mercurial/bdiff.h

shortest: never emit 0-length prefix even if unique

It turned out that the pure version of our code for finding the
shortest unique nodeid prefix would return a 0-length string if that
was unique (because there was at most one revision in the
disambiguation set). That's kind of correct, but it can't be used as
input, so we shouldn't return it. Let's just adjust the given
minlength up to at least 1. This fixes test-template-functions.t,
which was failing in pure mode.

Differential Revision: https://phab.mercurial-scm.org/D5181

#ifndef _HG_BDIFF_H_
#define _HG_BDIFF_H_

#include "compat.h"

struct bdiff_line {
	int hash, n, e;
	ssize_t len;
	const char *l;
};

struct bdiff_hunk;
struct bdiff_hunk {
	int a1, a2, b1, b2;
	struct bdiff_hunk *next;
};

int bdiff_splitlines(const char *a, ssize_t len, struct bdiff_line **lr);
int bdiff_diff(struct bdiff_line *a, int an, struct bdiff_line *b, int bn,
               struct bdiff_hunk *base);
void bdiff_freehunks(struct bdiff_hunk *l);

#endif