X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/d267477c115e50df1a9bf470ccda179161d5d376..773dc73ff2e12aa636dcc6dd06da8d5750d577f8:/src/bindings/lua/simgrid_lua.c

diff --git a/src/bindings/lua/simgrid_lua.c b/src/bindings/lua/simgrid_lua.c
index fdaa403be5..b4b3763b8d 100644
--- a/src/bindings/lua/simgrid_lua.c
+++ b/src/bindings/lua/simgrid_lua.c
@@ -6,499 +6,24 @@
 
 /* SimGrid Lua bindings                                                     */
 
-#include "simgrid_lua.h"
+#include "lua_private.h"
 #include "lua_state_cloner.h"
 #include "lua_utils.h"
+#include "xbt.h"
+#include "msg/msg.h"
+#include "simdag/simdag.h"
+#include "surf/surfxml_parse.h"
+#include "gras.h"
+#include <lauxlib.h>
 
 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(lua, bindings, "Lua Bindings");
 
-#define TASK_MODULE_NAME "simgrid.task"
-#define HOST_MODULE_NAME "simgrid.host"
-// Surf (bypass XML)
-#define LINK_MODULE_NAME "simgrid.link"
-#define ROUTE_MODULE_NAME "simgrid.route"
-#define PLATF_MODULE_NAME "simgrid.platf"
-
 static lua_State* sglua_maestro_state;
 
 int luaopen_simgrid(lua_State *L);
-static void register_c_functions(lua_State *L);
+static void sglua_register_c_functions(lua_State *L);
 static int run_lua_code(int argc, char **argv);
 
