Don't append to a truncated line in the journal.

Related to square/okhttp#1099

src/main/java/com/jakewharton/disklrucache/DiskLruCache.java

@@ -224,8 +224,6 @@ public static DiskLruCache open(File directory, int appVersion, int valueCount,
       try {
         cache.readJournal();
         cache.processJournal();
-        cache.journalWriter = new BufferedWriter(
-            new OutputStreamWriter(new FileOutputStream(cache.journalFile, true), Util.US_ASCII));
         return cache;
       } catch (IOException journalIsCorrupt) {
         System.out
@@ -272,6 +270,14 @@ private void readJournal() throws IOException {
         }
       }
       redundantOpCount = lineCount - lruEntries.size();
+
+      // If we ended on a truncated line, rebuild the journal before appending to it.
+      if (reader.hasUnterminatedLine()) {
+        rebuildJournal();
+      } else {
+        journalWriter = new BufferedWriter(new OutputStreamWriter(
+            new FileOutputStream(journalFile, true), Util.US_ASCII));
+      }
     } finally {
       Util.closeQuietly(reader);
     }

src/main/java/com/jakewharton/disklrucache/StrictLineReader.java

@@ -176,6 +176,10 @@ public String toString() {
     }
   }
 
+  public boolean hasUnterminatedLine() {
+    return end == -1;
+  }
+
   /**
    * Reads new input data into the buffer. Call only with pos == end or end == -1,
    * depending on the desired outcome if the function throws.

src/test/java/com/jakewharton/disklrucache/DiskLruCacheTest.java

@@ -375,6 +375,12 @@ public final class DiskLruCacheTest {
     writer.close();
     cache = DiskLruCache.open(cacheDir, appVersion, 2, Integer.MAX_VALUE);
     assertThat(cache.get("k1")).isNull();
+
+    // The journal is not corrupt when editing after a truncated line.
+    set("k1", "C", "D");
+    cache.close();
+    cache = DiskLruCache.open(cacheDir, appVersion, 2, Integer.MAX_VALUE);
+    assertValue("k1", "C", "D");
   }
 
   @Test public void openWithTooManyFileSizesClearsDirectory() throws Exception {