Add support for binary checksum files

cache/src/main/scala/coursier/Cache.scala

@@ -838,6 +838,18 @@ object Cache {
     parseChecksumLine(lines) orElse parseChecksumAlternative(lines)
   }
 
+  def parseRawChecksum(content: Array[Byte]): Option[BigInteger] =
+    if (content.length == 16 || content.length == 20)
+      Some(new BigInteger(content))
+    else {
+      val s = new String(content, UTF_8)
+      val lines = s
+        .lines
+        .toVector
+
+      parseChecksumLine(lines) orElse parseChecksumAlternative(lines)
+    }
+
   // matches md5 or sha1
   private val checksumPattern = Pattern.compile("^[0-9a-f]{32}([0-9a-f]{8})?")
 
@@ -870,9 +882,7 @@ object Cache {
           val sumFile = localFile(sumUrl, cache, artifact.authentication.map(_.user))
 
           Task {
-            val sumOpt = parseChecksum(
-              new String(FileUtil.readAllBytes(sumFile), UTF_8)
-            )
+            val sumOpt = parseRawChecksum(FileUtil.readAllBytes(sumFile))
 
             sumOpt match {
               case None =>

cache/src/main/scala/coursier/Platform.scala

@@ -1,6 +1,7 @@
 package coursier
 
 import java.io._
+import java.nio.charset.Charset
 
 import scala.language.implicitConversions
 
@@ -23,6 +24,8 @@ object Platform {
     buffer.toByteArray
   }
 
+  private lazy val UTF_8 = Charset.forName("UTF-8")
+
   def readFully(is: => InputStream) =
     Task {
       \/.fromTryCatchNonFatal {
@@ -31,7 +34,7 @@ object Platform {
           try readFullySync(is0)
           finally is0.close()
 
-        new String(b, "UTF-8")
+        new String(b, UTF_8)
       } .leftMap{
         case e: java.io.FileNotFoundException if e.getMessage != null =>
           s"Not found: ${e.getMessage}"

cli/src/main/scala-2.11/coursier/cli/spark/Assembly.scala

@@ -223,9 +223,7 @@ object Assembly {
           throw new Exception(s"SHA-1 file not found for ${a.url}")
       }
 
-      val sumOpt = Cache.parseChecksum(
-        new String(FileUtil.readAllBytes(f), "UTF-8")
-      )
+      val sumOpt = Cache.parseRawChecksum(FileUtil.readAllBytes(f))
 
       sumOpt match {
         case Some(sum) =>

tests/jvm/src/test/resources/empty.sha1

@@ -0,0 +1 @@
+ﾚ9｣硤kK
2Uｿ<55>`星ﾘ	

tests/jvm/src/test/scala/coursier/test/ChecksumTests.scala

@@ -22,7 +22,7 @@ object ChecksumTests extends TestSuite {
           assert(Cache.parseChecksum(other) == expected)
       }
 
-      * - {
+      'junk - {
         // https://repo1.maven.org/maven2/org/apache/spark/spark-core_2.11/1.2.0/spark-core_2.11-1.2.0.pom.sha1
         // as of 2016-03-02
         val junkSha1 =
@@ -34,7 +34,7 @@ object ChecksumTests extends TestSuite {
         sha1ParseTest(cleanSha1, junkSha1)
       }
 
-      * - {
+      'singleLine - {
         // https://repo1.maven.org/maven2/org/json/json/20080701/json-20080701.pom.sha1
         // as of 2016-03-05
         val dirtySha1 =
@@ -45,6 +45,18 @@ object ChecksumTests extends TestSuite {
 
         sha1ParseTest(cleanSha1, dirtySha1)
       }
+
+      'binarySha1 - {
+        val content = Platform.readFullySync(getClass.getResource("/empty.sha1").openStream())
+        val res = Cache.parseRawChecksum(content)
+        assert(res.nonEmpty)
+      }
+
+      'binaryMd5 - {
+        val content = Platform.readFullySync(getClass.getResource("/empty.md5").openStream())
+        val res = Cache.parseRawChecksum(content)
+        assert(res.nonEmpty)
+      }
     }
 
     'artifact - {