-/* ********************************************************************************* */
-/*                                simgrid.task API                                   */
-/* ********************************************************************************* */
-
-/**
- * \brief Ensures that a value in the stack is a valid task and returns it.
- * \param L a Lua state
- * \param index an index in the Lua stack
- * \return the C task corresponding to this Lua task
- */
-static m_task_t sglua_checktask(lua_State* L, int index)
-{
-  sglua_stack_dump("check task: ", L);
-  luaL_checktype(L, index, LUA_TTABLE);
-                                  /* ... task ... */
-  lua_getfield(L, index, "__simgrid_task");
-                                  /* ... task ... ctask */
-  m_task_t task = *((m_task_t*) luaL_checkudata(L, -1, TASK_MODULE_NAME));
-  lua_pop(L, 1);
-                                  /* ... task ... */
-
-  if (task == NULL) {
-    luaL_error(L, "This task was sent to someone else, you cannot access it anymore");
-  }
-
-  return task;
-}
-
-/**
- * \brief Creates a new task and leaves it onto the stack.
- * \param L a Lua state
- * \return number of values returned to Lua
- *
- * - Argument 1 (string): name of the task
- * - Argument 2 (number): computation size
- * - Argument 3 (number): communication size
- * - Return value (task): the task created
- */
-static int l_task_new(lua_State* L)
-{
-  XBT_DEBUG("Task new");
-  const char* name = luaL_checkstring(L, 1);
-  int comp_size = luaL_checkint(L, 2);
-  int msg_size = luaL_checkint(L, 3);
-                                  /* name comp comm */
-  lua_settop(L, 0);
-                                  /* -- */
-  m_task_t msg_task = MSG_task_create(name, comp_size, msg_size, NULL);
-
-  lua_newtable(L);
-                                  /* task */
-  m_task_t* lua_task = (m_task_t*) lua_newuserdata(L, sizeof(m_task_t));
-                                  /* task ctask */
-  *lua_task = msg_task;
-  luaL_getmetatable(L, TASK_MODULE_NAME);
-                                  /* task ctask mt */
-  lua_setmetatable(L, -2);
-                                  /* task ctask */
-  lua_setfield(L, -2, "__simgrid_task");
-                                  /* task */
-  return 1;
-}
-
-/**
- * \brief Returns the name of a task.
- * \param L a Lua state
- * \return number of values returned to Lua
- *
- * - Argument 1 (task): a task
- * - Return value (string): name of the task
- */
-static int l_task_get_name(lua_State* L)
-{
-  m_task_t task = sglua_checktask(L, 1);
-  lua_pushstring(L, MSG_task_get_name(task));
-  return 1;
-}
-
-/**
- * \brief Returns the computation duration of a task.
- * \param L a Lua state
- * \return number of values returned to Lua
- *
- * - Argument 1 (task): a task
- * - Return value (number): computation duration of this task
- */
-static int l_task_computation_duration(lua_State* L)
-{
-  m_task_t task = sglua_checktask(L, 1);
-  lua_pushnumber(L, MSG_task_get_compute_duration(task));
-  return 1;
-}
-
-/**
- * \brief Executes a task.
- * \param L a Lua state
- * \return number of values returned to Lua
- *
- * - Argument 1 (task): the task to execute
- * - Return value (number): error code
- */
-static int l_task_execute(lua_State* L)
-{
-  m_task_t task = sglua_checktask(L, 1);
-  int res = MSG_task_execute(task);
-  lua_pushnumber(L, res);
-  return 1;
-}
-
-/**
- * \brief Sends a task to a mailbox and waits for its completion.
- * \param L a Lua state
- * \return number of values returned to Lua
- *
- * - Argument 1 (task): the task to send
- * - Argument 2 (string): mailbox
- */
-static int l_task_send(lua_State* L)
-{
-  m_task_t task = sglua_checktask(L, 1);
-  const char* mailbox = luaL_checkstring(L, 2);
-                                  /* task mailbox */
-  lua_settop(L, 1);
-                                  /* task */
-  /* copy my stack into the task, so that the receiver can copy the lua task */
-  MSG_task_set_data(task, L);
-  MSG_error_t res = MSG_task_send(task, mailbox);
-  while (MSG_task_get_data(task) != NULL) {
-    /* don't mess up with my stack: the receiver didn't copy the data yet */
-    MSG_process_sleep(0);
-  }
-
-  if (res == MSG_OK) {
-    /* the receiver is the owner of the task and may destroy it:
-     * remove the C task on my side so that I don't garbage collect it */
-    lua_getfield(L, 1, "__simgrid_task");
-                                  /* task ctask */
-    m_task_t* udata = (m_task_t*) luaL_checkudata(L, -1, TASK_MODULE_NAME);
-    *udata = NULL;
-    lua_pop(L, 1);
-                                  /* task */
-  }
-  else {
-    switch (res) {
-    case MSG_TIMEOUT:
-      XBT_DEBUG("MSG_task_send failed : Timeout");
-      break;
-    case MSG_TRANSFER_FAILURE:
-      XBT_DEBUG("MSG_task_send failed : Transfer Failure");
-      break;
-    case MSG_HOST_FAILURE:
-      XBT_DEBUG("MSG_task_send failed : Host Failure ");
-      break;
-    default:
-      XBT_ERROR
-          ("MSG_task_send failed : Unexpected error , please report this bug");
-      break;
-    }
-  }
-  return 0;
-}
-
-/**
- * \brief Receives a task.
- * \param L a Lua state
- * \return number of values returned to Lua
- *
- * - Argument 1 (string): mailbox
- * - Argument 2 (number, optional): timeout (default is no timeout)
- * - Return value (task/nil): the task received or nil if the communication
- * has failed
- */
-static int l_task_recv(lua_State *L)
-{
-  m_task_t task = NULL;
-  const char* mailbox = luaL_checkstring(L, 1);
-  int timeout;
-  if (lua_gettop(L) >= 2) {
-                                  /* mailbox timeout */
-    timeout = luaL_checknumber(L, 2);
-  }
-  else {
-                                  /* mailbox */
-    timeout = -1;
-    /* no timeout by default */
-  }
-  lua_settop(L, 0);
-                                  /* -- */
-  MSG_error_t res = MSG_task_receive_with_timeout(&task, mailbox, timeout);
-
-  if (res == MSG_OK) {
-    /* copy the data directly from sender's stack */
-    lua_State* sender_stack = MSG_task_get_data(task);
-    sglua_copy_value(sender_stack, L);
-                                  /* task */
-    MSG_task_set_data(task, NULL);
-  }
-  else {
-    switch (res) {
-    case MSG_TIMEOUT:
-      XBT_DEBUG("MSG_task_receive failed : Timeout");
-      break;
-    case MSG_TRANSFER_FAILURE:
-      XBT_DEBUG("MSG_task_receive failed : Transfer Failure");
-      break;
-    case MSG_HOST_FAILURE:
-      XBT_DEBUG("MSG_task_receive failed : Host Failure ");
-      break;
-    default:
-      XBT_ERROR("MSG_task_receive failed : Unexpected error , please report this bug");
-      break;
-    }
-    lua_pushnil(L);
-                                  /* nil */
-  }
-                                  /* task/nil */
-  return 1;
-}
-
-static const luaL_reg task_functions[] = {
-  {"new", l_task_new},
-  {"name", l_task_get_name},
-  {"computation_duration", l_task_computation_duration},
-  {"execute", l_task_execute},
-  {"send", l_task_send},
-  {"recv", l_task_recv},
-  {NULL, NULL}
-};
-
-/**
- * \brief Finalizes the userdata of a task.
- * \param L a Lua state
- * \return number of values returned to Lua
- *
- * - Argument 1 (userdata): a C task, possibly NULL if it was sent to another
- * Lua state
- */
-static int l_task_gc(lua_State* L)
-{
-                                  /* ctask */
-  m_task_t task = *((m_task_t*) luaL_checkudata(L, 1, TASK_MODULE_NAME));
