interfaces/udev: add udev support code

interfaces/udev/udev.go

@@ -0,0 +1,41 @@
+// -*- Mode: Go; indent-tabs-mode: t -*-
+
+/*
+ * Copyright (C) 2016 Canonical Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+package udev
+
+import (
+	"fmt"
+	"os/exec"
+)
+
+// ReloadRules runs two commands that reload udev rule database.
+//
+// The commands are: udevadm control --reload-rules
+//                   udevadm trigger
+func ReloadRules() error {
+	output, err := exec.Command("udevadm", "control", "--reload-rules").CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("cannot reload udev rules: %s\nudev output:\n%s", err, string(output))
+	}
+	output, err = exec.Command("udevadm", "trigger").CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("cannot run udev triggers: %s\nudev output:\n%s", err, string(output))
+	}
+	return nil
+}

interfaces/udev/udev_test.go

@@ -0,0 +1,85 @@
+// -*- Mode: Go; indent-tabs-mode: t -*-
+
+/*
+ * Copyright (C) 2016 Canonical Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+package udev_test
+
+import (
+	"testing"
+
+	. "gopkg.in/check.v1"
+
+	"github.com/ubuntu-core/snappy/interfaces/udev"
+	"github.com/ubuntu-core/snappy/testutil"
+)
+
+func Test(t *testing.T) {
+	TestingT(t)
+}
+
+type uDevSuite struct{}
+
+var _ = Suite(&uDevSuite{})
+
+// Tests for ReloadRules()
+
+func (s *uDevSuite) TestReloadUDevRulesRunsUDevAdm(c *C) {
+	cmd := testutil.MockCommand(c, "udevadm", "")
+	defer cmd.Restore()
+	err := udev.ReloadRules()
+	c.Assert(err, IsNil)
+	c.Assert(cmd.Calls(), DeepEquals, []string{
+		"control --reload-rules",
+		"trigger",
+	})
+}
+
+func (s *uDevSuite) TestReloadUDevRulesReportsErrorsFromReloadRules(c *C) {
+	cmd := testutil.MockCommand(c, "udevadm", `
+if [ "$1" = "control" ]; then
+	echo "failure 1"
+	exit 1
+fi
+	`)
+	defer cmd.Restore()
+	err := udev.ReloadRules()
+	c.Assert(err.Error(), Equals, ""+
+		"cannot reload udev rules: exit status 1\n"+
+		"udev output:\n"+
+		"failure 1\n")
+	c.Assert(cmd.Calls(), DeepEquals, []string{"control --reload-rules"})
+}
+
+func (s *uDevSuite) TestReloadUDevRulesReportsErrorsFromTrigger(c *C) {
+	cmd := testutil.MockCommand(c, "udevadm", `
+if [ "$1" = "trigger" ]; then
+	echo "failure 2"
+	exit 2
+fi
+	`)
+	defer cmd.Restore()
+	err := udev.ReloadRules()
+	c.Assert(err.Error(), Equals, ""+
+		"cannot run udev triggers: exit status 2\n"+
+		"udev output:\n"+
+		"failure 2\n")
+	c.Assert(cmd.Calls(), DeepEquals, []string{
+		"control --reload-rules",
+		"trigger",
+	})
+}

testutil/exec.go

@@ -20,7 +20,6 @@
 package testutil
 
 import (
-	"bytes"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -32,72 +31,30 @@ import (
 
 // MockCmd allows mocking commands for testing.
 type MockCmd struct {
-	binDir    string
-	exeFile   string
-	logFile   string
-	countFile string
+	binDir  string
+	exeFile string
+	logFile string
 }
 
 // MockCommand adds a mocked command to PATH.
 //
-// The command logs all invocations to a dedicated log file and exits with the
-// specified code.
-func MockCommand(c *check.C, basename string, status int) *MockCmd {
+// The command logs all invocations to a dedicated log file. If script is
+// non-empty then it is used as is and the caller is responsible for how the
+// script behaves (exit code and any extra behavior). If script is empty then
+// the command exits successfully without any other side-effect.
+func MockCommand(c *check.C, basename, script string) *MockCmd {
 	binDir := c.MkDir()
 	exeFile := path.Join(binDir, basename)
 	logFile := path.Join(binDir, basename+".log")
-	countFile := path.Join(binDir, basename+".cnt")
 	err := ioutil.WriteFile(exeFile, []byte(fmt.Sprintf(""+
 		"#!/bin/sh\n"+
 		"echo \"$@\" >> %q\n"+
-		"exit %d\n", logFile, status)), 0700)
+		"%s\n", logFile, script)), 0700)
 	if err != nil {
 		panic(err)
 	}
 	os.Setenv("PATH", binDir+":"+os.Getenv("PATH"))
-	return &MockCmd{binDir: binDir, exeFile: exeFile, logFile: logFile, countFile: countFile}
-}
-
-// SetDynamicBehavior sets dynamic behavior, depending on the number of times
-// the command is invoked.
-//
-// The first argument defines the number of dynamic cases. The second argument
-// is a function that is called exactly n times (from 0 to n - 1).  Each time
-// the function returns a message that is printed to standard output and the
-// exit code to return in that case.
-//
-// If the command is called more than the expected number of times a diagnostic
-// message is printed to stderr and the command fails with code 1.
-func (cmd *MockCmd) SetDynamicBehavior(n int, fn func(int) (string, int)) {
-	buf := bytes.NewBuffer(nil)
-	buf.WriteString(fmt.Sprintf(
-		`#!/bin/sh
-echo "$@" >> %q
-case $(cat %q) in
-`, cmd.logFile, cmd.countFile))
-	for i := 0; i < n; i++ {
-		msg, status := fn(i)
-		buf.WriteString(fmt.Sprintf(
-			`    %d)
-        echo %d > %q
-        echo %q
-        exit %d
-        ;;
-`, i, i+1, cmd.countFile, msg, status))
-	}
-	buf.WriteString(
-		`esac
-echo "reached beyond dynamic behavior range!" >&2
-exit 1
-`)
-	err := ioutil.WriteFile(cmd.exeFile, buf.Bytes(), 0700)
-	if err != nil {
-		panic(err)
-	}
-	err = ioutil.WriteFile(cmd.countFile, []byte("0"), 0600)
-	if err != nil {
-		panic(err)
-	}
+	return &MockCmd{binDir: binDir, exeFile: exeFile, logFile: logFile}
 }
 
 // Restore removes the mocked command from PATH