From a67790c6f53e4b002556eca8438dbd56994ea056 Mon Sep 17 00:00:00 2001
From: "Kevin P. Fleming" <kpfleming@digium.com>
Date: Sun, 2 Nov 2008 23:34:39 +0000
Subject: [PATCH] instead of trying to forcibly load res_agi when app_stack is
 loaded (even if the administrator didn't want it loaded), use GCC weak
 symbols to determine whether it was loaded already or not; if it was loaded,
 then use it.

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@153709 65c4cc65-6c06-0410-ace0-fbb531ad65f3
---
 apps/app_stack.c                 | 21 ++++-----
 autoconf/ast_gcc_attribute.m4    |  2 +-
 configure                        | 74 ++++++++++++++++++++++++++++----
 configure.ac                     |  1 +
 include/asterisk/agi.h           | 16 ++++---
 include/asterisk/autoconfig.h.in |  3 ++
 include/asterisk/compiler.h      |  6 +++
 7 files changed, 96 insertions(+), 27 deletions(-)

diff --git a/apps/app_stack.c b/apps/app_stack.c
index 714eaae2c8..3f73e13d6b 100644
--- a/apps/app_stack.c
+++ b/apps/app_stack.c
@@ -26,7 +26,7 @@
  */
 
 /*** MODULEINFO
-	<depend>res_agi</depend>
+	<use>res_agi</use>
  ***/
 
 #include "asterisk.h"
@@ -38,6 +38,9 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 #include "asterisk/app.h"
 #include "asterisk/manager.h"
 #include "asterisk/channel.h"
+
+/* usage of AGI is optional, so indicate that to the header file */
+#define ASTERISK_AGI_OPTIONAL
 #include "asterisk/agi.h"
 
 /*** DOCUMENTATION
@@ -104,7 +107,6 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 		</description>
 	</application>
  ***/
-static int agi_loaded = 0;
 
 static const char *app_gosub = "Gosub";
 static const char *app_gosubif = "GosubIf";
@@ -537,7 +539,7 @@ static int unload_module(void)
 {
 	struct ast_context *con;
 
-	if (agi_loaded) {
+	if (ast_agi_unregister) {
 		ast_agi_unregister(ast_module_info->self, &gosub_agi_command);
 
 		if ((con = ast_context_find("app_stack_gosub_virtual_context"))) {
@@ -559,15 +561,10 @@ static int load_module(void)
 {
 	struct ast_context *con;
 
