A few words on everything daemon – systemd and power management overridden problem

For few weeks I had a strange problem with power management on my laptop. It is quite old Asus, really nicely supported by Linux community, so it was almost impossible to be any low-level problem. The problem was that, when I had lid of the laptop closed, system was always suspending, ignoring Plasma power management settings. This was really annoying, especially when I was leaving some background task and of course closing the lid to save power on turned off screen and then few minutes later realizing that the computer slept just after leaving it. Unfortunately I had not much time to investigate what was the reason.

Until today. It seems that systemd just started managing another part of my computer – power management. And was kind enough to ignore the fact that desktop environment is already managing it and set up its own configuration files. The effect was that it was intercepting lid close event and suspend the computer anyway.

So, if you encountered similar problem, then below are the details of what should be changed to turn that feature off.

  1. Open /etc/systemd/logind.conf with your favorite editor as root.
  2. Add following lines to [Login] section:
HandlePowerKey=ignore
HandleSuspendKey=suspend
HandleHibernateKey=hibernate
HandleLidSwitch=ignore
  1. Save and restart logind with:
systemctl restart systemd-logind.service

Now you should have gotten rid of systemd’s attempt to be the everything you need on Linux box (at least this time).

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Wget with SSL/TLS support for Android

wget dependency tree

wget dependency tree

Lately I have tried to download some file from a website to my Android smartphone. Simple thing, yeah? Well, not really. Unfortunately mobile browser developers removed many features from their mobile distributions. One of them is a possibility of downloading random page to disk as is. Instead (this is the case at least with Mozilla’s product) they are forcing “Download as PDF” feature. I had a bit of luck, because the file I was trying to download was MP4 movie, which is downloadable, maybe not in an intuitive way, but it is. But before I have found that feature hidden in a player’s context menu, I tried another solution – wget. Since I am great fan of terminals, I have busybox installed on my phone. Those of you, who know what exactly is busybox should know that this is set of lightweight variants of most standard UNIX tools. So, if they are lightweight, they had to cut some part of tool functionality, right? And in case of my busybox’s wget, they cut HTTPS support. And today, it is more likely to encounter site which is only HTTPS than one that is only HTTP, at least when talking about popular sites. So I had to get my own distribution of wget, that will not be such constrained one.

Not to get you bored too much, here you can find binary distribution of what I achieved to compile. It was compiled for ARMv7 platform using NDKr12b and API level 24 (Nougat), so it will probably not work on most of current Android phones, but if you read later, it is probably working on your device or even is outdated. If you are interested in recompiling binaries yourself, you can find detailed how-to in the next part of this article.

Dependencies

Before compiling wget itself, you have to have whole bunch of its dependencies. But at first, you of course need Android compiler. It is distributed as part of NDK and I won’t describe its installation here. Sources of every program compiled here can be grabbed from its official sites (list at the end of this post). The only exception is libtasn1, which required few hacks to be done to make it compile with Android bionic libc. Its source, ported to Android can be get from my github repo.

Let’s start with programs that does not depend on anything. For all projects, the procedure is more or less the same and can be described with simplified bash script:

tar -zxvf program-1.00.tar.gz
mkdir build
mkdir install
cd build
CC=arm-linux-androideabi-gcc AR=arm-linux-androideabi-ar RANLIB=arm-linux-androideabi-ranlib CFLAGS=-pie \
    ../program-1.00/configure --host=arm-linux --prefix=/data/local/root
make
make install DESTDIR=$(dirname `pwd`)/install/
cd ../install
tar -zcvf program.tar.gz *

gmp, libidn and libffi

For these three programs, the procedure above should work without any modification.

nettle

Since nettle depends on gmp, it has to be configured with paths to gmp binaries and headers in its CFLAGS and LDFLAGS variables. They should look like this:

CFLAGS="-pie -I`pwd`/../../gmp/install/data/local/root/include"
LDFLAGS="-L`pwd`/../../gmp/install/data/local/root/lib"

when invoking configure script.

