include the breakglass mountpoint in $PATH

That way, users don’t need to use the ./ prefix all the time.

breakglass.go

@@ -100,6 +100,10 @@ func main() {
 		log.Fatal(err)
 	}
 
+	if err := os.Setenv("PATH", unpackDir+":"+os.Getenv("PATH")); err != nil {
+		log.Fatal(err)
+	}
+
 	accept := func(listener net.Listener) {
 		for {
 			conn, err := listener.Accept()

ssh.go

@@ -7,6 +7,7 @@ import (
 	"log"
 	"os"
 	"os/exec"
+	"strings"
 	"sync"
 	"syscall"
 	"unsafe"
@@ -47,6 +48,32 @@ func handleChannel(newChannel ssh.NewChannel) {
 	}(channel, requests)
 }
 
+func expandPath(env []string) []string {
+	pwd, err := os.Getwd()
+	if err != nil {
+		return env
+	}
+	found := false
+	for idx, val := range env {
+		parts := strings.Split(val, "=")
+		if len(parts) < 2 {
+			continue // malformed entry
+		}
+		key := parts[0]
+		if key != "PATH" {
+			continue
+		}
+		val := strings.Join(parts[1:], "=")
+		env[idx] = fmt.Sprintf("%s=%s:%s", key, pwd, val)
+		found = true
+	}
+	if !found {
+		const busyboxDefaultPATH = "/sbin:/usr/sbin:/bin:/usr/bin"
+		env = append(env, fmt.Sprintf("PATH=%s:%s", pwd, busyboxDefaultPATH))
+	}
+	return env
+}
+
 type session struct {
 	env     []string
 	ptyf    *os.File
@@ -124,7 +151,7 @@ func (s *session) request(req *ssh.Request) error {
 		}
 
 		cmd := exec.Command(cmdline[0], cmdline[1:]...)
-		cmd.Env = s.env
+		cmd.Env = expandPath(s.env)
 		cmd.SysProcAttr = &syscall.SysProcAttr{}
 
 		if s.ttyf == nil {