Merge pull request #49118 from thaJeztah/reexec_clean

pkg/reexec: some cleaning up in preparation of moving to a separate module

pkg/reexec/command_linux.go

@@ -1,26 +0,0 @@
-package reexec
-
-import (
-	"os/exec"
-	"syscall"
-)
-
-// Command returns an [*exec.Cmd] which has Path as current binary which,
-// on Linux, is set to the in-memory version (/proc/self/exe) of the current
-// binary, it is thus safe to delete or replace the on-disk binary (os.Args[0]).
-//
-// On Linux, the Pdeathsig of [*exec.Cmd.SysProcAttr] is set to SIGTERM.
-// This signal will be sent to the process when the OS thread which created
-// the process dies.
-//
-// It is the caller's responsibility to ensure that the creating thread is
-// not terminated prematurely. See https://go.dev/issue/27505 for more details.
-func Command(args ...string) *exec.Cmd {
-	return &exec.Cmd{
-		Path: Self(),
-		Args: args,
-		SysProcAttr: &syscall.SysProcAttr{
-			Pdeathsig: syscall.SIGTERM,
-		},
-	}
-}

pkg/reexec/command_other.go

@@ -1,19 +0,0 @@
-//go:build freebsd || darwin || windows
-
-package reexec
-
-import (
-	"os/exec"
-)
-
-// Command returns *exec.Cmd with its Path set to the path of the current
-// binary using the result of [Self]. For example if current binary is
-// "my-binary" at "/usr/bin/" (or "my-binary.exe" at "C:\" on Windows),
-// then cmd.Path is set to "/usr/bin/my-binary" and "C:\my-binary.exe"
-// respectively.
-func Command(args ...string) *exec.Cmd {
-	return &exec.Cmd{
-		Path: Self(),
-		Args: args,
-	}
-}

pkg/reexec/command_unsupported.go

@@ -1,12 +0,0 @@
-//go:build !linux && !windows && !freebsd && !darwin
-
-package reexec
-
-import (
-	"os/exec"
-)
-
-// Command is unsupported on operating systems apart from Linux, Windows, and Darwin.
-func Command(args ...string) *exec.Cmd {
-	return nil
-}

pkg/reexec/reexec.go

@@ -3,7 +3,7 @@
 // Handlers can be registered with a name and the argv 0 of the exec of
 // the binary will be used to find and execute custom init paths.
 //
-// It is used in dockerd to work around forking limitations when using Go.
+// It is used to work around forking limitations when using Go.
 package reexec
 
 import (
@@ -36,10 +36,29 @@ func Init() bool {
 	return false
 }
 
-// Self returns the path to the current process's binary. On Linux, it
-// returns "/proc/self/exe", which provides the in-memory version of the
-// current binary, whereas on other platforms it attempts to looks up the
-// absolute path for os.Args[0], or otherwise returns os.Args[0] as-is.
+// Command returns an [*exec.Cmd] with its Path set to the path of the current
+// binary using the result of [Self].
+//
+// On Linux, the Pdeathsig of [*exec.Cmd.SysProcAttr] is set to SIGTERM.
+// This signal is sent to the process when the OS thread that created
+// the process dies.
+//
+// It is the caller's responsibility to ensure that the creating thread is
+// not terminated prematurely. See https://go.dev/issue/27505 for more details.
+func Command(args ...string) *exec.Cmd {
+	return command(args...)
+}
+
+// Self returns the path to the current process's binary.
+//
+// On Linux, it returns "/proc/self/exe", which provides the in-memory version
+// of the current binary. This makes it safe to delete or replace the on-disk
+// binary (os.Args[0]).
+//
+// On Other platforms, it attempts to look up the absolute path for os.Args[0],
+// or otherwise returns os.Args[0] as-is. For example if current binary is
+// "my-binary" at "/usr/bin/" (or "my-binary.exe" at "C:\" on Windows),
+// then it returns "/usr/bin/my-binary" and "C:\my-binary.exe" respectively.
 func Self() string {
 	if runtime.GOOS == "linux" {
 		return "/proc/self/exe"

pkg/reexec/reexec_linux.go

@@ -0,0 +1,16 @@
+package reexec
+
+import (
+	"os/exec"
+	"syscall"
+)
+
+func command(args ...string) *exec.Cmd {
+	return &exec.Cmd{
+		Path: Self(),
+		Args: args,
+		SysProcAttr: &syscall.SysProcAttr{
+			Pdeathsig: syscall.SIGTERM,
+		},
+	}
+}

pkg/reexec/reexec_other.go

@@ -0,0 +1,14 @@
+//go:build !linux
+
+package reexec
+
+import (
+	"os/exec"
+)
+
+func command(args ...string) *exec.Cmd {
+	return &exec.Cmd{
+		Path: Self(),
+		Args: args,
+	}
+}

pkg/reexec/reexec_test.go

@@ -6,8 +6,10 @@ import (
 	"testing"
 )
 
+const testReExec = "test-reexec"
+
 func init() {
-	Register("reexec", func() {
+	Register(testReExec, func() {
 		panic("Return Error")
 	})
 	Init()
@@ -16,17 +18,17 @@ func init() {
 func TestRegister(t *testing.T) {
 	defer func() {
 		if r := recover(); r != nil {
-			const expected = `reexec func already registered under name "reexec"`
+			const expected = `reexec func already registered under name "test-reexec"`
 			if r != expected {
 				t.Errorf("got %q, want %q", r, expected)
 			}
 		}
 	}()
-	Register("reexec", func() {})
+	Register(testReExec, func() {})
 }
 
 func TestCommand(t *testing.T) {
-	cmd := Command("reexec")
+	cmd := Command(testReExec)
 	w, err := cmd.StdinPipe()
 	if err != nil {
 		t.Fatalf("Error on pipe creation: %v", err)