some janitorial work (comments, small refactoring)

loadlib.c

@@ -1,5 +1,5 @@
 /*
-** $Id: loadlib.c,v 1.113 2014/03/12 20:57:40 roberto Exp roberto $
+** $Id: loadlib.c,v 1.114 2014/07/16 13:56:14 roberto Exp roberto $
 ** Dynamic library loader for Lua
 ** See Copyright Notice in lua.h
 **
@@ -97,20 +97,33 @@
 
 #define LIB_FAIL	"open"
 
-
-/* error codes for ll_loadfunc */
-#define ERRLIB		1
-#define ERRFUNC		2
-
 #define setprogdir(L)		((void)0)
 
 
 /*
 ** system-dependent functions
 */
-static void ll_unloadlib (void *lib);
-static void *ll_load (lua_State *L, const char *path, int seeglb);
-static lua_CFunction ll_sym (lua_State *L, void *lib, const char *sym);
+
+/*
+** unload library 'lib'
+*/
+static void lsys_unloadlib (void *lib);
+
+/*
+** load C library in file 'path'. If 'seeglb', load with all names in
+** the library global.
+** Returns the library; in case of error, returns NULL plus an
+** error string in the stack.
+*/
+static void *lsys_load (lua_State *L, const char *path, int seeglb);
+
+/*
+** Try to find a function named 'sym' in library 'lib'.
+** Returns the function; in case of error, returns NULL plus an
+** error string in the stack.
+*/
+static lua_CFunction lsys_sym (lua_State *L, void *lib, const char *sym);
+
 
 
 
@@ -126,19 +139,19 @@ static lua_CFunction ll_sym (lua_State *L, void *lib, const char *sym);
 
 #include <dlfcn.h>
 
-static void ll_unloadlib (void *lib) {
+static void lsys_unloadlib (void *lib) {
   dlclose(lib);
 }
 
 
-static void *ll_load (lua_State *L, const char *path, int seeglb) {
+static void *lsys_load (lua_State *L, const char *path, int seeglb) {
   void *lib = dlopen(path, RTLD_NOW | (seeglb ? RTLD_GLOBAL : RTLD_LOCAL));
   if (lib == NULL) lua_pushstring(L, dlerror());
   return lib;
 }
 
 
-static lua_CFunction ll_sym (lua_State *L, void *lib, const char *sym) {
+static lua_CFunction lsys_sym (lua_State *L, void *lib, const char *sym) {
   lua_CFunction f = (lua_CFunction)dlsym(lib, sym);
   if (f == NULL) lua_pushstring(L, dlerror());
   return f;
@@ -190,12 +203,12 @@ static void pusherror (lua_State *L) {
     lua_pushfstring(L, "system error %d\n", error);
 }
 
-static void ll_unloadlib (void *lib) {
+static void lsys_unloadlib (void *lib) {
   FreeLibrary((HMODULE)lib);
 }
 
 
-static void *ll_load (lua_State *L, const char *path, int seeglb) {
+static void *lsys_load (lua_State *L, const char *path, int seeglb) {
   HMODULE lib = LoadLibraryExA(path, NULL, LUA_LLE_FLAGS);
   (void)(seeglb);  /* not used: symbols are 'global' by default */
   if (lib == NULL) pusherror(L);
@@ -203,7 +216,7 @@ static void *ll_load (lua_State *L, const char *path, int seeglb) {
 }
 
 
-static lua_CFunction ll_sym (lua_State *L, void *lib, const char *sym) {
+static lua_CFunction lsys_sym (lua_State *L, void *lib, const char *sym) {
   lua_CFunction f = (lua_CFunction)GetProcAddress((HMODULE)lib, sym);
   if (f == NULL) pusherror(L);
   return f;
@@ -226,19 +239,19 @@ static lua_CFunction ll_sym (lua_State *L, void *lib, const char *sym) {
 #define DLMSG	"dynamic libraries not enabled; check your Lua installation"
 
 
-static void ll_unloadlib (void *lib) {
+static void lsys_unloadlib (void *lib) {
   (void)(lib);  /* not used */
 }
 
