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Each item in Wikipedia's [list of types of memory errors](https://en.wikipedia.org/wiki/Memory_safety#Types_of_memory_errors) and what Crowbar does to prevent them.
# Access errors
## Buffer overflow
Crowbar addresses buffer overflow with bounds checking.
In C, the type `char *` can point to a single character, a null-terminated string of unknown length, a buffer of fixed size, or nothing at all.
In Crowbar, the type `char *` can only point to either a single character or nothing at all.
If a buffer is declared as `char[50] name;` then it has type `char[50]`, and can be implicitly converted to `(char[50])*`, a pointer-to-50-chars.
If memory is dynamically allocated, it works as follows:
```crowbar
void process(size_t bufferSize, char[bufferSize] buffer) {
// do some work with buffer, given that we know its size
}
int main(int argc, (char[1024?])[argc] argv) {
size_t bufferSize = getBufferSize();
(char[bufferSize])* buffer = malloc(bufferSize);
process(bufferSize, buffer);
free(buffer);
}
```
Note that `malloc` as part of the Crowbar standard library has signature `(char[size])* malloc(size_t size);` and so no cast is needed above.
Note as well that the type of `argv` is complicated.
This is because the elements of `argv` have unconstrained size.
TODO figure out if that's the right way to handle that
## Buffer over-read
bounds checking again
## Race condition
uhhhhh 🤷♀️
## Page fault
bounds checking, dubious-pointer checking
## Use after free
`free(x);` not followed by `x = NULL;` is a compiler error
# Uninitialized variables
C already warns about these in most cases, so we're good.
## Null pointer dereference
dubious-pointer checking
## Wild pointers
let C handle it
# Memory leak
## Stack exhaustion
uhhhhhh 🤷♀️
## Heap exhaustion
that counts as error handling, just the `malloc`-shaped kind
## Double free
this is just use-after-free but the use is calling free on it
## Invalid free
don't do that
## Mismatched free
how does that even happen
## Unwanted aliasing
uhhh don't do that?
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