[question] Can it generate a stackstrace?

[arturo32]

Like, a list of variable's names and their current state (values) at each line. Sorry if this is a silly question.

I have been trying to develop an educational website that can compile and run student's C/C++ code to teach them how pointers and memory work.

Currently my solution sends the code to a backend where it's compiled and run through a modified version of valgrind. It would be WONDERFUL if this process could happen inside the browser, so that's why I am so interested in this project.

[tyfkda]

Could you tell me what kind of information is needed?
I don't plan to implement that feature immediately, but I think it could be useful as debug information.

[arturo32]

Could you tell me what kind of information is needed? I don't plan to implement that feature immediately, but I think it could be useful as debug information.

An ordered list of states of each line that was executed, structured by stack frames (function calls). Each state could have a line number and the stacks associated with it. Each stack then could have:

• A name (the function name like main, fibonacci, etc);
• Variables names from the current scope (stack) and their values, types and addresses;

For example, for the code bellow

void sieve(int n) {
    uint8_t *notprime = calloc(sizeof(*notprime), n);
    if (notprime == NULL) {
        exit(1);
    }

    for (int i = 2; i < n; ++i) {
        if (notprime[i])
            continue;
        printf("%d\n", i);
        for (int j = i * i; j < n; j += i)
            notprime[j] = true;
    }
    free(notprime);
}

int main(int argc, char *argv[]) {
    int n = 100;
    if (argc > 1) {
        n = atoi(argv[1]);
        if (n < 2) {
            return 1;
        }
    }
    sieve(n);
    return 0;
}

The second line of the sieve function could have the following information:

{
    "6":{
        "heap": [...],
        "stack": [
            {
                "funcName": "main",
                "line": 24,
                "localVars": [...]
            },
            {
                "funcName": "sieve",
                "line": 2,
                "localVars": [
                    "n": {
                         "type": "int",
                         "value": 100,
                         "address": "0xFFF000B40",
                    },
                    "notprime": {
                         "type": "uint8_t*",
                         "value": "0xFFF000A21"
                         "address": "0xFFF000B48"
                    }
                ]
            }
        ]
    }
}

Sorry for the extra information, I was inspired by the JSON structure that my website uses. The possible interfaces that could be developed using this structured stacktrace are endless!