 
-static void *ll_load (lua_State *L, const char *path, int seeglb) {
+static void *lsys_load (lua_State *L, const char *path, int seeglb) {
   (void)(path); (void)(seeglb);  /* not used */
   lua_pushliteral(L, DLMSG);
   return NULL;
 }
 
 
-static lua_CFunction ll_sym (lua_State *L, void *lib, const char *sym) {
+static lua_CFunction lsys_sym (lua_State *L, void *lib, const char *sym) {
   (void)(lib); (void)(sym);  /* not used */
   lua_pushliteral(L, DLMSG);
   return NULL;
@@ -248,7 +261,10 @@ static lua_CFunction ll_sym (lua_State *L, void *lib, const char *sym) {
 #endif
 
 
-static void *ll_checkclib (lua_State *L, const char *path) {
+/*
+** return registry.CLIBS[path]
+*/
+static void *checkclib (lua_State *L, const char *path) {
   void *plib;
   lua_getfield(L, LUA_REGISTRYINDEX, CLIBS);
   lua_getfield(L, -1, path);
@@ -258,7 +274,11 @@ static void *ll_checkclib (lua_State *L, const char *path) {
 }
 
 
-static void ll_addtoclib (lua_State *L, const char *path, void *plib) {
+/*
+** registry.CLIBS[path] = plib        -- for queries
+** registry.CLIBS[#CLIBS + 1] = plib  -- also keep a list of all libraries
+*/
+static void addtoclib (lua_State *L, const char *path, void *plib) {
   lua_getfield(L, LUA_REGISTRYINDEX, CLIBS);
   lua_pushlightuserdata(L, plib);
   lua_pushvalue(L, -1);
@@ -269,33 +289,49 @@ static void ll_addtoclib (lua_State *L, const char *path, void *plib) {
 
 
 /*
-** __gc tag method for CLIBS table: calls 'll_unloadlib' for all lib
+** __gc tag method for CLIBS table: calls 'lsys_unloadlib' for all lib
 ** handles in list CLIBS
 */
 static int gctm (lua_State *L) {
   int n = luaL_len(L, 1);
   for (; n >= 1; n--) {  /* for each handle, in reverse order */
     lua_rawgeti(L, 1, n);  /* get handle CLIBS[n] */
-    ll_unloadlib(lua_touserdata(L, -1));
+    lsys_unloadlib(lua_touserdata(L, -1));
     lua_pop(L, 1);  /* pop handle */
   }
   return 0;
 }
 
 
-static int ll_loadfunc (lua_State *L, const char *path, const char *sym) {
-  void *reg = ll_checkclib(L, path);  /* check loaded C libraries */
+
+/* error codes for 'lookforfunc' */
+#define ERRLIB		1
+#define ERRFUNC		2
+
+/*
+** Look for a C function named 'sym' in a dynamically loaded library
+** 'path'.
+** First, check whether the library is already loaded; if not, try
+** to load it.
+** Then, if 'sym' is '*', return true (as library has been loaded).
+** Otherwise, look for symbol 'sym' in the library and push a
+** C function with that symbol.
+** Return 0 and 'true' or a function in the stack; in case of
+** errors, return an error code and an error message in the stack.
+*/
+static int lookforfunc (lua_State *L, const char *path, const char *sym) {
+  void *reg = checkclib(L, path);  /* check loaded C libraries */
   if (reg == NULL) {  /* must load library? */
-    reg = ll_load(L, path, *sym == '*');
+    reg = lsys_load(L, path, *sym == '*');  /* global symbols if 'sym'=='*' */
     if (reg == NULL) return ERRLIB;  /* unable to load library */
-    ll_addtoclib(L, path, reg);
+    addtoclib(L, path, reg);
   }
   if (*sym == '*') {  /* loading only library (no function)? */
     lua_pushboolean(L, 1);  /* return 'true' */
     return 0;  /* no errors */
   }
   else {
-    lua_CFunction f = ll_sym(L, reg, sym);
+    lua_CFunction f = lsys_sym(L, reg, sym);
     if (f == NULL)
       return ERRFUNC;  /* unable to find function */
     lua_pushcfunction(L, f);  /* else create new function */
@@ -307,7 +343,7 @@ static int ll_loadfunc (lua_State *L, const char *path, const char *sym) {
 static int ll_loadlib (lua_State *L) {
   const char *path = luaL_checkstring(L, 1);
   const char *init = luaL_checkstring(L, 2);
-  int stat = ll_loadfunc(L, path, init);
+  int stat = lookforfunc(L, path, init);
   if (stat == 0)  /* no errors? */
     return 1;  /* return the loaded function */
   else {  /* error; error message is on stack top */
@@ -416,21 +452,29 @@ static int searcher_Lua (lua_State *L) {
 }
 
