Develop Reference

How to build boost 1.69.0 for Android with NDK r18b using dec1/Boost-for-Android?

I tried to use https://github.com/dec1/Boost-for-Android to compile boost for Android. It reports 1.69.0 is supported for NDK r18b. I'm under Windows 7.
Even if this is reported as working, I encounter many problems when trying to run the provided script:
Downloaded boost 1.69.0
Downloaded sources
Modified BOOST_SRC_DIR to point to folder containing "1.69.0" boost folder
Modified ANDROID_NDK_ROOT to point to ndk folder
Modified ABIS="armeabi-v7a,x86"
Modified LINKAGE="static"
Added Cygwin to my path (as this is a .sh file I need to run)
Ran doIt.sh
Got non blocking errors:
-nLe fichier sp?cifi? est introuvable.
ERROR: Unsupported HOST_TAG: windows-x86_64
Then I got final error
## COMMAND: mkdir /tmp/ndk-/tmp/build-11600/build-boost/armeabi-v7a/llvm/host-bin
## COMMAND: ./bootstrap.sh --with-toolset=cc Building Boost.Build engine
with toolset cc... Failed to build Boost.Build build engine Consult
'bootstrap.log' for more details ERROR: Could not bootstrap Boost build
'bootstrap.log'reports gcc: not found
Added MinGW to my PATH (to have gcc be found), then retried:
Now I get in 'bootstrap.log':
cc -o bootstrap/jam0 command.c compile.c constants.c debug.c execcmd.c frames.c function.c glob.c hash.c hdrmacro.c headers.c jam.c jambase.c jamgram.c lists.c make.c make1.c object.c option.c output.c parse.c pathsys.c regexp.c rules.c scan.c search.c subst.c timestamp.c variable.c modules.c strings.c filesys.c builtins.c class.c cwd.c native.c md5.c w32_getreg.c modules/set.c modules/path.c modules/regex.c modules/property-set.c modules/sequence.c modules/order.c execunix.c fileunix.c pathunix.c
command.c:1:0: sorry, unimplemented: 64-bit mode not compiled in
There is no 'cc' available in my PATH, dunno where this is supposed to be found
Any idea what I may be doing wrong?

Sorry, only building on linux is officially supported. Mac and Windows should work fine too but details of setting up the relevant environments (eg cgwin or homebrew) is beyond the scope of what this project tries to do.
If you want to use windows as a host you have two easiest options are:
Use virtual machines eg. VirtualBox or and create a linux virtual machine where you do the building.
You can also simply download and use the precompiled binaries I have made available
No matter what os you use to build under, the resulting binaries can then be copied to windows and used from then on as if you had built on windows to start with (theyre cross compiled for android).

Issue in Linking a C Library compiled with CMake in Android.

I am building a daemon on Android Platform. For which I have cross compiled the existing code, which is present in Linux to Android. Please consider my below 2 cases -
I cross compile the code using Cmake with Android NDK-15 and push manually to the board on which Android Code is available. The path in which we push is /system/lib. Then if I try to execute my daemon (which is also pushed manually to /system/bin ) everything works fine.
But,
2 The cross compiled library have been pushed into the AOSP code by writing an Android.mk file written in vendor specific folder. I have used BUILD_PREBUILTS method and was successfully able to push the libraries to /system/lib. Now, when I try to execute my application (Compiled with CMake ) I get a linker error.
Below is the error which I get ( Reference Example ) -
Below is the folder structure -
Total Number of folders - 3
a. abc folder which produces output libabc.so and links to libdef.so and
libghi.so
b. def folder which produces output libdef.so
c. ghi folder which produces output libghi.so
When I push all the 3 libraries (libabc.so, libdef.so, libghi.so ) directly in /system/lib and my executable (drive_test) which links all the 3 libraries, I have no issue. But, when I push it along with AOSP build I get the following error on execution of the executable (drive_test) -
a. Unable to link ../abc/def.so file.
I am unable to debug how to solve this linker issue. I am not getting whether it is because of CMake (or) any other issue.

If you're trying to make a system daemon (something that goes in /system/bin), don't use the NDK. Just use the AOSP build system.
In mydaemon/Android.bp (make sure to add this path to the root Android.bp file):
cc_library {
name: "libmylib",
srcs: ["mylib.cpp"],
}
cc_binary {
name: "mydaemon",
srcs: ["mydaemon.cpp"],
shared_libs: ["libmylib"],
}
The build system will deal with getting libraries and binaries into the right place for you.

