getaddrinfo: Properly set errno for NSS function lookup failure

2 files changed, 15 insertions, 6 deletions

diff --git a/ChangeLog b/ChangeLog
index 4d8c6f6744..4229a83b9c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 2017-09-01  Florian Weimer  <fweimer@redhat.com>
 
+	* sysdeps/posix/getaddrinfo.c (gaih_inet): Make reporting of NSS
+	function lookup failures more reliable.
+
+2017-09-01  Florian Weimer  <fweimer@redhat.com>
+
 	* sysdeps/posix/getaddrinfo.c (gethosts): Use h_errno directly.
 	(getcanonname): Likewise.
 	(gaih_inet): Likewise.
diff --git a/sysdeps/posix/getaddrinfo.c b/sysdeps/posix/getaddrinfo.c
index 4edd5e2a1b..95b514873d 100644
--- a/sysdeps/posix/getaddrinfo.c
+++ b/sysdeps/posix/getaddrinfo.c
@@ -922,13 +922,17 @@ gaih_inet (const char *name, const struct gaih_service *service,
 		    }
 		  else
 		    {
+		      /* Could not locate any of the lookup functions.
+			 The NSS lookup code does not consistently set
+			 errno, so we need to supply our own error
+			 code here.  The root cause could either be a
+			 resource allocation failure, or a missing
+			 service function in the DSO (so it should not
+			 be listed in /etc/nsswitch.conf).  Assume the
+			 former, and return EBUSY.  */
 		      status = NSS_STATUS_UNAVAIL;
-		      /* Could not load any of the lookup functions.  Indicate
-		         an internal error if the failure was due to a system
-			 error other than the file not being found.  We use the
-			 errno from the last failed callback.  */
-		      if (errno != 0 && errno != ENOENT)
-			__set_h_errno (NETDB_INTERNAL);
+		     __set_h_errno (NETDB_INTERNAL);
+		     __set_errno (EBUSY);
 		    }
 		}