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avoid C stack overflow during parsing

This commit is contained in:
Roberto Ierusalimschy 2002-11-22 14:35:20 -02:00
parent 007f229568
commit 04b143ddf9
3 changed files with 22 additions and 4 deletions
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3
llex.h
View File

@ -1,5 +1,5 @@
/* /*
** $Id: llex.h,v 1.44 2002/09/03 11:57:38 roberto Exp roberto $ ** $Id: llex.h,v 1.45 2002/10/08 18:46:08 roberto Exp roberto $
** Lexical Analyzer ** Lexical Analyzer
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@ -59,6 +59,7 @@ typedef struct LexState {
ZIO *z; /* input stream */ ZIO *z; /* input stream */
Mbuffer *buff; /* buffer for tokens */ Mbuffer *buff; /* buffer for tokens */
TString *source; /* current source name */ TString *source; /* current source name */
int nestlevel; /* level of nested non-terminals */
} LexState; } LexState;

8
llimits.h
View File

@ -1,5 +1,5 @@
/* /*
** $Id: llimits.h,v 1.46 2002/10/08 18:46:08 roberto Exp roberto $ ** $Id: llimits.h,v 1.47 2002/10/22 17:18:28 roberto Exp roberto $
** Limits, basic types, and some other `installation-dependent' definitions ** Limits, basic types, and some other `installation-dependent' definitions
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@ -165,4 +165,10 @@ typedef unsigned long Instruction;
#endif #endif
/* maximum number of syntactical nested non-terminals */
#ifndef LUA_MAXPARSERLEVEL
#define LUA_MAXPARSERLEVEL 200
#endif
#endif #endif

15
lparser.c
View File

@ -1,5 +1,5 @@
/* /*
** $Id: lparser.c,v 1.196 2002/10/16 20:40:58 roberto Exp roberto $ ** $Id: lparser.c,v 1.197 2002/11/22 13:59:04 roberto Exp roberto $
** Lua Parser ** Lua Parser
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@ -26,6 +26,10 @@
#define getlocvar(fs, i) ((fs)->f->locvars[(fs)->actvar[i]]) #define getlocvar(fs, i) ((fs)->f->locvars[(fs)->actvar[i]])
#define enterlevel(ls) if (++(ls)->nestlevel > LUA_MAXPARSERLEVEL) \
luaX_syntaxerror(ls, "too many syntax levels");
#define leavelevel(ls) ((ls)->nestlevel--)
/* /*
** nodes for block list (list of active blocks) ** nodes for block list (list of active blocks)
@ -356,6 +360,7 @@ Proto *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff) {
struct LexState lexstate; struct LexState lexstate;
struct FuncState funcstate; struct FuncState funcstate;
lexstate.buff = buff; lexstate.buff = buff;
lexstate.nestlevel = 0;
luaX_setinput(L, &lexstate, z, luaS_new(L, zname(z))); luaX_setinput(L, &lexstate, z, luaS_new(L, zname(z)));
open_func(&lexstate, &funcstate); open_func(&lexstate, &funcstate);
next(&lexstate); /* read first token */ next(&lexstate); /* read first token */
@ -364,6 +369,7 @@ Proto *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff) {
close_func(&lexstate); close_func(&lexstate);
lua_assert(funcstate.prev == NULL); lua_assert(funcstate.prev == NULL);
lua_assert(funcstate.f->nupvalues == 0); lua_assert(funcstate.f->nupvalues == 0);
lua_assert(lexstate.nestlevel == 0);
return funcstate.f; return funcstate.f;
} }
@ -749,7 +755,9 @@ static const struct {
*/ */
static BinOpr subexpr (LexState *ls, expdesc *v, int limit) { static BinOpr subexpr (LexState *ls, expdesc *v, int limit) {
BinOpr op; BinOpr op;
UnOpr uop = getunopr(ls->t.token); UnOpr uop;
enterlevel(ls);
uop = getunopr(ls->t.token);
if (uop != OPR_NOUNOPR) { if (uop != OPR_NOUNOPR) {
next(ls); next(ls);
subexpr(ls, v, UNARY_PRIORITY); subexpr(ls, v, UNARY_PRIORITY);
@ -768,6 +776,7 @@ static BinOpr subexpr (LexState *ls, expdesc *v, int limit) {
luaK_posfix(ls->fs, op, v, &v2); luaK_posfix(ls->fs, op, v, &v2);
op = nextop; op = nextop;
} }
leavelevel(ls);
return op; /* return first untreated operator */ return op; /* return first untreated operator */
} }
@ -1299,11 +1308,13 @@ static void body (LexState *ls, expdesc *e, int needself, int line) {
static void chunk (LexState *ls) { static void chunk (LexState *ls) {
/* chunk -> { stat [`;'] } */ /* chunk -> { stat [`;'] } */
int islast = 0; int islast = 0;
enterlevel(ls);
while (!islast && !block_follow(ls->t.token)) { while (!islast && !block_follow(ls->t.token)) {
islast = statement(ls); islast = statement(ls);
testnext(ls, ';'); testnext(ls, ';');
lua_assert(ls->fs->freereg >= ls->fs->nactvar); lua_assert(ls->fs->freereg >= ls->fs->nactvar);
ls->fs->freereg = ls->fs->nactvar; /* free registers */ ls->fs->freereg = ls->fs->nactvar; /* free registers */
} }
leavelevel(ls);
} }