Output leading zeroes in maven export checksums

private/tools/java/rules/jvm/external/maven/MavenPublisher.java

@@ -123,18 +123,18 @@ private static CompletableFuture<Void> upload(
   }
 
   private static String toSha1(byte[] toHash) {
-    return toHexS("SHA-1", toHash);
+    return toHexS("%040x", "SHA-1", toHash);
   }
 
   private static String toMd5(byte[] toHash) {
-    return toHexS("MD5", toHash);
+    return toHexS("%032x", "MD5", toHash);
   }
 
-  private static String toHexS(String algorithm, byte[] toHash) {
+  private static String toHexS(String fmt, String algorithm, byte[] toHash) {
     try {
       MessageDigest digest = MessageDigest.getInstance(algorithm);
       digest.update(toHash);
-      return new BigInteger(1, digest.digest()).toString(16);
+      return String.format(fmt, new BigInteger(1, digest.digest()));
     } catch (NoSuchAlgorithmException e) {
       throw new RuntimeException(e);
     }

tests/integration/java_export/PublishShapeTest.java

@@ -7,7 +7,9 @@
 import org.junit.rules.TemporaryFolder;
 
 import java.io.File;
+import java.io.FileOutputStream;
 import java.io.IOException;
+import java.io.PrintStream;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
@@ -18,6 +20,12 @@
 import static org.junit.Assume.assumeFalse;
 
 public class PublishShapeTest {
+    // Jar content is fake, but chosen to produce leading zero in the checksum
+    // to be sure leading zeroes aren't omitted
+    private static final String JAR_CONTENTS = "magic!";
+    private static final String JAR_MD5 = "05427eba78c92912c86d004b9857d6a0";
+    private static final String JAR_SHA1 = "cbb0126a346a4dd6694fc48e3a94174fd1c7fa93";
+
     @Rule
     public TemporaryFolder temp = new TemporaryFolder();
 
@@ -34,17 +42,25 @@ public void publishingToAFileEndPointLooksCorrect() throws IOException, Interrup
         Path repoRoot = publish("com.example:my-lib:1.0.0");
 
         // Check that the files are where we expect them to be
-        assertTrue(Files.exists(repoRoot.resolve("com/example/my-lib/1.0.0/my-lib-1.0.0.jar")));
-        assertTrue(Files.exists(repoRoot.resolve("com/example/my-lib/1.0.0/my-lib-1.0.0.jar.md5")));
-        assertTrue(Files.exists(repoRoot.resolve("com/example/my-lib/1.0.0/my-lib-1.0.0.jar.sha1")));
+        checkJarShape(repoRoot, "com/example/my-lib/1.0.0/my-lib-1.0.0.jar");
+        checkJarShape(repoRoot, "com/example/my-lib/1.0.0/my-lib-1.0.0-sources.jar");
+        checkJarShape(repoRoot, "com/example/my-lib/1.0.0/my-lib-1.0.0-javadoc.jar");
+    }
+
+    private void checkJarShape(Path repoRoot, String path) throws IOException {
+        assertTrue(Files.exists(repoRoot.resolve(path)));
+        assertTrue(Files.exists(repoRoot.resolve(path + ".md5")));
+        assertTrue(Files.exists(repoRoot.resolve(path + ".sha1")));
 
-        assertTrue(Files.exists(repoRoot.resolve("com/example/my-lib/1.0.0/my-lib-1.0.0-sources.jar")));
-        assertTrue(Files.exists(repoRoot.resolve("com/example/my-lib/1.0.0/my-lib-1.0.0-sources.jar.md5")));
-        assertTrue(Files.exists(repoRoot.resolve("com/example/my-lib/1.0.0/my-lib-1.0.0-sources.jar.sha1")));
+        // Basic checksum format check
+        String md5 = new String(Files.readAllBytes(repoRoot.resolve(path + ".md5")));
+        assertEquals(32, md5.length());
+        String sha1 = new String(Files.readAllBytes(repoRoot.resolve(path + ".sha1")));
+        assertEquals(40, sha1.length());
 
-        assertTrue(Files.exists(repoRoot.resolve("com/example/my-lib/1.0.0/my-lib-1.0.0-javadoc.jar")));
-        assertTrue(Files.exists(repoRoot.resolve("com/example/my-lib/1.0.0/my-lib-1.0.0-javadoc.jar.md5")));
-        assertTrue(Files.exists(repoRoot.resolve("com/example/my-lib/1.0.0/my-lib-1.0.0-javadoc.jar.sha1")));
+        // Check checksum values
+        assertEquals(JAR_MD5, md5);
+        assertEquals(JAR_SHA1, sha1);
     }
 
     private Path publish(String coordinates) throws IOException, InterruptedException {
@@ -56,7 +72,7 @@ private Path publish(String coordinates) throws IOException, InterruptedExceptio
 
         // The publisher doesn't validate inputs (though remote maven repos do)
         // so we'll stub out the bits we need.
-        File stubJar = temp.newFile("dummy.jar");
+        File stubJar = writeFile("dummy.jar", JAR_CONTENTS);
         File pomXml = temp.newFile("pom.xml");
 
         // We'd prefer to use `bazel run`, but this is a reasonable proxy for
@@ -87,4 +103,13 @@ private Path publish(String coordinates) throws IOException, InterruptedExceptio
 
         return repoRoot.toPath();
     }
+
+    private File writeFile(String name, String contents) throws IOException {
+        File file = temp.newFile(name);
+
+        try (PrintStream out = new PrintStream(new FileOutputStream(file))) {
+            out.print(contents);
+        }
+        return file;
+    }
 }