/
buildid.go
69 lines (63 loc) · 1.73 KB
/
buildid.go
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package build
import (
"debug/elf"
"encoding/binary"
"encoding/hex"
"errors"
"io"
"golang.org/x/xerrors"
)
// from binutils/include/elf/common.h
const NT_GNU_BUILD_ID = 3
// from go/src/cmd/internal/buildid
func readAligned4(r io.Reader, sz int32) ([]byte, error) {
full := (sz + 3) &^ 3
data := make([]byte, full)
_, err := io.ReadFull(r, data)
if err != nil {
return nil, err
}
data = data[:sz]
return data, nil
}
var errBuildIdNotFound = errors.New(".note.gnu.build-id not present")
// based on go/src/cmd/internal/buildid.ReadELFNote
func readBuildid(filename string) (string, error) {
f, err := elf.Open(filename)
if err != nil {
return "", err
}
defer f.Close()
sect := f.Section(".note.gnu.build-id")
if sect == nil {
return "", errBuildIdNotFound
}
if got, want := sect.Type, elf.SHT_NOTE; got != want {
return "", xerrors.Errorf("ELF note type = %v, want %v", got, want)
}
r := sect.Open()
var meta struct {
Namesize, Descsize, NoteType int32
}
if err := binary.Read(r, f.ByteOrder, &meta); err != nil {
return "", xerrors.Errorf("read namesize failed: %v", err)
}
if got, want := meta.NoteType, int32(NT_GNU_BUILD_ID); got != want {
return "", xerrors.Errorf("note type = %v, want %v", got, want)
}
noteName, err := readAligned4(r, meta.Namesize)
if err != nil {
return "", xerrors.Errorf("read name failed: %v", err)
}
if got, want := string(noteName), "GNU\x00"; got != want {
return "", xerrors.Errorf("note name = %q, want %q", got, want)
}
desc, err := readAligned4(r, meta.Descsize)
if err != nil {
return "", xerrors.Errorf("read desc failed: %v", err)
}
if len(desc) < 2 {
return "", xerrors.Errorf("desc too short: %d, want ≥ 2", len(desc))
}
return hex.EncodeToString(desc), nil
}