veyron/lib/modules: provide a means to auto-register subprocesses.
Change-Id: I8f01f3da16bf223e7af1613d637742608c84cc86
diff --git a/lib/modules/shell.go b/lib/modules/shell.go
index b467fbc..96ed5d5 100644
--- a/lib/modules/shell.go
+++ b/lib/modules/shell.go
@@ -42,7 +42,6 @@
import (
"flag"
- "fmt"
"io"
"io/ioutil"
"os"
@@ -70,18 +69,28 @@
help string
}
-type childRegistrar struct {
- sync.Mutex
- mains map[string]Main
+type childEntryPoint struct {
+ fn Main
+ help string
}
-var child = &childRegistrar{mains: make(map[string]Main)}
+type childRegistrar struct {
+ sync.Mutex
+ mains map[string]*childEntryPoint
+}
+
+var child = &childRegistrar{mains: make(map[string]*childEntryPoint)}
// NewShell creates a new instance of Shell. If this new instance is
// is a test and no identity has been configured in the environment
// via VEYRON_IDENTITY then CreateAndUseNewID will be used to configure a new
// ID for the shell and its children.
-func NewShell() *Shell {
+// NewShell takes optional regexp patterns that can be used to specify
+// subprocess commands that are implemented in the same binary as this shell
+// (i.e. have been registered using modules.RegisterChild) to be
+// automatically added to it. If the patterns fail to match any such command
+// then they have no effect.
+func NewShell(patterns ...string) *Shell {
// TODO(cnicolaou): should create a new identity if one doesn't
// already exist
sh := &Shell{
@@ -94,6 +103,9 @@
panic(err)
}
}
+ for _, pattern := range patterns {
+ child.addSubprocesses(sh, pattern)
+ }
return sh
}
@@ -125,10 +137,14 @@
// as a subprocess. In addition, the child process must call RegisterChild
// using the same name used here and provide the function to be executed
// in the child.
-func (sh *Shell) AddSubprocess(name string, help string) {
+func (sh *Shell) AddSubprocess(name, help string) {
if !child.hasCommand(name) {
vlog.Infof("Warning: %q is not registered with modules.Dispatcher", name)
}
+ sh.addSubprocess(name, help)
+}
+
+func (sh *Shell) addSubprocess(name string, help string) {
entryPoint := ShellEntryPoint + "=" + name
sh.mu.Lock()
sh.cmds[name] = &commandDesc{func() command { return newExecHandle(entryPoint) }, help}
@@ -168,15 +184,22 @@
// Start starts the specified command, it returns a Handle which can be used
// for interacting with that command. The Shell tracks all of the Handles
// that it creates so that it can shut them down when asked to.
-func (sh *Shell) Start(command string, args ...string) (Handle, error) {
+// Commands may have already been registered with the Shell using AddFunction
+// or AddSubprocess, but if not, they will treated as subprocess commands
+// and an attempt made to run them. Such 'dynamically' started subprocess
+// commands are not remembered the by Shell and do not provide a 'help'
+// message etc; their handles are remembered and will be acted on by
+// the Cleanup method. If the non-registered subprocess command does not
+// exist then the Start command will return an error.
+func (sh *Shell) Start(name string, args ...string) (Handle, error) {
sh.mu.Lock()
- cmd := sh.cmds[command]
- if cmd == nil {
- sh.mu.Unlock()
- return nil, fmt.Errorf("command %q is not available", command)
- }
- expanded := append([]string{command}, sh.expand(args...)...)
+ cmd := sh.cmds[name]
sh.mu.Unlock()
+ if cmd == nil {
+ entryPoint := ShellEntryPoint + "=" + name
+ cmd = &commandDesc{func() command { return newExecHandle(entryPoint) }, ""}
+ }
+ expanded := append([]string{name}, sh.expand(args...)...)
h, err := cmd.factory().start(sh, expanded...)
if err != nil {
return nil, err
