X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/0a49a7a4f1090b6f1ce1d0f9d969804c9226b53e..8d6d5106a6f1bcba010877d55932a8d8dcfa88bd:/src/src/os.c

diff --git a/src/src/os.c b/src/src/os.c
index b8d369307..ee754f9f2 100644
--- a/src/src/os.c
+++ b/src/src/os.c
@@ -1,10 +1,8 @@
-/* $Cambridge: exim/src/src/os.c,v 1.8 2009/11/16 19:50:37 nm4 Exp $ */
-
 /*************************************************
 *     Exim - an Internet mail transport agent    *
 *************************************************/
 
-/* Copyright (c) University of Cambridge 1995 - 2009 */
+/* Copyright (c) University of Cambridge 1995 - 2014 */
 /* See the file NOTICE for conditions of use and distribution. */
 
 #ifdef STAND_ALONE
@@ -167,8 +165,8 @@ that have nothing. It provides a basic translation for the common standard
 signal numbers. I've been extra cautious with the ifdef's here. Probably more
 than is necessary... */
 
-char *
-os_strsignal(int n)
+const char *
+os_strsignal(const int n)
 {
 switch (n)
   {
@@ -284,8 +282,8 @@ switch (n)
 exit codes into text, but this function is implemented this way so that if any
 OS does have such a thing, it could be used instead of this build-in one. */
 
-char *
-os_strexit(int n)
+const char *
+os_strexit(const int n)
 {
 switch (n)
   {
@@ -797,6 +795,50 @@ return yield;
 
 
 
+/* ----------------------------------------------------------------------- */
+
+/***********************************************************
+*                 DNS Resolver Base Finder                 *
+***********************************************************/
+
+/* We need to be able to set options for the system resolver(5), historically
+made available as _res.  At least one OS (NetBSD) now no longer provides this
+directly, instead making you call a function per thread to get a handle.
+Other OSs handle thread-safe resolver differently, in ways which fail if the
+programmer creates their own structs. */
+
+#if !defined(OS_GET_DNS_RESOLVER_RES) && !defined(COMPILE_UTILITY)
+
+#include <resolv.h>
+
+/* confirmed that res_state is typedef'd as a struct* on BSD and Linux, will
+find out how unportable it is on other OSes, but most resolver implementations
+should be descended from ISC's bind.
+
+Linux and BSD do:
+  define _res (*__res_state())
+identically.  We just can't rely on __foo functions.  It's surprising that use
+of _res has been as portable as it has, for so long.
+
+So, since _res works everywhere, and everything can decode the struct, I'm
+going to gamble that res_state is a typedef everywhere and use that as the
+return type.
+*/
+
+res_state
+os_get_dns_resolver_res(void)
+{
+  return &_res;
+}
+
+#endif /* OS_GET_DNS_RESOLVER_RES */
+
+
+/* ----------------------------------------------------------------------- */
+
+
+
+
 
 /*************************************************
 **************************************************