Develop Reference

Preventing spurious -m32 flag when running running setup.py build_ext

I'm trying to cross-compile numpy for arm (BeagleBone & RPi). I am running on debian buster, with a 32bit cross-compilation toolchain, including i386 (32bit) libraries and all necessary arm toolchains.
When I run:
export CC=arm-linux-gnueabihf-gcc CXX=arm-linux-gnueabihf-g++ AR=arm-linux-gnueabihf-ar RANLIB=arm-linux-gnueabihf-ranlib; \
python3 setup.py build_ext --inplace
I get the following error:
C compiler: arm-linux-gnueabihf-gcc -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O3 -Wall -m32 -I/usr/include/i386-linux-gnu/ -m32 -I/usr/include/i386-linux-gnu/ -fPIC
compile options: '-Inumpy/core/src/common -Inumpy/core/src -Inumpy/core -Inumpy/core/src/npymath -Inumpy/core/src/multiarray -Inumpy/core/src/umath -Inumpy/core/src/npysort -I/usr/local/include/python3.7m -c'
arm-linux-gnueabihf-gcc: _configtest.c
arm-linux-gnueabihf-gcc: error: unrecognized command line option ‘-m32’; did you mean ‘-mbe32’?
I've traced through numpy's setup.py file and found that ultimately these settings seem to be generated in the distutils.core._setup_distribution.get_command_obj("build") call.
The error is quite self explanatory, and trying to run the command without the -m32 flags seems to work correctly.
Edit: further digging has revealed that these parameters come to the build script via:
sysconfig.get_config_var("LDSHARED")
I'm still stumped because the following still doesn't work:
$LDSHARED="gcc -pthread -shared" python3 -c "import sysconfig; print(sysconfig.get_config_var('LDSHARED'))"
gcc -pthread -shared -m32 -m32

Turns out this LDSHARED parameter is coming from the Makefile that was used during the build of the python host itself. Under most scenarios it makes sense to have it this way, but a combination of cross-compiling and the arm gcc not accepting that flag made it problematic...
This may very well be unresolvable and I have instead resorted to capturing the parameter from the gcc itself via a symlink/bash script.

Building pywt on ubuntu

I have problems building pywt from source on Ubuntu.
When I run python setup.py build, I get the following error:
running build
running build_py
running build_ext
Cython is not installed. Using compiled file: src/_pywt.pyx
building 'pywt._pywt' extension
creating build/temp.linux-x86_64-2.7
creating build/temp.linux-x86_64-2.7/src
gcc -pthread -fno-strict-aliasing -g -O2 -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -fPIC -DPY_EXTENSION -Isrc -I/usr/local/include/python2.7 -c src/_pywt.c -o build/temp.linux-x86_64-2.7/src/_pywt.o
gcc: error: src/_pywt.c: No such file or directory
gcc: fatal error: no input files
compilation terminated.
error: command 'gcc' failed with exit status 4
When I run cython --version I get the following output:
Cython version 0.21.1

pywt can be installed as an Ubuntu package using apt-get:
sudo apt-get install python-pywt

Python API: C Extension install error

I'm using Mac, and I am trying to write my own c code to use it from Python. I'm new to this, and trying out a sample example from http://www.tutorialspoint.com/python/python_further_extensions.htm.
But, when I run the setup.py file to install my c file, it gives me an error, and I'm not sure what to do. Below is the resulting error message. Thanks a lot!
$ sudo python3 setup.py install
Password:
running install
running build
running build_ext
building 'sample' extension
clang -Wno-unused-result -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -I/usr/local/include -I/usr/local/opt/sqlite/include -DFOO=1 -UBAR -I/some/dir -I/usr/local/Cellar/python3/3.4.2_1/Frameworks/Python.framework/Versions/3.4/include/python3.4m -c pysample.c -o build/temp.macosx-10.10-x86_64-3.4/pysample.o
clang -bundle -undefined dynamic_lookup -L/usr/local/lib -L/usr/local/opt/sqlite/lib build/temp.macosx-10.10-x86_64-3.4/pysample.o -L/usr/local/lib -lsample -o build/lib.macosx-10.10-x86_64-3.4/sample.so
ld: library not found for -lsample
clang: error: linker command failed with exit code 1 (use -v to see invocation)
error: command 'clang' failed with exit status 1

Failed to build the bsdiff module

Good afternoon all,
I am having trouble using the bsdiff module with Python. While I can use shell scripts I would prefer to have a cross-platform solution.
I have downloaded bsdiff4-1.1.4 and attempt to run setup.py as follows:
Files list:
bsdiff4 build CHANGELOG.txt do.sh examples Makefile README.rst setup.py
I run:
python3 setup.py build
And I get this error:
/usr/lib/python3.4/distutils/dist.py:260: UserWarning: Unknown distribution option: 'entry_points'
warnings.warn(msg)
running build
running build_py
running build_ext
building 'bsdiff4.core' extension
x86_64-linux-gnu-gcc -pthread -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -g -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security -D_FORTIFY_SOURCE=2 -fPIC -I/usr/include/python3.4m -c bsdiff4/core.c -o build/temp.linux-x86_64-3.4/bsdiff4/core.o
bsdiff4/core.c:8:20: fatal error: Python.h: No such file or directory
#include <Python.h>
^
compilation terminated.
error: command 'x86_64-linux-gnu-gcc' failed with exit status 1
I want to be able to use python to apply patches to binary files.
Any help appreciated.
José

You need to install apt-get install python3-dev.
ubuntu python3-dev
header files and a static library for Python
If it is your system python you will need sudo

Installing rdiff on docker containers

I am trying to make a backup solution off docker containers using rdiff. I have python install and the python-dev packages but when I run the install command:
python ./setup.py install
I get the following error
running install
running build
running build_py
running build_ext
building 'rdiff_backup._librsync' extension
gcc -pthread -fno-strict-aliasing -g -O2 -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -fPIC -I/usr/local/include/python2.7 -c _librsyncmodule.c -o build/temp.linux-x86_64-2.7/_librsyncmodule.o
_librsyncmodule.c:25:22: fatal error: librsync.h: No such file or directory
compilation terminated.
error: command 'gcc' failed with exit status 1

Your container needs the librsync-dev package.