fccoelho fccoelho - 3 months ago 20
C Question

How to properly wrap a C library with Python CFFI

I am trying to wrap a very simple C library containing only two .C source files: dbc2dbf.c and blast.c

I am doing the following (from the documentation):

import os
from cffi import FFI
blastbuilder = FFI()
ffibuilder = FFI()
with open(os.path.join(os.path.dirname(__file__), "c-src/blast.c")) as f:
blastbuilder.set_source("blast", f.read(), libraries=["c"])
with open(os.path.join(os.path.dirname(__file__), "c-src/blast.h")) as f:
blastbuilder.cdef(f.read())
blastbuilder.compile(verbose=True)

with open('c-src/dbc2dbf.c','r') as f:
ffibuilder.set_source("_readdbc",
f.read(),
libraries=["c"])

with open(os.path.join(os.path.dirname(__file__), "c-src/blast.h")) as f:
ffibuilder.cdef(f.read(), override=True)

if __name__ == "__main__":
# ffibuilder.include(blastbuilder)
ffibuilder.compile(verbose=True)


This is not quite working. I think I am not including blast.c correctly;

can anyone help?

Answer

Here is the solution (tested):

import os
from cffi import FFI

ffibuilder = FFI()

PATH = os.path.dirname(__file__)

with open(os.path.join(PATH, 'c-src/dbc2dbf.c'),'r') as f:
    ffibuilder.set_source("_readdbc",
                          f.read(),
                          libraries=["c"],
                          sources=[os.path.join(PATH, "c-src/blast.c")],
                          include_dirs=[os.path.join(PATH, "c-src/")]
                          )
ffibuilder.cdef(
    """
    static unsigned inf(void *how, unsigned char **buf);
    static int outf(void *how, unsigned char *buf, unsigned len);
    void dbc2dbf(char** input_file, char** output_file);
    """
)

with open(os.path.join(PATH, "c-src/blast.h")) as f:
    ffibuilder.cdef(f.read(), override=True)

if __name__ == "__main__":
    ffibuilder.compile(verbose=True)
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