-  /* the task is NULL if I sent it to someone else */
-  if (task != NULL) {
-    MSG_task_destroy(task);
-  }
-  return 0;
-}
-
-/**
- * \brief Returns a string representation of a C task.
- * \param L a Lua state
- * \return number of values returned to Lua
- *
- * - Argument 1 (userdata): a task
- * - Return value (string): a string describing this task
- */
-static int l_task_tostring(lua_State* L)
-{
-  m_task_t task = *((m_task_t*) luaL_checkudata(L, 1, TASK_MODULE_NAME));
-  lua_pushfstring(L, "Task: %p", task);
-  return 1;
-}
-
-static const luaL_reg task_meta[] = {
-  {"__gc", l_task_gc},
-  {"__tostring", l_task_tostring},
-  {NULL, NULL}
-};
-
-/* ********************************************************************************* */
-/*                                simgrid.host API                                   */
-/* ********************************************************************************* */
-
-/**
- * \brief Ensures that a value in the stack is a host and returns it.
- * \param L a Lua state
- * \param index an index in the Lua stack
- * \return the C host corresponding to this Lua host
- */
-static m_host_t sglua_checkhost(lua_State * L, int index)
-{
-  m_host_t *pi, ht;
-  luaL_checktype(L, index, LUA_TTABLE);
-  lua_getfield(L, index, "__simgrid_host");
-  pi = (m_host_t *) luaL_checkudata(L, lua_gettop(L), HOST_MODULE_NAME);
-  if (pi == NULL)
-    luaL_typerror(L, index, HOST_MODULE_NAME);
-  ht = *pi;
-  if (!ht)
-    luaL_error(L, "null Host");
-  lua_pop(L, 1);
-  return ht;
-}
-
-/**
- * \brief Returns a host given its name.
- * \param L a Lua state
- * \return number of values returned to Lua
- *
- * - Argument 1 (string): name of a host
- * - Return value (host): the corresponding host
- */
-static int l_host_get_by_name(lua_State * L)
-{
-  const char *name = luaL_checkstring(L, 1);
-  XBT_DEBUG("Getting Host from name...");
-  m_host_t msg_host = MSG_get_host_by_name(name);
-  if (!msg_host) {
-    luaL_error(L, "null Host : MSG_get_host_by_name failed");
-  }
-  lua_newtable(L);              /* create a table, put the userdata on top of it */
-  m_host_t *lua_host = (m_host_t *) lua_newuserdata(L, sizeof(m_host_t));
-  *lua_host = msg_host;
-  luaL_getmetatable(L, HOST_MODULE_NAME);
-  lua_setmetatable(L, -2);
-  lua_setfield(L, -2, "__simgrid_host");        /* put the userdata as field of the table */
-  /* remove the args from the stack */
-  lua_remove(L, 1);
-  return 1;
-}
-
-/**
- * \brief Returns the name of a host.
- * \param L a Lua state
- * \return number of values returned to Lua
- *
- * - Argument 1 (host): a host
- * - Return value (string): name of this host
- */
-static int l_host_get_name(lua_State * L)
-{
-  m_host_t ht = sglua_checkhost(L, 1);
-  lua_pushstring(L, MSG_host_get_name(ht));
-  return 1;
-}
-
-/**
- * \brief Returns the number of existing hosts.
- * \param L a Lua state
- * \return number of values returned to Lua
- *
- * - Return value (number): number of hosts
- */
-static int l_host_number(lua_State * L)
-{
-  lua_pushnumber(L, MSG_get_host_number());
-  return 1;
-}
-
-/**
- * \brief Returns the host given its index.
- * \param L a Lua state
- * \return number of values returned to Lua
- *
- * - Argument 1 (number): an index (1 is the first)
- * - Return value (host): the host at this index
- */
-static int l_host_at(lua_State * L)
-{
-  int index = luaL_checkinteger(L, 1);
-  m_host_t host = MSG_get_host_table()[index - 1];      // lua indexing start by 1 (lua[1] <=> C[0])
-  lua_newtable(L);              /* create a table, put the userdata on top of it */
-  m_host_t *lua_host = (m_host_t *) lua_newuserdata(L, sizeof(m_host_t));
-  *lua_host = host;
-  luaL_getmetatable(L, HOST_MODULE_NAME);
-  lua_setmetatable(L, -2);
-  lua_setfield(L, -2, "__simgrid_host");        /* put the userdata as field of the table */
-  return 1;
-}
-
-/**
- * \brief Returns the host where the current process is located.
- * \param L a Lua state
- * \return number of values returned to Lua
- *
- * - Return value (host): the current host
- */
-static int l_host_self(lua_State * L)
-{
-                                  /* -- */
-  m_host_t host = MSG_host_self();
-  lua_newtable(L);
-                                  /* table */
-  m_host_t* lua_host = (m_host_t*) lua_newuserdata(L, sizeof(m_host_t));
-                                  /* table ud */
-  *lua_host = host;
-  luaL_getmetatable(L, HOST_MODULE_NAME);
-                                  /* table ud mt */
-  lua_setmetatable(L, -2);
-                                  /* table ud */
-  lua_setfield(L, -2, "__simgrid_host");
-                                  /* table */
-  return 1;
-}
-
-/**
- * \brief Returns the value of a host property.
- * \param L a Lua state
- * \return number of values returned to Lua
- *
- * - Argument 1 (host): a host
- * - Argument 2 (string): name of the property to get
- * - Return value (string): the value of this property
- */
-static int l_host_get_property_value(lua_State * L)
-{
-  m_host_t ht = sglua_checkhost(L, 1);
-  const char *prop = luaL_checkstring(L, 2);
-  lua_pushstring(L,MSG_host_get_property_value(ht,prop));
-  return 1;
-}
-
-/**
- * \brief Makes the current process sleep for a while.
- * \param L a Lua state
- * \return number of values returned to Lua
- *
- * - Argument 1 (number): duration of the sleep
- */
-static int l_host_sleep(lua_State *L)
-{
-  int time = luaL_checknumber(L, 1);
-  MSG_process_sleep(time);
-  return 0;
-}
-
-/**
- * \brief Destroys a host.
- * \param L a Lua state
- * \return number of values returned to Lua
- *
- * - Argument 1 (host): the host to destroy
- */
-static int l_host_destroy(lua_State *L)
-{
-  m_host_t ht = sglua_checkhost(L, 1);
-  __MSG_host_destroy(ht);
-  return 0;
-}
-
-static const luaL_reg host_functions[] = {
-  {"get_by_name", l_host_get_by_name},
-  {"name", l_host_get_name},
-  {"number", l_host_number},
-  {"at", l_host_at},
-  {"self", l_host_self},
-  {"get_prop_value", l_host_get_property_value},
-  {"sleep", l_host_sleep},
-  {"destroy", l_host_destroy},
-  // Bypass XML Methods
-  {"set_function", console_set_function},
-  {"set_property", console_host_set_property},
-  {NULL, NULL}
-};
-
-/**
- * \brief Returns a string representation of a host.
- * \param L a Lua state
- * \return number of values returned to Lua
- *
- * - Argument 1 (userdata): a host
- * - Return value (string): a string describing this host
- */
-static int l_host_tostring(lua_State * L)
-{
-  lua_pushfstring(L, "Host :%p", lua_touserdata(L, 1));
-  return 1;
-}
-
-static const luaL_reg host_meta[] = {
-  {"__tostring", l_host_tostring},
-  {0, 0}
-};
-
 /* ********************************************************************************* */
 /*                           lua_stub_generator functions                            */
 /* ********************************************************************************* */
@@ -527,9 +52,9 @@ static int gras_add_process_function(lua_State * L)
   if (xbt_dict_is_empty(machine_set)
       || xbt_dict_is_empty(process_function_set)
       || xbt_dynar_is_empty(process_list)) {
-    process_function_set = xbt_dict_new();
+    process_function_set = xbt_dict_new_homogeneous(NULL);
     process_list = xbt_dynar_new(sizeof(s_process_t), s_process_free);
-    machine_set = xbt_dict_new();
+    machine_set = xbt_dict_new_homogeneous(NULL);
   }
 
