abrown38andClaude Opus 5.5
3c0808591f
Subnets served per interface, pools, reservations, options at three levels, leases in SQLite saved before the ACK, ping and decline conflict checks, validated changes with history and undo, users and tokens, an audit log, a Kea importer, a sandboxed systemd unit and Debian packages. Tested with real udhcpc and dhcpcd clients in Docker (scripts/e2e.sh). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
41 lines
1.2 KiB
Go
41 lines
1.2 KiB
Go
package main
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import (
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"errors"
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"fmt"
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"os"
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"path/filepath"
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"syscall"
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)
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// errInUse means another process holds the database lock.
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var errInUse = errors.New("the database is in use by a running stewardd or by 'stewardd restore'")
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// lockDatabase takes the exclusive lock (on DATABASE.lock) that marks the
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// database as in use by a running stewardd or by 'stewardd restore', so a
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// restore can never replace the database under a running stewardd, and two
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// stewardds can't serve the same database. Other commands (backup, user, ...)
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// don't take it: they work alongside a running stewardd.
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func lockDatabase(db string) (release func(), err error) {
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if err := os.MkdirAll(filepath.Dir(db), 0o750); err != nil {
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return nil, err
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}
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path := db + ".lock"
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// Read-only is enough for flock, and works whoever created the file.
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f, err := os.OpenFile(path, os.O_RDONLY|os.O_CREATE, 0o640)
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if err != nil {
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return nil, err
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}
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if err := syscall.Flock(int(f.Fd()), syscall.LOCK_EX|syscall.LOCK_NB); err != nil {
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f.Close()
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if errors.Is(err, syscall.EWOULDBLOCK) {
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return nil, errInUse
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}
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return nil, fmt.Errorf("locking %s: %w", path, err)
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}
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return func() {
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syscall.Flock(int(f.Fd()), syscall.LOCK_UN)
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f.Close()
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}, nil
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}
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