From ca7685ef50a0970662a55e3ad84b7cba73c2f2d0 Mon Sep 17 00:00:00 2001
From: Vladimir Gordiychuk <folyga@gmail.com>
Date: Wed, 16 Aug 2017 02:04:24 +0300
Subject: [PATCH] protobuf-lite: ProtoLiteUtils fix infinite loop

InputStream by contract can return zero if requested length equal to zero.

```
If len is zero, then no bytes are read and 0 is returned;
otherwise, there is an attempt to read at least one byte.
If no byte is available because the stream is at end of file,
the value -1 is returned; otherwise, at least one byte is read
and stored into b.
```

Close #3323
---
 .../io/grpc/protobuf/lite/ProtoLiteUtils.java | 17 +++++++---
 .../protobuf/lite/ProtoLiteUtilsTest.java     | 33 +++++++++++++++++++
 2 files changed, 45 insertions(+), 5 deletions(-)

diff --git a/protobuf-lite/src/main/java/io/grpc/protobuf/lite/ProtoLiteUtils.java b/protobuf-lite/src/main/java/io/grpc/protobuf/lite/ProtoLiteUtils.java
index 8914201341..2a88a3f891 100644
--- a/protobuf-lite/src/main/java/io/grpc/protobuf/lite/ProtoLiteUtils.java
+++ b/protobuf-lite/src/main/java/io/grpc/protobuf/lite/ProtoLiteUtils.java
@@ -128,12 +128,19 @@ public class ProtoLiteUtils {
                 buf = new byte[size];
                 bufs.set(new WeakReference<byte[]>(buf));
               }
-              int chunkSize;
-              int position = 0;
-              while ((chunkSize = stream.read(buf, position, size - position)) != -1) {
-                position += chunkSize;
+
+              int remaining = size;
+              while (remaining > 0) {
+                int position = size - remaining;
+                int count = stream.read(buf, position, remaining);
+                if (count == -1) {
+                  break;
+                }
+                remaining -= count;
               }
-              if (size != position) {
+
+              if (remaining != 0) {
+                int position = size - remaining;
                 throw new RuntimeException("size inaccurate: " + size + " != " + position);
               }
               cis = CodedInputStream.newInstance(buf, 0, size);
diff --git a/protobuf-lite/src/test/java/io/grpc/protobuf/lite/ProtoLiteUtilsTest.java b/protobuf-lite/src/test/java/io/grpc/protobuf/lite/ProtoLiteUtilsTest.java
index d47e089a02..c4a4d32174 100644
--- a/protobuf-lite/src/test/java/io/grpc/protobuf/lite/ProtoLiteUtilsTest.java
+++ b/protobuf-lite/src/test/java/io/grpc/protobuf/lite/ProtoLiteUtilsTest.java
@@ -29,6 +29,7 @@ import com.google.protobuf.Enum;
 import com.google.protobuf.InvalidProtocolBufferException;
 import com.google.protobuf.Type;
 import io.grpc.Drainable;
+import io.grpc.KnownLength;
 import io.grpc.Metadata;
 import io.grpc.MethodDescriptor.Marshaller;
 import io.grpc.MethodDescriptor.PrototypeMarshaller;
@@ -215,4 +216,36 @@ public class ProtoLiteUtilsTest {
 
     ProtoLiteUtils.setExtensionRegistry(null);
   }
+
+  @Test
+  public void parseFromKnowLengthInputStream() throws Exception {
+    Marshaller<Type> marshaller = ProtoLiteUtils.marshaller(Type.getDefaultInstance());
+    Type expect = Type.newBuilder().setName("expected name").build();
+
+    Type result = marshaller.parse(new CustomKnownLengthInputStream(expect.toByteArray()));
+    assertEquals(expect, result);
+  }
+
+  private static class CustomKnownLengthInputStream extends InputStream implements KnownLength {
+    private int position = 0;
+    private byte[] source;
+
+    private CustomKnownLengthInputStream(byte[] source) {
+      this.source = source;
+    }
+
+    @Override
+    public int available() throws IOException {
+      return source.length - position;
+    }
+
+    @Override
+    public int read() throws IOException {
+      if (position == source.length) {
+        return -1;
+      }
+
+      return source[position++];
+    }
+  }
 }