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fix: atomic writes, volatile journal, ASCII console banners - #56
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Power-loss safety improvements for the Raspberry Pi deployment: 1. Atomic file writes (new zeclock/atomic_write.py): - All config/state writes now use temp file + fsync + rename - Guarantees files are either old or new, never truncated - Applied to: zeclock.ini, plugins.yaml, update version/history 2. Journald switched to volatile (RAM-only): - Continuous journal writes were the #1 source of f2fs corruption - Logs no longer survive reboots but /data stays healthy - RuntimeMaxUse=10M caps RAM usage Files using atomic writes: - clock.py (_persist_wifi_addr) - rest_remote.py (save config, save plugins, persist brightness, import) - updater.py (version file, history.json) - plugin_config.py (create default config)
Terminal on RPi does not support emoji (width=2) or Unicode box-drawing characters, causing misaligned banner borders. Use plain ASCII characters (+, |, =) instead.
ojacques
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Problem
Repeated f2fs corruption on the Raspberry Pi after power loss. Root cause: direct file writes (
open(path, 'w')) and continuous journald writes to/data.Additionally, console banners displayed on the RPi terminal (tty1) were misaligned because emoji and Unicode box-drawing characters have inconsistent widths on the Linux framebuffer console.
Changes
1. Atomic file writes (
zeclock/atomic_write.py)New utility module implementing the crash-safe write pattern:
fsync()the file descriptoros.replace()(atomic POSIX rename)fsync()the directoryApplied to all config/state writes:
zeclock.ini(brightness, wifi_addr, full config save, import)plugins.yaml(plugin config save, default creation)current-version(OTA updater)history.json(OTA update history)2. Journald switched to volatile (RAM)
Storage=volatilereplacesStorage=persistent/data3. ASCII-only console banners
_show_console_bannerand_show_connected_bannerwith plain ASCII (+,|,=)main()print statementsResult
/dataare guaranteed to be either the previous valid version or the new complete version at any point during a power cut.