From 371e927323cd106de0187e1e0d9f5eb2e833a218 Mon Sep 17 00:00:00 2001
From: Tiago Quelhas <tjgq@google.com>
Date: Wed, 8 Nov 2023 01:25:12 -0800
Subject: [PATCH] Print an error message when the downloader configuration file
 is missing.

Fixes #20058.

Closes #20061.

PiperOrigin-RevId: 580442451
Change-Id: Ic0a856e843428d655b6d11d437af7be76f3cc573
---
 .../build/lib/bazel/BazelRepositoryModule.java        |  4 +++-
 .../lib/bazel/repository/downloader/UrlRewriter.java  |  3 +--
 .../downloader/UrlRewriterParseException.java         | 11 +++++++++--
 3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/main/java/com/google/devtools/build/lib/bazel/BazelRepositoryModule.java b/src/main/java/com/google/devtools/build/lib/bazel/BazelRepositoryModule.java
index d3f9fe382f03c0..ff2236ea3dbddf 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/BazelRepositoryModule.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/BazelRepositoryModule.java
@@ -411,7 +411,9 @@ public void beforeCommand(CommandEnvironment env) throws AbruptExitException {
         throw new AbruptExitException(
             detailedExitCode(
                 String.format(
-                    "Failed to parse downloader config at %s: %s", e.getLocation(), e.getMessage()),
+                    "Failed to parse downloader config%s: %s",
+                    e.getLocation() != null ? String.format(" at %s", e.getLocation()) : "",
+                    e.getMessage()),
                 Code.BAD_DOWNLOADER_CONFIG));
       }
 
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/repository/downloader/UrlRewriter.java b/src/main/java/com/google/devtools/build/lib/bazel/repository/downloader/UrlRewriter.java
index dbef8a1368b627..3cb965c1bd946d 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/repository/downloader/UrlRewriter.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/repository/downloader/UrlRewriter.java
@@ -36,7 +36,6 @@
 import java.io.IOException;
 import java.io.Reader;
 import java.io.StringReader;
-import java.io.UncheckedIOException;
 import java.net.MalformedURLException;
 import java.net.URI;
 import java.net.URISyntaxException;
@@ -98,7 +97,7 @@ public static UrlRewriter getDownloaderUrlRewriter(String configPath, Reporter r
     try (BufferedReader reader = Files.newBufferedReader(Paths.get(configPath))) {
       return new UrlRewriter(log, configPath, reader);
     } catch (IOException e) {
-      throw new UncheckedIOException(e);
+      throw new UrlRewriterParseException(e.getMessage());
     }
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/repository/downloader/UrlRewriterParseException.java b/src/main/java/com/google/devtools/build/lib/bazel/repository/downloader/UrlRewriterParseException.java
index 57a95901d00dcb..bfc995bff0544d 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/repository/downloader/UrlRewriterParseException.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/repository/downloader/UrlRewriterParseException.java
@@ -13,17 +13,24 @@
 // limitations under the License.
 package com.google.devtools.build.lib.bazel.repository.downloader;
 
+import javax.annotation.Nullable;
 import net.starlark.java.syntax.Location;
 
 /** An {@link Exception} thrown when failed to parse {@link UrlRewriterConfig}. */
 public class UrlRewriterParseException extends Exception {
-  private final Location location;
 
-  public UrlRewriterParseException(String message, Location location) {
+  @Nullable private final Location location;
+
+  public UrlRewriterParseException(String message) {
+    this(message, /* location= */ null);
+  }
+
+  public UrlRewriterParseException(String message, @Nullable Location location) {
     super(message);
     this.location = location;
   }
 
+  @Nullable
   public Location getLocation() {
     return location;
   }