setup_mpatch_cffi.py

py3: add a bytes version of os.name

os.name returns unicodes on py3. Most of our checks are like
    os.name == 'nt'

Because of the transformer, on the right hand side we have b'nt'. The
condition will never satisfy even if os.name returns 'nt' as that will be an
unicode.
We either need to encode every occurence of os.name or have a
new variable which is much cleaner. Now we have pycompat.osname.
There are around 53 occurences of os.name in the codebase which needs to
be replaced by pycompat.osname to support Python 3.

from __future__ import absolute_import

import cffi
import os

ffi = cffi.FFI()
mpatch_c = os.path.join(os.path.join(os.path.dirname(__file__), 'mercurial',
                                     'mpatch.c'))
ffi.set_source("_mpatch_cffi", open(mpatch_c).read(),
               include_dirs=["mercurial"])
ffi.cdef("""

struct mpatch_frag {
       int start, end, len;
       const char *data;
};

struct mpatch_flist {
       struct mpatch_frag *base, *head, *tail;
};

extern "Python" struct mpatch_flist* cffi_get_next_item(void*, ssize_t);

int mpatch_decode(const char *bin, ssize_t len, struct mpatch_flist** res);
ssize_t mpatch_calcsize(size_t len, struct mpatch_flist *l);
void mpatch_lfree(struct mpatch_flist *a);
static int mpatch_apply(char *buf, const char *orig, size_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);
""")

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