-# termux-packages
-Scripts and patches for building Termux packages
+termux-packages
+===============
+This project contains scripts and patches to cross compile and package packages for
+the [Termux](http://termux.com/) Android application.
+
+The scripts and patches to build each package is licensed under the same license as
+the actual package (so the patches and scripts to build bash are licensed under
+the same license as bash, while the patches and scripts to build python are licensed
+under the same license as python, etc).
+
+NOTE: This is in a rough state - be prepared for some work and frustrations, and give
+feedback if you find incorrect our outdated things!
+
+Initial setup
+=============
+Building packages are for now only tested to work on Ubuntu 15.04. Perform the following
+setup steps:
+
+* Run `ubuntu-setup.sh` to install required packages and setup the `/data/` folder (see below).
+
+* Install the Android SDK at `$HOME/lib/android-sdk`. Override this by setting the environment
+variable `$ANDROID_HOME` to point at another location.
+
+* Install the Android NDK, version r10e, at `$HOME/lib/android-ndk`. Override this by setting
+the environment variable `$NDK` to point at another location.
+
+Alternatively a Dockerfile is provided which sets up a pristine image
+suitable for building packages. To build the docker image, run the
+following command:
+
+ docker build --rm=true -t termux .
+
+After build is successful, you can open an interactive prompt inside the
+container using:
+
+ docker run --rm=true -ti termux /bin/bash
+
+
+Building a package
+==================
+In a non-rooted Android device an app such as Termux may not write to system locations,
+which is why every package is installed inside the private file area of the Termux app:
+
+ PREFIX=/data/data/com.termux/files/usr
+
+For simplicity while developing and building, the build scripts here assume that a /data
+folder is reserved for use on the host builder and install everything there.
+
+The basic flow is then to run "./build-package.sh $PKG", which:
+* Sets up a patched stand-alone Android NDK toolchain
+
+* Reads packages/$PKG/build.sh to find out where to find the source code of the package and how to build it.
+
+* Applies all patches in packages/$PKG/\*.patch
+
+* Builds the package and installs it to $PREFIX
+
+* Creates a dpkg package file for distribution.
+
+Reading and following build-package.sh is the best way to understand what's going on here.
+
+
+Additional utilities
+====================
+* build-all.sh: used for building all packages in the correct order (using buildorder.py)
+
+* check-pie.sh: Used for verifying that all binaries are using PIE, which is required for Android 5+
+
+* detect-hardlinks.sh: Used for finding if any packages uses hardlinks, which does not work on Android M
+
+* check-versions.sh: used for checking for package updates
+
+* clean-rebuild-all.sh: used for doing a clean rebuild of all packages (takes a couple of hours)
+
+* list-packages.sh: used for listing all packages with a one-line summary
+
+
+Resources about cross-compiling packages
+========================================
+* [Linux From Scratch](http://www.linuxfromscratch.org/blfs/view/svn/index.html)
+
+* [Beyond Linux From Scratch](http://www.linuxfromscratch.org/blfs/view/svn/)
+
+* [Cross-Compiled Linux From Scratch](http://cross-lfs.org/view/svn/x86_64-64/)
+
+* [OpenWrt](https://openwrt.org/), an embedded Linx distribution, contains [patches and build scripts](https://dev.openwrt.org/browser/packages)
+
+* http://dan.drown.org/android contains [patches for cross-compiling to Android](http://dan.drown.org/android/src/) as well as [work notes](http://dan.drown.org/android/worknotes.html), including a modified dynamic linker to avoid messing with LD_LIBRARY_PATH.
+
+* [CCTools](http://cctools.info/index.php?title=Main_Page) is an Android native IDE containing [patches for several programs](https://code.google.com/p/cctools/source/browse/#svn%2Ftrunk%2Fcctools-repo%2Fpatches) and [a bug tracker](https://code.google.com/p/cctools/issues/list).
+
+* [BotBrew](http://botbrew.com/) was a package manager for rooted devices with [sources on github](https://github.com/jyio/botbrew). Based on opkg and was transitioning to apt.
