python cffi parsing error when defining a struct

Question

I am trying to use python-cffi to wrap C code. The following example_build.py shows an attempt to wrap lstat() call:

import cffi

ffi = cffi.FFI()
ffi.set_source("_cstat",
        """
        #include <sys/types.h>
        #include <sys/stat.h>
        #include <unistd.h>
        """,
        libraries=[])

ffi.cdef("""
        struct stat {
            mode_t  st_mode;
            off_t   st_size;
            ...;
        };
        int lstat(const char *path, struct stat *buf);
""")


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

When compile python example_build.py will complain that parsing error for mode_t st_mode.

cffi.api.CDefError: cannot parse "mode_t  st_mode;"
:4:13: before: mode_t

A similar example given from the manual doesn't have any problems though. What am I missing? TIA.

Armin Rigo · Accepted Answer · 2015-10-21 22:23:39Z

5

You need to inform CFFI that mode_t and off_t are some integer types. The easiest way is to add these lines first in the cdef():

typedef int... mode_t;   /* means "mode_t is some integer type" */
typedef int... off_t;

answered Oct 21, 2015 at 22:23

Armin Rigo

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2 Comments

socketpair Over a year ago

real type width may differ. PLEASE DO NOT DEFINE JUST TO INT

Armin Rigo Over a year ago

@socketpair: no, the point of the syntax typedef int... off_t;, with the ellipsis, is precisely to ask CFFI to find the real type width for you. It doesn't mean "use exactly int".

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