[erlang-questions] Building erl_interface with mingw (an unfinished tale)

Davide Marquês <>
Wed Apr 22 10:56:48 CEST 2009


Hi there!

I was (almost) able to compile erl_interface using mingw (with some
unhealthy hacks along the way) and I'd like to get your feedback on whether
this would be the correct way to go.
Actually, since I have no *useful* experience using gcc and related tools
I'm prepared to have someone telling me that I really didn't had to
recompile erl_interface.
Either way, this might be useful for others that might be thinking of taking
the same path... :)

My setup: Windows XP, OTP_R13B (I started off with OTP_R13A so paths will
vary), MSYS + MinGW.

I started off following the erl_interface tutorial (
http://erlang.org/doc/tutorial/erl_interface.html) and things broke when I
tried to compile:
     /c/Projectos/eNotify/src/native/port
    $ gcc.exe ei.c erl_comm.c -o extprg.exe
-Ic:/erl5.7/lib/erl_interface-3.6/include
-Lc:/erl5.7/lib/erl_interface-3.6/lib -lei -lerl_interface
    Warning: .drectve `/DEFAULTLIB:"uuid.lib" /DEFAULTLIB:"uuid.lib"
/DEFAULTLIB:"LIBCMT" /DEFAULTLIB:"OLDNAMES" ' unrecognized
    Warning: .drectve `/DEFAULTLIB:"uuid.lib" /DEFAULTLIB:"uuid.lib"
/DEFAULTLIB:"LIBCMT" /DEFAULTLIB:"OLDNAMES" ' unrecognized
    Warning: .drectve `/DEFAULTLIB:"uuid.lib" /DEFAULTLIB:"uuid.lib"
/DEFAULTLIB:"LIBCMT" /DEFAULTLIB:"OLDNAMES" ' unrecognized
    Warning: .drectve `/DEFAULTLIB:"uuid.lib" /DEFAULTLIB:"uuid.lib"
/DEFAULTLIB:"LIBCMT" /DEFAULTLIB:"OLDNAMES" ' unrecognized
    Warning: .drectve `/DEFAULTLIB:"uuid.lib" /DEFAULTLIB:"uuid.lib"
/DEFAULTLIB:"LIBCMT" /DEFAULTLIB:"OLDNAMES" ' unrecognized

c:/erl5.7/lib/erl_interface-3.6/lib/erl_interface.lib(C:/cygwin/ldisk/daily_build/otp_build_win32_r13a.2009-03-16_22/otp_src_R13A/lib/erl_interface/
obj.mt/win32/erl_malloc.o):(.text+0x47): undefined reference to `ei_malloc'

c:/erl5.7/lib/erl_interface-3.6/lib/erl_interface.lib(C:/cygwin/ldisk/daily_build/otp_build_win32_r13a.2009-03-16_22/otp_src_R13A/lib/erl_interface/
obj.mt/win32/erl_malloc.o):(.text+0x7c): undefined reference to `ei_realloc'
    (...)


c:/erl5.7/lib/erl_interface-3.6/lib/erl_interface.lib(C:/cygwin/ldisk/daily_build/otp_build_win32_r13a.2009-03-16_22/otp_src_R13A/lib/erl_interface/
obj.mt/win32/erl_error.o):(.text+0xa2): more undefined references to
`__iob_func' follow
    collect2: ld returned 1 exit status

??? :|
The ei.lib and erl_interface.lib files were in
c:/erl5.7/lib/erl_interface-3.6/lib so I was expecting this to work. :\

A little online research (
http://erlang.org/pipermail/erlang-questions/2003-September/009854.html)
lead me think that the .lib files weren't GCC-compliant (and what I needed
were .a files).
So it would be a simple matter of getting the source and compiling
erl_interface again (famous last words).

This is were someone can come in and say "No! No! No! You just had to do
XPTO."
Considering no XPTO existed I went along to try and build erl_interface.

First I tried to just build it using the files that were available on the
windows binary distribution but it failed complaining about a missing /make/
target.mk.
So I:

   - got the otp_src_R13A sourcecode
   - did a ./configure
   - exported ERL_TOP=c:/otp_src_R13A
   - IIRC
      - got something about a missing c:/otp_src_R13A/make/i686-pc-mingw32/
      otp.mk folder
      - which I copied and renamed from c:/otp_src_R13A/make/otp.mk.in (I'm
      guessing something is responsible for this step)
      - added the necessary LIBS = -lwsock32 to
   c:/otp_src_R13A/lib/erl_interface/src/i686-pc-mingw32/Makefile
   - did a successful build
      - which resulted in two files: libei.a and liberl_interface.a getting
      placed in c:/otp_src_R13A/lib/erl_interface/obj.debug/i686-pc-mingw32/
      - I created a folder c:/otp_src_R13A/lib/erl_interface/lib
      - and copied the two files there

