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File getaddrinfo-errno.patch of Package glibc

2017-09-01  Florian Weimer  <fweimer@redhat.com>

	[BZ #21915]
	[BZ #21922]
	* sysdeps/posix/getaddrinfo.c (gethosts): Look at NSS function
	result to determine success or failure, not the errno value.
	* nss/Makefile (tests): Add tst-nss-files-hosts-erange.
	(tst-nss-files-hosts-erange): Link with -ldl.
	* nss/tst-nss-files-hosts-erange.c: New file.
	* nss/tst-resolv-basic.c (response): Handle nodata.example.
	(do_test): Add NO_DATA tests.
	* resolv/tst-resolv-basic.c (test_nodata_nxdomain): New function.
	(do_test): Call it.

2017-09-01  Florian Weimer  <fweimer@redhat.com>

	[BZ #21922]
	* sysdeps/posix/getaddrinfo.c (gaih_inet): Report EAI_NODATA error
	coming from gethostbyname2_r.

2017-09-01  Florian Weimer  <fweimer@redhat.com>

	* sysdeps/posix/getaddrinfo.c (gaih_inet): Only use h_errno if
	status indicates it is set.

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.

2017-09-01  Florian Weimer  <fweimer@redhat.com>

	* sysdeps/posix/getaddrinfo.c (gethosts): Use errno directly.
	(getcanonname): Likewise.
	(gaih_inet): Likewise.

2017-08-08  Florian Weimer  <fweimer@redhat.com>

	* sysdeps/posix/getaddrinfo.c (gaih_inet): Remove unreachable
	return statement.

Index: glibc-2.26/nss/Makefile
===================================================================
--- glibc-2.26.orig/nss/Makefile
+++ glibc-2.26/nss/Makefile
@@ -58,6 +58,11 @@ tests			= test-netdb test-digits-dots ts
 			  tst-nss-test5
 xtests			= bug-erange
 
