filters.go

package libimage

import (
	"context"
	"fmt"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	filtersPkg "github.com/containers/common/pkg/filters"
	"github.com/containers/common/pkg/timetype"
	"github.com/pkg/errors"
	"github.com/sirupsen/logrus"
)

// filterFunc is a prototype for a positive image filter.  Returning `true`
// indicates that the image matches the criteria.
type filterFunc func(*Image) (bool, error)

// filterImages returns a slice of images which are passing all specified
// filters.
func filterImages(images []*Image, filters []filterFunc) ([]*Image, error) {
	if len(filters) == 0 {
		return images, nil
	}
	result := []*Image{}
	for i := range images {
		include := true
		var err error
		for _, filter := range filters {
			include, err = filter(images[i])
			if err != nil {
				return nil, err
			}
			if !include {
				break
			}
		}
		if include {
			result = append(result, images[i])
		}
	}
	return result, nil
}

// compileImageFilters creates `filterFunc`s for the specified filters.  The
// required format is `key=value` with the following supported keys:
//           after, since, before, containers, dangling, id, label, readonly, reference, intermediate
func (r *Runtime) compileImageFilters(ctx context.Context, options *ListImagesOptions) ([]filterFunc, error) {
	logrus.Tracef("Parsing image filters %s", options.Filters)

	filterFuncs := []filterFunc{}
	for _, filter := range options.Filters {
		var key, value string
		split := strings.SplitN(filter, "=", 2)
		if len(split) != 2 {
			return nil, errors.Errorf("invalid image filter %q: must be in the format %q", filter, "filter=value")
		}

		key = split[0]
		value = split[1]
		switch key {

		case "after", "since":
			img, _, err := r.LookupImage(value, nil)
			if err != nil {
				return nil, errors.Wrapf(err, "could not find local image for filter %q", filter)
			}
			filterFuncs = append(filterFuncs, filterAfter(img.Created()))

		case "before":
			img, _, err := r.LookupImage(value, nil)
			if err != nil {
				return nil, errors.Wrapf(err, "could not find local image for filter %q", filter)
			}
			filterFuncs = append(filterFuncs, filterBefore(img.Created()))

		case "containers":
			switch value {
			case "false", "true":
			case "external":
				if options.IsExternalContainerFunc == nil {
					return nil, fmt.Errorf("libimage error: external containers filter without callback")
				}
			default:
				return nil, fmt.Errorf("unsupported value %q for containers filter", value)
			}
			filterFuncs = append(filterFuncs, filterContainers(value, options.IsExternalContainerFunc))

		case "dangling":
			dangling, err := strconv.ParseBool(value)
			if err != nil {
				return nil, errors.Wrapf(err, "non-boolean value %q for dangling filter", value)
			}
			filterFuncs = append(filterFuncs, filterDangling(ctx, dangling))

		case "id":
			filterFuncs = append(filterFuncs, filterID(value))

		case "intermediate":
			intermediate, err := strconv.ParseBool(value)
			if err != nil {
				return nil, errors.Wrapf(err, "non-boolean value %q for intermediate filter", value)
			}
			filterFuncs = append(filterFuncs, filterIntermediate(ctx, intermediate))

		case "label":
			filterFuncs = append(filterFuncs, filterLabel(ctx, value))

		case "readonly":
			readOnly, err := strconv.ParseBool(value)
			if err != nil {
				return nil, errors.Wrapf(err, "non-boolean value %q for readonly filter", value)
			}
			filterFuncs = append(filterFuncs, filterReadOnly(readOnly))

		case "reference":
			filterFuncs = append(filterFuncs, filterReference(value))

		case "until":
			ts, err := timetype.GetTimestamp(value, time.Now())
			if err != nil {
				return nil, err
			}
			seconds, nanoseconds, err := timetype.ParseTimestamps(ts, 0)
			if err != nil {
				return nil, err
			}
			until := time.Unix(seconds, nanoseconds)
			filterFuncs = append(filterFuncs, filterBefore(until))

		default:
			return nil, errors.Errorf("unsupported image filter %q", key)
		}
	}

	return filterFuncs, nil
}

// filterReference creates a reference filter for matching the specified value.
func filterReference(value string) filterFunc {
	// Replacing all '/' with '|' so that filepath.Match() can work '|'
	// character is not valid in image name, so this is safe.
	//
	// TODO: this has been copied from Podman and requires some more review
	// and especially tests.
	filter := fmt.Sprintf("*%s*", value)
	filter = strings.ReplaceAll(filter, "/", "|")
	return func(img *Image) (bool, error) {
		if len(value) < 1 {
			return true, nil
		}
		for _, name := range img.Names() {
			newName := strings.ReplaceAll(name, "/", "|")
			match, _ := filepath.Match(filter, newName)
			if match {
				return true, nil
			}
		}
		return false, nil
	}
}

// filterLabel creates a label for matching the specified value.
func filterLabel(ctx context.Context, value string) filterFunc {
	return func(img *Image) (bool, error) {
		labels, err := img.Labels(ctx)
		if err != nil {
			return false, err
		}
		return filtersPkg.MatchLabelFilters([]string{value}, labels), nil
	}
}

// filterAfter creates an after filter for matching the specified value.
func filterAfter(value time.Time) filterFunc {
	return func(img *Image) (bool, error) {
		return img.Created().After(value), nil
	}
}

// filterBefore creates a before filter for matching the specified value.
func filterBefore(value time.Time) filterFunc {
	return func(img *Image) (bool, error) {
		return img.Created().Before(value), nil
	}
}

// filterReadOnly creates a readonly filter for matching the specified value.
func filterReadOnly(value bool) filterFunc {
	return func(img *Image) (bool, error) {
		return img.IsReadOnly() == value, nil
	}
}

// filterContainers creates a container filter for matching the specified value.
func filterContainers(value string, fn IsExternalContainerFunc) filterFunc {
	return func(img *Image) (bool, error) {
		ctrs, err := img.Containers()
		if err != nil {
			return false, err
		}
		if value != "external" {
			boolValue := value == "true"
			return (len(ctrs) > 0) == boolValue, nil
		}

		// Check whether all associated containers are external ones.
		for _, c := range ctrs {
			isExternal, err := fn(c)
			if err != nil {
				return false, fmt.Errorf("checking if %s is an external container in filter: %w", c, err)
			}
			if !isExternal {
				return isExternal, nil
			}
		}
		return true, nil
	}
}

// filterDangling creates a dangling filter for matching the specified value.
func filterDangling(ctx context.Context, value bool) filterFunc {
	return func(img *Image) (bool, error) {
		isDangling, err := img.IsDangling(ctx)
		if err != nil {
			return false, err
		}
		return isDangling == value, nil
	}
}

// filterID creates an image-ID filter for matching the specified value.
func filterID(value string) filterFunc {
	return func(img *Image) (bool, error) {
		return img.ID() == value, nil
	}
}

// filterIntermediate creates an intermediate filter for images.  An image is
// considered to be an intermediate image if it is dangling (i.e., no tags) and
// has no children (i.e., no other image depends on it).
func filterIntermediate(ctx context.Context, value bool) filterFunc {
	return func(img *Image) (bool, error) {
		isIntermediate, err := img.IsIntermediate(ctx)
		if err != nil {
			return false, err
		}
		return isIntermediate == value, nil
	}
}