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comments + small code changes around stack usage when 'luaL_checkstack'

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raises an error (and needs the stack to create the error message...)
This commit is contained in:
Roberto Ierusalimschy
2015-12-14 09:59:27 -02:00
parent e383941652
commit bda090b961
1 changed files with 21 additions and 5 deletions
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26
lauxlib.c
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@@ -1,5 +1,5 @@
/* /*
** $Id: lauxlib.c,v 1.283 2015/10/06 16:10:22 roberto Exp roberto $ ** $Id: lauxlib.c,v 1.284 2015/11/19 19:16:22 roberto Exp roberto $
** Auxiliary functions for building Lua libraries ** Auxiliary functions for building Lua libraries
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@@ -198,6 +198,10 @@ static void tag_error (lua_State *L, int arg, int tag) {
} }
/*
** The use of 'lua_pushfstring' ensures this function does not
** need reserved stack space when called.
*/
LUALIB_API void luaL_where (lua_State *L, int level) { LUALIB_API void luaL_where (lua_State *L, int level) {
lua_Debug ar; lua_Debug ar;
if (lua_getstack(L, level, &ar)) { /* check function at level */ if (lua_getstack(L, level, &ar)) { /* check function at level */
@@ -207,10 +211,14 @@ LUALIB_API void luaL_where (lua_State *L, int level) {
return; return;
} }
} }
lua_pushliteral(L, ""); /* else, no information available... */ lua_pushfstring(L, ""); /* else, no information available... */
} }
/*
** Again, the use of 'lua_pushvfstring' ensures this function does
** not need reserved stack space when called.
*/
LUALIB_API int luaL_error (lua_State *L, const char *fmt, ...) { LUALIB_API int luaL_error (lua_State *L, const char *fmt, ...) {
va_list argp; va_list argp;
va_start(argp, fmt); va_start(argp, fmt);
@@ -349,9 +357,17 @@ LUALIB_API int luaL_checkoption (lua_State *L, int arg, const char *def,
} }
/*
** Ensures the stack has at least 'space' extra slots, raising
** an error if it cannot fulfill the request. It adds some
** extra space so that, next time it is called (this function
** is typically called inside a loop), it has space to format
** the error message. (In case of an error without this extra
** space, Lua will generate the same 'stack overflow' error,
** but without 'msg'.)
*/
LUALIB_API void luaL_checkstack (lua_State *L, int space, const char *msg) { LUALIB_API void luaL_checkstack (lua_State *L, int space, const char *msg) {
/* keep some extra space to run error routines, if needed */ const int extra = 5; /* extra space to run error routines */
const int extra = LUA_MINSTACK;
if (!lua_checkstack(L, space + extra)) { if (!lua_checkstack(L, space + extra)) {
if (msg) if (msg)
luaL_error(L, "stack overflow (%s)", msg); luaL_error(L, "stack overflow (%s)", msg);
@@ -678,7 +694,7 @@ static int skipcomment (LoadF *lf, int *cp) {
if (c == '#') { /* first line is a comment (Unix exec. file)? */ if (c == '#') { /* first line is a comment (Unix exec. file)? */
do { /* skip first line */ do { /* skip first line */
c = getc(lf->f); c = getc(lf->f);
} while (c != EOF && c != '\n') ; } while (c != EOF && c != '\n');
*cp = getc(lf->f); /* skip end-of-line, if present */ *cp = getc(lf->f); /* skip end-of-line, if present */
return 1; /* there was a comment */ return 1; /* there was a comment */
} }