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We now check the state machines are not left in bogus states.

This commit is contained in:
Geoff Langdale 2018-07-30 10:40:25 +10:00
parent 847aa1ebab
commit 652dd2f2c6
1 changed files with 41 additions and 3 deletions
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44
main.cpp
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@ -483,6 +483,28 @@ u32 trans[MAX_STATES][256];
u32 states[MAX_DEPTH];
const int START_STATE = 1;
u32 valid_end_states[MAX_STATES] = {
0, // 0 state is by definition an error
1, // ok to still be in start state
1, // state 2: we've seen an { - if we left this level it's ok
0, // state 3 is abolished, we shouldn't be in it
0, // state 4 means we saw a string inside an object. We can't end like this!
0, // similarly state 5 means we saw a string followed by a colon.
0, // state 6 is abolished
1, // it's ok to finish on 7
0, // state 8 we've seen a comma inside an object - can't finish here
1, // state 9 is like state 2 only for arrays, so ok
0, // state 10 abolished
1, // state 11 is ok to finish on, we just saw a unary inside a array
0, // state 12 we've just seen a comma inside an array - can't finish
0, // state 13 is our weird start state. I think we shouldn't end on it as we need to see something
1, // state 14 is ok. Its an error to see something *more* here but not to be in this state
0, // we don't use state 15
};
// weird sub-machine for starting depth only
// we start at 13 and go to 14 on a single UNARY
// 14 doesn't have to have any transitions. Anything
@ -517,9 +539,23 @@ never_inline void init_state_machine() {
trans[ 5][(u32)UNARIES[i]] = 7;
trans[ 9][(u32)UNARIES[i]] = 11;
trans[12][(u32)UNARIES[i]] = 11;
#ifdef PERMIT_RANDOM_UNARIES_AT_TOP_LEVEL
// NOTE: if we permit JSON documents that
// contain a single number or string, then we
// allow all the unaries at the top level
trans[13][(u32)UNARIES[i]] = 14;
#endif
}
#ifndef PERMIT_RANDOM_UNARIES_AT_TOP_LEVEL
// NOTE: if we don't permit JSON documents that
// that contain a single number or string, we must
// make sure we accept the top-level closing braces
// that are delivered to the start depth only
trans[13]['}'] = 14;
trans[13][']'] = 14;
#endif
// back transitions when new things are open
trans[2]['{'] = 2;
trans[7]['{'] = 2;
@ -623,8 +659,10 @@ never_inline bool ape_machine(const u8 * buf, UNUSED size_t len, ParsedJson & pj
printf("Ending depth is %d\n", depth);
for (u32 i = 0; i < MAX_DEPTH; i++) {
if (states[i] == 0) {
// printf("states[%d] == 0\n", i);
if (!valid_end_states[states[i]]) {
#ifdef DEBUG
printf("Invalid ending state: states[%d] == %d\n", states[i]);
#endif
return false;
}
}