+
+* [Kivy recipes](https://github.com/kivy/python-for-android/tree/master/recipes) contains recipes for building packages for Android.
+
+
+Common porting problems
+=======================
+* The Android bionic libc does not have iconv and gettext/libintl functionality built in. A package from the NDK, libandroid-support,
+contains these and may be used by all packages.
+
+* "error: z: no archive symbol table (run ranlib)" usually means that the build machines libz is used instead of the one for cross compilation, due to the builder library -L path being setup incorrectly
+
+* rindex(3) is defined in <strings.h> but does not exist in NDK, but strrchr(3) from <string.h> is preferred anyway
+
+* <sys/termios.h> does not exist, but <termios.h> is the standard location.
+
+* <sys/fcntl.h> does not exist, but <fcntl.h> is the standard location.
+
+* glob(3) system function (glob.h) - not in bionic, but use the `libandroid-glob` package
+
+* cmake and cross compiling: http://www.cmake.org/Wiki/CMake_Cross_Compiling
+ CMAKE_FIND_ROOT_PATH=$TERMUX_PREFIX to search there.
+ CMAKE_FIND_ROOT_PATH_MODE_LIBRARY=ONLY and
+ CMAKE_FIND_ROOT_PATH_MODE_INCLUDE=ONLY
+ for only searching there and don't fall back to build machines
+
+* Android is removing sys/timeb.h because it was removed in POSIX 2008, but ftime(3) can be replaced with gettimeofday(2)
+
+* mempcpy(3) is a GNU extension. We have added it to <string.h> provided TERMUX_EXPOSE_MEMPCPY is defined,
+ so use something like CFLAGS+=" -DTERMUX_EXPOSE_MEMPCPY=1" for packages expecting that function to exist.
+
+
+dlopen() and RTLD_* flags
+=================================
+<dlfcn.h> declares
+
+ enum { RTLD_NOW=0, RTLD_LAZY=1, RTLD_LOCAL=0, RTLD_GLOBAL=2, RTLD_NOLOAD=4}; // 32-bit
+ enum { RTLD_NOW=2, RTLD_LAZY=1, RTLD_LOCAL=0, RTLD_GLOBAL=0x00100, RTLD_NOLOAD=4}; // 64-bit
+
+These differs from glibc ones in that
+
+1. They are not preprocessor #define:s so cannot be checked for with #ifdef RTLD_GLOBAL (dln.c in ruby does this)
+2. They differ in value from glibc ones, so cannot be hardcoded in files (DLFCN.py in python does this)
+3. They are missing some values (RTLD_BINDING_MASK, RTLD_NOLOAD, ...)
+
+
+RPATH, LD_LIBRARY_PATH AND RUNPATH
+==================================
+On desktop linux the linker searches for shared libraries in:
+
+1. RPATH - a list of directories which is linked into the executable, supported on most UNIX systems. It is ignored if RUNPATH is present.
+2. LD_LIBRARY_PATH - an environment variable which holds a list of directories
+3. RUNPATH - same as RPATH, but searched after LD_LIBRARY_PATH, supported only on most recent UNIX systems
+
+The Android linker (/system/bin/linker) does not support RPATH or RUNPATH, so we set LD_LIBRARY_PATH=$USR/lib and try to avoid building useless rpath entries with --disable-rpath configure flags. Another option to avoid depending on LD_LIBRARY_PATH would be supplying a custom linker - this is not done due to the overhead of maintaining a custom linker.
+
+
+Warnings about unused DT entries
+================================
+Starting from 5.1 the Android linker warns about VERNEED (0x6FFFFFFE) and VERNEEDNUM (0x6FFFFFFF) ELF dynamic sections:
+
+ WARNING: linker: $BINARY: unused DT entry: type 0x6ffffffe arg ...
+ WARNING: linker: $BINARY: unused DT entry: type 0x6fffffff arg ...
+These may come from version scripts in a Makefile such as:
+
+ -Wl,--version-script=$(top_srcdir)/proc/libprocps.sym
+The termux-elf-cleaner utilty is run from build-package.sh and should normally take care of that problem.
~mdw / termux-packages / blobdiff