Fixed issue where CipherSource as reporting the end of the cipher str…

…eam incorrectly.

This was happening if the wrapped (source) steam ended but we already read and deciphered more bytes than the last read requested. A test was added to capture the bug.

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
-        return if (streamEnd) -1 else 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
     }
 
 }

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

@@ -70,7 +70,7 @@ class CipherSourceTest {
     }
 
     @Test
-    fun read_cipheredChunked() {
+    fun read_cipheredChunked_exactCharacters() {
         val ciphered = encodeCipher.doFinal("okio oh my¿¡ okio oh my¿¡ okio oh my¿¡".toByteArray())
         val cipheredSource = Buffer().write(ciphered)
 
@@ -88,6 +88,22 @@ class CipherSourceTest {
         assertThat(output.readUtf8()).isEqualTo("okio oh my¿¡ okio oh my¿¡")
     }
 
+    @Test
+    fun read_cipheredChunked_untilStreamEnd() {
+        val ciphered = encodeCipher.doFinal("okio oh my¿¡ okio oh my¿¡ okio oh my¿¡".toByteArray())
+        val cipheredSource = Buffer().write(ciphered)
+
+        val decoded = CipherSource(cipheredSource, decodeCipher)
+
+        // Request 5 bytes until the stream claims to be empty
+        val output = Buffer()
+        var readBytesCount = Long.MAX_VALUE
+        while (readBytesCount > 0) {
+            readBytesCount = decoded.read(output, 5)
+        }
+        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())