vendor: add buildkit

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

vendor/github.com/moby/buildkit/util/apicaps/caps.go

@@ -0,0 +1,162 @@
+package apicaps
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+
+	pb "github.com/moby/buildkit/util/apicaps/pb"
+	"github.com/pkg/errors"
+)
+
+type PBCap = pb.APICap
+
+// ExportedProduct is the name of the product using this package.
+// Users vendoring this library may override it to provide better versioning hints
+// for their users (or set it with a flag to buildkitd).
+var ExportedProduct string
+
+// CapStatus defines the stability properties of a capability
+type CapStatus int
+
+const (
+	// CapStatusStable refers to a capability that should never be changed in
+	// backwards incompatible manner unless there is a serious security issue.
+	CapStatusStable CapStatus = iota
+	// CapStatusExperimental refers to a capability that may be removed in the future.
+	// If incompatible changes are made the previous ID is disabled and new is added.
+	CapStatusExperimental
+	// CapStatusPrerelease is same as CapStatusExperimental that can be used for new
+	// features before they move to stable.
+	CapStatusPrerelease
+)
+
+// CapID is type for capability identifier
+type CapID string
+
+// Cap describes an API feature
+type Cap struct {
+	ID                  CapID
+	Name                string // readable name, may contain spaces but keep in one sentence
+	Status              CapStatus
+	Enabled             bool
+	Deprecated          bool
+	SupportedHint       map[string]string
+	DisabledReason      string
+	DisabledReasonMsg   string
+	DisabledAlternative string
+}
+
+// CapList is a collection of capability definitions
+type CapList struct {
+	m map[CapID]Cap
+}
+
+// Init initializes definition for a new capability.
+// Not safe to be called concurrently with other methods.
+func (l *CapList) Init(cc ...Cap) {
+	if l.m == nil {
+		l.m = make(map[CapID]Cap, len(cc))
+	}
+	for _, c := range cc {
+		l.m[c.ID] = c
+	}
+}
+
+// All reports the configuration of all known capabilities
+func (l *CapList) All() []pb.APICap {
+	out := make([]pb.APICap, 0, len(l.m))
+	for _, c := range l.m {
+		out = append(out, pb.APICap{
+			ID:                  string(c.ID),
+			Enabled:             c.Enabled,
+			Deprecated:          c.Deprecated,
+			DisabledReason:      c.DisabledReason,
+			DisabledReasonMsg:   c.DisabledReasonMsg,
+			DisabledAlternative: c.DisabledAlternative,
+		})
+	}
+	sort.Slice(out, func(i, j int) bool {
+		return out[i].ID < out[j].ID
+	})
+	return out
+}
+
+// CapSet returns a CapSet for an capability configuration
+func (l *CapList) CapSet(caps []pb.APICap) CapSet {
+	m := make(map[string]*pb.APICap, len(caps))
+	for _, c := range caps {
+		if c.ID != "" {
+			c := c // capture loop iterator
+			m[c.ID] = &c
+		}
+	}
+	return CapSet{
+		list: l,
+		set:  m,
+	}
+}
+
+// CapSet is a configuration for detecting supported capabilities
+type CapSet struct {
+	list *CapList
+	set  map[string]*pb.APICap
+}
+
+// Supports returns an error if capability is not supported
+func (s *CapSet) Supports(id CapID) error {
+	err := &CapError{ID: id}
+	c, ok := s.list.m[id]
+	if !ok {
+		return errors.WithStack(err)
+	}
+	err.Definition = &c
+	state, ok := s.set[string(id)]
+	if !ok {
+		return errors.WithStack(err)
+	}
+	err.State = state
+	if !state.Enabled {
+		return errors.WithStack(err)
+	}
+	return nil
+}
+
+// CapError is an error for unsupported capability
+type CapError struct {
+	ID         CapID
+	Definition *Cap
+	State      *pb.APICap
+}
+
+func (e CapError) Error() string {
+	if e.Definition == nil {
+		return fmt.Sprintf("unknown API capability %s", e.ID)
+	}
+	typ := ""
+	if e.Definition.Status == CapStatusExperimental {
+		typ = "experimental "
+	}
+	if e.Definition.Status == CapStatusPrerelease {
+		typ = "prerelease "
+	}
+	name := ""
+	if e.Definition.Name != "" {
+		name = "(" + e.Definition.Name + ")"
+	}
+	b := &strings.Builder{}
+	fmt.Fprintf(b, "requested %sfeature %s %s", typ, e.ID, name)
+	if e.State == nil {
+		fmt.Fprint(b, " is not supported by build server")
+		if hint, ok := e.Definition.SupportedHint[ExportedProduct]; ok {
+			fmt.Fprintf(b, " (added in %s)", hint)
+		}
+		fmt.Fprintf(b, ", please update %s", ExportedProduct)
+	} else {
+		fmt.Fprint(b, " has been disabled on the build server")
+		if e.State.DisabledReasonMsg != "" {
+			fmt.Fprintf(b, ": %s", e.State.DisabledReasonMsg)
+		}
+	}
+	return b.String()
+}