many: abstract path to /bin/{true,false}

errtracker/errtracker_test.go

@@ -49,23 +49,26 @@ type ErrtrackerTestSuite struct {
 
 var _ = Suite(&ErrtrackerTestSuite{})
 
+var truePath = osutil.LookPathDefault("true", "/bin/true")
+var falsePath = osutil.LookPathDefault("false", "/bin/false")
+
 func (s *ErrtrackerTestSuite) SetUpTest(c *C) {
 	s.BaseTest.SetUpTest(c)
 
 	p := filepath.Join(c.MkDir(), "machine-id")
 	err := ioutil.WriteFile(p, []byte("bbb1a6a5bcdb418380056a2d759c3f7c"), 0644)
 	c.Assert(err, IsNil)
 	s.AddCleanup(errtracker.MockMachineIDPath(p))
-	s.AddCleanup(errtracker.MockHostSnapd("/bin/true"))
-	s.AddCleanup(errtracker.MockCoreSnapd("/bin/false"))
+	s.AddCleanup(errtracker.MockHostSnapd(truePath))
+	s.AddCleanup(errtracker.MockCoreSnapd(falsePath))
 }
 
 func (s *ErrtrackerTestSuite) TestReport(c *C) {
 	n := 0
 	identifier := ""
-	hostBuildID, err := osutil.ReadBuildID("/bin/true")
+	hostBuildID, err := osutil.ReadBuildID(truePath)
 	c.Assert(err, IsNil)
-	coreBuildID, err := osutil.ReadBuildID("/bin/false")
+	coreBuildID, err := osutil.ReadBuildID(falsePath)
 	c.Assert(err, IsNil)
 
 	prev := errtracker.SnapdVersion

osutil/buildid_test.go

@@ -34,6 +34,10 @@ type buildIDSuite struct{}
 
 var _ = Suite(&buildIDSuite{})
 
+var truePath = osutil.LookPathDefault("true", "/bin/true")
+var falsePath = osutil.LookPathDefault("false", "/bin/false")
+var gccPath = osutil.LookPathDefault("gcc", "/usr/bin/gcc")
+
 func buildID(c *C, fname string) string {
 	output, err := exec.Command("file", fname).CombinedOutput()
 	c.Assert(err, IsNil)
@@ -46,7 +50,7 @@ func buildID(c *C, fname string) string {
 }
 
 func (s *buildIDSuite) TestReadBuildID(c *C) {
-	for _, fname := range []string{"/bin/true", "/bin/false"} {
+	for _, fname := range []string{truePath, falsePath} {
 
 		id, err := osutil.ReadBuildID(fname)
 		c.Assert(err, IsNil)
@@ -56,7 +60,7 @@ func (s *buildIDSuite) TestReadBuildID(c *C) {
 
 func (s *buildIDSuite) TestReadBuildIDNoID(c *C) {
 	stripedTruth := filepath.Join(c.MkDir(), "true")
-	osutil.CopyFile("/bin/true", stripedTruth, 0)
+	osutil.CopyFile(truePath, stripedTruth, 0)
 	output, err := exec.Command("strip", "-R", ".note.gnu.build-id", stripedTruth).CombinedOutput()
 	c.Assert(string(output), Equals, "")
 	c.Assert(err, IsNil)
@@ -67,14 +71,14 @@ func (s *buildIDSuite) TestReadBuildIDNoID(c *C) {
 }
 
 func (s *buildIDSuite) TestReadBuildIDmd5(c *C) {
-	if !osutil.FileExists("/usr/bin/gcc") {
+	if !osutil.FileExists(gccPath) {
 		c.Skip("No gcc found")
 	}
 
 	md5Truth := filepath.Join(c.MkDir(), "true")
 	err := ioutil.WriteFile(md5Truth+".c", []byte(`int main(){return 0;}`), 0644)
 	c.Assert(err, IsNil)
-	output, err := exec.Command("gcc", "-Wl,-build-id=md5", "-xc", md5Truth+".c", "-o", md5Truth).CombinedOutput()
+	output, err := exec.Command(gccPath, "-Wl,-build-id=md5", "-xc", md5Truth+".c", "-o", md5Truth).CombinedOutput()
 	c.Assert(string(output), Equals, "")
 	c.Assert(err, IsNil)
 

osutil/exec_test.go

@@ -71,11 +71,11 @@ func (s *commandFromCoreSuite) TestCommandFromCore(c *C) {
 	root := filepath.Join(dirs.SnapMountDir, "/core/current")
 
 	os.MkdirAll(filepath.Join(root, "/usr/bin"), 0755)
-	osutil.CopyFile("/bin/true", filepath.Join(root, "/usr/bin/xdelta3"), 0)
+	osutil.CopyFile(truePath, filepath.Join(root, "/usr/bin/xdelta3"), 0)
 	cmd, err := osutil.CommandFromCore("/usr/bin/xdelta3", "--some-xdelta-arg")
 	c.Assert(err, IsNil)
 
-	out, err := exec.Command("/bin/sh", "-c", "readelf -l /bin/true |grep interpreter:|cut -f2 -d:|cut -f1 -d]").Output()
+	out, err := exec.Command("/bin/sh", "-c", fmt.Sprintf("readelf -l %s |grep interpreter:|cut -f2 -d:|cut -f1 -d]", truePath)).Output()
 	c.Assert(err, IsNil)
 	interp := strings.TrimSpace(string(out))
 
@@ -93,7 +93,7 @@ func (s *commandFromCoreSuite) TestCommandFromCoreSymlinkCycle(c *C) {
 	root := filepath.Join(dirs.SnapMountDir, "/core/current")
 
 	os.MkdirAll(filepath.Join(root, "/usr/bin"), 0755)
-	osutil.CopyFile("/bin/true", filepath.Join(root, "/usr/bin/xdelta3"), 0)
+	osutil.CopyFile(truePath, filepath.Join(root, "/usr/bin/xdelta3"), 0)
 
 	out, err := exec.Command("/bin/sh", "-c", "readelf -l /bin/true |grep interpreter:|cut -f2 -d:|cut -f1 -d]").Output()
 	c.Assert(err, IsNil)

osutil/stat.go

@@ -63,3 +63,16 @@ func ExecutableExists(name string) bool {
 
 	return err == nil
 }
+
+var lookPath func(name string) (string, error) = exec.LookPath
+
+// LookPathDefault searches for a given command name in all directories
+// listed in the environment variable PATH and returns the found path or the
+// provided default path.
+func LookPathDefault(name string, defaultPath string) string {
+	p, err := lookPath(name)
+	if err != nil {
+		return defaultPath
+	}
+	return p
+}

osutil/stat_test.go

@@ -20,6 +20,7 @@
 package osutil
 
 import (
+	"fmt"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -89,3 +90,13 @@ func (ts *StatTestSuite) TestExecutableExists(c *C) {
 	c.Assert(os.Chmod(fname, 0755), IsNil)
 	c.Check(ExecutableExists("xyzzy"), Equals, true)
 }
+
+func (s *StatTestSuite) TestLookPathDefaultGivesCorrectPath(c *C) {
+	lookPath = func(name string) (string, error) { return "/bin/true", nil }
+	c.Assert(LookPathDefault("true", "/bin/foo"), Equals, "/bin/true")
+}
+
+func (s *StatTestSuite) TestLookPathDefaultReturnsDefaultWhenNotFound(c *C) {
+	lookPath = func(name string) (string, error) { return "", fmt.Errorf("Not found") }
+	c.Assert(LookPathDefault("bar", "/bin/bla"), Equals, "/bin/bla")
+}