bugfix: we might miss the linker option -ldl when we shouldn't.

Author: agentzh

config

@@ -12,29 +12,31 @@ ngx_lua_opt_I=
 ngx_lua_opt_L=
 
 if [ -n "$LUAJIT_INC" -o -n "$LUAJIT_LIB" ]; then
-    # explicitly set Lua lib path
-    ngx_feature="LuaJIT library in $LUAJIT_LIB and $LUAJIT_INC (specified by the LUAJIT_LIB and LUAJIT_INC env)"
+    # explicitly set LuaJIT paths
+
+    # attempt to link with -ldl, static linking on Linux requires it.
+    ngx_feature="LuaJIT library in $LUAJIT_LIB and $LUAJIT_INC (specified by the LUAJIT_LIB and LUAJIT_INC env, with -ldl)"
     ngx_feature_path="$LUAJIT_INC"
     ngx_lua_opt_I="-I$LUAJIT_INC"
     ngx_lua_opt_L="-L$LUAJIT_LIB"
     if [ $NGX_RPATH = YES ]; then
-        ngx_feature_libs="-R$LUAJIT_LIB $ngx_lua_opt_L -lluajit-5.1 -lm"
+        ngx_feature_libs="-R$LUAJIT_LIB $ngx_lua_opt_L -lluajit-5.1 -lm -ldl"
     else
-        ngx_feature_libs="$ngx_lua_opt_L -lluajit-5.1 -lm"
+        ngx_feature_libs="$ngx_lua_opt_L -lluajit-5.1 -lm -ldl"
     fi
 
     . auto/feature
 
     if [ $ngx_found = no ]; then
-        # retry with -ldl, static linking on Linux requires it.
-        ngx_feature="LuaJIT library in $LUAJIT_LIB and $LUAJIT_INC (specified by the LUAJIT_LIB and LUAJIT_INC env, with -ldl)"
+        # retry without -ldl
+        ngx_feature="LuaJIT library in $LUAJIT_LIB and $LUAJIT_INC (specified by the LUAJIT_LIB and LUAJIT_INC env)"
         ngx_feature_path="$LUAJIT_INC"
         ngx_lua_opt_I="-I$LUAJIT_INC"
         ngx_lua_opt_L="-L$LUAJIT_LIB"
         if [ $NGX_RPATH = YES ]; then
-            ngx_feature_libs="-R$LUAJIT_LIB $ngx_lua_opt_L -lluajit-5.1 -lm -ldl"
+            ngx_feature_libs="-R$LUAJIT_LIB $ngx_lua_opt_L -lluajit-5.1 -lm"
         else
-            ngx_feature_libs="$ngx_lua_opt_L -lluajit-5.1 -lm -ldl"
+            ngx_feature_libs="$ngx_lua_opt_L -lluajit-5.1 -lm"
         fi
 
         . auto/feature
@@ -65,19 +67,34 @@ END
     esac
 else
     if [ -n "$LUA_INC" -o -n "$LUA_LIB" ]; then
-        # explicitly set Lua lib path
+        # explicitly set Lua paths
         ngx_feature="Lua library in $LUA_LIB and $LUA_INC (specified by the LUA_LIB and LUA_INC env)"
         ngx_feature_path="$LUA_INC"
         ngx_lua_opt_I="-I$LUA_INC"
         ngx_lua_opt_L="-L$LUA_LIB"
         if [ $NGX_RPATH = YES ]; then
-            ngx_feature_libs="-R$LUA_LIB $ngx_lua_opt_L -llua -lm"
+            ngx_feature_libs="-R$LUA_LIB $ngx_lua_opt_L -llua -lm -ldl"
         else
-            ngx_feature_libs="$ngx_lua_opt_L -llua -lm"
+            ngx_feature_libs="$ngx_lua_opt_L -llua -lm -ldl"
         fi
 
         . auto/feature
 
+        if [ $ngx_found = no ]; then
+            # retry without -ldl
+
+            ngx_feature_path="$LUA_INC"
+            ngx_lua_opt_I="-I$LUA_INC"
+            ngx_lua_opt_L="-L$LUA_LIB"
+            if [ $NGX_RPATH = YES ]; then
+                ngx_feature_libs="-R$LUA_LIB $ngx_lua_opt_L -llua -lm"
+            else
+                ngx_feature_libs="$ngx_lua_opt_L -llua -lm"
+            fi
+
+            . auto/feature
+        fi
+
         if [ $ngx_found = no ]; then
             cat << END
             $0: error: ngx_http_lua_module requires the Lua or LuaJIT library and LUA_LIB is defined as $LUA_LIB and LUA_INC (path for lua.h) is $LUA_INC, but we cannot find standard Lua there.
@@ -175,25 +192,25 @@ END
         fi
 
         if [ $ngx_found = no ]; then
-            # Gentoo with LuaJIT-2.0
+            # Gentoo with LuaJIT-2.0, try with -ldl
             ngx_feature="LuaJIT library in /usr/"
             ngx_feature_path="/usr/include/luajit-2.0"
             if [ $NGX_RPATH = YES ]; then
-                ngx_feature_libs="-R/usr/lib -L/usr/lib -lm -lluajit-5.1"
+                ngx_feature_libs="-R/usr/lib -L/usr/lib -lm -lluajit-5.1 -ldl"
             else
-                ngx_feature_libs="-L/usr/lib -lm -lluajit-5.1"
+                ngx_feature_libs="-L/usr/lib -lm -lluajit-5.1 -ldl"
             fi
             . auto/feature
         fi
 
         if [ $ngx_found = no ]; then
-            # Gentoo with LuaJIT-2.0, retry with -ldl
+            # Gentoo with LuaJIT 2.0
             ngx_feature="LuaJIT library in /usr/"
             ngx_feature_path="/usr/include/luajit-2.0"
             if [ $NGX_RPATH = YES ]; then
-                ngx_feature_libs="-R/usr/lib -L/usr/lib -lm -lluajit-5.1 -ldl"
+                ngx_feature_libs="-R/usr/lib -L/usr/lib -lm -lluajit-5.1"
             else
-                ngx_feature_libs="-L/usr/lib -lm -lluajit-5.1 -ldl"
+                ngx_feature_libs="-L/usr/lib -lm -lluajit-5.1"
             fi
             . auto/feature
         fi