libtasn1

This was the hardest part for me, but should go smoothly now. Script below should do the work correctly:

git clone git@github.com:v3l0c1r4pt0r/android_external_libtasn1.git
mkdir build
mkdir install
cd build
CC=arm-linux-androideabi-gcc AR=arm-linux-androideabi-ar RANLIB=arm-linux-androideabi-ranlib CFLAGS=-pie \
    ../libtasn1/configure --host=arm-linux --prefix=/data/local/root --disable-doc
make
make install DESTDIR=$(dirname `pwd`)/install/
cd ../install
tar -zcvf libtasn1.tar.gz

p11-kit

This is the last dependency of gnutls which is the only, but very important dependency of wget. Just embedding libtasn1 and libffi should do the job well.

CFLAGS="-pie -I`pwd`/../../libtasn1/install/data/local/root/include"
LDFLAGS="-L`pwd`/../../libtasn1/install/data/local/root/lib -L`pwd`/../../libffi/install/data/local/root/lib"

Notice that libffi has no headers, so we add it just to CFLAGS here!

gnutls

This one was more complicated than the rest. As I mentioned above, it is very important to wget functionality. However wget’s dependency on it could probably be turned off, we would not have TLS support then. When compiling it I had some problems that seemed to be serious. There were a few errors while making it, so I had to call make twice and even though it failed. Despite that it seem to work after make install, which obviously failed too. In my case following script did the job:

mkdir build
mkdir install
cd build
CC=arm-linux-androideabi-gcc AR=arm-linux-androideabi-ar RANLIB=arm-linux-androideabi-ranlib \
    CFLAGS="-pie -I`pwd`/../../gmp/install/data/local/root/include -I`pwd`/../../nettle/install/data/local/root/include -I`pwd`/../../libtasn1/install/data/local/root/include -I`pwd`/../../libidn/install/data/local/root/include -I`pwd`/../../p11-kit/install/data/local/root/include" \
    LDFLAGS="-L`pwd`/../../gmp/install/data/local/root/lib -L`pwd`/../../nettle/install/data/local/root/lib -L`pwd`/../../libtasn1/install/data/local/root/lib -L`pwd`/../../libidn/install/data/local/root/lib -L`pwd`/../../p11-kit/install/data/local/root/lib" \
    ../gnutls-3.4.9/configure --host=arm-linux --prefix=/data/local/root --disable-cxx --disable-tools
make || make
make install DESTDIR=$(dirname `pwd`)/install/ || true
cd ../install
tar -zcvf file.tar.gz *

Compilation

Since we should now have all dependencies compiled, we can try compiling wget itself. The procedure here is the same as with dependencies. We just have to pass path to gnutls. And then standard configure, make, make install should work. However if your NDK installation is fairly new and you were not hacking it before, you most likely don’t have <sys/fcntl.h> header and make should complain about that. Luckily Android itself have this header present, but for reason unknown it is kept in include directory directly. To make wget, and any other program that uses it, compile you can just point “sys/” instance to <fcntl.h> with symlink or do something like that:

echo "#include <fcntl.h>" > $TOOLCHAIN/sysroot/usr/include/sys/fcntl.h

where $TOOLCHAIN/sysroot is path at which you have your headers placed. Depending on tutorial you were using for making it work it may have different structure.

Installation

All commands I presented above implies that you have your custom-compiled binaries in “/data/local/root”. I made it that way to have clear separation between default and busybox binaries. If you want to have them somewhere else, you should pass it to configure scripts of all programs you are compiling. After successful compilation of all tools, I have made single tarball containing all compilation output (this file’s link was placed above). Its content can be installed into Android by typing

tar -zxvf wget-with-deps.tar.gz -C/

using adb shell or terminal emulator.

Sources

Below you can find links to sources of all programs nedded to follow this tutorial.

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