 
+/*
+** Try to find a load function for module 'modname' at file 'filename'.
+** First, change '.' to '_' in 'modname'; then, if 'modname' has
+** the form X-Y (that is, it has an "ignore mark"), build a function
+** name "luaopen_X" and look for it. (For compatibility, if that
+** fails, it also tries "luaopen_Y".) If there is no ignore mark,
+** look for a function named "luaopen_modname".
+*/
 static int loadfunc (lua_State *L, const char *filename, const char *modname) {
-  const char *funcname;
+  const char *openfunc;
   const char *mark;
   modname = luaL_gsub(L, modname, ".", LUA_OFSEP);
   mark = strchr(modname, *LUA_IGMARK);
   if (mark) {
     int stat;
-    funcname = lua_pushlstring(L, modname, mark - modname);
-    funcname = lua_pushfstring(L, LUA_POF"%s", funcname);
-    stat = ll_loadfunc(L, filename, funcname);
+    openfunc = lua_pushlstring(L, modname, mark - modname);
+    openfunc = lua_pushfstring(L, LUA_POF"%s", openfunc);
+    stat = lookforfunc(L, filename, openfunc);
     if (stat != ERRFUNC) return stat;
     modname = mark + 1;  /* else go ahead and try old-style name */
   }
-  funcname = lua_pushfstring(L, LUA_POF"%s", modname);
-  return ll_loadfunc(L, filename, funcname);
+  openfunc = lua_pushfstring(L, LUA_POF"%s", modname);
+  return lookforfunc(L, filename, openfunc);
 }
 
 
@@ -686,24 +730,31 @@ static void createsearcherstable (lua_State *L) {
     lua_pushcclosure(L, searchers[i], 1);
     lua_rawseti(L, -2, i+1);
   }
+#if defined(LUA_COMPAT_LOADERS)
+  lua_pushvalue(L, -1);  /* make a copy of 'searchers' table */
+  lua_setfield(L, -3, "loaders");  /* put it in field `loaders' */
+#endif
+  lua_setfield(L, -2, "searchers");  /* put it in field 'searchers' */
 }
 
 
-LUAMOD_API int luaopen_package (lua_State *L) {
-  /* create table CLIBS to keep track of loaded C libraries */
-  luaL_getsubtable(L, LUA_REGISTRYINDEX, CLIBS);
-  lua_createtable(L, 0, 1);  /* metatable for CLIBS */
+/*
+** create table CLIBS to keep track of loaded C libraries,
+** setting a finalizer to close all libraries when closing state.
+*/
+static void createclibstable (lua_State *L) {
+  luaL_getsubtable(L, LUA_REGISTRYINDEX, CLIBS);  /* create CLIBS table */
+  lua_createtable(L, 0, 1);  /* create metatable for CLIBS */
   lua_pushcfunction(L, gctm);
   lua_setfield(L, -2, "__gc");  /* set finalizer for CLIBS table */
   lua_setmetatable(L, -2);
-  /* create `package' table */
-  luaL_newlib(L, pk_funcs);
+}
+
+
+LUAMOD_API int luaopen_package (lua_State *L) {
+  createclibstable(L);
+  luaL_newlib(L, pk_funcs);  /* create `package' table */
   createsearcherstable(L);
-#if defined(LUA_COMPAT_LOADERS)
-  lua_pushvalue(L, -1);  /* make a copy of 'searchers' table */
-  lua_setfield(L, -3, "loaders");  /* put it in field `loaders' */
-#endif
-  lua_setfield(L, -2, "searchers");  /* put it in field 'searchers' */
   /* set field 'path' */
   setpath(L, "path", LUA_PATHVARVERSION, LUA_PATH_VAR, LUA_PATH_DEFAULT);
   /* set field 'cpath' */