+# Tests which need libdl
+ifeq (yes,$(build-shared))
+tests += tst-nss-files-hosts-erange
+endif
+
 # If we have a thread library then we can test cancellation against
 # some routines like getpwuid_r.
 ifeq (yes,$(have-thread-library))
@@ -154,3 +159,5 @@ $(patsubst %,$(objpfx)%.out,$(tests)) :
 ifeq (yes,$(have-thread-library))
 $(objpfx)tst-cancel-getpwuid_r: $(shared-thread-library)
 endif
+
+$(objpfx)tst-nss-files-hosts-erange: $(libdl)
Index: glibc-2.26/nss/tst-nss-files-hosts-erange.c
===================================================================
--- /dev/null
+++ glibc-2.26/nss/tst-nss-files-hosts-erange.c
@@ -0,0 +1,109 @@
+/* Parse /etc/hosts in multi mode with a trailing long line (bug 21915).
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+
+#include <dlfcn.h>
+#include <errno.h>
+#include <gnu/lib-names.h>
+#include <netdb.h>
+#include <nss.h>
+#include <support/check.h>
+#include <support/check_nss.h>
+#include <support/namespace.h>
+#include <support/test-driver.h>
+#include <support/xunistd.h>
+
+struct support_chroot *chroot_env;
+
+#define X10 "XXXXXXXXXX"
+#define X100 X10 X10 X10 X10 X10 X10 X10 X10 X10 X10
+#define X1000 X100 X100 X100 X100 X100 X100 X100 X100 X100 X100
+
+static void
+prepare (int argc, char **argv)
+{
+  chroot_env = support_chroot_create
+    ((struct support_chroot_configuration)
+     {
+       .resolv_conf = "",
+       .hosts =
+         "127.0.0.1   localhost localhost.localdomain\n"
+         "::1         localhost localhost.localdomain\n"
+         "192.0.2.1   example.com\n"
+         "#" X1000 X100 "\n",
+       .host_conf = "multi on\n",
+     });
+}
+
+static int
+do_test (void)
+{
+  support_become_root ();
+  if (!support_can_chroot ())
+    return EXIT_UNSUPPORTED;
+
+  __nss_configure_lookup ("hosts", "files");
+  if (dlopen (LIBNSS_FILES_SO, RTLD_LAZY) == NULL)
+    FAIL_EXIT1 ("could not load " LIBNSS_DNS_SO ": %s", dlerror ());
+
+  xchroot (chroot_env->path_chroot);
+
+  errno = ERANGE;
+  h_errno = NETDB_INTERNAL;
+  check_hostent ("gethostbyname example.com",
+                 gethostbyname ("example.com"),
+                 "name: example.com\n"
+                 "address: 192.0.2.1\n");
+  errno = ERANGE;
+  h_errno = NETDB_INTERNAL;
+  check_hostent ("gethostbyname2 AF_INET example.com",
+                 gethostbyname2 ("example.com", AF_INET),
+                 "name: example.com\n"
+                 "address: 192.0.2.1\n");
+  {
+    struct addrinfo hints =
+      {
+        .ai_family = AF_UNSPEC,
+        .ai_socktype = SOCK_STREAM,
+        .ai_protocol = IPPROTO_TCP,
+      };
+    errno = ERANGE;
+    h_errno = NETDB_INTERNAL;
+    struct addrinfo *ai;
+    int ret = getaddrinfo ("example.com", "80", &hints, &ai);
+    check_addrinfo ("example.com AF_UNSPEC", ai, ret,
+                    "address: STREAM/TCP 192.0.2.1 80\n");
+    if (ret == 0)
+      freeaddrinfo (ai);
+
+    hints.ai_family = AF_INET;
+    errno = ERANGE;
+    h_errno = NETDB_INTERNAL;
+    ret = getaddrinfo ("example.com", "80", &hints, &ai);
+    check_addrinfo ("example.com AF_INET", ai, ret,
+                    "address: STREAM/TCP 192.0.2.1 80\n");
+    if (ret == 0)
+      freeaddrinfo (ai);
+  }
+
+  support_chroot_free (chroot_env);
+  return 0;
+}
+
+#define PREPARE prepare
+#include <support/test-driver.c>
Index: glibc-2.26/resolv/tst-resolv-basic.c
===================================================================
--- glibc-2.26.orig/resolv/tst-resolv-basic.c
+++ glibc-2.26/resolv/tst-resolv-basic.c
@@ -50,7 +50,7 @@ response (const struct resolv_response_c
     qname_compare = qname + 2;
   else
     qname_compare = qname;
-  enum {www, alias, nxdomain, long_name} requested_qname;
+  enum {www, alias, nxdomain, long_name, nodata} requested_qname;
   if (strcmp (qname_compare, "www.example") == 0)
     requested_qname = www;
   else if (strcmp (qname_compare, "alias.example") == 0)
@@ -59,6 +59,8 @@ response (const struct resolv_response_c
     requested_qname = nxdomain;
   else if (strcmp (qname_compare, LONG_NAME) == 0)
     requested_qname = long_name;
+  else if (strcmp (qname_compare, "nodata.example") == 0)
+    requested_qname = nodata;
   else
     {
       support_record_failure ();
@@ -87,6 +89,8 @@ response (const struct resolv_response_c
       resolv_response_close_record (b);
       resolv_response_open_record (b, "www.example", qclass, qtype, 0);
       break;
+    case nodata:
+      return;
     case nxdomain:
       FAIL_EXIT1 ("unreachable");
     }
@@ -267,6 +271,55 @@ test_bug_21295 (void)
     }
 }
 
