[s00d]

Problem

On macOS, that_detached() still uses spawn_detached(), which extra-forks and _exit(0)s without waitpid. The intermediate child becomes a zombie (Z / <defunct>).

This is the same class of bug as #119, but #119 only changed with_detached(). The default-open path (that_detached) was left on the old double-fork.

/usr/bin/open already detaches via LaunchServices (LSOpenCFURLRef / NSWorkspace). The launched app is not a child of the caller. Extra fork+setsid is unnecessary on macOS and is what produces the zombies.

Reproducer

open::that_detached("https://example.com")?;
// ps -o pid,ppid,stat,command -p <parent>
// → short-lived /usr/bin/open child with STAT=Z

Seen in a long-lived Tauri app: each URL open left a zombie. After many opens the process table filled with defunct /usr/bin/open children.

Tracked from the consumer side: tauri-apps/plugins-workspace#3544
(tauri-plugin-opener calls open::that_detached() when with is None.)

Why a bump of 5.3.4 / 5.4.1 is not enough

API	macOS after #119 (5.3.4+)
with_detached()	waits for /usr/bin/open (.status())
that_detached()	still spawn_detached() → zombies

Verified locally against open 5.4.1: calling that_detached("https://example.com") five times left 5 zombie children. After this patch: 0.

Fix

Mirror with_detached():

• macOS: that_detached() → that() (wait for /usr/bin/open to return). The opened app still outlives the caller because LaunchServices owns it.
• other platforms: keep spawn_detached() so launchers that stay attached (e.g. some xdg-open setups) do not die with the parent (tauri-apps/tauri#6849).

Tests

macos::tests::that_detached_does_not_leave_zombie_children opens https://example.com several times and asserts the parent’s zombie child count does not increase.

Local: cargo test and cargo clippy -- -D warnings pass on macOS.

Note on #6849

Waiting for /usr/bin/open does not re-bind the launched app as a child. SIGKILL of the caller after open returns leaves TextEdit / the browser running. Confirmed locally and on GitHub Actions macos-14 / macos-15.

Made with Cursor

[Byron]

Thanks a lot! I could validate that the test catches the problem, and that the fix works.
Will create a new release momentarily.

[Byron]

And here it is: https://github.com/Byron/open-rs/releases/tag/v5.4.2