annotate mercurial/mpatch.h @ 40324:6637b079ae45

lfs: autoload the extension when cloning from repo with lfs enabled

This is based on a patch by Gregory Szorc.  I made small adjustments to
clean up the messaging when the server has the extension enabled, but the
client has it disabled (to prevent autoloading).  Additionally, I added
a second server capability to distinguish between the server having the
extension enabled, and the server having LFS commits.  This helps prevent
unnecessary requirement propagation- the client shouldn't add a requirement
that the server doesn't have, just because the server had the extension
loaded.  The TODO I had about advertising a capability when the server can
natively serve up blobs isn't relevant anymore (we've had 2 releases that
support this), so I dropped it.

Currently, we lazily add the "lfs" requirement to a repo when we first
encounter LFS data. Due to a pretxnchangegroup hook that looks for LFS
data, this can happen at the end of clone.

Now that we have more control over how repositories are created, we can
do better.

This commit adds a repo creation option to add the "lfs" requirement.
hg.clone() sets this creation option if the remote peer is advertising
lfs usage (as opposed to just support needed to push).

So, what this change effectively does is have cloned repos
automatically inherit the "lfs" requirement.

Differential Revision: https://phab.mercurial-scm.org/D5130

#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