   xbt_dict_set(machine_set, process_host, NULL, NULL);
@@ -567,22 +92,6 @@ static int gras_generate(lua_State * L)
   return 0;
 }
 
-/* ********************************************************************************* */
-/*                               simgrid.platf API                                   */
-/* ********************************************************************************* */
-
-static const luaL_reg platf_functions[] = {
-    {"open", console_open},
-    {"close", console_close},
-    {"AS_open", console_AS_open},
-    {"AS_close", console_AS_close},
-    {"host_new", console_add_host},
-    {"link_new", console_add_link},
-    {"router_new", console_add_router},
-    {"route_new", console_add_route},
-    {NULL, NULL}
-};
-
 /* ********************************************************************************* */
 /*                                  simgrid API                                      */
 /* ********************************************************************************* */
@@ -594,9 +103,9 @@ static const luaL_reg platf_functions[] = {
  *
  * - Argument 1 (string): name of the deployment file to load
  */
-static int launch_application(lua_State * L)
-{
-  const char *file = luaL_checkstring(L, 1);
+static int launch_application(lua_State* L) {
+
+  const char* file = luaL_checkstring(L, 1);
   MSG_function_register_default(run_lua_code);
   MSG_launch_application(file);
   return 0;
@@ -609,9 +118,9 @@ static int launch_application(lua_State * L)
  *
  * - Argument 1 (string): name of the platform file to load
  */
-static int create_environment(lua_State * L)
-{
-  const char *file = luaL_checkstring(L, 1);
+static int create_environment(lua_State* L) {
+
+  const char* file = luaL_checkstring(L, 1);
   XBT_DEBUG("Loading environment file %s", file);
   MSG_create_environment(file);
   return 0;
@@ -624,9 +133,9 @@ static int create_environment(lua_State * L)
  *
  * - Argument 1 (string): the text to print
  */
-static int debug(lua_State * L)
-{
-  const char *str = luaL_checkstring(L, 1);
+static int debug(lua_State* L) {
+
+  const char* str = luaL_checkstring(L, 1);
   XBT_DEBUG("%s", str);
   return 0;
 }
@@ -638,9 +147,9 @@ static int debug(lua_State * L)
  *
  * - Argument 1 (string): the text to print
  */
-static int info(lua_State * L)
-{
-  const char *str = luaL_checkstring(L, 1);
+static int info(lua_State* L) {
+
+  const char* str = luaL_checkstring(L, 1);
   XBT_INFO("%s", str);
   return 0;
 }
@@ -650,18 +159,31 @@ static int info(lua_State * L)
  * \param L a Lua state
  * \return number of values returned to Lua
  */
-static int run(lua_State * L)
-{
+static int run(lua_State*  L) {
+
   MSG_main();
   return 0;
 }
 
