mercurial/cffi/bdiffbuild.py

packaging: update keyring on Windows to avoid spurious stacktraces

When challenged for a network password, this would spew on Windows before it
actually used the stored password:

```
Error initializing plugin EntryPoint(name='libsecret', value='keyring.backends.libsecret', group='keyring.backends').
Traceback (most recent call last):
  File "keyring.backend", line 198, in _load_plugins
    init_func = ep.load()
  File "importlib.metadata", line 77, in load
    module = import_module(match.group('module'))
  File "importlib", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
  File "<frozen importlib._bootstrap>", line 984, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'keyring.backends.libsecret'
Error initializing plugin EntryPoint(name='macOS', value='keyring.backends.macOS', group='keyring.backends').
Traceback (most recent call last):
  File "keyring.backend", line 198, in _load_plugins
    init_func = ep.load()
  File "importlib.metadata", line 77, in load
    module = import_module(match.group('module'))
  File "importlib", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
  File "<frozen importlib._bootstrap>", line 984, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'keyring.backends.macOS'
```

We're kinda threading a needle here because the next version of `keyring`
(currently at 23.7.0) requires `importlib-metadata` 3.6+, which PyOxidizer 0.22
doesn't support[1].

[1] https://github.com/indygreg/PyOxidizer/issues/609

import cffi
import os

ffi = cffi.FFI()
with open(
    os.path.join(os.path.join(os.path.dirname(__file__), '..'), 'bdiff.c')
) as f:
    ffi.set_source(
        "mercurial.cffi._bdiff", f.read(), include_dirs=['mercurial']
    )
ffi.cdef(
    """
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);
void free(void*);
"""
)

if __name__ == '__main__':
    ffi.compile()