Android Tess-two: library configuration using cygwin

i am following this tutorial here to use Tesseract libs for android. and in step(b) in the link posted, it says: b.export TESSERACT_PATH=${PWD}/external/tesseract-3.01
and in cygwin i wrote the following:
dm#me /cygdrive/e/Data/private/Fr/OCR/libs/tess-two-
master/tess-two-master/tess-two
but when i execute it i receive the belwo error:
$ export C:\Program Files (x86)\Tesseract-OCR=${PWD}\external\tesseract-3.01
-bash: syntax error near unexpected token `('
please let me know how to fix it, as i am a beginner to cygwin.
update:
i tried ezrepotein4 answer, and now it gives me "not a valid identifier". please , let me know what is "external\tesseract-3.01", i do not have these files/folders...and what is PWD. thanks

In this tutorial author uses few linux commands:
cd which changes directory - it is an equevalent of windows dir
export which sets environment variable
Before exporting any variable you should change directory to your project dir, because all $PWD strings in further commands will be replaced by your current directory.
This tutorial assumes that you compiled tesseract and leptonica and you keep them in project-dir/tess-two/external directory as tesseract-3.01 and leptonica-1.68. Source code for those libraries are in tess-two/jni directory in repository as stated in README.md https://github.com/rmtheis/tess-two/blob/master/README.md
Code which you are trying yo execute is incorrect both syntactically and semantically. It is incorrect syntactically because you all spaces are treated as separators between arguments. Semantically you are trying to set variable C:\Program Files (x86)\Tesseract-OCR to value of ${PWD}\external\tesseract-3.01. Instead you should set TESSERACT_PATH variable.
To do this try command TESSERACT_PATH=${PWD}/external/tesseract-3.01 as stated in tutorial. This means that you are setting variable TESSERACT_PATH to folder external/tesseract-3.01 in your current dir.
To further inspect a value of this variable type: echo $TESSERACT_PATH.

Build errors while cross compile C source project with android standalone toolchain

I m trying to build old c code with android standalone tool chain and it keeps failing on
following error :
fatal error: ftw.h: No such file or directory
Not sure how to include these headers from android.
Thanks,

ftw.h is included in android-21 platform (ndk 10c):
MBA-Anton:android-ndk-r10c asmirnov$ find /softdev/android-ndk-r10c -name "ftw.h"
/softdev/android-ndk-r10c/platforms/android-21/arch-arm/usr/include/ftw.h
/softdev/android-ndk-r10c/platforms/android-21/arch-arm64/usr/include/ftw.h
/softdev/android-ndk-r10c/platforms/android-21/arch-mips/usr/include/ftw.h
/softdev/android-ndk-r10c/platforms/android-21/arch-mips64/usr/include/ftw.h
/softdev/android-ndk-r10c/platforms/android-21/arch-x86/usr/include/ftw.h
/softdev/android-ndk-r10c/platforms/android-21/arch-x86_64/usr/include/ftw.h

This was an old message, but as I am on a similar ftw-hunt today: as of my writing this, ftw.h does not exist in contemporary android ndk include dirs.
Here are external links to source code for ftw* which may be useful:
http://www.opensource.apple.com/source/ksh/ksh-4/ksh/src/lib/libast/comp/ftw.c
http://www.opensource.apple.com/source/ksh/ksh-4/ksh/src/lib/libast/comp/ftw.h
Also, ftwalk.c is located as above but libast/misc/ftwalk.c (stackoverflow will not let me post a third link cause I'm a newb).

How to build i686-linux-android-gfortran for android-ndk8b (x86 arch Android)?

I tried building i686-linux-android-gfortran using build-gcc.sh following this
(it's for androdindk-7b) but I get error about link.h. I added link.h from here, but it gives further more errors.
Has anyone tried enabling i686-linux-android-gfortran for x86 Android?