+/**
+ * \brief Returns the current simulated time.
+ * \param L a Lua state
+ * \return number of values returned to Lua
+ *
+ * - Return value (number): the simulated time
+ */
+static int get_clock(lua_State* L) {
+
+  lua_pushnumber(L, MSG_get_clock());
+  return 1;
+}
+
 /**
  * \brief Cleans the simulation.
  * \param L a Lua state
  * \return number of values returned to Lua
  */
-static int clean(lua_State * L)
+static int simgrid_gc(lua_State * L)
 {
   MSG_clean();
   return 0;
@@ -730,7 +252,7 @@ static const luaL_Reg simgrid_functions[] = {
   {"debug", debug},
   {"info", info},
   {"run", run},
-  {"clean", clean},
+  {"get_clock", get_clock},
   /* short names */
   {"platform", create_environment},
   {"application", launch_application},
@@ -806,7 +328,7 @@ int luaopen_simgrid(lua_State *L)
   lua_newtable(L);
   lua_setfield(L, LUA_REGISTRYINDEX, "simgrid.maestro_tables");
 
-  register_c_functions(L);
+  sglua_register_c_functions(L);
 
   return 1;
 }
@@ -829,42 +351,45 @@ lua_State* sglua_get_maestro(void) {
 }
 
 /**
- * \brief Makes the appropriate Simgrid functions available to the Lua world.
+ * \brief Makes the core functions available to the Lua world.
  * \param L a Lua world
  */
-void register_c_functions(lua_State *L) {
-
+static void sglua_register_core_functions(lua_State *L)
+{
   /* register the core C functions to lua */
   luaL_register(L, "simgrid", simgrid_functions);
+                                  /* simgrid */
 
