fix: use golang.org/x/sys/execabs (#224)

Closes https://github.com/ooni/probe-engine/issues/1195

internal/cmd/e2epostprocess/main.go

@@ -7,9 +7,10 @@ import (
 	"io/ioutil"
 	"log"
 	"os"
-	"os/exec"
 	"path/filepath"
 	"strings"
+
+	"golang.org/x/sys/execabs"
 )
 
 func fatalOnError(err error) {
@@ -70,7 +71,7 @@ func main() {
 				options = append(options, *entry.Input)
 			}
 			log.Printf("run: go %s", strings.Join(options, " "))
-			cmd := exec.Command("go", options...)
+			cmd := execabs.Command("go", options...)
 			cmd.Stdout, cmd.Stderr = os.Stdout, os.Stderr
 			err = cmd.Run()
 			fatalOnError(err)

internal/cmd/jafar/iptables/iptables_integration_test.go

@@ -7,12 +7,13 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"net/url"
-	"os/exec"
 	"runtime"
 	"strings"
 	"testing"
 	"time"
 
+	"golang.org/x/sys/execabs"
+
 	"github.com/apex/log"
 	"github.com/ooni/probe-cli/v3/internal/cmd/jafar/resolver"
 	"github.com/ooni/probe-cli/v3/internal/cmd/jafar/uncensored"
@@ -295,7 +296,7 @@ func TestHijackHTTP(t *testing.T) {
 	if err == nil {
 		t.Fatal("expected an error here")
 	}
-	var exitErr *exec.ExitError
+	var exitErr *execabs.ExitError
 	if !errors.As(err, &exitErr) {
 		t.Fatal("not the error type we expected")
 	}
@@ -335,7 +336,7 @@ func TestHijackHTTPS(t *testing.T) {
 		t.Fatal("expected an error here")
 	}
 	t.Log(err)
-	var exitErr *exec.ExitError
+	var exitErr *execabs.ExitError
 	if !errors.As(err, &exitErr) {
 		t.Fatal("not the error type we expected")
 	}

internal/cmd/jafar/main.go

@@ -10,11 +10,12 @@ import (
 	"net"
 	"net/http"
 	"os"
-	"os/exec"
 	"os/signal"
 	"strings"
 	"syscall"
 
+	"golang.org/x/sys/execabs"
+
 	"github.com/apex/log"
 	"github.com/apex/log/handlers/cli"
 	"github.com/miekg/dns"
@@ -243,7 +244,7 @@ func mustx(err error, message string, osExit func(int)) {
 	if err != nil {
 		var (
 			exitcode = 1
-			exiterr  *exec.ExitError
+			exiterr  *execabs.ExitError
 		)
 		if errors.As(err, &exiterr) {
 			exitcode = exiterr.ExitCode()

internal/engine/shellx/shellx.go

@@ -4,9 +4,10 @@ package shellx
 import (
 	"errors"
 	"os"
-	"os/exec"
 	"strings"
 
+	"golang.org/x/sys/execabs"
+
 	"github.com/apex/log"
 	"github.com/google/shlex"
 	"github.com/ooni/probe-cli/v3/internal/engine/model"
@@ -22,7 +23,7 @@ type runconfig struct {
 
 func run(config runconfig) error {
 	config.loginfof("exec: %s %s", config.name, strings.Join(config.args, " "))
-	cmd := exec.Command(config.name, config.args...)
+	cmd := execabs.Command(config.name, config.args...)
 	cmd.Stdout = config.stdout
 	cmd.Stderr = config.stderr
 	err := cmd.Run()