-# 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.
+
+
+Overview
+========
+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, which requires setup:
+ sudo mkdir /data
+ sudo chown $USER /data
+
+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
+ - Packages the package in one or more .dpkg files for distribution
+Reading and following build-package.sh is the best way to understand what's going on here.
+
+Additional utilities are contained here:
+ - 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+
+ - 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 libglob package
+
+* undefined reference to 'rpl_malloc' and/or 'rpl_realloc': These functions are added by some autoconf setups
+ when it fails to detect 0-safe malloc and realloc during cross-compilating. Avoided by defining
+ "ac_cv_func_malloc_0_nonnull=yes ac_cv_func_realloc_0_nonnull=yes".
+ See http://wiki.buici.com/xwiki/bin/view/Programing+C+and+C%2B%2B/Autoconf+and+RPL_MALLOC
+
+* 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
+=================================
+<dlfn.h> declares
+
+> enum { RTLD_NOW = 2, RTLD_LAZY = 1, RTLD_LOCAL = 0, RTLD_GLOBAL = 0x00100, RTLD_NOLOAD = 4}; // 64 bit
+> enum { RTLD_NOW = 0, RTLD_LAZY = 1, RTLD_LOCAL = 0, RTLD_GLOBAL = 2, RTLD_NOLOAD = 4}; // 32 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, e.g. on most current Linux 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.
+
+
+Bootstrapping
+=============
+To get files on device one option is:
+ udpsvd -vE 0.0.0.0 8069 tftpd -c . # Run on device. -c arg to allow file uploading
+ printf "mode binary\nput out.md\nquit" | tftp 192.168.0.12 8069 # on computer
+Another is with ftp:
+ tcpsvd -vE 0.0.0.0 8021 ftpd -w . # Run on device. -w arg to allow file uploading
+ printf "put tmp.c\nquit" | ftp -n 192.168.0.12 8021 # Run on computer. -n arg to use anonymous login
+NOTE: The ftpd and tftpd programs has been patched to run without chroot. This means that the directory
+ serving is only the starting point and clients may cd out of if the access the whole system!
+
~mdw / termux-packages / commitdiff