Building a C extension

Florian_Kasper · 2 July 2014 14:10

Hi,

After reading the discussion about "the death of Mailing lists", I thought it would be good to post this question directly here:

I have a gem, I want to build the C extensions for. The gem source is located here: https://github.com/nirnanaaa/cracklib .

If I build the source now on my mac (Mavericks) all the headers are found and the gem gets built. All test cases pass correctly

.

Building the gem on Travis results in an error:

...

/home/travis/.rvm/rubies/ruby-2.1.1/bin/ruby -I. ../../../../ext/cracklib/extconf.rb

checking for sys/types.h... *** ../../../../ext/cracklib/extconf.rb failed ***

Could not create Makefile due to some reason, probably lack of necessary

libraries and/or headers. Check the mkmf.log file for more details. You may

need configuration options.

Provided configuration options:

--with-opt-dir

--without-opt-dir

--with-opt-include

--without-opt-include=${opt-dir}/include

--with-opt-lib

--without-opt-lib=${opt-dir}/lib

--with-make-prog

--without-make-prog

--srcdir=../../../../ext/cracklib

--curdir

--ruby=/home/travis/.rvm/rubies/ruby-2.1.1/bin/ruby

/home/travis/.rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/mkmf.rb:456:in `try_do': The compiler failed to generate an executable file. (RuntimeError)

You have to install development tools first.

...

However the packages "build-essential gcc automake" got installed on the before_install step of travis' config

Maybe this is related to changing the HEADER_DIRS and LIB_DIRS in the extconf.rb ?

Hope someone could help.

Thanks,

Flo

Eric_MSP_Veith · 2 July 2014 15:08

Hi Flo,

···

On Wednesday 02 July 2014 16:10:10, Florian Kasper <mosny@zyg.li> wrote:

However the packages "build-essential gcc automake" got installed on the
before_install step of travis' config

Maybe this is related to changing the HEADER_DIRS and LIB_DIRS in the
extconf.rb ?

build-essential pulls in libc6-dev, which contains /usr/include/sys/types.h.
If that's the culprit, the include paths are wrong.

Could you post the actual compiler command line? It should be in mkmf.log.

HTH

--- Eric

Florian_Kasper · 3 July 2014 11:16

Hi Eric,

thanks for helping me. I completely forgot about mkmf.log . Here is the content of this log:

$ find . -type f -name mkmf.log|xargs cat
"gcc -o conftest
  -I/home/travis/.rvm/rubies/ruby-1.9.3-p545/include/ruby-1.9.1/x86_64-linux
  -I/home/travis/.rvm/rubies/ruby-1.9.3-p545/include/ruby-1.9.1/ruby/backward
  -I/home/travis/.rvm/rubies/ruby-1.9.3-p545/include/ruby-1.9.1
  -I../../../../ext/cracklib
  -O3
  -ggdb
  -Wall
  -Wextra
  -Wno-unused-parameter
  -Wno-parentheses
  -Wno-long-long
  -Wno-missing-field-initializers
  -Wpointer-arith
  -Wwrite-strings
  -Wdeclaration-after-statement
  -Wimplicit-function-declaration
  -fPIC conftest.c
  -L.
  -L/home/travis/.rvm/rubies/ruby-1.9.3-p545/lib
  -Wl,-R/home/travis/.rvm/rubies/ruby-1.9.3-p545/lib
  -L.
  -rdynamic
  -Wl,-export-dynamic
  -lcrack
  -Wl,-R -Wl,/home/travis/.rvm/rubies/ruby-1.9.3-p545/lib
  -L/home/travis/.rvm/rubies/ruby-1.9.3-p545/lib
  -lruby
  -lpthread
  -lrt
  -ldl
  -lcrypt
  -lm
  -lc"
/usr/bin/ld: cannot find -lcrack
collect2: ld returned 1 exit status
checked program was:
/* begin */
1: #include "ruby.h"
2:
3: int main(int argc, char **argv)
4: {
5: return 0;
6: }
/* end */

I formatted the output to be more readable. As you already guessed the linker include option for cracklib under $GEMROOT/vendor/cracklib/lib is missing.

Adding the HEADER_DIRS and LIB_DIRS directly to the LDFLAGS resulted in exactly the same error:

"gcc
  -o conftest
  -I/home/travis/.rvm/rubies/ruby-2.0.0-p451/include/ruby-2.0.0/x86_64-linux
  -I/home/travis/.rvm/rubies/ruby-2.0.0-p451/include/ruby-2.0.0/ruby/backward
  -I/home/travis/.rvm/rubies/ruby-2.0.0-p451/include/ruby-2.0.0
  -I../../../../ext/cracklib
  -I/home/travis/build/nirnanaaa/cracklib/vendor/cracklib/lib
  -I/opt/local/include
  -I/usr/local/include
  -I/home/travis/.rvm/rubies/ruby-2.0.0-p451/include
  -I/usr/include
  -I/include
  -O3
  -fno-fast-math
  -ggdb3
  -Wall
  -Wextra
  -Wno-unused-parameter
  -Wno-parentheses
  -Wno-long-long
  -Wno-missing-field-initializers
  -Wunused-variable
  -Wpointer-arith
  -Wwrite-strings
  -Wdeclaration-after-statement
  -Wimplicit-function-declaration
  -fPIC conftest.c
  -L.
  -L/home/travis/.rvm/rubies/ruby-2.0.0-p451/lib -Wl,-R/home/travis/.rvm/rubies/ruby-2.0.0-p451/lib
  -L/home/travis/build/nirnanaaa/cracklib/vendor/cracklib/lib -Wl,-R/home/travis/build/nirnanaaa/cracklib/vendor/cracklib/lib
  -L/usr/local/lib -Wl,-R/usr/local/lib
  -L/home/travis/.rvm/rubies/ruby-2.0.0-p451/lib -Wl,-R/home/travis/.rvm/rubies/ruby-2.0.0-p451/lib
  -L/usr/lib -Wl,-R/usr/lib
  -L/lib -Wl,-R/lib
  -L.
  -fstack-protector
  -rdynamic
  -Wl,
  -export-dynamic
  -lcrack
  -I /home/travis/build/nirnanaaa/cracklib/vendor/cracklib/lib
  -I /opt/local/include
  -I /usr/local/include
  -I /home/travis/.rvm/rubies/ruby-2.0.0-p451/include
  -I /usr/include
  -I /include
  -L /home/travis/build/nirnanaaa/cracklib/vendor/cracklib/lib
  -L /usr/local/lib
  -L /home/travis/.rvm/rubies/ruby-2.0.0-p451/lib
  -L /usr/lib
  -L /lib '-Wl,-rpath,/../lib' -Wl,-R -Wl,/home/travis/.rvm/rubies/ruby-2.0.0-p451/lib -L/home/travis/.rvm/rubies/ruby-2.0.0-p451/lib -lruby -lpthread -lrt -ldl -lcrypt -lm -lc"
/usr/bin/ld: cannot find -lcrack
collect2: ld returned 1 exit status
checked program was:
/* begin */
1: #include "ruby.h"
2:
3: int main(int argc, char **argv)
4: {
5: return 0;
6: }
/* end */

···

---
Flo
On July 2, 2014 at 5:10:03 PM, Eric MSP Veith (eveith@wwweb-library.net) wrote: