an option: the classroom
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locks the desktop and forbids the scripting console, and Plasma answers
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"Widgets are locked" — measured.
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classroom-desktop-wallpaper repair, if the shell is stopped
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classroom-desktop-wallpaper --check say what is wrong, change nothing
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classroom-desktop-wallpaper FILE work on FILE instead
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"""
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import os
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import re
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import sys
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WALLPAPER = "/usr/share/backgrounds/ekklesia/classroom-calm.png"
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WALLPAPER_PLUGIN = "org.kde.image"
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# Plasma's two desktop containments: Folder View, which is what the
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# classroom's desktops are, and the plain Desktop. Panels, the system tray
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# a 0.2.2-era profile may still carry and anything else are not desktops.
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DESKTOP_PLUGINS = ("org.kde.plasma.folder", "org.kde.desktopcontainment")
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# What the layout writes onto a desktop, so a repaired desktop and a
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# freshly built one say the same thing.
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WALLPAPER_KEYS = (
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("FillMode", "2"),
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("Image", f"file://{WALLPAPER}"),
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)
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APPLETSRC = "plasma-org.kde.plasma.desktop-appletsrc"
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CONTAINMENT = re.compile(r"^\[Containments\]\[(\d+)\]$")
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# key=value, with KConfig's optional [$i]-style flags or [locale] after
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# the key. The flags are kept when a value is replaced.
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ENTRY = re.compile(r"^([^=\[\s]+)((?:\[[^\]]*\])*)=(.*)$")
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def say(message):
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print(f"classroom-desktop-wallpaper: {message}", flush=True)
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def groups(lines):
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"""[(name, header, end)]: lines[header] is the group's header line, or
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-1 for the lines before the first group, and end is exclusive."""
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found = []
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name, header = None, -1
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for index, line in enumerate(lines):
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stripped = line.strip()
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if stripped.startswith("[") and stripped.endswith("]"):
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found.append((name, header, index))
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name, header = stripped, index
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found.append((name, header, len(lines)))
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return found
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def find_group(lines, name):
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for group, header, end in groups(lines):
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if group == name:
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return header, end
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return None
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def entry(line):
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match = ENTRY.match(line.rstrip("\n"))
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return (match.group(1), match.group(2), match.group(3)) if match else None
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def desktops(lines):
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"""The ids of the desktop containments, whatever they are numbered."""
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ids = []
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for name, header, end in groups(lines):
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match = CONTAINMENT.match(name or "")
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if not match:
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continue
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for line in lines[header + 1:end]:
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parsed = entry(line)
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if parsed and parsed[0] == "plugin" and parsed[2] in DESKTOP_PLUGINS:
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ids.append(match.group(1))
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break
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return ids
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def set_entry(lines, group, key, value):
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"""Make `key=value` true in an existing group. Returns what changed,
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or None when it already was."""
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header, end = find_group(lines, group)
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last = header
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for index in range(header + 1, end):
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parsed = entry(lines[index])
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if lines[index].strip():
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last = index
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if parsed and parsed[0] == key:
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if parsed[2] == value:
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return None
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lines[index] = f"{key}{parsed[1]}={value}\n"
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return f"{key} was [{parsed[2]}]"
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lines.insert(last + 1, f"{key}={value}\n")
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return f"{key} was missing"
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def add_group(lines, containment, group):
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"""A new group, placed after the last of its containment's own."""
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prefix = f"[Containments][{containment}]"
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after = None
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for name, header, end in groups(lines):
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if name == prefix or (name or "").startswith(prefix + "["):
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after = end
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# Back over the blank lines that separate it from the next group, so
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# the new one sits with its containment and the spacing stays as
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# KConfig writes it.
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while after > 0 and not lines[after - 1].strip():
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after -= 1
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if after > 0 and not lines[after - 1].endswith("\n"):
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lines[after - 1] += "\n"
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block = ["\n", f"{group}\n"]
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block += [f"{key}={value}\n" for key, value in WALLPAPER_KEYS]
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lines[after:after] = block
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def converge(text):
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"""The file as it should be, and what was changed to make it so."""
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lines = text.splitlines(keepends=True)
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changes = []
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for containment in desktops(lines):
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top = f"[Containments][{containment}]"
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change = set_entry(lines, top, "wallpaperplugin", WALLPAPER_PLUGIN)
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if change:
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changes.append(f"desktop {containment}: {change}")
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group = f"{top}[Wallpaper][{WALLPAPER_PLUGIN}][General]"
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if find_group(lines, group) is None:
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add_group(lines, containment, group)
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changes.append(f"desktop {containment}: had no wallpaper configured")
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continue
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for key, value in WALLPAPER_KEYS:
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change = set_entry(lines, group, key, value)
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if change:
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changes.append(f"desktop {containment}: {change}")
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return "".join(lines), changes
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def default_path():
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home = os.environ.get("XDG_CONFIG_HOME") or os.path.expanduser("~/.config")
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return os.path.join(home, APPLETSRC)
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def shell_running(proc="/proc"):
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"""plasmashell running as this user. Read from /proc rather than asked
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of systemd, so a shell started any way at all counts, and rather than
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of pgrep, which nothing guarantees is installed."""
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uid = os.getuid()
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for pid in os.listdir(proc):
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if not pid.isdigit():
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continue
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try:
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with open(os.path.join(proc, pid, "comm"), encoding="utf-8") as handle:
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name = handle.read().strip()
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if name == "plasmashell" and os.stat(os.path.join(proc, pid)).st_uid == uid:
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return True
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except OSError:
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# Gone while it was being looked at.
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continue
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return False
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def write(path, text):
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"""Replace the file whole, so a full disk or a power cut leaves the old
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one rather than half of a new one."""
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temporary = f"{path}.classroom-new"
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mode = os.stat(path).st_mode & 0o7777
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with open(temporary, "w", encoding="utf-8") as handle:
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handle.write(text)
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handle.flush()
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os.fsync(handle.fileno())
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os.chmod(temporary, mode)
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os.replace(temporary, path)
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def main(argv):
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check = "--check" in argv
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paths = [arg for arg in argv if not arg.startswith("--")]
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path = paths[0] if paths else default_path()
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try:
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with open(path, "r", encoding="utf-8") as handle:
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before = handle.read()
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except FileNotFoundError:
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say("no desktop configuration yet; the layout writes the wallpaper")
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return 0
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except OSError as error:
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say(f"cannot read {path}: {error}")
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return 0
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after, changes = converge(before)
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found = desktops(before.splitlines(keepends=True))
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if not found:
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say("no desktop in the configuration yet; Plasma's default is the "
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"classroom's wallpaper package")
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return 0
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if not changes:
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say(f"desktop {', '.join(found)}: the classroom wallpaper already")
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return 0
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for change in changes:
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say(change)
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if check:
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say("not changed (--check)")
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return 1
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# The shell owns the live file. Anything else is just a file.
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if not paths and shell_running():
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say("plasmashell is running, and editing its file underneath it")
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say("destroys the panel. Apply it with:")
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say(" systemctl --user restart plasma-plasmashell.service")
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say("which repairs the file before the shell starts again.")
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return 1
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try:
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write(path, after)
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except OSError as error:
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say(f"cannot write {path}: {error}")
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return 1
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say(f"the wallpaper is now configured on desktop {', '.join(found)}")
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return 0
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if __name__ == "__main__":
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sys.exit(main(sys.argv[1:]))
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