/
abi.go
206 lines (176 loc) · 3.95 KB
/
abi.go
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package ebpf
import (
"bufio"
"bytes"
"errors"
"fmt"
"io"
"os"
"syscall"
"github.com/cilium/ebpf/internal"
)
// MapABI are the attributes of a Map which are available across all supported kernels.
type MapABI struct {
Type MapType
KeySize uint32
ValueSize uint32
MaxEntries uint32
Flags uint32
}
func newMapABIFromSpec(spec *MapSpec) *MapABI {
return &MapABI{
spec.Type,
spec.KeySize,
spec.ValueSize,
spec.MaxEntries,
spec.Flags,
}
}
func newMapABIFromFd(fd *internal.FD) (string, *MapABI, error) {
info, err := bpfGetMapInfoByFD(fd)
if err != nil {
if errors.Is(err, syscall.EINVAL) {
abi, err := newMapABIFromProc(fd)
return "", abi, err
}
return "", nil, err
}
return "", &MapABI{
MapType(info.mapType),
info.keySize,
info.valueSize,
info.maxEntries,
info.flags,
}, nil
}
func newMapABIFromProc(fd *internal.FD) (*MapABI, error) {
var abi MapABI
err := scanFdInfo(fd, map[string]interface{}{
"map_type": &abi.Type,
"key_size": &abi.KeySize,
"value_size": &abi.ValueSize,
"max_entries": &abi.MaxEntries,
"map_flags": &abi.Flags,
})
if err != nil {
return nil, err
}
return &abi, nil
}
// Equal returns true if two ABIs have the same values.
func (abi *MapABI) Equal(other *MapABI) bool {
switch {
case abi.Type != other.Type:
return false
case abi.KeySize != other.KeySize:
return false
case abi.ValueSize != other.ValueSize:
return false
case abi.MaxEntries != other.MaxEntries:
return false
case abi.Flags != other.Flags:
return false
default:
return true
}
}
// ProgramABI are the attributes of a Program which are available across all supported kernels.
type ProgramABI struct {
Type ProgramType
}
func newProgramABIFromSpec(spec *ProgramSpec) *ProgramABI {
return &ProgramABI{
spec.Type,
}
}
func newProgramABIFromFd(fd *internal.FD) (string, *ProgramABI, error) {
info, err := bpfGetProgInfoByFD(fd)
if err != nil {
if errors.Is(err, syscall.EINVAL) {
return newProgramABIFromProc(fd)
}
return "", nil, err
}
var name string
if bpfName := internal.CString(info.name[:]); bpfName != "" {
name = bpfName
} else {
name = internal.CString(info.tag[:])
}
return name, &ProgramABI{
Type: ProgramType(info.progType),
}, nil
}
func newProgramABIFromProc(fd *internal.FD) (string, *ProgramABI, error) {
var (
abi ProgramABI
name string
)
err := scanFdInfo(fd, map[string]interface{}{
"prog_type": &abi.Type,
"prog_tag": &name,
})
if errors.Is(err, errMissingFields) {
return "", nil, &internal.UnsupportedFeatureError{
Name: "reading ABI from /proc/self/fdinfo",
MinimumVersion: internal.Version{4, 11, 0},
}
}
if err != nil {
return "", nil, err
}
return name, &abi, nil
}
func scanFdInfo(fd *internal.FD, fields map[string]interface{}) error {
raw, err := fd.Value()
if err != nil {
return err
}
fh, err := os.Open(fmt.Sprintf("/proc/self/fdinfo/%d", raw))
if err != nil {
return err
}
defer fh.Close()
if err := scanFdInfoReader(fh, fields); err != nil {
return fmt.Errorf("%s: %w", fh.Name(), err)
}
return nil
}
var errMissingFields = errors.New("missing fields")
func scanFdInfoReader(r io.Reader, fields map[string]interface{}) error {
var (
scanner = bufio.NewScanner(r)
scanned int
)
for scanner.Scan() {
parts := bytes.SplitN(scanner.Bytes(), []byte("\t"), 2)
if len(parts) != 2 {
continue
}
name := bytes.TrimSuffix(parts[0], []byte(":"))
field, ok := fields[string(name)]
if !ok {
continue
}
if n, err := fmt.Fscanln(bytes.NewReader(parts[1]), field); err != nil || n != 1 {
return fmt.Errorf("can't parse field %s: %v", name, err)
}
scanned++
}
if err := scanner.Err(); err != nil {
return err
}
if scanned != len(fields) {
return errMissingFields
}
return nil
}
// Equal returns true if two ABIs have the same values.
func (abi *ProgramABI) Equal(other *ProgramABI) bool {
switch {
case abi.Type != other.Type:
return false
default:
return true
}
}