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better limits for 'sting.rep' and 'string.packsize'

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This commit is contained in:
Roberto Ierusalimschy 2014-12-11 11:40:40 -02:00
parent 81ecaf6178
commit ef7d29c666
1 changed files with 17 additions and 12 deletions
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29
lstrlib.c
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@ -1,5 +1,5 @@
/*
** $Id: lstrlib.c,v 1.218 2014/12/04 16:25:40 roberto Exp roberto $
** $Id: lstrlib.c,v 1.219 2014/12/10 11:36:03 roberto Exp roberto $
** Standard library for string operations and pattern-matching
** See Copyright Notice in lua.h
*/
@ -36,6 +36,15 @@
#define uchar(c) ((unsigned char)(c))
/*
** Some sizes are better limited to fit in 'int', but must also fit in
** 'size_t'. (We assume that 'lua_Integer' cannot be smaller than 'int'.)
*/
#define MAXSIZE \
(sizeof(size_t) < sizeof(int) ? (~(size_t)0) : (size_t)(INT_MAX))
static int str_len (lua_State *L) {
size_t l;
@ -105,13 +114,6 @@ static int str_upper (lua_State *L) {
}
/* reasonable limit to avoid arithmetic overflow and strings too big */
#if LUA_MAXINTEGER / 2 <= 0x10000000
#define MAXSIZE ((size_t)(LUA_MAXINTEGER / 2))
#else
#define MAXSIZE ((size_t)0x10000000)
#endif
static int str_rep (lua_State *L) {
size_t l, lsep;
const char *s = luaL_checklstring(L, 1, &l);
@ -1033,7 +1035,7 @@ static int getnum (const char **fmt, int df) {
int a = 0;
do {
a = a*10 + *((*fmt)++) - '0';
} while (digit(**fmt) && a < (INT_MAX/10 - 10));
} while (digit(**fmt) && a < ((int)MAXSIZE/10 - 10));
return a;
}
}
@ -1261,12 +1263,15 @@ static int str_pack (lua_State *L) {
static int str_packsize (lua_State *L) {
Header h;
const char *fmt = luaL_checkstring(L, 1); /* format string */
lua_Integer totalsize = 0; /* accumulate total size of result */
size_t totalsize = 0; /* accumulate total size of result */
initheader(L, &h);
while (*fmt != '\0') {
int size, ntoalign;
KOption opt = getdetails(&h, totalsize, &fmt, &size, &ntoalign);
totalsize += ntoalign + size;
size += ntoalign; /* total space used by option */
luaL_argcheck(L, totalsize <= MAXSIZE - size, 1,
"format result too large");
totalsize += size;
switch (opt) {
case Kstring: /* strings with length count */
case Kzstr: /* zero-terminated string */
@ -1275,7 +1280,7 @@ static int str_packsize (lua_State *L) {
default: break;
}
}
lua_pushinteger(L, totalsize);
lua_pushinteger(L, (lua_Integer)totalsize);
return 1;
}