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_PROMPT can have non-string values

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'get_prompt' uses 'luaL_tolstring' to convert _PROMPT or _PROMPT2
value to a string. That conversion may invoke a '__tostring'
metamethod.
This commit is contained in:
Roberto Ierusalimschy
2020-10-26 11:15:51 -03:00
parent d742a193e5
commit 69b71a6919
2 changed files with 37 additions and 6 deletions
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16
lua.c
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@@ -416,14 +416,18 @@ static int handle_luainit (lua_State *L) {
/*
** Returns the string to be used as a prompt by the interpreter.
** Return the string to be used as a prompt by the interpreter. Leave
** the string (or nil, if using the default value) on the stack, to keep
** it anchored.
*/
static const char *get_prompt (lua_State *L, int firstline) {
const char *p;
lua_getglobal(L, firstline ? "_PROMPT" : "_PROMPT2");
p = lua_tostring(L, -1);
if (p == NULL) p = (firstline ? LUA_PROMPT : LUA_PROMPT2);
return p;
if (lua_getglobal(L, firstline ? "_PROMPT" : "_PROMPT2") == LUA_TNIL)
return (firstline ? LUA_PROMPT : LUA_PROMPT2); /* use the default */
else { /* apply 'tostring' over the value */
const char *p = luaL_tolstring(L, -1, NULL);
lua_remove(L, -2); /* remove original value */
return p;
}
}
/* mark in error messages for incomplete statements */