kubernetes/vendor/github.com/cilium/ebpf/internal/feature.go
Kir Kolyshkin f3cdfc488e vendor: bump runc to rc95
runc rc95 contains a fix for CVE-2021-30465.

runc rc94 provides fixes and improvements.

One notable change is cgroup manager's Set now accept Resources rather
than Cgroup (see https://github.com/opencontainers/runc/pull/2906).
Modify the code accordingly.

Also update runc dependencies (as hinted by hack/lint-depdendencies.sh):

        github.com/cilium/ebpf v0.5.0
        github.com/containerd/console v1.0.2
        github.com/coreos/go-systemd/v22 v22.3.1
        github.com/godbus/dbus/v5 v5.0.4
        github.com/moby/sys/mountinfo v0.4.1
        golang.org/x/sys v0.0.0-20210426230700-d19ff857e887
        github.com/google/go-cmp v0.5.4
        github.com/kr/pretty v0.2.1
        github.com/opencontainers/runtime-spec v1.0.3-0.20210326190908-1c3f411f0417

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
2021-05-19 23:51:59 -07:00

101 lines
2.5 KiB
Go

package internal
import (
"errors"
"fmt"
"sync"
)
// ErrNotSupported indicates that a feature is not supported by the current kernel.
var ErrNotSupported = errors.New("not supported")
// UnsupportedFeatureError is returned by FeatureTest() functions.
type UnsupportedFeatureError struct {
// The minimum Linux mainline version required for this feature.
// Used for the error string, and for sanity checking during testing.
MinimumVersion Version
// The name of the feature that isn't supported.
Name string
}
func (ufe *UnsupportedFeatureError) Error() string {
if ufe.MinimumVersion.Unspecified() {
return fmt.Sprintf("%s not supported", ufe.Name)
}
return fmt.Sprintf("%s not supported (requires >= %s)", ufe.Name, ufe.MinimumVersion)
}
// Is indicates that UnsupportedFeatureError is ErrNotSupported.
func (ufe *UnsupportedFeatureError) Is(target error) bool {
return target == ErrNotSupported
}
type featureTest struct {
sync.RWMutex
successful bool
result error
}
// FeatureTestFn is used to determine whether the kernel supports
// a certain feature.
//
// The return values have the following semantics:
//
// err == ErrNotSupported: the feature is not available
// err == nil: the feature is available
// err != nil: the test couldn't be executed
type FeatureTestFn func() error
// FeatureTest wraps a function so that it is run at most once.
//
// name should identify the tested feature, while version must be in the
// form Major.Minor[.Patch].
//
// Returns an error wrapping ErrNotSupported if the feature is not supported.
func FeatureTest(name, version string, fn FeatureTestFn) func() error {
v, err := NewVersion(version)
if err != nil {
return func() error { return err }
}
ft := new(featureTest)
return func() error {
ft.RLock()
if ft.successful {
defer ft.RUnlock()
return ft.result
}
ft.RUnlock()
ft.Lock()
defer ft.Unlock()
// check one more time on the off
// chance that two go routines
// were able to call into the write
// lock
if ft.successful {
return ft.result
}
err := fn()
switch {
case errors.Is(err, ErrNotSupported):
ft.result = &UnsupportedFeatureError{
MinimumVersion: v,
Name: name,
}
fallthrough
case err == nil:
ft.successful = true
default:
// We couldn't execute the feature test to a point
// where it could make a determination.
// Don't cache the result, just return it.
return fmt.Errorf("detect support for %s: %w", name, err)
}
return ft.result
}
}