+/* Run tests which do not expect any data.  */
+static void
+test_nodata_nxdomain (void)
+{
+  /* Iterate through different address families.  */
+  int families[] = { AF_UNSPEC, AF_INET, AF_INET6, -1 };
+  for (int i = 0; families[i] >= 0; ++i)
+    /* If do_tcp, prepend "t." to the name to trigger TCP
+       fallback.  */
+    for (int do_tcp = 0; do_tcp < 2; ++do_tcp)
+      /* If do_nxdomain, trigger an NXDOMAIN error (DNS failure),
+         otherwise use a NODATA response (empty but successful
+         answer).  */
+      for (int do_nxdomain = 0; do_nxdomain < 2; ++do_nxdomain)
+        {
+          int family = families[i];
+          char *name = xasprintf ("%s%s.example",
+                                  do_tcp ? "t." : "",
+                                  do_nxdomain ? "nxdomain" : "nodata");
+
+          if (family != AF_UNSPEC)
+            {
+              if (do_nxdomain)
+                check_h (name, family, "error: HOST_NOT_FOUND\n");
+              else
+                check_h (name, family, "error: NO_ADDRESS\n");
+            }
+
+          const char *expected;
+          if (do_nxdomain)
+            expected = "error: Name or service not known\n";
+          else
+            expected = "error: No address associated with hostname\n";
+
+          check_ai (name, "80", family, expected);
+
+          struct addrinfo hints =
+            {
+              .ai_family = family,
+              .ai_flags = AI_V4MAPPED | AI_ALL,
+            };
+          check_ai_hints (name, "80", hints, expected);
+          hints.ai_flags |= AI_CANONNAME;
+          check_ai_hints (name, "80", hints, expected);
+
+          free (name);
+        }
+}
+
 static int
 do_test (void)
 {
@@ -439,29 +492,8 @@ do_test (void)
             "address: DGRAM/UDP 2001:db8::4 80\n"
             "address: RAW/IP 2001:db8::4 80\n");
 
-  check_h ("nxdomain.example", AF_INET,
-           "error: HOST_NOT_FOUND\n");
-  check_h ("nxdomain.example", AF_INET6,
-           "error: HOST_NOT_FOUND\n");
-  check_ai ("nxdomain.example", "80", AF_UNSPEC,
-            "error: Name or service not known\n");
-  check_ai ("nxdomain.example", "80", AF_INET,
-            "error: Name or service not known\n");
-  check_ai ("nxdomain.example", "80", AF_INET6,
-            "error: Name or service not known\n");
-
-  check_h ("t.nxdomain.example", AF_INET,
-           "error: HOST_NOT_FOUND\n");
-  check_h ("t.nxdomain.example", AF_INET6,
-           "error: HOST_NOT_FOUND\n");
-  check_ai ("t.nxdomain.example", "80", AF_UNSPEC,
-            "error: Name or service not known\n");
-  check_ai ("t.nxdomain.example", "80", AF_INET,
-            "error: Name or service not known\n");
-  check_ai ("t.nxdomain.example", "80", AF_INET6,
-            "error: Name or service not known\n");
-
   test_bug_21295 ();
+  test_nodata_nxdomain ();
 
   resolv_test_end (aux);
 
Index: glibc-2.26/support/namespace.h
===================================================================
--- glibc-2.26.orig/support/namespace.h
+++ glibc-2.26/support/namespace.h
@@ -66,7 +66,9 @@ struct support_chroot_configuration
 {
   /* File contents.  The files are not created if the field is
      NULL.  */
-  const char *resolv_conf;
+  const char *resolv_conf;      /* /etc/resolv.conf.  */
+  const char *hosts;            /* /etc/hosts.  */
+  const char *host_conf;        /* /etc/host.conf.  */
 };
 
 /* The result of the creation of a chroot.  */
@@ -78,8 +80,11 @@ struct support_chroot
   /* Path to the chroot directory.  */
   char *path_chroot;
 
-  /* Path to the /etc/resolv.conf file.  */
-  char *path_resolv_conf;
+  /* Paths to files in the chroot.  These are absolute and outside of
+     the chroot.  */
+  char *path_resolv_conf;       /* /etc/resolv.conf.  */
+  char *path_hosts;             /* /etc/hosts.  */
+  char *path_host_conf;         /* /etc/host.conf.  */
 };
 
 /* Create a chroot environment.  The returned data should be freed
Index: glibc-2.26/support/support_chroot.c
===================================================================
--- glibc-2.26.orig/support/support_chroot.c
+++ glibc-2.26/support/support_chroot.c
@@ -24,6 +24,23 @@
 #include <support/test-driver.h>
 #include <support/xunistd.h>
 
