From c57a06ad4ae9e953496730507e02a613f69bddac Mon Sep 17 00:00:00 2001
From: Dan Jaglowski <jaglows3@gmail.com>
Date: Thu, 5 Oct 2023 15:16:55 -0600
Subject: [PATCH] [chore][pkg/stanza] Clarify and fix truncated file func

---
 .../fileconsumer/internal/reader/reader.go    | 22 ++++++++++++-------
 pkg/stanza/fileconsumer/roller_other.go       |  4 ++--
 2 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/pkg/stanza/fileconsumer/internal/reader/reader.go b/pkg/stanza/fileconsumer/internal/reader/reader.go
index 6d4194d0361f..c2115f1fb9ed 100644
--- a/pkg/stanza/fileconsumer/internal/reader/reader.go
+++ b/pkg/stanza/fileconsumer/internal/reader/reader.go
@@ -12,6 +12,7 @@ import (
 
 	"go.uber.org/zap"
 
+	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza/attrs"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza/decode"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza/fileconsumer/emit"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza/fileconsumer/internal/fingerprint"
@@ -187,24 +188,29 @@ func min0(a, b int) int {
 	return b
 }
 
-// validateFingerprint checks whether or not the reader still has a valid file handle.
+// ValidateOrClose returns true if the reader still has a valid file handle, false otherwise.
+// If false is returned, the file handle should be considered closed.
 //
-// It creates a new fingerprint from the old file handle and compares it to the
+// It may create a new fingerprint from the old file handle and compare it to the
 // previously known fingerprint. If there has been a change to the fingerprint
-// (other than appended data), the file is considered invalid. Consequently, the
+// (other than appended data), the file is considered truncated. Consequently, the
 // reader will automatically close the file and drop the handle.
-//
-// The function returns true if the file handle is still valid, false otherwise.
-func (r *Reader) ValidateFingerprint() bool {
+func (r *Reader) ValidateOrClose() bool {
 	if r.file == nil {
 		return false
 	}
 	refreshedFingerprint, err := fingerprint.New(r.file, r.FingerprintSize)
 	if err != nil {
-		r.logger.Debugw("Failed to create fingerprint", zap.Error(err))
+		r.logger.Debugw("Closing unreadable file", zap.Error(err), zap.String(attrs.LogFileName, r.FileName))
+		r.Close()
 		return false
 	}
-	return refreshedFingerprint.StartsWith(r.Fingerprint)
+	if refreshedFingerprint.StartsWith(r.Fingerprint) {
+		return true
+	}
+	r.logger.Debugw("Closing truncated file", zap.String(attrs.LogFileName, r.FileName))
+	r.Close()
+	return false
 }
 
 func (r *Reader) AtEOF() bool {
diff --git a/pkg/stanza/fileconsumer/roller_other.go b/pkg/stanza/fileconsumer/roller_other.go
index efda6b3a2731..0d2910530f63 100644
--- a/pkg/stanza/fileconsumer/roller_other.go
+++ b/pkg/stanza/fileconsumer/roller_other.go
@@ -34,8 +34,8 @@ OUTER:
 				// At this point, we know that the file has been rotated. However, we do not know
 				// if it was moved or truncated. If truncated, then both handles point to the same
 				// file, in which case we should only read from it using the new reader. We can use
-				// the validateFingerprint method to establish that the file has not been truncated.
-				if !oldReader.ValidateFingerprint() {
+				// the ValidateOrClose method to establish that the file has not been truncated.
+				if !oldReader.ValidateOrClose() {
 					continue OUTER
 				}
 			}