Module spawn 

Two-mode process spawning. Free functions only — no module-internal traits.

Modes (only two; the dangerous combination detached + caller-pipes has no API surface):

• spawn_daemon — detached lifetime, sanitized file-or-NUL stdio, sanitized handle list, no console window, ignores parent’s Ctrl-C. The returned DaemonChild does NOT die when dropped.
• spawn — contained lifetime, caller-controlled stdio via SpawnStdio, sanitized handle list, no console window by default (opt in via SpawnStdio::show_console), bounded drain. The returned SpawnedChild kills the child on Drop.

Sanitized handle inheritance

Both modes inherit ONLY the three stdio handles we resolve here. On Windows we use PROC_THREAD_ATTRIBUTE_HANDLE_LIST to whitelist exactly the resolved handles. On Unix the spawned child runs a pre_exec closure that walks /proc/self/fd (or /dev/fd) and closes every fd > 2.

Motivation: when a process tree has a pipe-redirected ancestor (Python subprocess.Popen(stdout=PIPE), IDE language-server hosts, CI runners, etc.), every intermediate CreateProcessW(bInheritHandles=TRUE) on Windows — and every fork+exec of a non-O_CLOEXEC fd on Unix — duplicates that orphaned pipe write-end into the new child. The original reader at the top never sees EOF.

Issue: https://github.com/zackees/running-process/issues/110.

Structs

DaemonChild

Handle for a detached child that is not terminated when dropped.

DaemonStdio

Caller-supplied output bindings for a detached synchronous child.

SpawnStdio

Caller-supplied stdio bindings for a contained synchronous child.

SpawnedChild

Handle and optional parent pipe ends for a contained child.

Enums

DaemonStdioSource

Output destination accepted by the detached-child path.

EnvironmentPolicy

Selects the base environment used for a newly spawned process.

StdioSource

Standard-stream source or destination for a contained child.

SyncEnvironment

Environment base selected by the shared caller for a synchronous spawn.

Constants

DAEMON_MARKER_ENV_VAR

Set on every child spawned through the daemon path, so a process can be recognized as a declared daemon rather than inferred to be one.

Traits

SpawnedChildControl

Native control operations for a contained child.

Functions

spawn

Spawn command as a contained child with caller-controlled stdio. Sanitized handles, and no console (DETACHED_PROCESS on Windows). Child dies when the returned SpawnedChild is dropped.

spawn_daemon

Spawn command as a detached daemon. NUL stdio, sanitized handles, no console window, ignores parent’s Ctrl-C / SIGINT (Windows: CREATE_NEW_PROCESS_GROUP + DETACHED_PROCESS; Unix: setsid puts the daemon in a new session so it’s not in the parent’s foreground group).

spawn_daemon_breaking_away_from_job

Like spawn_daemon, but the child also breaks away from any Job Object the spawner belongs to (Windows; a no-op elsewhere).

spawn_daemon_breaking_away_with_env_policy

spawn_daemon_breaking_away_from_job with an explicit env policy.

spawn_daemon_with_clear_env

Like spawn_daemon but with explicit control over whether the daemon’s inherited env is passed through to the child.

spawn_daemon_with_env_policy

Spawn a detached daemon using an explicit environment policy.

spawn_daemon_with_environment

Spawn a daemon using an explicit live environment base.

spawn_daemon_with_explicit_environment

Spawn a daemon from a caller-assembled complete environment base.

spawn_daemon_with_stdio

Spawn a detached daemon with file-or-NUL stdout and stderr.

spawn_daemon_with_stdio_and_env_policy

spawn_daemon_with_stdio with an explicit environment policy.

spawn_with_env_policy

Spawn a contained child using an explicit environment policy.

spawn_with_environment

Spawn a contained child using an explicit live environment base.

spawn_with_explicit_environment

Spawn a contained child from a caller-assembled complete environment base.