How to deallocate a returned string from Javascript?

[begilbert-sys]

I have the following function in C++:

extern "C" {

char* solve(char* string) {
    char* result = (char*)malloc(strlen(string) * sizeof(char));
    // fill up result 
    return result;
}
}

Which I then call from JS like so:
Module.ccall("solve", "string", ["string"], ["insert string here"])

There is of course a memory leak because the returned char array never gets deallocated. But I'm unsure of how to deallocate that memory from JS.

[sbc100]

I don't believe that is possible with ccall since ccall automatically converts the returned pointer to a JS string, so you don't have access to the underlying pointer to then call Module._free() on it.

Perhaps you could restructure your code so that it returns a pointers to fixed location that gets freed on the next call:

char* solve(char* string) {
    static char* result = NULL;
    result = (char*)realloc(result, strlen(string) * sizeof(char));
    // fill up result 
    return result;
}