bugfixes

[csd113]

Fix: backup validation, logging rotation, and DB consistency improvements

This PR completes updates to backup.rs and logging.rs, along with several fixes across the database layer.

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Summary of Changes

db/posts.rs

• Add custom theme linker #13 – Constant-time comparison

  • Replaced custom constant_time_eq with subtle::ConstantTimeEq
  • Use: a.ct_eq(b).into()
  • Added import: use subtle::ConstantTimeEq as _
  • Removed hand-rolled implementation

• Pruned dead code, bumped version, fixed typos #16 – Poll vote race condition

  • Updated cast_vote query:
    • JOINs polls table
    • Adds expiry guard: sql AND (p.expires_at IS NULL OR p.expires_at > unixepoch())
  • Prevents race between handler validation and INSERT

• Proper error logging output #25 – edit_window_secs semantics

  • 0 → no time limit (skips check via Option)
  • Negative → fallback to 300s
  • Positive → used as-is

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handlers/admin/backup.rs

• update readme for 1.0.13 #19 – SQLite validation

  • Added magic byte check (b"SQLite format 3\0") after extracting chan.db
  • Applied to:
    • admin_restore
    • restore_saved_board_backup
  • Invalid DB now returns 400 Bad Request before rusqlite usage

• Alpha v1.1.0dev3 api hooks #30 – Duplicate encoding logic removed

  • Removed inner encode_q / nibble definitions
  • Introduced single module-level encode_q
  • Shared across:
    • admin_restore
    • restore_saved_board_backup
    • board_restore

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db/logging.rs (moved from logging.rs)

• bugfixes #33 – Log rotation

  • Replaced rolling::never with rolling::daily
  • Logs now rotate automatically: rustchan.log.YYYY-MM-DD

• Location + API updates

  • Moved file to: db/logging.rs
  • Renamed log_dir → db_dir
  • Logs now stored alongside chan.db
  • Updated documentation accordingly

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Required Follow-ups

• Update module declaration: