lib/cmdline: removing "help ..." from the space of possible command
arguments to make it possible to distinguish between binary-based
subcommands with and without children when generating recursive help
Change-Id: Id8e28055823bc9168466079c09aa3dcd707c208d
diff --git a/cmdline/cmdline.go b/cmdline/cmdline.go
index 549ac5b..61778dc 100644
--- a/cmdline/cmdline.go
+++ b/cmdline/cmdline.go
@@ -17,10 +17,15 @@
// precedes it. Flags registered on flag.CommandLine are considered global
// flags, and are allowed anywhere a command-specific flag is allowed.
//
-// Pretty usage documentation is automatically generated, and accessible either
-// via the standard -h / -help flags from the Go flag package, or a special help
-// command. The help command is automatically appended to commands that already
-// have at least one child, and don't already have a "help" child.
+// Pretty usage documentation is automatically generated, and
+// accessible either via the standard -h / -help flags from the Go
+// flag package, or a special help command. The help command is
+// automatically appended to commands that already have at least one
+// child, and don't already have a "help" child. Commands that do not
+// have any children will exit with an error if invoked with the "help
+// ..." arguments; this behavior is relied on when generating
+// recursive help to distinguish between binary-based subcommands with
+// and without children.
//
// Pitfalls
//
@@ -42,6 +47,7 @@
"io/ioutil"
"os"
"os/exec"
+ "reflect"
"strings"
"v.io/x/lib/envvar"
@@ -326,8 +332,12 @@
return nil, nil, env.UsageErrorf("%s: unknown command %q", cmdPath, subName)
}
return nil, nil, env.UsageErrorf("%s: doesn't take arguments", cmdPath)
+ case reflect.DeepEqual(args, []string{helpName, "..."}):
+ return nil, nil, env.UsageErrorf("%s: unsupported help invocation", cmdPath)
}
- // INVARIANT: cmd.Runner != nil && len(args) > 0 && cmd.ArgsName != ""
+ // INVARIANT:
+ // cmd.Runner != nil && len(args) > 0 &&
+ // cmd.ArgsName != "" && args != []string{"help", "..."}
return cmd.Runner, args, nil
}
diff --git a/cmdline/cmdline_test.go b/cmdline/cmdline_test.go
index d2c56ae..a119512 100644
--- a/cmdline/cmdline_test.go
+++ b/cmdline/cmdline_test.go
@@ -2695,3 +2695,6 @@
}
runTestCases(t, cmd, tests)
}
+
+// TODO(toddw): Add a test for the case when "help ..." is passed to a
+// childless subcommand.