+/* If CONTENTS is not NULL, write it to the file at DIRECTORY/RELPATH,
+   and store the name in *ABSPATH.  If CONTENTS is NULL, store NULL in
+   *ABSPATH.  */
+static void
+write_file (const char *directory, const char *relpath, const char *contents,
+            char **abspath)
+{
+  if (contents != NULL)
+    {
+      *abspath = xasprintf ("%s/%s", directory, relpath);
+      add_temp_file (*abspath);
+      support_write_file_string (*abspath, contents);
+    }
+  else
+    *abspath = NULL;
+}
+
 struct support_chroot *
 support_chroot_create (struct support_chroot_configuration conf)
 {
@@ -39,15 +56,10 @@ support_chroot_create (struct support_ch
   xmkdir (path_etc, 0777);
   add_temp_file (path_etc);
 
-  if (conf.resolv_conf != NULL)
-    {
-      /* Create an empty resolv.conf file.  */
-      chroot->path_resolv_conf = xasprintf ("%s/resolv.conf", path_etc);
-      add_temp_file (chroot->path_resolv_conf);
-      support_write_file_string (chroot->path_resolv_conf, conf.resolv_conf);
-    }
-  else
-    chroot->path_resolv_conf = NULL;
+  write_file (path_etc, "resolv.conf", conf.resolv_conf,
+              &chroot->path_resolv_conf);
+  write_file (path_etc, "hosts", conf.hosts, &chroot->path_hosts);
+  write_file (path_etc, "host.conf", conf.host_conf, &chroot->path_host_conf);
 
   free (path_etc);
 
@@ -67,5 +79,7 @@ support_chroot_free (struct support_chro
 {
   free (chroot->path_chroot);
   free (chroot->path_resolv_conf);
+  free (chroot->path_hosts);
+  free (chroot->path_host_conf);
   free (chroot);
 }
Index: glibc-2.26/sysdeps/posix/getaddrinfo.c
===================================================================
--- glibc-2.26.orig/sysdeps/posix/getaddrinfo.c
+++ glibc-2.26/sysdeps/posix/getaddrinfo.c
@@ -241,48 +241,43 @@ convert_hostent_to_gaih_addrtuple (const
 