-	if (!ast_module_check("res_agi.so")) {
-		if (ast_load_resource("res_agi.so") == AST_MODULE_LOAD_SUCCESS) {
-			agi_loaded = 1;
-		}
-	} else {
-		agi_loaded = 1;
-	}
-
-	if (agi_loaded) {
+	/* usage of AGI is optional, so check to see if the ast_agi_register()
+	   function is available; if so, use it.
+	*/
+	if (ast_agi_register) {
 		con = ast_context_find_or_create(NULL, NULL, "app_stack_gosub_virtual_context", "app_stack");
 		if (!con) {
 			ast_log(LOG_ERROR, "Virtual context 'app_stack_gosub_virtual_context' does not exist and unable to create\n");
diff --git a/autoconf/ast_gcc_attribute.m4 b/autoconf/ast_gcc_attribute.m4
index d47d375e69..167bb4e79d 100644
--- a/autoconf/ast_gcc_attribute.m4
+++ b/autoconf/ast_gcc_attribute.m4
@@ -7,7 +7,7 @@ AC_MSG_CHECKING(for compiler 'attribute $1' support)
 saved_CFLAGS="$CFLAGS"
 CFLAGS="$CFLAGS -Werror"
 AC_COMPILE_IFELSE(
-	AC_LANG_PROGRAM([static void __attribute__(($1)) *test(void *muffin, ...) {}],
+	AC_LANG_PROGRAM([void __attribute__(($1)) *test(void *muffin, ...) {}],
 			[]),
 	AC_MSG_RESULT(yes)
 	AC_DEFINE_UNQUOTED([HAVE_ATTRIBUTE_$1], 1, [Define to 1 if your GCC C compiler supports the '$1' attribute.]),
diff --git a/configure b/configure
index 4d141dc104..5a9a37f56f 100755
--- a/configure
+++ b/configure
@@ -1,5 +1,5 @@
 #! /bin/sh
-# From configure.ac Revision: 153365 .
+# From configure.ac Revision: 153578 .
 # Guess values for system-dependent variables and create Makefiles.
 # Generated by GNU Autoconf 2.61 for asterisk 1.6.
 #
@@ -16833,7 +16833,7 @@ _ACEOF
 cat confdefs.h >>conftest.$ac_ext
 cat >>conftest.$ac_ext <<_ACEOF
 /* end confdefs.h.  */
-static void __attribute__((pure)) *test(void *muffin, ...) {}
+void __attribute__((pure)) *test(void *muffin, ...) {}
 int
 main ()
 {
@@ -16889,7 +16889,7 @@ _ACEOF
 cat confdefs.h >>conftest.$ac_ext
 cat >>conftest.$ac_ext <<_ACEOF
 /* end confdefs.h.  */
-static void __attribute__((malloc)) *test(void *muffin, ...) {}
+void __attribute__((malloc)) *test(void *muffin, ...) {}
 int
 main ()
 {
@@ -16945,7 +16945,7 @@ _ACEOF
 cat confdefs.h >>conftest.$ac_ext
 cat >>conftest.$ac_ext <<_ACEOF
 /* end confdefs.h.  */
-static void __attribute__((const)) *test(void *muffin, ...) {}
+void __attribute__((const)) *test(void *muffin, ...) {}
 int
 main ()
 {
@@ -17001,7 +17001,7 @@ _ACEOF
 cat confdefs.h >>conftest.$ac_ext
 cat >>conftest.$ac_ext <<_ACEOF
 /* end confdefs.h.  */
-static void __attribute__((unused)) *test(void *muffin, ...) {}
+void __attribute__((unused)) *test(void *muffin, ...) {}
 int
 main ()
 {
@@ -17057,7 +17057,7 @@ _ACEOF
 cat confdefs.h >>conftest.$ac_ext
 cat >>conftest.$ac_ext <<_ACEOF
 /* end confdefs.h.  */
-static void __attribute__((always_inline)) *test(void *muffin, ...) {}
+void __attribute__((always_inline)) *test(void *muffin, ...) {}
 int
 main ()
 {
@@ -17113,7 +17113,7 @@ _ACEOF
 cat confdefs.h >>conftest.$ac_ext
 cat >>conftest.$ac_ext <<_ACEOF
 /* end confdefs.h.  */
-static void __attribute__((deprecated)) *test(void *muffin, ...) {}
+void __attribute__((deprecated)) *test(void *muffin, ...) {}
 int
 main ()
 {
@@ -17169,7 +17169,7 @@ _ACEOF
 cat confdefs.h >>conftest.$ac_ext
 cat >>conftest.$ac_ext <<_ACEOF
 /* end confdefs.h.  */
-static void __attribute__((sentinel)) *test(void *muffin, ...) {}
+void __attribute__((sentinel)) *test(void *muffin, ...) {}
 int
 main ()
 {
@@ -17225,7 +17225,7 @@ _ACEOF
 cat confdefs.h >>conftest.$ac_ext
 cat >>conftest.$ac_ext <<_ACEOF
 /* end confdefs.h.  */
-static void __attribute__((warn_unused_result)) *test(void *muffin, ...) {}
+void __attribute__((warn_unused_result)) *test(void *muffin, ...) {}
 int
 main ()
 {
@@ -17271,6 +17271,62 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 CFLAGS="$saved_CFLAGS"
 
