rust-dirstate: panic if the DirstateMap counters go below 0
When modifying the API I hit some... interesting errors (trying to allocate
178GB of RAM, for example) because I failed to keep the counters correctly
updated.
This counter underflow is likely to happen when code is changed around
and can have up to eat-your-dirstate level of consequences, which is not nice.
The very small runtime cost of checking these counters should really not be an
issue and will help us uncover bugs when/if they do appear in the future.
Differential Revision: https://phab.mercurial-scm.org/D12430
#ifndef HG_MPATCH_H
#define HG_MPATCH_H
#define MPATCH_ERR_NO_MEM -3
#define MPATCH_ERR_CANNOT_BE_DECODED -2
#define MPATCH_ERR_INVALID_PATCH -1
struct mpatch_frag {
int start, end, len;
const char *data;
};
struct mpatch_flist {
struct mpatch_frag *base, *head, *tail;
};
int mpatch_decode(const char *bin, ssize_t len, struct mpatch_flist **res);
ssize_t mpatch_calcsize(ssize_t len, struct mpatch_flist *l);
void mpatch_lfree(struct mpatch_flist *a);
int mpatch_apply(char *buf, const char *orig, ssize_t len,
struct mpatch_flist *l);
struct mpatch_flist *
mpatch_fold(void *bins, struct mpatch_flist *(*get_next_item)(void *, ssize_t),
ssize_t start, ssize_t end);
#endif