[PATCH][BZ #14719] Return EAI_SYSTEM from getaddrinfo if we run outof fds

[Siddhesh Poyarekar <siddhesh at redhat dot com>]

Hi,

As described in the bug report, the current behaviour for getaddrinfo
when it runs out of file descriptors is to return EAI_NOTFOUND, which
is incorrect.  Since a system error has occurred, it should be
returning EAI_SYSTEM so that the real cause of the failure could be
seen from errno.  Attached patch does that.  Tested on x86_64 Fedora
16 for AF_INET, AF_UNSPEC and AF_INET6.  OK to commit?

Regards,
Siddhesh

ChangeLog:

	[BZ #14719]
	* nss/getXXbyYY_r.c (INTERNAL (REENTRANT_NAME)): Set h_errno to
	NETDB_INTERNAL when NSS_STATUS_UNAVAIL.
	* resolv/nss_dns/dns-host.c (_nss_dns_gethostbyname3_r): Set
	h_errno to NETDB_INTERNAL when errno is EMFILE or ENFILE.
	(_nss_dns_gethostbyname4_r): Likewise.
	* sysdeps/posix/getaddrinfo.c (gaih_inet): Set result to
	EAI_SYSTEM if NSS_STATUS_UNAVAIL.

diff --git a/nss/getXXbyYY_r.c b/nss/getXXbyYY_r.c
index f296ed1..dfa0dfc 100644
--- a/nss/getXXbyYY_r.c
+++ b/nss/getXXbyYY_r.c
@@ -284,8 +284,13 @@ done:
 #endif
   *result = status == NSS_STATUS_SUCCESS ? resbuf : NULL;
 #ifdef NEED_H_ERRNO
-  if (status != NSS_STATUS_SUCCESS && ! any_service)
-    /* We were not able to use any service.  */
+  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;
+  else if (status != NSS_STATUS_SUCCESS && !any_service)
+    /* We were no able to use any service.  */
     *h_errnop = NO_RECOVERY;
 #endif
 #ifdef POSTPROCESS
diff --git a/resolv/nss_dns/dns-host.c b/resolv/nss_dns/dns-host.c
index 6b62c05..102afb2 100644
--- a/resolv/nss_dns/dns-host.c
+++ b/resolv/nss_dns/dns-host.c
@@ -199,6 +199,10 @@ _nss_dns_gethostbyname3_r (const char *name, int af, struct hostent *result,
 	  status = NSS_STATUS_TRYAGAIN;
 	  h_errno = TRY_AGAIN;
 	  break;
+	/* System has run out of file descriptors.  */
+	case EMFILE:
+	case ENFILE:
+	  h_errno = NETDB_INTERNAL;
 	case ECONNREFUSED:
 	case ETIMEDOUT:
 	  status = NSS_STATUS_UNAVAIL;
@@ -311,14 +315,25 @@ _nss_dns_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat,
 			      &ans2p, &nans2p, &resplen2);
   if (n < 0)
     {
-      if (errno == ESRCH)
+      switch (errno)
 	{
+	case ESRCH:
 	  status = NSS_STATUS_TRYAGAIN;
 	  h_errno = TRY_AGAIN;
+	  break;
+	/* System has run out of file descriptors.  */
+	case EMFILE:
+	case ENFILE:
+	  h_errno = NETDB_INTERNAL;
+	case ECONNREFUSED:
+	case ETIMEDOUT:
+	  status = NSS_STATUS_UNAVAIL;
+	  break;
+	default:
+	  status = NSS_STATUS_NOTFOUND;
+	  break;
 	}
-      else
-	status = (errno == ECONNREFUSED
-		  ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND);
+
       *herrnop = h_errno;
       if (h_errno == TRY_AGAIN)
 	*errnop = EAGAIN;
diff --git a/sysdeps/posix/getaddrinfo.c b/sysdeps/posix/getaddrinfo.c
index 672571e..ad5ae01 100644
--- a/sysdeps/posix/getaddrinfo.c
+++ b/sysdeps/posix/getaddrinfo.c
@@ -1049,6 +1049,12 @@ gaih_inet (const char *name, const struct gaih_service *service,
 
 	  _res.options |= old_res_options & RES_USE_INET6;
 
+	  if (status == NSS_STATUS_UNAVAIL)
+	    {
+	      result = GAIH_OKIFUNSPEC | -EAI_SYSTEM;
+	      goto free_and_return;
+	    }
+
 	  if (no_data != 0 && no_inet6_data != 0)
 	    {
 	      /* If both requests timed out report this.  */