Merge pull request #9912 from mvo5/snap-run-gdbserver-early-error

snap: provide a useful error message if gdbserver is not installed

cmd/snap/cmd_run.go

@@ -1175,6 +1175,16 @@ func (x *cmdRun) runSnapConfine(info *snap.Info, securityTag, snapApp, hook stri
 	} else if x.Gdb {
 		return x.runCmdUnderGdb(cmd, envForExec)
 	} else if x.useGdbserver() {
+		if _, err := exec.LookPath("gdbserver"); err != nil {
+			// TODO: use xerrors.Is(err, exec.ErrNotFound) once
+			// we moved off from go-1.9
+			if execErr, ok := err.(*exec.Error); ok {
+				if execErr.Err == exec.ErrNotFound {
+					return fmt.Errorf("please install gdbserver on your system")
+				}
+			}
+			return err
+		}
 		return x.runCmdUnderGdbserver(cmd, envForExec)
 	} else if x.useStrace() {
 		return x.runCmdUnderStrace(cmd, envForExec)

cmd/snap/cmd_run_test.go

@@ -1569,3 +1569,17 @@ func (s *RunSuite) TestSnapRunHookKernelImplicitBase(c *check.C) {
 	c.Check(execEnv, testutil.Contains, "SNAP_REVISION=42")
 	c.Check(nModel, check.Equals, 1)
 }
+
+func (s *RunSuite) TestRunGdbserverNoGdbserver(c *check.C) {
+	oldPath := os.Getenv("PATH")
+	os.Setenv("PATH", "/no-path:/really-not")
+	defer os.Setenv("PATH", oldPath)
+
+	defer mockSnapConfine(dirs.DistroLibExecDir)()
+	snaptest.MockSnapCurrent(c, string(mockYaml), &snap.SideInfo{
+		Revision: snap.R("x2"),
+	})
+
+	_, err := snaprun.Parser(snaprun.Client()).ParseArgs([]string{"run", "--gdbserver", "snapname.app"})
+	c.Assert(err, check.ErrorMatches, "please install gdbserver on your system")
+}