add Machine gRPC service

internal/sshexec/executor.go

@@ -0,0 +1,41 @@
+package cmdexec
+
+import (
+	"context"
+	"regexp"
+	"strings"
+)
+
+type Executor interface {
+	Run(ctx context.Context, cmd string) (string, error)
+	Close() error
+}
+
+// Quote* functions are copied from github.com/alessio/shellescape package.
+var pattern = regexp.MustCompile(`[^\w@%+=:,./-]`)
+
+// Quote returns a shell-escaped version of the string s. The returned value
+// is a string that can safely be used as one token in a shell command line.
+func Quote(s string) string {
+	if len(s) == 0 {
+		return "''"
+	}
+
+	if pattern.MatchString(s) {
+		return "'" + strings.ReplaceAll(s, "'", "'\"'\"'") + "'"
+	}
+
+	return s
+}
+
+// QuoteCommand returns a shell-escaped version of the command arguments.
+// The returned value is a string that can safely be used as shell command arguments.
+func QuoteCommand(args ...string) string {
+	l := make([]string, len(args))
+
+	for i, s := range args {
+		l[i] = Quote(s)
+	}
+
+	return strings.Join(l, " ")
+}