From 4047eec8c8dfb7d0cad366dc826707cd6d8c650b Mon Sep 17 00:00:00 2001
From: Aditya <aditya@bncw.in>
Date: Sun, 30 Aug 2026 03:04:12 +0530
Subject: [PATCH] fix: delete the previous content when a file is replaced

ReplaceFile rewrites the metadata entry in place to point at the new
content, which leaves the data the file used to hold with no entry
referencing it. CleanUp walks metadata and only frees a source it can
still reach from an entry, so that data is never reclaimed, with or
without deleteNewFile.

Capture the entry before it is rewritten and delete its source, unless
another entry still shares the same SHA1.

Closes #407
---
 internal/storage/FileServing.go      | 16 ++++++++++++
 internal/storage/FileServing_test.go | 38 ++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/internal/storage/FileServing.go b/internal/storage/FileServing.go
index 64ce9f70..e0b76788 100644
--- a/internal/storage/FileServing.go
+++ b/internal/storage/FileServing.go
@@ -384,6 +384,7 @@ func ReplaceFile(fileId, newFileContentId string, delete bool) (models.File, err
 		return models.File{}, ErrorReplaceE2EFile
 	}
 
+	previousContent := file
 	file.Name = newFileContent.Name
 	file.Size = newFileContent.Size
 	file.SHA1 = newFileContent.SHA1
@@ -392,12 +393,27 @@ func ReplaceFile(fileId, newFileContentId string, delete bool) (models.File, err
 	file.SizeBytes = newFileContent.SizeBytes
 	file.Encryption = newFileContent.Encryption
 	database.SaveMetaData(file)
+	deleteUnreferencedSource(previousContent)
 	if delete {
 		DeleteFile(newFileContent.Id, true)
 	}
 	return file, nil
 }
 
+// deleteUnreferencedSource deletes the stored data of a file that no metadata entry points at anymore.
+// CleanUp only reaches sources that are still referenced by an entry, so the content a replaced file
+// used to hold would otherwise stay in storage for good.
+func deleteUnreferencedSource(file models.File) {
+	for _, metadata := range database.GetAllMetadata() {
+		if metadata.SHA1 == file.SHA1 {
+			return
+		}
+	}
+	if FileExists(file, configuration.Get().DataDir) {
+		deleteSource(file, configuration.Get().DataDir)
+	}
+}
+
 func isChangeRequested(parametersToChange, parameter int) bool {
 	return parametersToChange&parameter != 0
 }
diff --git a/internal/storage/FileServing_test.go b/internal/storage/FileServing_test.go
index d8369d62..1cfdddd5 100644
--- a/internal/storage/FileServing_test.go
+++ b/internal/storage/FileServing_test.go
@@ -895,6 +895,44 @@ func TestReplaceFile(t *testing.T) {
 	_, ok = GetFile(newFile.Id)
 	test.IsEqualBool(t, ok, false)
 }
+func TestReplaceFileDeletesPreviousContent(t *testing.T) {
+	dataDir := configuration.Get().DataDir
+	previousSha1 := "replacedoldcontent"
+	newSha1 := "replacednewcontent"
+	test.IsNil(t, os.WriteFile(dataDir+"/"+previousSha1, []byte("old"), 0600))
+	test.IsNil(t, os.WriteFile(dataDir+"/"+newSha1, []byte("new"), 0600))
+
+	original := models.File{
+		Id:                 "replacesourceoriginal",
+		Name:               "old.txt",
+		Size:               "3 B",
+		SHA1:               previousSha1,
+		ContentType:        "text/plain",
+		UnlimitedDownloads: true,
+		UnlimitedTime:      true,
+		SizeBytes:          3,
+	}
+	replacement := models.File{
+		Id:                 "replacesourcenew",
+		Name:               "new.txt",
+		Size:               "3 B",
+		SHA1:               newSha1,
+		ContentType:        "text/plain",
+		UnlimitedDownloads: true,
+		UnlimitedTime:      true,
+		SizeBytes:          3,
+	}
+	database.SaveMetaData(original)
+	database.SaveMetaData(replacement)
+
+	_, err := ReplaceFile(original.Id, replacement.Id, false)
+	test.IsNil(t, err)
+
+	_, err = os.Stat(dataDir + "/" + previousSha1)
+	test.IsEqualBool(t, os.IsNotExist(err), true)
+	test.FileExists(t, dataDir+"/"+newSha1)
+}
+
 func TestParallelDownloads(t *testing.T) {
 	const allowedDownloads = 5