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checking consistency of jumps (and some other details)

v5-2
Roberto Ierusalimschy 24 years ago
parent
95da574dbc
commit
3c649ce123
1 changed files with 75 additions and 26 deletions
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  1. 101
      ldebug.c

101
ldebug.c
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@ -1,5 +1,5 @@
/*
** $Id: ldebug.c,v 1.61 2001/02/09 18:37:33 roberto Exp roberto $
** $Id: ldebug.c,v 1.62 2001/02/09 20:22:29 roberto Exp roberto $
** Debug Interface
** See Copyright Notice in lua.h
*/
@ -316,49 +316,82 @@ LUA_API int lua_getinfo (lua_State *L, const char *what, lua_Debug *ar) {
/*
** {======================================================
** Symbolic Execution
** Symbolic Execution and code checker
** =======================================================
*/
#define check(x) if (!(x)) return 0;
/*#define check(x) if (!(x)) return 0;*/
#define check(x) assert(x)
#define checkjump(pt, pc) check(0 <= (pc) && (pc) < (pt)->sizecode)
static Instruction luaG_symbexec (const Proto *pt, int lastpc, int stackpos) {
static int checklineinfo (const Proto *pt) {
int *lineinfo = pt->lineinfo;
if (lineinfo == NULL) return 1;
check(pt->sizelineinfo >= 2 && lineinfo[pt->sizelineinfo-1] == MAX_INT);
if (*lineinfo < 0) lineinfo++;
check(*lineinfo == 0);
return 1;
}
static int precheck (const Proto *pt) {
check(checklineinfo(pt));
check(pt->maxstacksize <= MAXSTACK);
check(pt->numparams+pt->is_vararg <= pt->maxstacksize);
check(GET_OPCODE(pt->code[pt->sizecode-1]) == OP_RETURN);
return 1;
}
/* value for non-initialized entries in array stacklevel */
#define SL_EMPTY 255
#define checkstacklevel(sl,top,pc) \
if (sl) { if (sl[pc] == SL_EMPTY) sl[pc] = top; else check(sl[pc] == top); }
static Instruction luaG_symbexec (const Proto *pt, int lastpc, int stackpos,
unsigned char *sl) {
int stack[MAXSTACK]; /* stores last instruction that changed a stack entry */
const Instruction *code = pt->code;
int top = pt->numparams;
int pc = 0;
if (pt->is_vararg) /* varargs? */
top++; /* `arg' */
check (top <= pt->maxstacksize && pt->maxstacksize <= MAXSTACK);
checkstacklevel(sl, top, pc);
while (pc < lastpc) {
const Instruction i = code[pc++];
OpCode op = GET_OPCODE(i);
int push = (int)luaK_opproperties[op].push;
int pop = (int)luaK_opproperties[op].pop;
int arg1 = 0;
int arg2 = 0;
int push, pop;
check(op < NUM_OPCODES);
push = (int)luaK_opproperties[op].push;
pop = (int)luaK_opproperties[op].pop;
switch ((enum Mode)luaK_opproperties[op].mode) {
case iO: break;
case iU: arg1 = GETARG_U(i); break;
case iU: arg1 = GETARG_U(i); check(arg1 >= 0); break;
case iS: arg1 = GETARG_S(i); break;
case iAB: arg1 = GETARG_A(i); arg2 = GETARG_B(i); break;
case iAB:
arg1 = GETARG_A(i); arg2 = GETARG_B(i); check(arg1 >= 0); break;
}
check(0 <= top && top <= pt->maxstacksize);
switch (op) {
case OP_RETURN: {
check(arg1 <= top);
pop = top-arg1;
break;
}
case OP_CALL: {
if (arg2 == MULT_RET) arg2 = 1;
check(arg1 < top);
pop = top-arg1;
push = arg2;