I then tried using those two files to build the erl_interface tutorial
program with this result:
         /c/Projectos/eNotify/src/native/port
        $ gcc.exe ei.c erl_comm.c -o extprg.exe
-Ic:/otp_src_R13A/lib/erl_interface/include
-Lc:/otp_src_R13A/lib/erl_interface/lib -lei -lerl_interface

c:/otp_src_R13A/lib/erl_interface/lib/liberl_interface.a(erl_malloc.o): In
function `erl_malloc':
        c:/otp_src_R13A/lib/erl_interface/src/legacy/erl_malloc.c:221:
undefined reference to `ei_malloc'

c:/otp_src_R13A/lib/erl_interface/lib/liberl_interface.a(erl_malloc.o): In
function `erl_realloc':
        c:/otp_src_R13A/lib/erl_interface/src/legacy/erl_malloc.c:231:
undefined reference to `ei_realloc'

c:/otp_src_R13A/lib/erl_interface/lib/liberl_interface.a(erl_malloc.o): In
function `erl_free':
        c:/otp_src_R13A/lib/erl_interface/src/legacy/erl_malloc.c:238:
undefined reference to `ei_free'
        ...

c:/otp_src_R13A/lib/erl_interface/lib/liberl_interface.a(erl_fix_alloc.o):
In function `erl_eterm_alloc':
        c:/otp_src_R13A/lib/erl_interface/src/legacy/erl_fix_alloc.c:111:
undefined reference to `__erl_errno_place'
        collect2: ld returned 1 exit status

Which (other than the initial warnings) is exactly the same problem as the
one I got with the original compilation.
Here I took a look at the build process and realized that the erl_interface
build process had also produced a bunch of .o files in another folder:
c:/erl5.7/lib/erl_interface/obj.st.debug/i686-pc-mingw32/

Since the compiler was nagging me about missing .o files I just included
them all in:
         /c/Projectos/eNotify/src/native/port
        $ gcc.exe ei.c erl_comm.c -o extprg.exe
c:/otp_src_R13A/lib/erl_interface/include/*.o
-Ic:/otp_src_R13A/lib/erl_interface/include
-Lc:/otp_src_R13A/lib/erl_interface/lib -lei -lerl_interface -lwsock32
        c:/otp_src_R13A/lib/erl_interface/include/erl_resolve.o: In function
`erl_gethostbyname_r':
        c:/otp_src_R13A/lib/erl_interface/src/legacy/erl_resolve.c:58:
undefined reference to `ei_gethostbyname_r'
        c:/otp_src_R13A/lib/erl_interface/include/erl_resolve.o: In function
`erl_gethostbyaddr_r':
        c:/otp_src_R13A/lib/erl_interface/src/legacy/erl_resolve.c:70:
undefined reference to `ei_gethostbyaddr_r'
        collect2: ld returned 1 exit status

:| This is another struggle.
Under certain circumstances (mine) the functions ei_gethostbyname_r and
ei_gethostbyaddr_r aren't included in the compilation of the ei_resolve.c
file.
Being completely astray from my original goal, and after figuring out that
these were the reentrant versions of the same functions without the _r and
that on windows the original ones are already thread safe (
http://daniel.haxx.se/projects/portability/), I just went ahead and added
these *_r functions calling out to original ones (on the $ifdef __WIN32__
part ). This was the unhealthy hack part. :)
Of course that worked (to shut the compiler up at least). :P
     /c/Projectos/eNotify/src/native/port
    $ gcc.exe ei.c erl_comm.c -o extprg.exe
c:/otp_src_R13A/lib/erl_interface/include/*.o
-Ic:/otp_src_R13A/lib/erl_interface/include
-Lc:/otp_src_R13A/lib/erl_interface/lib -lei -lerl_interface -lwsock32

Finally that got me a working extprg.exe that I was able to complete the
tutorial with!

<sleep break + upgrade to R13B>

I picked up were I left off: being able to compile IF including all of the
.o files.
Some [n00b] research -> http://en.wikipedia.org/wiki/Ar_(Unix) &
http://linux.die.net/man/1/ar
Got me to check if all the .o files the linker was complaining about were
getting archived in the two .a files.
And indeed, all of them were on libei.a.

I unpacked the .o files from libeia.a and replaced it with a call to those
.o:
     /c/Projectos/eNotify/src/native/port
    $ gcc.exe -o extprg.exe ei.c erl_comm.c
/c/otp_src_R13B/lib/erl_interface/obj/i686-pc-mingw32/*.o
/c/otp_src_R13B/lib/erl_interface/obj/i686-pc-mingw32/liberl_interface.a
-Ic:/otp_src_R13B/lib/erl_interface/include -lwsock32

And guess what... It worked! :)

So what am I missing here? Is it normal that "ar"ed files don't link
correctly? Is it mingw? Or is it just me? :)
Any(!!!) clues are more than welcome! :)

Cheers,
Davide :)
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