 
+{ echo "$as_me:$LINENO: checking for compiler 'attribute weak' support" >&5
+echo $ECHO_N "checking for compiler 'attribute weak' support... $ECHO_C" >&6; }
+saved_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS -Werror"
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+void __attribute__((weak)) *test(void *muffin, ...) {}
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+  { echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_ATTRIBUTE_weak 1
+_ACEOF
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	{ echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+CFLAGS="$saved_CFLAGS"
+
+
 { echo "$as_me:$LINENO: checking for -ffunction-sections support" >&5
 echo $ECHO_N "checking for -ffunction-sections support... $ECHO_C" >&6; }
 saved_CFLAGS="${CFLAGS}"
diff --git a/configure.ac b/configure.ac
index d1bd700e48..43940aa4ef 100644
--- a/configure.ac
+++ b/configure.ac
@@ -472,6 +472,7 @@ AST_GCC_ATTRIBUTE(always_inline)
 AST_GCC_ATTRIBUTE(deprecated)
 AST_GCC_ATTRIBUTE(sentinel)
 AST_GCC_ATTRIBUTE(warn_unused_result)
+AST_GCC_ATTRIBUTE(weak)
 
 AC_MSG_CHECKING(for -ffunction-sections support)
 saved_CFLAGS="${CFLAGS}"
diff --git a/include/asterisk/agi.h b/include/asterisk/agi.h
index 7c1a0aa68d..609e988156 100644
--- a/include/asterisk/agi.h
+++ b/include/asterisk/agi.h
@@ -55,11 +55,17 @@ typedef struct agi_command {
 	AST_LIST_ENTRY(agi_command) list;
 } agi_command;
 
-int ast_agi_fdprintf(struct ast_channel *chan, int fd, char *fmt, ...);
-int ast_agi_register(struct ast_module *mod, agi_command *cmd);
-int ast_agi_unregister(struct ast_module *mod, agi_command *cmd);
-void ast_agi_register_multiple(struct ast_module *mod, agi_command *cmd, int len);
-void ast_agi_unregister_multiple(struct ast_module *mod, agi_command *cmd, int len);
+#if defined(ASTERISK_AGI_OPTIONAL)
+#define AGI_WEAK attribute_weak
+#else
+#define AGI_WEAK
+#endif
+
+int AGI_WEAK ast_agi_fdprintf(struct ast_channel *chan, int fd, char *fmt, ...);
+int AGI_WEAK ast_agi_register(struct ast_module *mod, agi_command *cmd);
+int AGI_WEAK ast_agi_unregister(struct ast_module *mod, agi_command *cmd);
+void AGI_WEAK ast_agi_register_multiple(struct ast_module *mod, agi_command *cmd, int len);
+void AGI_WEAK ast_agi_unregister_multiple(struct ast_module *mod, agi_command *cmd, int len);
 
 #if defined(__cplusplus) || defined(c_plusplus)
 }
diff --git a/include/asterisk/autoconfig.h.in b/include/asterisk/autoconfig.h.in
index 79134bd3c1..983f2cc376 100644
--- a/include/asterisk/autoconfig.h.in
+++ b/include/asterisk/autoconfig.h.in
@@ -117,6 +117,9 @@
    attribute. */
 #undef HAVE_ATTRIBUTE_warn_unused_result
 
+/* Define to 1 if your GCC C compiler supports the 'weak' attribute. */
+#undef HAVE_ATTRIBUTE_weak
+
 /* Define this to indicate the ${BKTR_DESCRIP} library */
 #undef HAVE_BKTR
 
diff --git a/include/asterisk/compiler.h b/include/asterisk/compiler.h
index b2db7ffdb3..0468cd3d92 100644
--- a/include/asterisk/compiler.h
+++ b/include/asterisk/compiler.h
@@ -68,4 +68,10 @@
 /* Some older version of GNU gcc (3.3.5 on OpenBSD 4.3 for example) dont like 'NULL' as sentinel */
 #define SENTINEL ((char *)NULL)
 
+#ifdef HAVE_ATTRIBUTE_weak
+#define attribute_weak __attribute__((weak))
+#else
+#define attribute_weak
+#endif
+
 #endif /* _ASTERISK_COMPILER_H */
-- 
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