[PATCH v2.1][BZ #15339] Avoid returning EAI_SYSTEM when there's a network error

[Siddhesh Poyarekar <siddhesh at redhat dot com>]

Hi,

I've updated this patch to fix another case that the original patch
broke.  The case can be seen here:

https://bugzilla.redhat.com/show_bug.cgi?id=958652

Dmitry, could you please run your testsuite against this to see if
anything breaks?  It's unlikely, but I'd like to be sure.

Thanks,

	[BZ #15339]
	* nss/getXXbyYY_r.c (REENTRANT_NAME): Set NETDB_INTERNAL only
	when no services were used.
	* sysdeps/posix/getaddrinfo.c (gaih_inet): Set h_errno.
	Return EAI_SYSTEM if h_errno is NETDB_INTERNAL.

commit e656c197931865499a33db8237265ce9de860363
Author: Siddhesh Poyarekar <siddhesh@redhat.com>
Date:   Wed May 15 20:46:11 2013 +0530

    Set EAI_SYSTEM only when h_errno is NETDB_INTERNAL
    
    Fixes BZ #15339.
    
    NSS_STATUS_UNAVAIL may mean that a necessary input resource is not
    available.  This could occur in a number of cases including when the
    network is down, system runs out of file descriptors, etc.  The
    correct differentiator in such a case is the h_errno, which gives the
    nature of failure.  In case of failures other than a simple 'not
    found', we set h_errno as NETDB_INTERNAL and let errno be the
    identifier for the exact error.

diff --git a/nss/getXXbyYY_r.c b/nss/getXXbyYY_r.c
index 1067744..9e4d110 100644
--- a/nss/getXXbyYY_r.c
+++ b/nss/getXXbyYY_r.c
@@ -284,11 +284,11 @@ done:
 #endif
   *result = status == NSS_STATUS_SUCCESS ? resbuf : NULL;
 #ifdef NEED_H_ERRNO
-  if (status == NSS_STATUS_UNAVAIL)
-    /* Either we failed to lookup the functions or the functions themselves
-       had a system error.  Set NETDB_INTERNAL here to let the caller know
-       that the errno may have the real reason for failure.  */
-      *h_errnop = NETDB_INTERNAL;
+  if (status == NSS_STATUS_UNAVAIL && !any_service && errno != ENOENT)
+    /* This happens when we weren't able to use a service for reasons other
+       than the module not being found.  In such a case, we'd want to tell the
+       caller that errno has the real reason for failure.  */
+    *h_errnop = NETDB_INTERNAL;
   else if (status != NSS_STATUS_SUCCESS && !any_service)
     /* We were not able to use any service.  */
     *h_errnop = NO_RECOVERY;
diff --git a/sysdeps/posix/getaddrinfo.c b/sysdeps/posix/getaddrinfo.c
index d368306..bde7dfe 100644
--- a/sysdeps/posix/getaddrinfo.c
+++ b/sysdeps/posix/getaddrinfo.c
@@ -1035,7 +1035,14 @@ gaih_inet (const char *name, const struct gaih_service *service,
 			}
 		    }
 		  else
-		    status = NSS_STATUS_UNAVAIL;
+		    {
+		      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.  */
+		      if (errno != 0 && errno != ENOENT)
+			__set_h_errno (NETDB_INTERNAL);
+		    }
 		}
 
 	      if (nss_next_action (nip, status) == NSS_ACTION_RETURN)
@@ -1049,7 +1056,7 @@ gaih_inet (const char *name, const struct gaih_service *service,
 
 	  _res.options |= old_res_options & RES_USE_INET6;
 
-	  if (status == NSS_STATUS_UNAVAIL)
+	  if (h_errno == NETDB_INTERNAL)
 	    {
 	      result = GAIH_OKIFUNSPEC | -EAI_SYSTEM;
 	      goto free_and_return;