windows: prevent bytes from being passed to registry APIs
There was a TortoiseHg bug report in this area[1], and from inspection, it looks
like passing `b""` as `valname` would fail to convert to unicode. The
underlying API allows both `""` and `NULL` to return the default value for the
key.
[1] https://foss.heptapod.net/mercurial/tortoisehg/thg/-/issues/5803
#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