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Embed .lua files into falco executable

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Instead of having .lua files external to the program responsible for
loading rules, embed the contents of those files into the executable
and load them as strings instead of as files:

Add a cmake custom command below userspace/engine/lua that calls a
bash script lua-to-cpp.sh to generate falco_engine_lua_files.{cpp,hh}
that are compiled into the falco engine library.

The script creates a .cpp file that has const char * symbols for each
file, as well as lists of files that should be loaded when the falco
engine is loaded. There are actually two lists:

- lua_module_strings: these are loaded and also added to the lua
  runtime package.preload table, so they are available when lua code
  require()s them.

- lua_code_strings: these are loaded *and* evaluated, so the functions
  in them are availble to be called from C++.

This simplifies some of the falco_common methods, as there's no need
to keep track of a "main" lua file to load or paths from which the lua
loader should find files for modules, and there's no need to keep
track of an "alternate" lua directory that occurs for debug builds.

Also, there's no need to include any .lua files in the installed
packages, as they're built into the falco binary.

Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
This commit is contained in:
Mark Stemm
2022-01-06 14:29:32 -08:00
committed by poiana
parent 08df1c63cf
commit c86615f68c
7 changed files with 138 additions and 81 deletions
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82
userspace/engine/falco_common.cpp
View File

@@ -19,6 +19,7 @@ limitations under the License.
#include "config_falco_engine.h"
#include "falco_common.h"
#include "banned.h" // This raises a compilation error when certain functions are used
#include "falco_engine_lua_files.hh"
std::vector<std::string> falco_common::priority_names = {
"Emergency",
@@ -48,68 +49,33 @@ falco_common::~falco_common()
}
}
void falco_common::init(const char *lua_main_filename, const char *alternate_lua_dir)
void falco_common::init()
{
ifstream is;
string lua_dir = FALCO_ENGINE_LUA_DIR;
string lua_main_path = lua_dir + lua_main_filename;
is.open(lua_main_path);
if (!is.is_open())
// Strings in the list lua_module_strings need to be loaded as
// lua modules, which also involves adding them to the
// package.module table.
for(const auto &pair : lua_module_strings)
{
lua_dir = alternate_lua_dir;
lua_main_path = lua_dir + lua_main_filename;
lua_getglobal(m_ls, "package");
lua_getfield(m_ls, -1, "preload");
is.open(lua_main_path);
if (!is.is_open())
if(luaL_loadstring(m_ls, pair.first))
{
throw falco_exception("Could not find Falco Lua entrypoint (tried " +
string(FALCO_ENGINE_LUA_DIR) + lua_main_filename + ", " +
string(alternate_lua_dir) + lua_main_filename + ")");
throw falco_exception("Failed to load embedded lua code " +
string(pair.second) + ": " + lua_tostring(m_ls, -1));
}
lua_setfield(m_ls, -2, pair.second);
}
// Strings in the list lua_code_strings need to be loaded and
// evaluated so any public functions can be directly called.
for(const auto &str : lua_code_strings)
{
if(luaL_loadstring(m_ls, str) || lua_pcall(m_ls, 0, 0, 0))
{
throw falco_exception("Failed to load + evaluate embedded lua code " +
string(str) + ": " + lua_tostring(m_ls, -1));
}
}
// Initialize Lua interpreter
add_lua_path(lua_dir);
// Load the main program, which defines all the available functions.
string scriptstr((istreambuf_iterator<char>(is)),
istreambuf_iterator<char>());
if(luaL_loadstring(m_ls, scriptstr.c_str()) || lua_pcall(m_ls, 0, 0, 0))
{
throw falco_exception("Failed to load script " +
lua_main_path + ": " + lua_tostring(m_ls, -1));
}
}
void falco_common::add_lua_path(string &path)
{
string cpath = string(path);
path += "?.lua";
cpath += "?.so";
lua_getglobal(m_ls, "package");
lua_getfield(m_ls, -1, "path");
string cur_path = lua_tostring(m_ls, -1 );
cur_path += ';';
lua_pop(m_ls, 1);
cur_path.append(path.c_str());
lua_pushstring(m_ls, cur_path.c_str());
lua_setfield(m_ls, -2, "path");
lua_getfield(m_ls, -1, "cpath");
string cur_cpath = lua_tostring(m_ls, -1 );
cur_cpath += ';';
lua_pop(m_ls, 1);
cur_cpath.append(cpath.c_str());
lua_pushstring(m_ls, cur_cpath.c_str());
lua_setfield(m_ls, -2, "cpath");
lua_pop(m_ls, 1);
}