container: remove custom cmd initialisation

This part of the interface is very unintuitive and only used for testing, even in testing it is inelegant and can be done better.

Signed-off-by: Ophestra <cat@gensokyo.uk>

container/container.go

@@ -35,9 +35,6 @@ type (
 		// with behaviour identical to its [exec.Cmd] counterpart.
 		ExtraFiles []*os.File
 
-		// Custom [exec.Cmd] initialisation function.
-		CommandContext func(ctx context.Context) (cmd *exec.Cmd)
-
 		// param encoder for shim and init
 		setup *gob.Encoder
 		// cancels cmd
@@ -122,13 +119,8 @@ func (p *Container) Start() error {
 		p.SeccompPresets |= seccomp.PresetDenyTTY
 	}
 
-	if p.CommandContext != nil {
-		p.cmd = p.CommandContext(ctx)
-	} else {
-		p.cmd = exec.CommandContext(ctx, MustExecutable())
-		p.cmd.Args = []string{"init"}
-	}
-
+	p.cmd = exec.CommandContext(ctx, MustExecutable())
+	p.cmd.Args = []string{"init"}
 	p.cmd.Stdin, p.cmd.Stdout, p.cmd.Stderr = p.Stdin, p.Stdout, p.Stderr
 	p.cmd.WaitDelay = p.WaitDelay
 	if p.Cancel != nil {

container/container_test.go

@@ -6,7 +6,6 @@ import (
 	"encoding/gob"
 	"log"
 	"os"
-	"os/exec"
 	"strings"
 	"syscall"
 	"testing"
@@ -26,6 +25,11 @@ const (
 	ignoreV = -1
 )
 
+func TestMain(m *testing.M) {
+	container.TryArgv0(hlog.Output{}, hlog.Prepare, internal.InstallOutput)
+	os.Exit(m.Run())
+}
+
 func TestContainer(t *testing.T) {
 	{
 		oldVerbose := hlog.Load()
@@ -96,7 +100,6 @@ func TestContainer(t *testing.T) {
 			c.Uid = 1000
 			c.Gid = 100
 			c.Hostname = tc.host
-			c.CommandContext = commandContext
 			c.Stdout, c.Stderr = os.Stdout, os.Stderr
 			c.Ops = tc.ops
 			c.SeccompRules = tc.rules
@@ -121,11 +124,7 @@ func TestContainer(t *testing.T) {
 				Place("/etc/hostname", []byte(c.Args[5]))
 			// in case test has cgo enabled
 			var libPaths []string
-			if entries, err := ldd.ExecFilter(ctx,
-				commandContext,
-				func(v []byte) []byte {
-					return bytes.SplitN(v, []byte("TestHelperInit\n"), 2)[1]
-				}, os.Args[0]); err != nil {
+			if entries, err := ldd.Exec(ctx, os.Args[0]); err != nil {
 				log.Fatalf("ldd: %v", err)
 			} else {
 				libPaths = ldd.Path(entries)
@@ -197,14 +196,6 @@ func TestContainerString(t *testing.T) {
 	}
 }
 
-func TestHelperInit(t *testing.T) {
-	if len(os.Args) != 5 || os.Args[4] != "init" {
-		return
-	}
-	container.SetOutput(hlog.Output{})
-	container.Init(hlog.Prepare, internal.InstallOutput)
-}
-
 func TestHelperCheckContainer(t *testing.T) {
 	if len(os.Args) != 6 || os.Args[4] != "check" {
 		return
@@ -274,8 +265,3 @@ func TestHelperCheckContainer(t *testing.T) {
 		}
 	})
 }
-
-func commandContext(ctx context.Context) *exec.Cmd {
-	return exec.CommandContext(ctx, os.Args[0], "-test.v",
-		"-test.run=TestHelperInit", "--", "init")
-}