Delete file already wrote partially into attachment folder when content is terminated with an error (#4286)

#### What type of PR is this?

/kind bug
/area core
/milestone 2.8.x

#### What this PR does / why we need it:

If content is terminated with an error, the file already wrote partially into attachment folder won't be cleaned.

Imagine a scenario where we check that the content size is not larger than 2MB when we write content to the attachments folder. Once the limit is reached, files that have been partially written should be cleaned instead of being kept.

#### Does this PR introduce a user-facing change?

```release-note
None
```

application/src/main/java/run/halo/app/core/extension/attachment/endpoint/LocalAttachmentUploadHandler.java

@@ -3,6 +3,7 @@ package run.halo.app.core.extension.attachment.endpoint;
 import static java.nio.file.StandardOpenOption.CREATE_NEW;
 import static run.halo.app.infra.utils.FileNameUtils.randomFileName;
 import static run.halo.app.infra.utils.FileUtils.checkDirectoryTraversal;
+import static run.halo.app.infra.utils.FileUtils.deleteFileSilently;
 
 import java.io.IOException;
 import java.net.URI;
@@ -236,6 +237,9 @@ class LocalAttachmentUploadHandler implements AttachmentHandler {
                         var fileName = randomFileName(oldPath.toString(), 4);
                         pathRef.set(oldPath.resolveSibling(fileName));
                     }))
+                // Delete file already wrote partially into attachment folder
+                // in case of content is terminated with an error
+                .onErrorResume(t -> deleteFileSilently(pathRef.get()).then(Mono.error(t)))
                 .then(Mono.fromSupplier(pathRef::get));
         });
     }

application/src/main/java/run/halo/app/infra/utils/FileUtils.java

@@ -26,6 +26,8 @@ import lombok.extern.slf4j.Slf4j;
 import org.springframework.lang.NonNull;
 import org.springframework.util.AntPathMatcher;
 import org.springframework.util.Assert;
+import reactor.core.publisher.Mono;
+import reactor.core.scheduler.Schedulers;
 import run.halo.app.infra.exception.AccessDeniedException;
 
 /**
@@ -243,6 +245,21 @@ public abstract class FileUtils {
         }
     }
 
+    public static Mono<Boolean> deleteFileSilently(Path file) {
+        return Mono.fromSupplier(
+                () -> {
+                    if (file == null || !Files.isRegularFile(file)) {
+                        return false;
+                    }
+                    try {
+                        return Files.deleteIfExists(file);
+                    } catch (IOException ignored) {
+                        return false;
+                    }
+                })
+            .subscribeOn(Schedulers.boundedElastic());
+    }
+
     public static void copy(Path source, Path dest, CopyOption... options) {
         try {
             Files.copy(source, dest, options);
@@ -277,4 +294,5 @@ public abstract class FileUtils {
             }
         });
     }
+
 }

application/src/test/java/run/halo/app/infra/utils/FileUtilsTest.java

@@ -4,7 +4,7 @@ import static java.util.Objects.requireNonNull;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static run.halo.app.infra.utils.FileUtils.checkDirectoryTraversal;
-import static run.halo.app.infra.utils.FileUtils.deleteRecursivelyAndSilently;
+import static run.halo.app.infra.utils.FileUtils.deleteFileSilently;
 import static run.halo.app.infra.utils.FileUtils.jar;
 import static run.halo.app.infra.utils.FileUtils.unzip;
 import static run.halo.app.infra.utils.FileUtils.zip;
@@ -16,14 +16,17 @@ import java.nio.file.NoSuchFileException;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.zip.ZipInputStream;
-import org.junit.jupiter.api.AfterEach;
-import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+import reactor.test.StepVerifier;
 import run.halo.app.infra.exception.AccessDeniedException;
 
 class FileUtilsTest {
 
+    @TempDir
+    Path tempDirectory;
+
     @Nested
     class DirectoryTraversalTest {
 
@@ -49,18 +52,6 @@ class FileUtilsTest {
     @Nested
     class ZipTest {
 
-        Path tempDirectory;
-
-        @BeforeEach
-        void setUp() throws IOException {
-            tempDirectory = Files.createTempDirectory("halo-test-fileutils-zip-");
-        }
-
-        @AfterEach
-        void cleanUp() {
-            deleteRecursivelyAndSilently(tempDirectory);
-        }
-
         @Test
         void zipFolderAndUnzip() throws IOException, URISyntaxException {
             var uri = requireNonNull(getClass().getClassLoader().getResource("folder-to-zip"))
@@ -104,5 +95,23 @@ class FileUtilsTest {
             assertThrows(NoSuchFileException.class, () ->
                 jar(Paths.get("no-such-folder"), tempDirectory.resolve("example.zip")));
         }
+
     }
+
+    @Test
+    void deleteFileSilentlyTest() throws IOException {
+        StepVerifier.create(deleteFileSilently(null))
+            .expectNext(false)
+            .verifyComplete();
+
+        StepVerifier.create(deleteFileSilently(tempDirectory))
+            .expectNext(false)
+            .verifyComplete();
+
+        StepVerifier.create(
+                deleteFileSilently(Files.createFile(tempDirectory.resolve("for-deleting"))))
+            .expectNext(true)
+            .verifyComplete();
+    }
+
 }