Fixed issue when using CipherSource and fully relying on it reporting -1 only if nothing was written to the Sink.

This was happening when using Okio's BufferedSource which short-cuts reading even if bytes were written to the wrapped Buffer. A test was added to capture the bug.

Author: erickok

lib/src/main/java/nl/nl2312/okio/cipher/CipherSource.kt

@@ -53,8 +53,8 @@ class CipherSource(
         val bytesToReturn = bytesRequested.coerceAtMost(decipheredBuffer.size())
         sink.write(decipheredBuffer, bytesToReturn)
 
-        // Return number of written deciphered bytes, or -1 if the source stream is exhausted and our buffer is empty
-        return if (streamEnd && decipheredBuffer.size() == 0L) -1 else bytesToReturn
+        // Return number of written deciphered bytes, or -1 if there is nothing more to decipher
+        return if (bytesToReturn > 0) bytesToReturn else -1
     }
 
 }

lib/src/test/java/nl/nl2312/okio/cipher/CipherSourceTest.kt

@@ -4,6 +4,8 @@ import com.google.common.truth.Truth.assertThat
 import nl.nl2312.okio.base64.Base64Source
 import okio.Buffer
 import okio.ByteString
+import okio.Okio
+import okio.Source
 import org.junit.Test
 import java.security.SecureRandom
 import javax.crypto.Cipher
@@ -104,6 +106,21 @@ class CipherSourceTest {
         assertThat(output.readUtf8()).isEqualTo("okio oh my¿¡ okio oh my¿¡ okio oh my¿¡")
     }
 
+    @Test
+    fun read_buffered_whileBytesRead() {
+        val ciphered = encodeCipher.doFinal("okio oh my¿¡ okio oh my¿¡ okio oh my¿¡".toByteArray())
+        val cipheredSource = Buffer().write(ciphered)
+
+        val decoded = CipherSource(cipheredSource, decodeCipher)
+
+        // Okio's RealBufferedSource.read(Buffer, Long) will only write to the given buffer when the
+        // CipherSource.read(Buffer, Long) returns a non-negative byes read could
+        val buffer = Okio.buffer(decoded as Source)
+        val output = Buffer()
+        buffer.read(output, 8192)
+        assertThat(output.readUtf8()).isEqualTo("okio oh my¿¡ okio oh my¿¡ okio oh my¿¡")
+    }
+
     @Test
     fun read_base64Wrapped() {
         val ciphered = encodeCipher.doFinal("okio oh my¿¡".toByteArray())