x.ref/lib/exec: add an option to allow bypassing the parent/child protocol.
Change-Id: I4c12c4d80d64021a6bf0671f19b4468455c7bad1
diff --git a/lib/exec/parent.go b/lib/exec/parent.go
index 0c31dcf..ddb3d5b 100644
--- a/lib/exec/parent.go
+++ b/lib/exec/parent.go
@@ -21,15 +21,17 @@
)
var (
- ErrAuthTimeout = errors.New("timeout in auth handshake")
- ErrTimeout = errors.New("timeout waiting for child")
- ErrSecretTooLarge = errors.New("secret is too large")
+ ErrAuthTimeout = errors.New("timeout in auth handshake")
+ ErrTimeout = errors.New("timeout waiting for child")
+ ErrSecretTooLarge = errors.New("secret is too large")
+ ErrNotUsingProtocol = errors.New("not using parent/child exec protocol")
)
// A ParentHandle is the Parent process' means of managing a single child.
type ParentHandle struct {
c *exec.Cmd
config Config
+ protocol bool // true if we're using the parent/child protocol.
secret string
statusRead *os.File
statusWrite *os.File
@@ -71,11 +73,19 @@
// ExecParentHandleOpt makes TimeKeeperOpt an instance of ParentHandleOpt.
func (TimeKeeperOpt) ExecParentHandleOpt() {}
+// UseExecProtocolOpt can be used to control whether parent/child handshake
+// protocol is used. WaitForReady will return immediately with an error if
+// this option is set to false.
+type UseExecProtocolOpt bool
+
+func (UseExecProtocolOpt) ExecParentHandleOpt() {}
+
// NewParentHandle creates a ParentHandle for the child process represented by
// an instance of exec.Cmd.
func NewParentHandle(c *exec.Cmd, opts ...ParentHandleOpt) *ParentHandle {
cfg, secret := NewConfig(), ""
tk := timekeeper.RealTime()
+ protocol := true
for _, opt := range opts {
switch v := opt.(type) {
case ConfigOpt:
@@ -84,15 +94,18 @@
secret = string(v)
case TimeKeeperOpt:
tk = v
+ case UseExecProtocolOpt:
+ protocol = bool(v)
default:
vlog.Errorf("Unrecognized parent option: %v", v)
}
}
return &ParentHandle{
- c: c,
- config: cfg,
- secret: secret,
- tk: tk,
+ c: c,
+ protocol: protocol,
+ config: cfg,
+ secret: secret,
+ tk: tk,
}
}
@@ -109,6 +122,11 @@
}
nenv = append(nenv, e)
}
+
+ if !p.protocol {
+ return p.c.Start()
+ }
+
p.c.Env = append(nenv, consts.ExecVersionVariable+"="+version1)
// Create anonymous pipe for communicating data between the child
@@ -161,6 +179,7 @@
return err
}
return nil
+
}
// copy is like io.Copy, but it also treats the receipt of the special eofChar
@@ -209,6 +228,9 @@
// WaitForReady will wait for the child process to become ready.
func (p *ParentHandle) WaitForReady(timeout time.Duration) error {
+ if !p.protocol {
+ return ErrNotUsingProtocol
+ }
// An invariant of WaitForReady is that both statusWrite and statusRead
// get closed before WaitForStatus returns (statusRead gets closed by
// waitForStatus).
