make AllLocations accept a context (#2518)

The previous implementation would leak a goroutine if the caller of
AllLocations stopped iterating early. Now, accept a context so that the
caller can cancel the AllLocations iterator rather than leak the
goroutine.

Signed-off-by: Will Murphy <will.murphy@anchore.com>

syft/internal/fileresolver/unindexed_directory.go

@@ -1,6 +1,8 @@
 package fileresolver
 
 import (
+	"context"
+	"errors"
 	"fmt"
 	"io"
 	"io/fs"
@@ -225,8 +227,9 @@ func (u UnindexedDirectory) RelativeFileByPath(l file.Location, p string) *file.
 
 // - NO symlink resolution should be performed on results
 // - returns locations for any file or directory
-func (u UnindexedDirectory) AllLocations() <-chan file.Location {
+func (u UnindexedDirectory) AllLocations(ctx context.Context) <-chan file.Location {
 	out := make(chan file.Location)
+	errWalkCanceled := fmt.Errorf("walk canceled")
 	go func() {
 		defer close(out)
 		err := afero.Walk(u.fs, u.absPath("."), func(p string, info fs.FileInfo, err error) error {
@@ -235,10 +238,14 @@ func (u UnindexedDirectory) AllLocations() <-chan file.Location {
 				return nil
 			}
 			p = strings.TrimPrefix(p, "/")
-			out <- file.NewLocation(p)
-			return nil
+			select {
+			case out <- file.NewLocation(p):
+				return nil
+			case <-ctx.Done():
+				return errWalkCanceled
+			}
 		})
-		if err != nil {
+		if err != nil && !errors.Is(err, errWalkCanceled) {
 			log.Debug(err)
 		}
 	}()