 #define gethosts(_family, _type) \
  {									      \
-  int herrno;								      \
   struct hostent th;							      \
-  struct hostent *h;							      \
   char *localcanon = NULL;						      \
   no_data = 0;								      \
-  while (1) {								      \
-    rc = 0;								      \
-    status = DL_CALL_FCT (fct, (name, _family, &th,			      \
-				tmpbuf->data, tmpbuf->length,		      \
-				&rc, &herrno, NULL, &localcanon));	      \
-    if (rc != ERANGE || herrno != NETDB_INTERNAL)			      \
-      break;								      \
-    if (!scratch_buffer_grow (tmpbuf))					      \
-      {									      \
-	__resolv_context_enable_inet6 (res_ctx, res_enable_inet6);	      \
-	__resolv_context_put (res_ctx);					      \
-	result = -EAI_MEMORY;						      \
-	goto free_and_return;						      \
-      }									      \
-  }									      \
-  if (status == NSS_STATUS_SUCCESS && rc == 0)				      \
-    h = &th;								      \
-  else									      \
-    h = NULL;								      \
-  if (rc != 0)								      \
+  while (1)								      \
     {									      \
-      if (herrno == NETDB_INTERNAL)					      \
+      status = DL_CALL_FCT (fct, (name, _family, &th,			      \
+				  tmpbuf->data, tmpbuf->length,		      \
+				  &errno, &h_errno, NULL, &localcanon));      \
+      if (status != NSS_STATUS_TRYAGAIN || h_errno != NETDB_INTERNAL	      \
+	  || errno != ERANGE)						      \
+	break;								      \
+      if (!scratch_buffer_grow (tmpbuf))				      \
+	{								      \
+	  __resolv_context_enable_inet6 (res_ctx, res_enable_inet6);	      \
+	  __resolv_context_put (res_ctx);				      \
+	  result = -EAI_MEMORY;						      \
+	  goto free_and_return;						      \
+	}								      \
+    }									      \
+  if (status == NSS_STATUS_NOTFOUND					      \
+      || status == NSS_STATUS_TRYAGAIN || status == NSS_STATUS_UNAVAIL)	      \
+    {									      \
+      if (h_errno == NETDB_INTERNAL)					      \
 	{								      \
-	  __set_h_errno (herrno);					      \
 	  __resolv_context_enable_inet6 (res_ctx, res_enable_inet6);	      \
 	  __resolv_context_put (res_ctx);				      \
 	  result = -EAI_SYSTEM;						      \
 	  goto free_and_return;						      \
 	}								      \
-      if (herrno == TRY_AGAIN)						      \
+      if (h_errno == TRY_AGAIN)						      \
 	no_data = EAI_AGAIN;						      \
       else								      \
-	no_data = herrno == NO_DATA;					      \
+	no_data = h_errno == NO_DATA;					      \
     }									      \
-  else if (h != NULL)							      \
+  else if (status == NSS_STATUS_SUCCESS)				      \
     {									      \
-      if (!convert_hostent_to_gaih_addrtuple (req, _family,h, &addrmem))      \
+      if (!convert_hostent_to_gaih_addrtuple (req, _family, &th, &addrmem))   \
 	{								      \
 	  __resolv_context_enable_inet6 (res_ctx, res_enable_inet6);	      \
 	  __resolv_context_put (res_ctx);				      \
@@ -334,10 +329,8 @@ getcanonname (service_user *nip, struct
   if (cfct != NULL)
     {
       char buf[256];
-      int herrno;
-      int rc;
       if (DL_CALL_FCT (cfct, (at->name ?: name, buf, sizeof (buf),
-			      &s, &rc, &herrno)) != NSS_STATUS_SUCCESS)
+			      &s, &errno, &h_errno)) != NSS_STATUS_SUCCESS)
 	/* If the canonical name cannot be determined, use the passed
 	   string.  */
 	s = (char *) name;
@@ -353,7 +346,6 @@ gaih_inet (const char *name, const struc
   const struct gaih_typeproto *tp = gaih_inet_typeproto;
   struct gaih_servtuple *st = (struct gaih_servtuple *) &nullserv;
   struct gaih_addrtuple *at = NULL;
-  int rc;
   bool got_ipv6 = false;
   const char *canon = NULL;
   const char *orig_name = name;
@@ -395,7 +387,8 @@ gaih_inet (const char *name, const struc
 	      st = (struct gaih_servtuple *)
 		alloca_account (sizeof (struct gaih_servtuple), alloca_used);
 
-	      if ((rc = gaih_inet_serv (service->name, tp, req, st, tmpbuf)))
+	      int rc = gaih_inet_serv (service->name, tp, req, st, tmpbuf);
+	      if (__glibc_unlikely (rc != 0))
 		return rc;
 	    }
 	  else
@@ -420,13 +413,9 @@ gaih_inet (const char *name, const struc
 		    alloca_account (sizeof (struct gaih_servtuple),
 				    alloca_used);
 
-		  if ((rc = gaih_inet_serv (service->name,
-					    tp, req, newp, tmpbuf)))
-		    {
-		      if (rc)
-			continue;
-		      return rc;
-		    }
+		  if (gaih_inet_serv (service->name,
+				      tp, req, newp, tmpbuf) != 0)
+		    continue;
 
 		  *pst = newp;
 		  pst = &(newp->next);
@@ -499,7 +488,7 @@ gaih_inet (const char *name, const struc
 	    idn_flags |= IDNA_USE_STD3_ASCII_RULES;
 
 	  char *p = NULL;
-	  rc = __idna_to_ascii_lz (name, &p, idn_flags);
+	  int rc = __idna_to_ascii_lz (name, &p, idn_flags);
 	  if (rc != IDNA_SUCCESS)
 	    {
 	      /* No need to jump to free_and_return here.  */
@@ -600,14 +589,13 @@ gaih_inet (const char *name, const struc
 	      int rc;
 	      struct hostent th;
 	      struct hostent *h;
-	      int herrno;
 
