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package oci
import (
"bytes"
"context"
"fmt"
"os"
"path/filepath"
"github.com/docker/docker/pkg/idtools"
"github.com/moby/buildkit/executor"
"github.com/moby/buildkit/identity"
"github.com/pkg/errors"
)
const defaultHostname = "buildkitsandbox"
func GetHostsFile(ctx context.Context, stateDir string, extraHosts []executor.HostIP, idmap *idtools.IdentityMapping, hostname string) (string, func(), error) {
if len(extraHosts) != 0 || hostname != defaultHostname {
return makeHostsFile(stateDir, extraHosts, idmap, hostname)
}
_, err := g.Do(ctx, stateDir, func(ctx context.Context) (struct{}, error) {
_, _, err := makeHostsFile(stateDir, nil, idmap, hostname)
return struct{}{}, err
})
if err != nil {
return "", nil, err
}
return filepath.Join(stateDir, "hosts"), func() {}, nil
}
func makeHostsFile(stateDir string, extraHosts []executor.HostIP, idmap *idtools.IdentityMapping, hostname string) (string, func(), error) {
p := filepath.Join(stateDir, "hosts")
if len(extraHosts) != 0 || hostname != defaultHostname {
p += "." + identity.NewID()
}
_, err := os.Stat(p)
if err == nil {
return "", func() {}, nil
}
if !errors.Is(err, os.ErrNotExist) {
return "", nil, err
}
b := &bytes.Buffer{}
if _, err := b.Write([]byte(initHostsFile(hostname))); err != nil {
return "", nil, err
}
for _, h := range extraHosts {
if _, err := b.Write([]byte(fmt.Sprintf("%s\t%s\n", h.IP.String(), h.Host))); err != nil {
return "", nil, err
}
}
tmpPath := p + ".tmp"
if err := os.WriteFile(tmpPath, b.Bytes(), 0644); err != nil {
return "", nil, err
}
if idmap != nil {
root := idmap.RootPair()
if err := os.Chown(tmpPath, root.UID, root.GID); err != nil {
return "", nil, err
}
}
if err := os.Rename(tmpPath, p); err != nil {
return "", nil, err
}
return p, func() {
os.RemoveAll(p)
}, nil
}
func initHostsFile(hostname string) string {
var hosts string
if hostname != "" {
hosts = fmt.Sprintf("127.0.0.1 localhost %s", hostname)
} else {
hosts = fmt.Sprintf("127.0.0.1 localhost %s", defaultHostname)
}
hosts = fmt.Sprintf("%s\n::1 localhost ip6-localhost ip6-loopback\n", hosts)
return hosts
}
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