Merge pull request #277 from buzzcz/fix/filename-too-long

fix: filename too long in some cases

Author: apotterri

agent/src/main/java/com/appland/appmap/process/hooks/RecordingSupport.java

@@ -79,7 +79,6 @@ public static void stopRecording(TestDetails details, Boolean succeeded, String
     logger.debug("Recording stopped for {}",
         canonicalName(details.definedClass, details.isStatic, details.methodId));
     String filePath = Recorder.sanitizeFilename(String.join("_", details.definedClass, details.methodId));
-    filePath += ".appmap.json";
 
     Metadata metadata = recorder.getMetadata();
     if (succeeded != null) {

agent/src/main/java/com/appland/appmap/process/hooks/RequestRecording.java

@@ -67,7 +67,7 @@ public static void stop(HttpServletRequest req) {
 
     Recording recording = Recorder.getInstance().stopThread();
     String filename = String.format("%.3f_%s", startTime.toEpochMilli() / 1000.0, req.getRequestURI());
-    filename = Recorder.sanitizeFilename(filename) + ".appmap.json";
+    filename = Recorder.sanitizeFilename(filename);
     recording.moveTo(filename);
   }
 

agent/src/main/java/com/appland/appmap/record/Recorder.java

@@ -1,6 +1,9 @@
 package com.appland.appmap.record;
 
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
@@ -13,6 +16,7 @@
 import com.appland.appmap.output.v1.CodeObject;
 import com.appland.appmap.output.v1.Event;
 import com.appland.appmap.util.Logger;
+import org.apache.commons.lang3.RandomStringUtils;
 
 /**
  * Keep track of what's going on in the current thread.
@@ -51,14 +55,44 @@ public class Recorder {
   private static final String ERROR_SESSION_PRESENT = "an active recording session already exists";
   private static final String ERROR_NO_SESSION = "there is no active recording session";
 
+  private static final Integer FILENAME_MAX_LENGTH = 255; // Max length of a filename on most filesystems
+  private static final Integer HASH_LENGTH = 7; // Arbitrary but Git provides it's a reasonable value
+  private static final String APPMAP_SUFFIX = ".appmap.json";
+
   private static final Recorder instance = new Recorder();
 
   private final ActiveSession activeSession = new ActiveSession();
   private final CodeObjectTree globalCodeObjects = new CodeObjectTree();
   private final Map<Long, ThreadState> threadState = new ConcurrentHashMap<>();
 
   public static String sanitizeFilename(String filename) {
-    return filename.replaceAll("[^a-zA-Z0-9-_]", "_");
+    String sanitizedFilename = filename.replaceAll("[^a-zA-Z0-9-_]", "_");
+
+    if (sanitizedFilename.length() > FILENAME_MAX_LENGTH - APPMAP_SUFFIX.length()) {
+      int part = FILENAME_MAX_LENGTH - APPMAP_SUFFIX.length() - 1 - HASH_LENGTH;
+      sanitizedFilename = sanitizedFilename.substring(0, part) + "-" + hashFilename(sanitizedFilename.substring(part));
+    }
+
+    return sanitizedFilename + APPMAP_SUFFIX;
+  }
+
+  private static String hashFilename(String filename) {
+    MessageDigest digest;
+    try {
+      digest = MessageDigest.getInstance("SHA-256");
+    } catch (NoSuchAlgorithmException e) {
+      return RandomStringUtils.random(HASH_LENGTH);
+    }
+    byte[] hash = digest.digest(filename.getBytes(StandardCharsets.UTF_8));
+    StringBuilder hexString = new StringBuilder(2 * hash.length);
+    for (byte b : hash) {
+      String hex = Integer.toHexString(0xff & b);
+      if (hex.length() == 1) {
+        hexString.append('0');
+      }
+      hexString.append(hex);
+    }
+    return hexString.substring(0, HASH_LENGTH);
   }
 
   /**
@@ -363,7 +397,7 @@ public void record(String name, Runnable fn) throws ActiveSessionException, IOEx
     this.start(metadata);
     fn.run();
     Recording recording = this.stop();
-    recording.moveTo(fileName + ".appmap.json");
+    recording.moveTo(fileName);
   }
 
   // Mockito can't stub methods on the Collection<ThreadState>

agent/src/test/java/com/appland/appmap/record/RecorderTest.java

@@ -28,6 +28,8 @@
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
 import java.util.concurrent.Semaphore;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 import org.apache.commons.lang3.StringUtils;
 import org.junit.jupiter.api.AfterEach;
@@ -239,4 +241,16 @@ public void testMultithreadCheckpoint() throws InterruptedException {
     es.shutdown();
   }
 
+  @Test
+  public void testSanitizeFilename() {
+    assertEquals("foo.appmap.json", Recorder.sanitizeFilename("foo"));
+
+    String longFilename = StringUtils.repeat("foo", 100);
+    Pattern p = Pattern.compile("([fo]*?)-538355d.appmap.json");
+    Matcher m = p.matcher(Recorder.sanitizeFilename(longFilename));
+    assertTrue(m.find());
+    assertEquals(255, m.group(0).length());
+    assertEquals(235, m.group(1).length());
+  }
+
 }