Close input files after processing each one (#2796) (#2808)

readStream opened an *os.File but returned a *bufio.Reader, so the
*os.File type switch in streamEvaluator.EvaluateFiles never matched and
no input file was ever closed. allAtOnceEvaluator.EvaluateFiles did not
attempt to close them at all. Descriptors were only released at process
exit or by the os.File finaliser, so a multi-file run could exhaust the
file descriptor limit.

readStream now returns an explicit cleanup function alongside the reader,
which both evaluators call once the file has been processed.

Co-authored-by: Pablo Garcia <pablito@MacBook-Neo-de-Pablo.local>
Co-authored-by: Mike Farah <mikefarah@gmail.com>
Co-authored-by: Cursor <cursoragent@cursor.com>

pkg/yqlib/stream_evaluator.go

@@ -5,7 +5,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"os"
 )
 
 // A yaml expression evaluator that runs the expression multiple times for each given yaml document.
@@ -50,21 +49,17 @@ func (s *streamEvaluator) EvaluateFiles(expression string, filenames []string, p
 	}
 
 	for _, filename := range filenames {
-		reader, err := readStream(filename)
+		reader, cleanup, err := readStream(filename)
 
 		if err != nil {
 			return err
 		}
 		processedDocs, err := s.Evaluate(filename, reader, node, printer, decoder)
+		cleanup()
 		if err != nil {
 			return err
 		}
 		totalProcessDocs = totalProcessDocs + processedDocs
-
-		switch reader := reader.(type) {
-		case *os.File:
-			safelyCloseFile(reader)
-		}
 	}
 
 	if totalProcessDocs == 0 {