68 lines
2.0 KiB
Go
68 lines
2.0 KiB
Go
//go:build !windows
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package gui
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import (
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"crypto/sha256"
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"encoding/hex"
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"errors"
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"os"
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"path/filepath"
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"strings"
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"syscall"
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)
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// heldInstance is the open lock file of the magpie that holds its
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// instance; it stays open, so locked, until this process ends.
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var heldInstance *os.File
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// instanceLock is where the magpie running exe on the config in dir holds
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// its lock. A copy elsewhere (the owner's magpie-dev) has its own, but
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// every installed magpie — a magpie.app wherever it is, or Homebrew's,
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// whose path has its version in it — shares one: the Mac reopening the
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// copy the user ran after a shutdown while Open at login starts the one
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// it was turned on for, or a copy run translocated from Downloads, put
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// two birds in the menu bar (inaction on Discord).
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func instanceLock(dir, exe string) string {
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if r, err := filepath.EvalSymlinks(exe); err == nil {
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exe = r
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}
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if installedCopy(exe) {
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exe = "installed"
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}
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sum := sha256.Sum256([]byte(dir + "\x00" + exe))
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return filepath.Join(dir, "app-"+hex.EncodeToString(sum[:6])+".lock")
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}
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// installedCopy is whether exe is an installed magpie: the program of an
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// app bundle, or Homebrew's.
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func installedCopy(exe string) bool {
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exe = filepath.ToSlash(exe)
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return strings.Contains(exe, ".app/Contents/MacOS/") || strings.Contains(exe, "/Cellar/magpie/")
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}
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// holdInstance takes the lock at path for this process, or reports that
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// another magpie holds it. It is a flock, which the system lets go when
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// its holder ends however it ends, so a Mac shut down with magpie running
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// leaves nothing behind that looks held (Crispin on Discord).
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func holdInstance(path string) (bool, error) {
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if err := os.MkdirAll(filepath.Dir(path), 0o700); err != nil {
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return false, err
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}
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f, err := os.OpenFile(path, os.O_CREATE|os.O_RDWR, 0o600)
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if err != nil {
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return false, err
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}
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err = syscall.Flock(int(f.Fd()), syscall.LOCK_EX|syscall.LOCK_NB)
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if errors.Is(err, syscall.EWOULDBLOCK) {
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f.Close()
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return false, nil
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}
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if err != nil {
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f.Close()
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return false, err
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}
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heldInstance = f
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return true, nil
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}
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