Handle multiline responses to dbus-launch
Users may not have dbus properly configured, and their machine may respond
to dbus-launch with a multiline string that prints a warning before returning
the expected output. The code handling this response assumed that it would
always find '=' before it finds '\n', but this not true in the case of a
multiline string. Rather, it is the other way around, and thus the code sliced
the response with a lower bound greater than its upper bound, leading to a
"panic: runtime error: slice bounds out of range" crash.
Fixes #151
diff --git a/conn_other.go b/conn_other.go
index 289044a..616dcf6 100644
--- a/conn_other.go
+++ b/conn_other.go
@@ -14,8 +14,10 @@
"strings"
)
+var execCommand = exec.Command
+
func getSessionBusPlatformAddress() (string, error) {
- cmd := exec.Command("dbus-launch")
+ cmd := execCommand("dbus-launch")
b, err := cmd.CombinedOutput()
if err != nil {
@@ -25,7 +27,7 @@
i := bytes.IndexByte(b, '=')
j := bytes.IndexByte(b, '\n')
- if i == -1 || j == -1 {
+ if i == -1 || j == -1 || i > j {
return "", errors.New("dbus: couldn't determine address of session bus")
}
diff --git a/exec_command_test.go b/exec_command_test.go
new file mode 100755
index 0000000..2b5350a
--- /dev/null
+++ b/exec_command_test.go
@@ -0,0 +1,61 @@
+package dbus
+
+import (
+ "fmt"
+ "os"
+ "os/exec"
+ "strconv"
+ "testing"
+)
+
+// How to mock exec.Command for unit tests
+// https://stackoverflow.com/q/45789101/10513533
+
+var mockedExitStatus = 0
+var mockedStdout string
+
+func fakeExecCommand(command string, args ...string) *exec.Cmd {
+ cs := []string{"-test.run=TestExecCommandHelper", "--", command}
+ cs = append(cs, args...)
+ cmd := exec.Command(os.Args[0], cs...)
+ es := strconv.Itoa(mockedExitStatus)
+ cmd.Env = []string{"GO_WANT_HELPER_PROCESS=1",
+ "STDOUT=" + mockedStdout,
+ "EXIT_STATUS=" + es}
+ return cmd
+}
+
+func TestExecCommandHelper(t *testing.T) {
+ if os.Getenv("GO_WANT_HELPER_PROCESS") != "1" {
+ return
+ }
+
+ fmt.Fprintf(os.Stdout, os.Getenv("STDOUT"))
+ i, _ := strconv.Atoi(os.Getenv("EXIT_STATUS"))
+ os.Exit(i)
+}
+
+func TestDbusLaunchMultilineResponse(t *testing.T) {
+ mockedExitStatus = 0
+ mockedStdout = `process 7616: D-Bus library appears to be incorrectly set up; failed to read machine uuid: UUID file '/etc/machine-id' should contain a hex string of length 32, not length 0, with no other text
+See the manual page for dbus-uuidgen to correct this issue.
+DBUS_SESSION_BUS_ADDRESS=unix:abstract=/tmp/dbus-0SO9YZUBGA,guid=ac22f2f3b9d228496b4d4b935cae3417
+DBUS_SESSION_BUS_PID=7620
+DBUS_SESSION_BUS_WINDOWID=16777217`
+ execCommand = fakeExecCommand
+ defer func() { execCommand = exec.Command }()
+ expOut := ""
+ expErr := "dbus: couldn't determine address of session bus"
+
+ out, err := getSessionBusPlatformAddress()
+ if string(out) != expOut {
+ t.Errorf("Expected %q, got %q", expOut, string(out))
+ }
+ if err == nil {
+ t.Error("Excepted error, got none")
+ } else {
+ if err.Error() != expErr {
+ t.Errorf("Expected error to be %q, got %q", expErr, err.Error())
+ }
+ }
+}
