lua-hash: introduce a lua hashing library using libubox.

libs/lua-hash/Makefile

@@ -0,0 +1,36 @@
+include $(TOPDIR)/rules.mk
+
+PKG_NAME:=lua-hash
+PKG_VERSION:=1
+
+PKG_BUILD_DIR := $(BUILD_DIR)/$(PKG_NAME)
+
+include $(INCLUDE_DIR)/package.mk
+
+define Package/lua-hash
+  SECTION:=libs
+  CATEGORY:=Libraries
+  TITLE:=Lua hash library
+  DEPENDS:=+lua +libubox
+endef
+
+define Build/Prepare
+	mkdir -p $(PKG_BUILD_DIR)
+	$(CP) ./src/* $(PKG_BUILD_DIR)/
+endef
+
+define Build/Configure
+endef
+
+define Build/Compile
+	CFLAGS="$(TARGET_CFLAGS)" \
+	CPPFLAGS="$(TARGET_CPPFLAGS)" \
+	$(MAKE) -C $(PKG_BUILD_DIR) $(TARGET_CONFIGURE_OPTS)
+endef
+
+define Package/lua-hash/install
+	$(INSTALL_DIR) $(1)/usr/lib/lua
+	$(CP) $(PKG_BUILD_DIR)/hash.so $(1)/usr/lib/lua/
+endef
+
+$(eval $(call BuildPackage,lua-hash))

libs/lua-hash/src/Makefile

@@ -0,0 +1,6 @@
+all: hash.so
+
+CFLAGS += -Wall
+
+hash.so: hash.c
+	$(CC) $(CPPFLAGS) $(CFLAGS) $(LDFLAGS) -shared -fPIC -o $@ $^ $(LDLIBS) -llua -lubox

libs/lua-hash/src/hash.c

@@ -0,0 +1,47 @@
+#include <libubox/md5.h>
+
+#include <lua.h>
+#include <lauxlib.h>
+#include <lualib.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define MD5_DIGEST_LEN 16
+#define MD5_STRLEN (2*MD5_DIGEST_LEN+1)
+
+static int md5(lua_State *L) {
+	size_t len;
+	const char *input = lua_tolstring(L, 1, &len);
+	if (input == NULL) {
+		lua_pushstring(L, "first argument: should be the input string");
+		lua_error(L);
+		__builtin_unreachable();
+	}
+
+	unsigned char digest[MD5_DIGEST_LEN];
+	char output[MD5_STRLEN];
+
+	struct md5_ctx ctx;
+	md5_begin(&ctx);
+	md5_hash(input, len, &ctx);
+	md5_end(digest, &ctx);
+
+	// fill the digest bytewise in the output string
+	int i;
+	for (i = 0; i < MD5_DIGEST_LEN; i++) {
+		sprintf(output + 2*i, "%02x", digest[i]);
+	}
+
+	lua_pushstring(L, output);
+	return 1;
+}
+
+static const luaL_Reg R[] = {
+	{"md5", md5},
+	{NULL, NULL },
+};
+
+LUALIB_API int luaopen_hash(lua_State *L) {
+	luaL_register(L, "hash", R);
+	return 1;
+}

libs/lua-hash/src/test.lua

@@ -0,0 +1,3 @@
+#!/usr/bin/lua
+hash = require "hash"
+assert(hash.md5('testing') == 'ae2b1fca515949e5d54fb22b8ed95575')