From a6f5f71a126fdf131a0673a99799c23348813361 Mon Sep 17 00:00:00 2001
From: Chris Nauroth <cnauroth@apache.org>
Date: Fri, 22 Aug 2014 04:05:56 +0000
Subject: [PATCH] HADOOP-10989. Merging change r1619659 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1619660 13f79535-47bb-0310-9956-ffa450edef68
---
 hadoop-common-project/hadoop-common/CHANGES.txt        |  3 +++
 .../src/org/apache/hadoop/security/hadoop_user_info.c  | 10 ++++++++++
 2 files changed, 13 insertions(+)

diff --git a/hadoop-common-project/hadoop-common/CHANGES.txt b/hadoop-common-project/hadoop-common/CHANGES.txt
index 65988d28c69..5547a669246 100644
--- a/hadoop-common-project/hadoop-common/CHANGES.txt
+++ b/hadoop-common-project/hadoop-common/CHANGES.txt
@@ -311,6 +311,9 @@ Release 2.6.0 - UNRELEASED
 
     HADOOP-10488. TestKeyProviderFactory fails randomly. (tucu)
 
+    HADOOP-10989. Work around buggy getgrouplist() implementations on Linux that
+    return 0 on failure. (cnauroth)
+
 Release 2.5.0 - 2014-08-11
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-common-project/hadoop-common/src/main/native/src/org/apache/hadoop/security/hadoop_user_info.c b/hadoop-common-project/hadoop-common/src/main/native/src/org/apache/hadoop/security/hadoop_user_info.c
index ca288ec7da2..e2438b1b06c 100644
--- a/hadoop-common-project/hadoop-common/src/main/native/src/org/apache/hadoop/security/hadoop_user_info.c
+++ b/hadoop-common-project/hadoop-common/src/main/native/src/org/apache/hadoop/security/hadoop_user_info.c
@@ -193,7 +193,17 @@ int hadoop_user_info_getgroups(struct hadoop_user_info *uinfo)
   ngroups = uinfo->gids_size;
   ret = getgrouplist(uinfo->pwd.pw_name, uinfo->pwd.pw_gid, 
                          uinfo->gids, &ngroups);
+  // Return value is different on Linux vs. FreeBSD.  Linux: the number of groups
+  // or -1 on error.  FreeBSD: 0 on success or -1 on error.  Unfortunately, we
+  // can't accept a 0 return on Linux, because buggy implementations have been
+  // observed to return 0 but leave the other out parameters in an indeterminate
+  // state.  This deviates from the man page, but it has been observed in
+  // practice.  See issue HADOOP-10989 for details.
+#ifdef __linux__
+  if (ret > 0) {
+#else
   if (ret >= 0) {
+#endif
     uinfo->num_gids = ngroups;
     ret = put_primary_gid_first(uinfo);
     if (ret) {