[Python-Dev] Undefined dlopen When Building Module On Android

[Cyd Haselton]

On Mon, Jan 19, 2015 at 8:51 AM, Cyd Haselton <chaselton at gmail.com> wrote:
> Hello,
> I'm struggling with a build issue on Android; I've posted to the
> general python list with no result, so I'm re-posting here in hopes
> that someone can help.  If this is the wrong place feel free to let me
> know.
>
> I'm attempting to build Python 2.7.8 on my Android device; I'm using
> an environment that simulates a Linux filesystem within the Android
> terminal using a port of fakechroot.  Within that environment I've
> ported and/or bootstrapped a number of Linux utilities (curl, git,
> openssl, gcc)
>
> I run ./configure, then make, and the executable and library are
> built.  The problem occurs when build_ext is run; the newly built
> python executable builds, then links _struct, and immediately
> afterwards I get an 'undefined reference to dlopen' error.
>
> If I run ./python setup.py --verbose -library-dirs /path/to/lib
> --libraries='c dl m' -f, the 'undefined reference to dlopen' error is
> thrown again.
>
> If I run ./python setup.py --verbose -library-dirs /path/to/lib
> --libraries='-lc -ldl -lm' -f the build continues past _struct...even
> though ld throws the expected 'unable to find -l-lc' and other errors.
>
> Let me know if you need me to provide additional information.  Any
> help would be greatly appreciated.
>
> Cyd


Additionally I took a strace of the error producing command. The
following is (hopefully) a relevant portion minus the various 'no such
file' lines before the correct lib is found (which it always is)

16513 open("/data/data/jackpal.androidterm/kbox2/bld/python/Python-2.7.8/Lib/distutils/unixccompiler.py",
O_RDONLY|O_LARGEFILE) = 3           16513
open("/data/data/jackpal.androidterm/kbox2/bld/python/Python-2.7.8/Lib/distutils/unixccompiler.pyc",
O_RDONLY|O_LARGEFILE) = 4       16513 vfork()
 = 16525
16513 wait4(16525,  <unfinished ...>
16525 open("/data/data/jackpal.androidterm/kbox2/bin/sh",
O_RDONLY|O_LARGEFILE) = 3
16525 execve("/data/data/jackpal.androidterm/kbox2/bin/sh", ["sh",
"-c", "gcc --sysroot=/usr/gcc-4.9.2/sysroot -print-multiarch >
build/temp.linux-armv7l-2.7/multiarch 2> /dev/null"], [/* 58 vars */])
= 0

*snip call to libc intercepted by libfakechroot*

16525 open("/system/lib/libc.so", O_RDONLY|O_LARGEFILE|0x80000) = 3
16525 open("/system/lib/libm.so", O_RDONLY|O_LARGEFILE|0x80000) = 3
16525 open("/dev/__properties__",
O_RDONLY|O_LARGEFILE|O_NOFOLLOW|0x80000) = 3
16525 open("build/temp.linux-armv7l-2.7/multiarch",
O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE, 0666) = 3
16525 open("/data/data/jackpal.androidterm/kbox2/dev/null",
O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE, 0666) = 3
16525 fork()                            = 16526
16525 wait4(-1,  <unfinished ...>
16526 open("/acct/uid/10186/tasks", O_RDWR|O_CREAT|O_LARGEFILE, 0666)
= -1 EACCES (Permission denied)

See attached for remainder
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