run: use internal.GetTempDir with os.MkdirTemp

Projects which are using buildah as a library and set `TMPDIR` manually
can stumble upon a use-case where `TMPDIR` was set to a relative path.

Such as `export TMPDIR=.` in such case buildah will try to create a
temporary root using `Mkdirtemp` leading to a point where bundle is not
generated correctly since path was relative.

Following use case can be resolved by making sure that buildah always
converts relative path to absolute path and `GetTempDir` does it well.

Example reproducer with podman

```Dockerfile
FROM alpine
RUN echo hello
```

```console
export TMPDIR=.
podman build --no-cache -t test .
```

Expected failure
```console
STEP 1/2: FROM alpine
STEP 2/2: RUN echo hello
error running container: checking permissions on "buildah2341274198": stat buildah2341274198: no such file or directory
ERRO[0000] did not get container create message from subprocess: EOF
Error: building at STEP "RUN echo hello": while running runtime: exit status 1
```

Closes: RHEL-2598

Signed-off-by: Aditya R <[email protected]>

internal/tmpdir/tmpdir_test.go

@@ -2,6 +2,7 @@ package tmpdir
 
 import (
 	"os"
+	"path/filepath"
 	"testing"
 
 	"github.com/containers/common/pkg/config"
@@ -26,6 +27,14 @@ func TestGetTempDir(t *testing.T) {
 	err = os.Unsetenv("TMPDIR")
 	require.NoError(t, err)
 
+	// relative TMPDIR should be automatically converted to absolute
+	err = os.Setenv("TMPDIR", ".")
+	require.NoError(t, err)
+	tmpdir = GetTempDir()
+	assert.True(t, filepath.IsAbs(tmpdir), "path from GetTempDir should always be absolute")
+	err = os.Unsetenv("TMPDIR")
+	require.NoError(t, err)
+
 	f, err := os.CreateTemp("", "containers.conf-")
 	require.NoError(t, err)
 	// close and remove the temporary file at the end of the program

run_freebsd.go

@@ -16,6 +16,7 @@ import (
 	"github.com/containers/buildah/copier"
 	"github.com/containers/buildah/define"
 	"github.com/containers/buildah/internal"
+	"github.com/containers/buildah/internal/tmpdir"
 	"github.com/containers/buildah/pkg/jail"
 	"github.com/containers/buildah/pkg/overlay"
 	"github.com/containers/buildah/pkg/parse"
@@ -72,7 +73,7 @@ func setChildProcess() error {
 }
 
 func (b *Builder) Run(command []string, options RunOptions) error {
-	p, err := os.MkdirTemp("", Package)
+	p, err := os.MkdirTemp(tmpdir.GetTempDir(), define.Package)
 	if err != nil {
 		return err
 	}

run_linux.go

@@ -19,6 +19,7 @@ import (
 	"github.com/containers/buildah/copier"
 	"github.com/containers/buildah/define"
 	"github.com/containers/buildah/internal"
+	"github.com/containers/buildah/internal/tmpdir"
 	"github.com/containers/buildah/internal/volumes"
 	"github.com/containers/buildah/pkg/overlay"
 	"github.com/containers/buildah/pkg/parse"
@@ -71,7 +72,7 @@ func setChildProcess() error {
 
 // Run runs the specified command in the container's root filesystem.
 func (b *Builder) Run(command []string, options RunOptions) error {
-	p, err := os.MkdirTemp("", define.Package)
+	p, err := os.MkdirTemp(tmpdir.GetTempDir(), define.Package)
 	if err != nil {
 		return err
 	}
@@ -499,7 +500,7 @@ func setupSlirp4netnsNetwork(config *config.Config, netns, cid string, options [
 		Mask: res.Subnet.Mask,
 	}}
 	netStatus := map[string]nettypes.StatusBlock{
-		slirp4netns.BinaryName: nettypes.StatusBlock{
+		slirp4netns.BinaryName: {
 			Interfaces: map[string]nettypes.NetInterface{
 				"tap0": {
 					Subnets: []nettypes.NetAddress{{IPNet: subnet}},
@@ -541,7 +542,7 @@ func setupPasta(config *config.Config, netns string, options []string) (func(),
 		Mask: net.IPv4Mask(255, 255, 255, 0),
 	}}
 	netStatus := map[string]nettypes.StatusBlock{
-		slirp4netns.BinaryName: nettypes.StatusBlock{
+		slirp4netns.BinaryName: {
 			Interfaces: map[string]nettypes.NetInterface{
 				"tap0": {
 					Subnets: []nettypes.NetAddress{{IPNet: subnet}},