break;
}
case OP_TAILCALL: {
check(arg1 <= top);
check(arg1 < top && arg2 <= top);
pop = top-arg2;
break;
}
@ -395,7 +428,7 @@ static Instruction luaG_symbexec (const Proto *pt, int lastpc, int stackpos) {
break;
}
case OP_SETTABLE: {
check(2 <= arg1 && arg1 <= top);
check(3 <= arg1 && arg1 <= top);
pop = arg2;
break;
}
@ -425,21 +458,24 @@ static Instruction luaG_symbexec (const Proto *pt, int lastpc, int stackpos) {
case OP_JMPGT:
case OP_JMPGE:
case OP_JMPT:
case OP_JMPF:
case OP_JMPF: {
checkjump(pt, pc+arg1);
check(pop <= top);
checkstacklevel(sl, top-pop, pc+arg1);
break;
}
case OP_JMP:
case OP_FORLOOP:
case OP_LFORLOOP: {
checkjump(pt, pc+arg1);
break;
}
case OP_PUSHNILJMP: {
checkjump(pt, pc+1);
checkstacklevel(sl, top, pc+arg1);
break;
}
case OP_JMPONT:
case OP_JMPONF: {
int newpc = pc + arg1;
int newpc = pc+arg1;
checkjump(pt, newpc);
checkstacklevel(sl, top, newpc);
/* jump is forward and do not skip `lastpc' and not full check? */
if (pc < newpc && newpc <= lastpc && stackpos >= 0) {
stack[top-1] = pc-1; /* value comes from `and'/`or' */
@ -448,14 +484,24 @@ static Instruction luaG_symbexec (const Proto *pt, int lastpc, int stackpos) {
}
break;
}
case OP_PUSHNILJMP: {
check(GET_OPCODE(code[pc]) == OP_PUSHINT); /* only valid sequence */
break;
}
case OP_FORPREP: {
int newpc = pc-arg1; /* jump is `negative' here */
check(top >= 3);
checkjump(pt, pc-arg1); /* jump is `negative' here */
checkjump(pt, newpc);
check(GET_OPCODE(code[newpc-1]) == OP_FORLOOP);
check(GETARG_S(code[newpc-1]) == arg1);
break;
}
case OP_LFORPREP: {
int newpc = pc-arg1; /* jump is `negative' here */
check(top >= 1);
checkjump(pt, pc-arg1); /* jump is `negative' here */
checkjump(pt, newpc);
check(GET_OPCODE(code[newpc-1]) == OP_LFORLOOP);
check(GETARG_S(code[newpc-1]) == arg1);
break;
}
case OP_PUSHINT:
@ -472,18 +518,21 @@ static Instruction luaG_symbexec (const Proto *pt, int lastpc, int stackpos) {
break;
}
}
check(0 <= pop && 0 <= push);
check(0 <= top-pop && top+(push-pop) <= pt->maxstacksize);
top -= pop;
check(0 <= top && top+push <= pt->maxstacksize);
while (push--) stack[top++] = pc-1;
checkstacklevel(sl, top, pc);
}
check(GET_OPCODE(code[pt->sizecode-1]) == OP_RETURN);
return (stackpos >= 0) ? code[stack[stackpos]] : 1;
}
int luaG_checkcode (const Proto *pt) {
return luaG_symbexec(pt, pt->sizecode-1, -1);
int luaG_checkcode (lua_State *L, const Proto *pt) {
unsigned char *sl = (unsigned char *)luaO_openspace(L, pt->sizecode);
int i;
for (i=0; i<pt->sizecode; i++)
sl[i] = SL_EMPTY;
return precheck(pt) && luaG_symbexec(pt, pt->sizecode-1, -1, sl);
}
@ -495,7 +544,7 @@ static const char *getobjname (lua_State *L, StkId obj, const char **name) {
Proto *p = infovalue(func)->func->f.l;
int pc = currentpc(func);
int stackpos = obj - (func+1); /* func+1 == function base */
Instruction i = luaG_symbexec(p, pc, stackpos);
Instruction i = luaG_symbexec(p, pc, stackpos, NULL);
lua_assert(pc != -1);
switch (GET_OPCODE(i)) {
case OP_GETGLOBAL: {

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