[sane-devel] why my backend don't work?
Wed, 10 Jul 2002 11:27:39 +0200
On Wed, Jul 10, 2002 at 04:27:51PM +0800, zhu wrote:
> I want to try a new backend which main file is m1200.c. Other
> files are m1200.h,m1200.conf,mscan.c and mscan.h.
Just a note: If you plan to include your backend into SANE later,
please change the names of at least the latter two files to e.g.
m1200-scan.* so it's easier to find out to which backend they belong.
> I did as followed:
> (1)Modified the backend/Makefile.in, added "m1200" in the list
> following "PRELOADABLE_BACKENDS = " ;
That will compile m1200.c.
> (2)Added "m1200.c m1200.conf m1200.h mscan.c mscan.h" in the list
> following "DISTFILES = " ;
If you run "make dist", your backend will be added to
sane-backends-*.tar.gz. That's not needed for compilation.
> (3)Added "libsane-m1200.la:
That's ok, if you need these two objects in your backend.
> (4)modified the "dll.conf",added "m1200"
> (5)make uninstall
> (6)execute sane-backends-1.0.8/configure
> (7)make (no error)
> (8)make install (no error)
So compilation is ok, but...
> My problem is ,when I type "scanimage -L",it says error ,error info is:
> scanimage:error while loading the shared libraries:
> /usr/local/lib/sane/libsane-m1200.so.1:undefined symbol: funcname
runtime-linking failed. It's easier to find such errors if you use
"configure --disable-shared" (use static linking).
> This "funcname" is a function declared in file mscan.h and
> defined in mscan.c,and called in the function "sane_init". In the
> file m1200.c ,I've not forgotten include the head file "mscan.h".
mscan.c is never compiled. The Makefile doesn't know about it. You
told the compiler: Hey, I have an external function "funcname" and I
will link the object file that includes the functions code. But you
1) Include mscan.c in m1200.c. Either by copying the code into that
file or by using #include. Not that nice but the easiest solution.
2) Link the two files together. Have a look at canon_pp in the
Makefile.in for an example, how to do it.
Keep in mind, that you shouldn't export functions, that don't start
with "sane_*" (the API-functions) or "sanei_*". And the symbols should
be unique. So if you use approach 2), you should name the xported
functions from mscan.c sumething like sanei_m1200_*.
When your backend works (at least to some degeree), we are interested
in which scanners it will support and where we can download it. We are
even more interested in a .desc file :-)