 	      while (1)
 		{
 		  rc = __gethostbyname2_r (name, AF_INET, &th,
 					   tmpbuf->data, tmpbuf->length,
-					   &h, &herrno);
-		  if (rc != ERANGE || herrno != NETDB_INTERNAL)
+					   &h, &h_errno);
+		  if (rc != ERANGE || h_errno != NETDB_INTERNAL)
 		    break;
 		  if (!scratch_buffer_grow (tmpbuf))
 		    {
@@ -629,15 +617,20 @@ gaih_inet (const char *name, const struc
 			}
 		      *pat = addrmem;
 		    }
+		  else
+		    {
+		      if (h_errno == NO_DATA)
+			result = -EAI_NODATA;
+		      else
+			result = -EAI_NONAME;
+		      goto free_and_return;
+		    }
 		}
 	      else
 		{
-		  if (herrno == NETDB_INTERNAL)
-		    {
-		      __set_h_errno (herrno);
-		      result = -EAI_SYSTEM;
-		    }
-		  else if (herrno == TRY_AGAIN)
+		  if (h_errno == NETDB_INTERNAL)
+		    result = -EAI_SYSTEM;
+		  else if (h_errno == TRY_AGAIN)
 		    result = -EAI_AGAIN;
 		  else
 		    /* We made requests but they turned out no data.
@@ -660,8 +653,7 @@ gaih_inet (const char *name, const struc
 	    {
 	      /* Try to use nscd.  */
 	      struct nscd_ai_result *air = NULL;
-	      int herrno;
-	      int err = __nscd_getai (name, &air, &herrno);
+	      int err = __nscd_getai (name, &air, &h_errno);
 	      if (air != NULL)
 		{
 		  /* Transform into gaih_addrtuple list.  */
@@ -752,9 +744,9 @@ gaih_inet (const char *name, const struc
 		goto free_and_return;
 	      else if (__nss_not_use_nscd_hosts == 0)
 		{
-		  if (herrno == NETDB_INTERNAL && errno == ENOMEM)
+		  if (h_errno == NETDB_INTERNAL && errno == ENOMEM)
 		    result = -EAI_MEMORY;
-		  else if (herrno == TRY_AGAIN)
+		  else if (h_errno == TRY_AGAIN)
 		    result = -EAI_AGAIN;
 		  else
 		    result = -EAI_SYSTEM;
@@ -793,24 +785,21 @@ gaih_inet (const char *name, const struc
 
 	      if (fct4 != NULL)
 		{
-		  int herrno;
-
 		  while (1)
 		    {
-		      rc = 0;
 		      status = DL_CALL_FCT (fct4, (name, pat,
 						   tmpbuf->data, tmpbuf->length,
-						   &rc, &herrno,
+						   &errno, &h_errno,
 						   NULL));
 		      if (status == NSS_STATUS_SUCCESS)
 			break;
 		      if (status != NSS_STATUS_TRYAGAIN
-			  || rc != ERANGE || herrno != NETDB_INTERNAL)
+			  || errno != ERANGE || h_errno != NETDB_INTERNAL)
 			{
-			  if (herrno == TRY_AGAIN)
+			  if (h_errno == TRY_AGAIN)
 			    no_data = EAI_AGAIN;
 			  else
-			    no_data = herrno == NO_DATA;
+			    no_data = h_errno == NO_DATA;
 			  break;
 			}
 
@@ -940,13 +929,17 @@ gaih_inet (const char *name, const struc
 		    }
 		  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);
 		    }
 		}
 
@@ -962,7 +955,10 @@ gaih_inet (const char *name, const struc
 	  __resolv_context_enable_inet6 (res_ctx, res_enable_inet6);
 	  __resolv_context_put (res_ctx);
 
-	  if (h_errno == NETDB_INTERNAL)
+	  /* If we have a failure which sets errno, report it using
+	     EAI_SYSTEM.  */
+	  if ((status == NSS_STATUS_TRYAGAIN || status == NSS_STATUS_UNAVAIL)
+	      && h_errno == NETDB_INTERNAL)
 	    {
 	      result = -EAI_SYSTEM;
 	      goto free_and_return;