view mercurial/mpatch.h @ 42136:10a6725dca6e

compression: introduce an official `zstd-revlog` requirement

This requirement supersedes `exp-compression-zstd`. However, we keep support for
the old requirement.

Strictly speaking, we do not need to add a new requirement, there are no logic
change making "new" repo incompatible with mercurial client using a version
that support `exp-compression-zstd`.

The choice to introduce a new requirement is motivated by the following:

* The previous requirement was explicitly "experimental". Using it by default
  could confuse users.

* adding support for a hypothetical third compression engine will requires new
  code, and will comes with its own requirement tool.

* We won't use it as the default for a while since I do not think we support
  zstd on all platform. I can imagine we'll gain another (unrelated but on my
  default) requirement by the time we turn this zstd by default.

#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