BUILD: lua: silence some compiler warnings about potential null derefs

These ones are on error paths that are properly handled by luaL_error()
which does a longjmp() but the compiler cannot know it. By adding an
__unreachable() statement in WILL_LJMP(), there is no ambiguity anymore.

This may be backported to 1.8 but the previous patch (BUILD: compiler:
add a new statement "__unreachable()") is needed for this.

diff --git a/src/hlua.c b/src/hlua.c
index aaa884073df8678ec1c2a8ef22a52c3af17b57c2..fe7c9097a41b79fcc1745ba046eb9920355afaab 100644 (file)
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -25,6 +25,7 @@
 #include <ebpttree.h>
 
 #include <common/cfgparse.h>
+#include <common/compiler.h>
 #include <common/xref.h>
 #include <common/hathreads.h>
 
@@ -67,7 +68,7 @@
  *   MAY_LJMP() marks an lua function that may use longjmp.
  */
 #define __LJMP
-#define WILL_LJMP(func) func
+#define WILL_LJMP(func) do { func; __unreachable(); } while (0)
 #define MAY_LJMP(func) func
 
 /* This couple of function executes securely some Lua calls outside of
@@ -2361,7 +2362,7 @@ __LJMP static int hlua_socket_connect_yield(struct lua_State *L, int status, lua
                return 2;
        }
 
-       appctx = objt_appctx(s->si[0].end);
+       appctx = __objt_appctx(s->si[0].end);
 
        /* Check for connection established. */
        if (appctx->ctx.hlua_cosocket.connected) {
@@ -2473,7 +2474,7 @@ __LJMP static int hlua_socket_connect(struct lua_State *L)
        }
 
        hlua = hlua_gethlua(L);
-       appctx = objt_appctx(s->si[0].end);
+       appctx = __objt_appctx(s->si[0].end);
 
        /* inform the stream that we want to be notified whenever the
         * connection completes.
@@ -5723,6 +5724,9 @@ static int hlua_register_task(lua_State *L)
                WILL_LJMP(luaL_error(L, "Lua out of memory error."));
 
        task = task_new(MAX_THREADS_MASK);
+       if (!task)
+               WILL_LJMP(luaL_error(L, "Lua out of memory error."));
+
        task->context = hlua;
        task->process = hlua_process_task;