105 lines
2.6 KiB
Go
105 lines
2.6 KiB
Go
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package efivar
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import (
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"bytes"
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"errors"
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"fmt"
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"io/ioutil"
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"os"
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"os/exec"
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"strconv"
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"strings"
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"github.com/google/uuid"
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)
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// const efiVarDir = "/sys/firmware/efi/efivars"
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const execPath = "/usr/bin/efivar"
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var VendorID = uuid.MustParse("638a24ce-a0ce-4908-8152-b2a4e8b2f29d")
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const (
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VarBootUUID = "HTTP_BOOT_UUID"
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VarBootPort = "HTTP_BOOT_MCAST_PORT"
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VarBootGroup = "HTTP_BOOT_MCAST_GROUP"
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VarBootIP = "HTTP_BOOT_IP"
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)
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var ErrNotFound = errors.New("variable not found")
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func toFullVarName(gid uuid.UUID, varName string) string {
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return strings.Join([]string{gid.String(), varName}, "-")
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}
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func numSliceToBytes(in []string) ([]byte, error) {
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res := []byte{}
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for i, n := range in {
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strippedN := strings.TrimSpace(n)
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if len(strippedN) == 0 {
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continue
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}
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intN, err := strconv.Atoi(strippedN)
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if err != nil {
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return nil, fmt.Errorf("invalid number %s at index %d", n, i)
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}
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if intN < 0 || intN > 255 {
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return nil, fmt.Errorf("value %d at index %d out of range", intN, i)
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}
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res = append(res, byte(intN))
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}
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return res, nil
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}
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func GetVar(gid uuid.UUID, varName string) ([]byte, error) {
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cmd := exec.Command(execPath, "-n", toFullVarName(gid, varName), "-d")
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var outBuf, errBuf bytes.Buffer
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cmd.Stdout = &outBuf
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cmd.Stderr = &errBuf
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err := cmd.Run()
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var exitErr exec.ExitError
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e := &exitErr
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if err != nil && !errors.As(err, &e) {
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return nil, err
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}
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if cmd.ProcessState.ExitCode() != 0 {
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stderr := errBuf.String()
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if strings.Contains(stderr, "No such file or directory") {
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return nil, ErrNotFound
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}
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return nil, fmt.Errorf("error getting variable, returncode %d, stderr %q", cmd.ProcessState.ExitCode(), stderr)
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}
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nums := strings.Split(outBuf.String(), " ")
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return numSliceToBytes(nums)
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}
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func SetVar(gid uuid.UUID, varName string, value []byte) error {
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tmpVarFile, err := os.CreateTemp("/tmp", "efitmpvar")
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if err != nil {
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return fmt.Errorf("failed to create tmp file to write variable: %w", err)
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}
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defer tmpVarFile.Close()
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defer os.Remove(tmpVarFile.Name())
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if err := ioutil.WriteFile(tmpVarFile.Name(), value, 0o500); err != nil {
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return fmt.Errorf("failed to write variable value to tmp file: %w", err)
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}
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cmd := exec.Command(execPath, "-n", toFullVarName(gid, varName), "-w", "-f", tmpVarFile.Name())
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var errBuf bytes.Buffer
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cmd.Stderr = &errBuf
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err = cmd.Run()
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var exitErr exec.ExitError
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e := &exitErr
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if err != nil && !errors.As(err, &e) {
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return err
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}
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if cmd.ProcessState.ExitCode() != 0 {
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stderr := errBuf.String()
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return fmt.Errorf("error setting variable, returncode %d, stderr %q", cmd.ProcessState.ExitCode(), stderr)
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}
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return nil
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}
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