commit 4fa1de1be89e1d64771a8e8cc725f991ece21819
Author: Tim Duesterhus <tim@bastelstu.be>
Date:   Sun Jan 12 13:55:41 2020 +0100

    MINOR: lua: Add HLUA_PREPEND_C?PATH build option
    
    This complements the lua-prepend-path configuration option to allow
    distro maintainers to add a default path for HAProxy specific Lua
    libraries.
    
    (cherry picked from commit 541fe1ec52a0f9e1912dea5b3a784406dbdfad22)
    Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/Makefile b/Makefile
index 8399f6ca3..bb494fac3 100644
--- a/Makefile
+++ b/Makefile
@@ -88,6 +88,8 @@
 #           installation only.
 #   DOCDIR  is set to "$(PREFIX)/doc/haproxy" by default and is used for
 #           installation only.
+#   HLUA_PREPEND_PATH may be used to prepend a folder to Lua's default package.path.
+#   HLUA_PREPEND_CPATH may be used to prepend a folder to Lua's default package.cpath.
 #
 # Other variables :
 #   PCRE_CONFIG    : force the binary path to get pcre config (by default
@@ -546,6 +548,14 @@ LUA_INC := $(firstword $(foreach lib,lua5.3 lua53 lua,$(call check_lua_inc,$(lib
 ifneq ($(LUA_INC),)
 OPTIONS_CFLAGS  += -I$(LUA_INC)
 endif
+ifneq ($(HLUA_PREPEND_PATH),)
+OPTIONS_CFLAGS  += -DHLUA_PREPEND_PATH=$(HLUA_PREPEND_PATH)
+BUILD_OPTIONS += HLUA_PREPEND_PATH=$(HLUA_PREPEND_PATH)
+endif
+ifneq ($(HLUA_PREPEND_CPATH),)
+OPTIONS_CFLAGS  += -DHLUA_PREPEND_CPATH=$(HLUA_PREPEND_CPATH)
+BUILD_OPTIONS += HLUA_PREPEND_CPATH=$(HLUA_PREPEND_CPATH)
+endif
 endif
 
 OPTIONS_LDFLAGS += $(LUA_LD_FLAGS) -l$(LUA_LIB_NAME) -lm
diff --git a/src/hlua.c b/src/hlua.c
index a245f9b7d..8ace405d4 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -7651,6 +7651,16 @@ void hlua_init(void)
 
 	/* Initialise lua. */
 	luaL_openlibs(gL.T);
+#define HLUA_PREPEND_PATH_TOSTRING1(x) #x
+#define HLUA_PREPEND_PATH_TOSTRING(x) HLUA_PREPEND_PATH_TOSTRING1(x)
+#ifdef HLUA_PREPEND_PATH
+	hlua_prepend_path(gL, "path", HLUA_PREPEND_PATH_TOSTRING(HLUA_PREPEND_PATH));
+#endif
+#ifdef HLUA_PREPEND_CPATH
+	hlua_prepend_path(gL, "cpath", HLUA_PREPEND_PATH_TOSTRING(HLUA_PREPEND_CPATH));
+#endif
+#undef HLUA_PREPEND_PATH_TOSTRING
+#undef HLUA_PREPEND_PATH_TOSTRING1
 
 	/* Set safe environment for the initialisation. */
 	if (!SET_SAFE_LJMP(gL.T)) {