Add util.Run/Exec

util/exec.go

@@ -0,0 +1,66 @@
+/*
+Copyright 2021 Robert S. Muhlestein.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package util
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"syscall"
+)
+
+// Exec (not to be confused with Execute) will check for the existence
+// of the first argument as an executable on the system and then execute
+// it using syscall.Exec(), which replaces the currently running program
+// with the new one in all respects (stdin, stdout, stderr, process ID,
+// signal handling, etc).
+//
+// Note that although this is exceptionally faster and cleaner than
+// calling any of the os/exec variations it may be less compatible with
+// different operating systems.
+func Exec(args ...string) error {
+	if len(args) == 0 {
+		return fmt.Errorf("missing name of executable")
+	}
+	path, err := exec.LookPath(args[0])
+	if err != nil {
+		return err
+	}
+	// exits the program unless there is an error
+	return syscall.Exec(path, args, os.Environ())
+}
+
+// Run checks for existence of first argument as an executable on the
+// system and then runs it without exiting in a way that is supported
+// across different operating systems. The stdin, stdout, and stderr are
+// connected directly to that of the calling program. Use more specific
+// exec alternatives if intercepting stdout and stderr are desired. Also
+// see Exec.
+func Run(args ...string) error {
+	if len(args) == 0 {
+		return fmt.Errorf("missing name of executable")
+	}
+	path, err := exec.LookPath(args[0])
+	if err != nil {
+		return err
+	}
+	cmd := exec.Command(path, args[1:]...)
+	cmd.Stdout = os.Stdout
+	cmd.Stdin = os.Stdin
+	cmd.Stderr = os.Stderr
+	return cmd.Run()
+}

util/exec_test.go

@@ -0,0 +1,76 @@
+/*
+Copyright 2021 Robert S. Muhlestein.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package util
+
+import (
+	"os"
+	"os/exec"
+	"testing"
+)
+
+// go coverage detection is fucked for this sort of stuff, oh well, we
+// did the test even if coverage falsely reports 50%
+func TestExec(t *testing.T) {
+	if os.Getenv("TESTING_EXEC") == "1" {
+		err := Exec("go", "version")
+		if err != nil {
+			t.Fatal(err)
+		}
+		return
+	}
+	cmd := exec.Command(os.Args[0], "-test.run=TestExec")
+	cmd.Env = append(os.Environ(), "TESTING_EXEC=1")
+	err := cmd.Run()
+	if err != nil {
+		t.Fatalf("process exited with %v", err)
+	}
+}
+
+func TestExec_noargs(t *testing.T) {
+	err := Exec()
+	if err == nil {
+		t.Error("should have failed since no command")
+	}
+}
+
+func TestRun_noargs(t *testing.T) {
+	err := Run()
+	if err == nil {
+		t.Error("should have failed since no command")
+	}
+}
+
+func TestRun_nocmd(t *testing.T) {
+	err := Run("__inoexist")
+	if err == nil {
+		t.Error("should have failed since no command")
+	}
+}
+
+func TestExec_nocmd(t *testing.T) {
+	err := Exec("__inoexist")
+	if err == nil {
+		t.Error("should have failed since no command")
+	}
+}
+
+func TestRun(t *testing.T) {
+	err := Run("go", "version")
+	if err != nil {
+		t.Error(err)
+	}
+}