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91 lines
1.9 KiB
91 lines
1.9 KiB
// +build !windows
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package bind
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import (
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"fmt"
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"log"
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"net"
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"os"
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"strconv"
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"syscall"
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)
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const tooBigErr = "bind: einhorn@%d not found (einhorn only passed %d fds)"
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const bindErr = "bind: could not bind einhorn@%d: not running under einhorn"
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const einhornErr = "bind: einhorn environment initialization error"
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const ackErr = "bind: error ACKing to einhorn: %v"
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var einhornNumFds int
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func envInt(val string) (int, error) {
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return strconv.Atoi(os.Getenv(val))
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}
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// Unfortunately this can't be a normal init function, because their execution
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// order is undefined, and we need to run before the init() in bind.go.
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func einhornInit() {
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mpid, err := envInt("EINHORN_MASTER_PID")
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if err != nil || mpid != os.Getppid() {
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return
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}
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einhornNumFds, err = envInt("EINHORN_FD_COUNT")
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if err != nil {
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einhornNumFds = 0
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return
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}
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// Prevent einhorn's fds from leaking to our children
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for i := 0; i < einhornNumFds; i++ {
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syscall.CloseOnExec(einhornFdMap(i))
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}
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}
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func usingEinhorn() bool {
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return einhornNumFds > 0
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}
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func einhornFdMap(n int) int {
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name := fmt.Sprintf("EINHORN_FD_%d", n)
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fno, err := envInt(name)
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if err != nil {
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log.Fatal(einhornErr)
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}
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return fno
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}
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func einhornBind(n int) (net.Listener, error) {
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if !usingEinhorn() {
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return nil, fmt.Errorf(bindErr, n)
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}
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if n >= einhornNumFds || n < 0 {
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return nil, fmt.Errorf(tooBigErr, n, einhornNumFds)
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}
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fno := einhornFdMap(n)
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f := os.NewFile(uintptr(fno), fmt.Sprintf("einhorn@%d", n))
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defer f.Close()
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return net.FileListener(f)
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}
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// Fun story: this is actually YAML, not JSON.
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const ackMsg = `{"command": "worker:ack", "pid": %d}` + "\n"
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func einhornAck() {
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if !usingEinhorn() {
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return
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}
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log.Print("bind: ACKing to einhorn")
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ctl, err := net.Dial("unix", os.Getenv("EINHORN_SOCK_PATH"))
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if err != nil {
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log.Fatalf(ackErr, err)
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}
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defer ctl.Close()
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_, err = fmt.Fprintf(ctl, ackMsg, os.Getpid())
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if err != nil {
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log.Fatalf(ackErr, err)
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}
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}
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