From https://groups.google.com/forum/#!msg/android-ndk/QR1qiN0jIpE/g0MHkhTd4YMJ as selalerer suggested. I didn't try this, so I'm posting as a community wiki for reference purposes.
Fortran for x86 Android
=================
The guide is based on this one, many thanks to Phil:
Compiling Android NDK with Objective-C-enabled gcc errors
1) Download and unpack Android NDK 'android-ndk-r8c', (the older -r8b NDK won't work due to missing link.h!):
wget http://dl.google.com/android/ndk/android-ndk-r8c-linux-x86.tar.bz2
2) Create somewhere a folder called 'toolchain-src' (e.g. inside the folder android-ndk-r8c),
'cd' to this new folder
3) Make sure to have git installed ('yum install git' or whatever..) and download
the toolchain sources:
git clone https://android.googlesource.com/toolchain/build.git
git clone https://android.googlesource.com/toolchain/gmp.git
git clone https://android.googlesource.com/toolchain/gdb.git
git clone https://android.googlesource.com/toolchain/mpc.git
git clone https://android.googlesource.com/toolchain/mpfr.git
git clone https://android.googlesource.com/toolchain/expat.git
4) Create the folder 'binutils', 'cd' to this directory, unpack
binutils-2.23 there:
wget ftp.gnu.org/gnu/binutils/binutils-2.23.tar.gz
tar -xvzf binutils-2.23.tar.gz
You should now have a folder toolchain-src/binutils/binutils-2.23
5) Change to folder toolchain-src/build, edit the Makefile.in, changing the line:
--with-gnu-as --with-gnu-ld --enable-languages=c,c++
to
--with-gnu-as --with-gnu-ld --enable-languages=c,c++,fortran
6) In the file android-ndk-r8c/build/tools/build-mingw64-toolchain.sh change the line:
var_append GCC_CONFIGURE_OPTIONS "--enable-languages=c,c++"
to
var_append GCC_CONFIGURE_OPTIONS "--enable-languages=c,c++,fortran"
7) In the file android-ndk-r8c/build/tools/build-gcc.sh, change the line:
EXTRA_CONFIG_FLAGS=$EXTRA_CONFIG_FLAGS" --disable-libquadmath --disable-plugin"
to
EXTRA_CONFIG_FLAGS=$EXTRA_CONFIG_FLAGS" --disable-libquadmath --disable-libquadmath-support --disable-plugin"
8) In the file android-ndk-r8c/build/tools/build-host-gcc.sh, change the line:
ARGS=$ARGS" --enable-languages=c,c++"
to
ARGS=$ARGS" --enable-languages=c,c++,fortran"
And change the line
ARGS=$ARGS" --disable-libquadmath --disable-plugin --disable-libitm --disable-bootstrap"
to
ARGS=$ARGS" --disable-libquadmath --disable-libquadmath-support --disable-plugin --disable-libitm --disable-bootstrap"
9) Build your new toolchain:
/your/path/to/android-ndk-r8c/build/tools/build-gcc.sh -j1 --gmp-version=5.0.5 --mpfr-version=2.4.2 --mpc-version=0.8.1 --binutils-version=2.23 --gdb-version=7.3.x /your/path/to/toolchain-src /your/path/to/android-ndk-r8c x86-4.7
(don't worry about messages like 'expr: warning: unportable BRE:')
10) And go down to your knees in front of the screen, praying to the Lord that somehow these
countless configure scripts doing checks that nobody needs, using an ugly shell language
that cooks your brain with indentation going from right to left, will somehow manage to
compile a zillion of far too small files (so that 10% of the time is spent on compilation
and 90% on starting up GCC), and after an hour of watching progress with
tail -F /tmp/ndk-YourUserName/build/toolchain/config.log
your toolchain will be magically ready. You'll find it in the android-ndk-r8c/toolchains folder.
11) Finally, 'cd' to the folder
'/your/path/to/android-ndk-r8c/toolchains/x86-4.7/prebuilt/linux-x86/i686-linux-android'
and run this command:
ln -s ../libexec libexec
Without this command, it may happen that g++ raises the error message
"g++: fatal error: -fuse-linker-plugin, but liblto_plugin.so not found".
Using strace, I found that g++ looks in the wrong folder, but the link
above lets it find the file liblto_plugin.so nevertheless.
And here are a few lessons learned on the way, so that Google finds this page:
*) To speed up the compilation, you can remove the '-j1'. But only after you got
it to work once, since building in parallel on multiple CPU cores was reported to
cause additional troubles.
*) The error message "Link tests are not allowed after GCC_NO_EXECUTABLES" shows up
when linking fails for x86 (works for ARM). The reason is that GCC does not include
the proper ANDROID_STARTFILE_SPEC and ANDROID_ENDFILE_SPEC from
gcc-4.6.1/gcc/config/linux-android.h. GCC 4.6.1 only specifies them for ARM, but not
for i386, GCC 4.8.0 however does. The GCCs downloaded from Google also do,
so best use Google's GCC.
*) The error message "fatal error: link.h: No such file or directory" also happens
with Google's GCC, and apparently (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50877)
only when you enable additional languages like objc or fortran.
The bug thread is here: http://gcc.gnu.org/ml/gcc-bugs/2012-08/msg00494.html
MIPS has link.h in android-ndk-r8b/platforms/android-9/arch-mips/usr/include
In android-ndk-r8c, link.h is now also present in android-9/arch-x86/usr/include/link.h,
so this bug was fixed.
*) The error message "fatal error: quadmath_weak.h: No such file or directory":
It also happens with the latest gcc-4.8, so we can just continue using Googles GCC 4.7.
Google itself uses --disable-libquadmath, but we additionally need --disable-libquadmathsupport
(see http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47648). So this needs to be added in
android-ndk-r8c/build/tools/build-gcc.sh
and
android-ndk-r8c/build/tools/build-host-gcc.sh
*) The error message "error: Pthreads are required to build libatomic"
Happens when building the ARM version of gcc-4.8 downloaded from gnu.org,
better stay with Google's GCCs.
*) The GCC that came with android-ndk-r8c didn't work for me (error message about
libstdc++.so.6 being too old), while the one in android-ndk-r8b worked
without problems. Since the android-ndk should support as many environments
as possible, I'm not sure why the Googlers decided to depend on a newer libstdc++,
but the good news are that building your own toolchain solves the issue.
*) If you get an error while compiling generic-morestack.c, then replace
#ifdef linux
// On Linux, the first two real time signals are used by the NPTL
with
#if defined(GLIBC) && defined(linux)
// On Linux, the first two real time signals are used by the NPTL