Fix SentryFileWriter and SentryFileOutputStream append overwrites file contents

CHANGELOG.md

@@ -7,6 +7,7 @@
 - Ensure potential callback exceptions are caught #2123 ([#2291](https://github.com/getsentry/sentry-java/pull/2291))
 - Remove verbose FrameMetricsAggregator failure logging ([#2293](https://github.com/getsentry/sentry-java/pull/2293))
 - Ignore broken regex for tracePropagationTarget ([#2288](https://github.com/getsentry/sentry-java/pull/2288))
+- Fix `SentryFileWriter`/`SentryFileOutputStream` append overwrites file contents ([#2304](https://github.com/getsentry/sentry-java/pull/2304))
 
 ### Features
 

sentry-android-core/src/test/java/io/sentry/android/core/SendCachedEnvelopeIntegrationTest.kt

@@ -100,13 +100,13 @@ class SendCachedEnvelopeIntegrationTest {
 
     @Test
     fun `when synchronous send times out, continues the task on a background thread`() {
-        val sut = fixture.getSut(hasStartupCrashMarker = true, delaySend = 50)
-        fixture.options.startupCrashFlushTimeoutMillis = 10
+        val sut = fixture.getSut(hasStartupCrashMarker = true, delaySend = 1000)
+        fixture.options.startupCrashFlushTimeoutMillis = 100
 
         sut.register(fixture.hub, fixture.options)
 
         // first wait until synchronous send times out and check that the logger was hit in the catch block
-        await.atLeast(11, MILLISECONDS)
+        await.atLeast(500, MILLISECONDS)
         verify(fixture.logger).log(
             eq(DEBUG),
             eq("Synchronous send timed out, continuing in the background.")

sentry/src/main/java/io/sentry/instrumentation/file/SentryFileOutputStream.java

@@ -24,7 +24,7 @@ public final class SentryFileOutputStream extends FileOutputStream {
   private final @NotNull FileIOSpanManager spanManager;
 
   public SentryFileOutputStream(final @Nullable String name) throws FileNotFoundException {
-    this(name != null ? new File(name) : null, HubAdapter.getInstance());
+    this(name != null ? new File(name) : null, false, HubAdapter.getInstance());
   }
 
   public SentryFileOutputStream(final @Nullable String name, final boolean append)
@@ -33,7 +33,7 @@ public SentryFileOutputStream(final @Nullable String name, final boolean append)
   }
 
   public SentryFileOutputStream(final @Nullable File file) throws FileNotFoundException {
-    this(file, HubAdapter.getInstance());
+    this(file, false, HubAdapter.getInstance());
   }
 
   public SentryFileOutputStream(final @Nullable File file, final boolean append)
@@ -45,9 +45,9 @@ public SentryFileOutputStream(final @NotNull FileDescriptor fdObj) {
     this(init(fdObj, null, HubAdapter.getInstance()), fdObj);
   }
 
-  SentryFileOutputStream(final @Nullable File file, final @NotNull IHub hub)
+  SentryFileOutputStream(final @Nullable File file, final boolean append, final @NotNull IHub hub)
       throws FileNotFoundException {
-    this(init(file, false, null, hub));
+    this(init(file, append, null, hub));
   }
 
   private SentryFileOutputStream(
@@ -72,7 +72,7 @@ private static FileOutputStreamInitData init(
       throws FileNotFoundException {
     final ISpan span = FileIOSpanManager.startSpan(hub, "file.write");
     if (delegate == null) {
-      delegate = new FileOutputStream(file);
+      delegate = new FileOutputStream(file, append);
     }
     return new FileOutputStreamInitData(
         file, append, span, delegate, hub.getOptions().isSendDefaultPii());

sentry/src/main/java/io/sentry/instrumentation/file/SentryFileWriter.java

@@ -30,7 +30,8 @@ public SentryFileWriter(final @NotNull FileDescriptor fd) {
     super(new SentryFileOutputStream(fd));
   }
 
-  SentryFileWriter(final @NotNull File file, final @NotNull IHub hub) throws FileNotFoundException {
-    super(new SentryFileOutputStream(file, hub));
+  SentryFileWriter(final @NotNull File file, final boolean append, final @NotNull IHub hub)
+      throws FileNotFoundException {
+    super(new SentryFileOutputStream(file, append, hub));
   }
 }

sentry/src/test/java/io/sentry/instrumentation/file/SentryFileOutputStreamTest.kt

@@ -22,13 +22,14 @@ class SentryFileOutputStreamTest {
         internal fun getSut(
             tmpFile: File? = null,
             activeTransaction: Boolean = true,
+            append: Boolean = false
         ): SentryFileOutputStream {
             whenever(hub.options).thenReturn(SentryOptions())
             sentryTracer = SentryTracer(TransactionContext("name", "op"), hub)
             if (activeTransaction) {
                 whenever(hub.span).thenReturn(sentryTracer)
             }
-            return SentryFileOutputStream(tmpFile, hub)
+            return SentryFileOutputStream(tmpFile, append, hub)
         }
     }
 

sentry/src/test/java/io/sentry/instrumentation/file/SentryFileWriterTest.kt

@@ -21,13 +21,14 @@ class SentryFileWriterTest {
         internal fun getSut(
             tmpFile: File,
             activeTransaction: Boolean = true,
+            append: Boolean = false
         ): SentryFileWriter {
             whenever(hub.options).thenReturn(SentryOptions())
             sentryTracer = SentryTracer(TransactionContext("name", "op"), hub)
             if (activeTransaction) {
                 whenever(hub.span).thenReturn(sentryTracer)
             }
-            return SentryFileWriter(tmpFile, hub)
+            return SentryFileWriter(tmpFile, append, hub)
         }
     }
 
@@ -36,7 +37,7 @@ class SentryFileWriterTest {
 
     private val fixture = Fixture()
 
-    private val tmpFile: File get() = tmpDir.newFile("test.txt")
+    private val tmpFile: File by lazy { tmpDir.newFile("test.txt") }
 
     @Test
     fun `captures a span`() {
@@ -53,4 +54,20 @@ class SentryFileWriterTest {
         assertEquals(fileIOSpan.isFinished, true)
         assertEquals(fileIOSpan.status, OK)
     }
+
+    @Test
+    fun `append works`() {
+        val writer1 = fixture.getSut(tmpFile, append = true)
+        writer1.use {
+            it.append("test")
+        }
+
+        // second writer should not overwrite the file contents, but append to the existing content
+        val writer2 = fixture.getSut(tmpFile, append = true)
+        writer2.use {
+            it.append("test2")
+        }
+
+        assertEquals("testtest2", tmpFile.readText())
+    }
 }