vendor: github.com/moby/buildkit v0.21.0-rc1

Signed-off-by: Jonathan A. Sternberg <jonathan.sternberg@docker.com>

vendor/github.com/moby/sys/user/idtools.go

@@ -0,0 +1,141 @@
+package user
+
+import (
+	"fmt"
+	"os"
+)
+
+// MkdirOpt is a type for options to pass to Mkdir calls
+type MkdirOpt func(*mkdirOptions)
+
+type mkdirOptions struct {
+	onlyNew bool
+}
+
+// WithOnlyNew is an option for MkdirAllAndChown that will only change ownership and permissions
+// on newly created directories.  If the directory already exists, it will not be modified
+func WithOnlyNew(o *mkdirOptions) {
+	o.onlyNew = true
+}
+
+// MkdirAllAndChown creates a directory (include any along the path) and then modifies
+// ownership to the requested uid/gid.  By default, if the directory already exists, this
+// function will still change ownership and permissions. If WithOnlyNew is passed as an
+// option, then only the newly created directories will have ownership and permissions changed.
+func MkdirAllAndChown(path string, mode os.FileMode, uid, gid int, opts ...MkdirOpt) error {
+	var options mkdirOptions
+	for _, opt := range opts {
+		opt(&options)
+	}
+
+	return mkdirAs(path, mode, uid, gid, true, options.onlyNew)
+}
+
+// MkdirAndChown creates a directory and then modifies ownership to the requested uid/gid.
+// By default, if the directory already exists, this function still changes ownership and permissions.
+// If WithOnlyNew is passed as an option, then only the newly created directory will have ownership
+// and permissions changed.
+// Note that unlike os.Mkdir(), this function does not return IsExist error
+// in case path already exists.
+func MkdirAndChown(path string, mode os.FileMode, uid, gid int, opts ...MkdirOpt) error {
+	var options mkdirOptions
+	for _, opt := range opts {
+		opt(&options)
+	}
+	return mkdirAs(path, mode, uid, gid, false, options.onlyNew)
+}
+
+// getRootUIDGID retrieves the remapped root uid/gid pair from the set of maps.
+// If the maps are empty, then the root uid/gid will default to "real" 0/0
+func getRootUIDGID(uidMap, gidMap []IDMap) (int, int, error) {
+	uid, err := toHost(0, uidMap)
+	if err != nil {
+		return -1, -1, err
+	}
+	gid, err := toHost(0, gidMap)
+	if err != nil {
+		return -1, -1, err
+	}
+	return uid, gid, nil
+}
+
+// toContainer takes an id mapping, and uses it to translate a
+// host ID to the remapped ID. If no map is provided, then the translation
+// assumes a 1-to-1 mapping and returns the passed in id
+func toContainer(hostID int, idMap []IDMap) (int, error) {
+	if idMap == nil {
+		return hostID, nil
+	}
+	for _, m := range idMap {
+		if (int64(hostID) >= m.ParentID) && (int64(hostID) <= (m.ParentID + m.Count - 1)) {
+			contID := int(m.ID + (int64(hostID) - m.ParentID))
+			return contID, nil
+		}
+	}
+	return -1, fmt.Errorf("host ID %d cannot be mapped to a container ID", hostID)
+}
+
+// toHost takes an id mapping and a remapped ID, and translates the
+// ID to the mapped host ID. If no map is provided, then the translation
+// assumes a 1-to-1 mapping and returns the passed in id #
+func toHost(contID int, idMap []IDMap) (int, error) {
+	if idMap == nil {
+		return contID, nil
+	}
+	for _, m := range idMap {
+		if (int64(contID) >= m.ID) && (int64(contID) <= (m.ID + m.Count - 1)) {
+			hostID := int(m.ParentID + (int64(contID) - m.ID))
+			return hostID, nil
+		}
+	}
+	return -1, fmt.Errorf("container ID %d cannot be mapped to a host ID", contID)
+}
+
+// IdentityMapping contains a mappings of UIDs and GIDs.
+// The zero value represents an empty mapping.
+type IdentityMapping struct {
+	UIDMaps []IDMap `json:"UIDMaps"`
+	GIDMaps []IDMap `json:"GIDMaps"`
+}
+
+// RootPair returns a uid and gid pair for the root user. The error is ignored
+// because a root user always exists, and the defaults are correct when the uid
+// and gid maps are empty.
+func (i IdentityMapping) RootPair() (int, int) {
+	uid, gid, _ := getRootUIDGID(i.UIDMaps, i.GIDMaps)
+	return uid, gid
+}
+
+// ToHost returns the host UID and GID for the container uid, gid.
+// Remapping is only performed if the ids aren't already the remapped root ids
+func (i IdentityMapping) ToHost(uid, gid int) (int, int, error) {
+	var err error
+	ruid, rgid := i.RootPair()
+
+	if uid != ruid {
+		ruid, err = toHost(uid, i.UIDMaps)
+		if err != nil {
+			return ruid, rgid, err
+		}
+	}
+
+	if gid != rgid {
+		rgid, err = toHost(gid, i.GIDMaps)
+	}
+	return ruid, rgid, err
+}
+
+// ToContainer returns the container UID and GID for the host uid and gid
+func (i IdentityMapping) ToContainer(uid, gid int) (int, int, error) {
+	ruid, err := toContainer(uid, i.UIDMaps)
+	if err != nil {
+		return -1, -1, err
+	}
+	rgid, err := toContainer(gid, i.GIDMaps)
+	return ruid, rgid, err
+}
+
+// Empty returns true if there are no id mappings
+func (i IdentityMapping) Empty() bool {
+	return len(i.UIDMaps) == 0 && len(i.GIDMaps) == 0
+}