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Bug: wrong 'nCcalls' when resuming a coroutine 

The counter 'nCcalls' now includes the number of CallInfo structures
pre-allocated (so that these "potential" C calls can be made without
checking 'nCcalls'). So, when copying this value from a thread to
another, in 'lua_resume', it must be corrected to the number of
CallInfo structures in the thread being resumed.
This commit is contained in:
Roberto Ierusalimschy 2018-07-11 16:11:50 -03:00
parent 84058b1506
commit 96f9643f33
2 changed files with 24 additions and 5 deletions
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9
ldo.c
View File

@ -1,5 +1,5 @@
/* /*
** $Id: ldo.c,v 2.201 2018/05/22 12:02:36 roberto Exp roberto $ ** $Id: ldo.c $
** Stack and Call structure of Lua ** Stack and Call structure of Lua
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@ -137,6 +137,7 @@ l_noret luaD_throw (lua_State *L, int errcode) {
int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) { int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
unsigned short oldnCcalls = L->nCcalls - L->nci; unsigned short oldnCcalls = L->nCcalls - L->nci;
struct lua_longjmp lj; struct lua_longjmp lj;
lua_assert(L->nCcalls >= L->nci);
lj.status = LUA_OK; lj.status = LUA_OK;
lj.previous = L->errorJmp; /* chain new error handler */ lj.previous = L->errorJmp; /* chain new error handler */
L->errorJmp = &lj; L->errorJmp = &lj;
@ -653,7 +654,10 @@ LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs,
} }
else if (L->status != LUA_YIELD) else if (L->status != LUA_YIELD)
return resume_error(L, "cannot resume dead coroutine", nargs); return resume_error(L, "cannot resume dead coroutine", nargs);
L->nCcalls = (from) ? from->nCcalls + 1 : 1; if (from == NULL)
L->nCcalls = 1;
else /* correct 'nCcalls' for this thread */
L->nCcalls = from->nCcalls - from->nci + L->nci + 1;
if (L->nCcalls >= LUAI_MAXCCALLS) if (L->nCcalls >= LUAI_MAXCCALLS)
return resume_error(L, "C stack overflow", nargs); return resume_error(L, "C stack overflow", nargs);
luai_userstateresume(L, nargs); luai_userstateresume(L, nargs);
@ -677,7 +681,6 @@ LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs,
*nresults = (status == LUA_YIELD) ? L->ci->u2.nyield *nresults = (status == LUA_YIELD) ? L->ci->u2.nyield
: cast_int(L->top - (L->ci->func + 1)); : cast_int(L->top - (L->ci->func + 1));
L->nny = oldnny; /* restore 'nny' */ L->nny = oldnny; /* restore 'nny' */
L->nCcalls--;
lua_unlock(L); lua_unlock(L);
return status; return status;
} }

20
lstate.h
View File

@ -1,5 +1,5 @@
/* /*
** $Id: lstate.h,v 2.159 2018/06/15 19:31:22 roberto Exp roberto $ ** $Id: lstate.h $
** Global State ** Global State
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@ -49,6 +49,22 @@
*/ */
/*
** About 'nCcalls': each thread in Lua (a lua_State) keeps a count of
** how many "C calls" it has in the C stack, to avoid C-stack overflow.
** This count is very rough approximation; it considers only recursive
** functions inside the interpreter, as non-recursive calls can be
** considered using a fixed (although unknown) amount of stack space.
**
** The proper count also includes the number of CallInfo structures
** allocated by Lua, as a kind of "potential" calls. So, when Lua
** calls a function (and "consumes" one CallInfo), it needs neither to
** increment nor to check 'nCcalls', as its use of C stack is already
** accounted for.
*/
struct lua_longjmp; /* defined in ldo.c */ struct lua_longjmp; /* defined in ldo.c */
@ -212,7 +228,7 @@ struct lua_State {
int basehookcount; int basehookcount;
int hookcount; int hookcount;
unsigned short nny; /* number of non-yieldable calls in stack */ unsigned short nny; /* number of non-yieldable calls in stack */
unsigned short nCcalls; /* number of nested C calls */ unsigned short nCcalls; /* number of nested C calls + 'nny' */
l_signalT hookmask; l_signalT hookmask;
lu_byte allowhook; lu_byte allowhook;
}; };