From adb015847de61d9ae308a7702d091664a907c291 Mon Sep 17 00:00:00 2001
From: cnauroth <cnauroth@apache.org>
Date: Thu, 15 Oct 2015 15:54:48 -0700
Subject: [PATCH] HADOOP-12479. ProtocMojo does not log the reason for a protoc
 compilation failure. Contributed by Chris Nauroth.

(cherry picked from commit fdd740622459625efe5e12f37577aa3f5746177f)
---
 .../hadoop-common/CHANGES.txt                 |  3 +++
 .../maven/plugin/protoc/ProtocMojo.java       |  6 +++++-
 .../apache/hadoop/maven/plugin/util/Exec.java | 19 ++++++++++++++++++-
 3 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/hadoop-common-project/hadoop-common/CHANGES.txt b/hadoop-common-project/hadoop-common/CHANGES.txt
index 50880a3ef8c..7bc04ffb20c 100644
--- a/hadoop-common-project/hadoop-common/CHANGES.txt
+++ b/hadoop-common-project/hadoop-common/CHANGES.txt
@@ -643,6 +643,9 @@ Release 2.8.0 - UNRELEASED
     HADOOP-12475. Replace guava Cache with ConcurrentHashMap for caching
     Connection in ipc Client (Walter Su via sjlee)
 
+    HADOOP-12479. ProtocMojo does not log the reason for a protoc compilation
+    failure. (cnauroth)
+
   OPTIMIZATIONS
 
     HADOOP-12051. ProtobufRpcEngine.invoke() should use Exception.toString()
diff --git a/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/protoc/ProtocMojo.java b/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/protoc/ProtocMojo.java
index b9be33e5de5..0dcac0e8e45 100644
--- a/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/protoc/ProtocMojo.java
+++ b/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/protoc/ProtocMojo.java
@@ -248,11 +248,15 @@ public class ProtocMojo extends AbstractMojo {
 
         exec = new Exec(this);
         out = new ArrayList<String>();
-        if (exec.run(command, out) != 0) {
+        List<String> err = new ArrayList<>();
+        if (exec.run(command, out, err) != 0) {
           getLog().error("protoc compiler error");
           for (String s : out) {
             getLog().error(s);
           }
+          for (String s : err) {
+            getLog().error(s);
+          }
           throw new MojoExecutionException("protoc failure");
         }
         // Write the new checksum file on success.
diff --git a/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/util/Exec.java b/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/util/Exec.java
index 37dbc72f2f2..ce3543cd418 100644
--- a/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/util/Exec.java
+++ b/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/util/Exec.java
@@ -42,12 +42,26 @@ public class Exec {
   /**
    * Runs the specified command and saves each line of the command's output to
    * the given list.
-   * 
+   *
    * @param command List containing command and all arguments
    * @param output List in/out parameter to receive command output
    * @return int exit code of command
    */
   public int run(List<String> command, List<String> output) {
+    return this.run(command, output, null);
+  }
+
+  /**
+   * Runs the specified command and saves each line of the command's output to
+   * the given list and each line of the command's stderr to the other list.
+   *
+   * @param command List containing command and all arguments
+   * @param output List in/out parameter to receive command output
+   * @param errors List in/out parameter to receive command stderr
+   * @return int exit code of command
+   */
+  public int run(List<String> command, List<String> output,
+      List<String> errors) {
     int retCode = 1;
     ProcessBuilder pb = new ProcessBuilder(command);
     try {
@@ -66,6 +80,9 @@ public class Exec {
       stdOut.join();
       stdErr.join();
       output.addAll(stdOut.getOutput());
+      if (errors != null) {
+        errors.addAll(stdErr.getOutput());
+      }
     } catch (Exception ex) {
       mojo.getLog().warn(command + " failed: " + ex.toString());
     }