id_mapper.go

package unpacker // import "github.com/SUSE/groot-btrfs/base_image_puller/unpacker"

import (
	"bytes"
	"os/exec"
	"strconv"

	"code.cloudfoundry.org/commandrunner"

	"code.cloudfoundry.org/lager"
	"github.com/SUSE/groot-btrfs/groot"
	errorspkg "github.com/pkg/errors"
)

type CommandIDMapper struct {
	newuidmapBin string
	newgidmapBin string
	cmdRunner    commandrunner.CommandRunner
}

func NewIDMapper(newuidmapBin, newgidmapBin string, cmdRunner commandrunner.CommandRunner) *CommandIDMapper {
	return &CommandIDMapper{
		newuidmapBin: newuidmapBin,
		newgidmapBin: newgidmapBin,
		cmdRunner:    cmdRunner,
	}
}

func (im *CommandIDMapper) MapUIDs(logger lager.Logger, pid int, mappings []groot.IDMappingSpec) error {
	logger = logger.Session("mapUID")
	return im.execute(logger, im.newuidmapBin, pid, mappings)
}

func (im *CommandIDMapper) MapGIDs(logger lager.Logger, pid int, mappings []groot.IDMappingSpec) error {
	logger = logger.Session("mapGID")
	return im.execute(logger, im.newgidmapBin, pid, mappings)
}

func (im *CommandIDMapper) execute(logger lager.Logger, command string, pid int, mappings []groot.IDMappingSpec) error {
	logger.Debug("starting")
	defer logger.Debug("ending")

	mappingArgs := append([]string{strconv.Itoa(pid)}, im.idMappingsToArgs(mappings)...)
	mapCmd := exec.Command(command, mappingArgs...)

	buffer := bytes.NewBuffer([]byte{})
	mapCmd.Stdout = buffer
	mapCmd.Stderr = buffer

	logger.Debug("starting-id-map", lager.Data{"path": mapCmd.Path, "args": mapCmd.Args})
	if err := im.cmdRunner.Run(mapCmd); err != nil {
		return errorspkg.Wrapf(err, "%s, %s", command, buffer.String())
	}

	return nil
}

func (im *CommandIDMapper) idMappingsToArgs(idMappings []groot.IDMappingSpec) (args []string) {
	for _, idMapping := range idMappings {
		args = append(args, im.idMappingToArgs(idMapping)...)
	}

	return args
}

func (im *CommandIDMapper) idMappingToArgs(idMapping groot.IDMappingSpec) []string {
	return []string{
		strconv.Itoa(idMapping.NamespaceID),
		strconv.Itoa(idMapping.HostID),
		strconv.Itoa(idMapping.Size),
	}
}