api: Add option to expose some internal functions

Purely for testing, add --enable-expose-statics option to configure
which converts some static internal functions to be externally visible.

ares_getnameinfo.c

@@ -77,7 +77,7 @@ static char *lookup_service(unsigned short port, int flags,
 static void append_scopeid(struct sockaddr_in6 *addr6, unsigned int scopeid,
                            char *buf, size_t buflen);
 #endif
-static char *ares_striendstr(const char *s1, const char *s2);
+STATIC_TESTABLE char *ares_striendstr(const char *s1, const char *s2);
 
 void ares_getnameinfo(ares_channel channel, const struct sockaddr *sa,
                       ares_socklen_t salen,
@@ -391,7 +391,7 @@ static void append_scopeid(struct sockaddr_in6 *addr6, unsigned int flags,
 #endif
 
 /* Determines if s1 ends with the string in s2 (case-insensitive) */
-static char *ares_striendstr(const char *s1, const char *s2)
+STATIC_TESTABLE char *ares_striendstr(const char *s1, const char *s2)
 {
   const char *c1, *c2, *c1_begin;
   int lo1, lo2;

ares_private.h

@@ -43,6 +43,13 @@
 #define INADDR_NONE 0xffffffff
 #endif
 
+#ifdef CARES_EXPOSE_STATICS
+/* Make some internal functions visible for testing */
+#define STATIC_TESTABLE
+#else
+#define STATIC_TESTABLE static
+#endif
+
 #if defined(WIN32) && !defined(WATT32)
 
 #define WIN_NS_9X      "System\\CurrentControlSet\\Services\\VxD\\MSTCP"

ares_search.c

@@ -44,7 +44,7 @@ static void search_callback(void *arg, int status, int timeouts,
 static void end_squery(struct search_query *squery, int status,
                        unsigned char *abuf, int alen);
 static int cat_domain(const char *name, const char *domain, char **s);
-static int single_domain(ares_channel channel, const char *name, char **s);
+STATIC_TESTABLE int single_domain(ares_channel channel, const char *name, char **s);
 
 void ares_search(ares_channel channel, const char *name, int dnsclass,
                  int type, ares_callback callback, void *arg)
@@ -225,7 +225,7 @@ static int cat_domain(const char *name, const char *domain, char **s)
  * the string we should query, in an allocated buffer.  If not, set *s
  * to NULL.
  */
-static int single_domain(ares_channel channel, const char *name, char **s)
+STATIC_TESTABLE int single_domain(ares_channel channel, const char *name, char **s)
 {
   size_t len = strlen(name);
   const char *hostaliases;

configure.ac

@@ -19,6 +19,7 @@ CARES_CHECK_OPTION_WARNINGS
 CARES_CHECK_OPTION_WERROR
 CARES_CHECK_OPTION_CURLDEBUG
 CARES_CHECK_OPTION_SYMBOL_HIDING
+CARES_CHECK_OPTION_EXPOSE_STATICS
 
 XC_CHECK_PATH_SEPARATOR
 

m4/cares-confopts.m4

@@ -219,6 +219,44 @@ AC_HELP_STRING([--disable-symbol-hiding],[Disable hiding of library internal sym
 ])
 
 
+dnl CARES_CHECK_OPTION_EXPOSE_STATICS
+dnl -------------------------------------------------
+dnl Verify if configure has been invoked with option
+dnl --enable-expose-statics or --disable-expose-statics,
+dnl setting shell variable want_expose_statics value.
+
+AC_DEFUN([CARES_CHECK_OPTION_EXPOSE_STATICS], [
+  AC_MSG_CHECKING([whether to expose internal static functions for testing])
+  OPT_EXPOSE_STATICS="default"
+  AC_ARG_ENABLE(expose-statics,
+AC_HELP_STRING([--enable-expose-statics],[Enable exposure of internal static functions for testing])
+AC_HELP_STRING([--disable-expose-statics],[Disable exposure of internal static functions for testing]),
+  OPT_EXPOSE_STATICS=$enableval)
+  case "$OPT_EXPOSE_STATICS" in
+    no)
+      dnl --disable-expose-statics option used.
+      want_expose_statics="no"
+      AC_MSG_RESULT([no])
+      ;;
+    default)
+      dnl configure's expose-statics option not specified.
+      dnl Handle this as if --disable-expose-statics option was given.
+      want_expose_statics="no"
+      AC_MSG_RESULT([no])
+      ;;
+    *)
+      dnl --enable-expose-statics option used.
+      want_expose_statics="yes"
+      AC_MSG_RESULT([yes])
+      ;;
+  esac
+  if test "$want_expose_statics" = "yes"; then
+    AC_DEFINE_UNQUOTED(CARES_EXPOSE_STATICS, 1,
+      [Defined for build that exposes internal static functions for testing.])
+  fi
+])
+
+
 dnl CARES_CHECK_OPTION_WARNINGS
 dnl -------------------------------------------------
 dnl Verify if configure has been invoked with option