-  /* register the task methods to lua */
-  luaL_openlib(L, TASK_MODULE_NAME, task_functions, 0);   // create methods table, add it to the globals
-  luaL_newmetatable(L, TASK_MODULE_NAME);       // create metatable for Task, add it to the Lua registry
-  luaL_openlib(L, 0, task_meta, 0);     // fill metatable
-  lua_pushliteral(L, "__index");
-  lua_pushvalue(L, -3);         // dup methods table
-  lua_rawset(L, -3);            // metatable.__index = methods
-  lua_pushliteral(L, "__metatable");
-  lua_pushvalue(L, -3);         // dup methods table
-  lua_rawset(L, -3);            // hide metatable:metatable.__metatable = methods
-  lua_pop(L, 1);                // drop metatable
-
-  /* register the hosts methods to lua */
-  luaL_openlib(L, HOST_MODULE_NAME, host_functions, 0);
-  luaL_newmetatable(L, HOST_MODULE_NAME);
-  luaL_openlib(L, 0, host_meta, 0);
-  lua_pushliteral(L, "__index");
-  lua_pushvalue(L, -3);
-  lua_rawset(L, -3);
-  lua_pushliteral(L, "__metatable");
-  lua_pushvalue(L, -3);
-  lua_rawset(L, -3);
+  /* set a finalizer that cleans simgrid, by adding to the simgrid module a
+   * dummy userdata whose __gc metamethod calls MSG_clean() */
+  lua_newuserdata(L, sizeof(void*));
+                                  /* simgrid udata */
+  lua_newtable(L);
+                                  /* simgrid udata mt */
+  lua_pushcfunction(L, simgrid_gc);
+                                  /* simgrid udata mt simgrid_gc */
+  lua_setfield(L, -2, "__gc");
+                                  /* simgrid udata mt */
+  lua_setmetatable(L, -2);
+                                  /* simgrid udata */
+  lua_setfield(L, -2, "__simgrid_loaded");
+                                  /* simgrid */
   lua_pop(L, 1);
+                                  /* -- */
+}
 
-  /* register the platform methods to lua */
-  luaL_openlib(L, PLATF_MODULE_NAME, platf_functions, 0);
-  luaL_newmetatable(L, PLATF_MODULE_NAME);
-  lua_pop(L, 1);
+/**
+ * \brief Creates the simgrid module and make it available to Lua.
+ * \param L a Lua world
+ */
+static void sglua_register_c_functions(lua_State *L)
+{
+  sglua_register_core_functions(L);
+  sglua_register_task_functions(L);
+  sglua_register_comm_functions(L);
+  sglua_register_host_functions(L);
+  sglua_register_process_functions(L);
+  sglua_register_platf_functions(L);
 }
 
 /**
@@ -877,13 +402,14 @@ static int run_lua_code(int argc, char **argv)
 {
   XBT_DEBUG("Run lua code %s", argv[0]);
 
+  /* create a new state, getting globals from maestro */
   lua_State *L = sglua_clone_maestro();
-  int res = 1;
+  MSG_process_set_data(MSG_process_self(), L);
 
   /* start the function */
   lua_getglobal(L, argv[0]);
   xbt_assert(lua_isfunction(L, -1),
-              "The lua function %s does not seem to exist", argv[0]);
+              "There is no Lua function with name `%s'", argv[0]);
 
   /* push arguments onto the stack */
   int i;
@@ -893,10 +419,11 @@ static int run_lua_code(int argc, char **argv)
   /* call the function */
   _XBT_GNUC_UNUSED int err;
   err = lua_pcall(L, argc - 1, 1, 0);
-  xbt_assert(err == 0, "error running function `%s': %s", argv[0],
+  xbt_assert(err == 0, "Error running function `%s': %s", argv[0],
               lua_tostring(L, -1));
 
   /* retrieve result */
+  int res = 1;
   if (lua_isnumber(L, -1)) {
     res = lua_tonumber(L, -1);
     lua_pop(L, 1);              /* pop returned value */
@@ -906,3 +433,21 @@ static int run_lua_code(int argc, char **argv)
 
   return res;
 }
+
+/**
+ * \brief Returns a string corresponding to an MSG error code.
+ * \param err an MSG error code
+ * \return a string describing this error
+ */
+const char* sglua_get_msg_error(MSG_error_t err) {
+
+  static const char* msg_errors[] = {
+      NULL,
+      "timeout",
+      "transfer failure",
+      "host failure",
+      "task canceled"
+  };
+
+  return msg_errors[err];
+}