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gnanam1990
dbdc04db61
On timeout the context cancelled only the shell, leaving backgrounded children (e.g. 'sleep 3 & wait') orphaned. Worse, those children inherited the stdout/stderr pipes, so Run() blocked until they exited — far past the timeout. Set Setpgid and a Cancel that SIGKILLs the whole process group on POSIX, plus a WaitDelay backstop so a lingering child can't hang Wait. On Windows, set WaitDelay only (no process groups).
45 lines
1.5 KiB
Go
45 lines
1.5 KiB
Go
//go:build !windows
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package tools
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import (
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"errors"
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"os/exec"
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"syscall"
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"time"
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)
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// bashWaitDelay bounds how long Wait blocks for the I/O pipes to drain after the
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// process has exited or the context's Cancel has run. Without it, a backgrounded
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// child that inherited the shell's stdout/stderr keeps those pipes open and
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// Run() hangs long past the timeout waiting for EOF. Var (not const) so tests
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// can shorten it.
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var bashWaitDelay = 2 * time.Second
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// hardenProcessLifetime makes a bash command killable as a single unit so a
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// timeout cannot leak backgrounded children.
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//
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// Setpgid puts the shell into a new process group; since `sh -c` runs without
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// job control, every process it forks (including `&` jobs) inherits that group.
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// On context cancellation we signal the whole group (negative pid) instead of
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// just the shell, so orphaned children die with it. WaitDelay is the backstop:
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// if a child still holds the I/O pipes after the group is killed, Wait gives up
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// rather than blocking forever.
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func hardenProcessLifetime(command *exec.Cmd) {
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if command.SysProcAttr == nil {
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command.SysProcAttr = &syscall.SysProcAttr{}
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}
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command.SysProcAttr.Setpgid = true
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command.WaitDelay = bashWaitDelay
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command.Cancel = func() error {
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if command.Process == nil {
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return nil
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}
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// Negative pid targets the process group led by the shell.
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if err := syscall.Kill(-command.Process.Pid, syscall.SIGKILL); err != nil && !errors.Is(err, syscall.ESRCH) {
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return err
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}
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return nil
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}
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}
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