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Insist on better asserts

I never really liked C's assert() feature. If an assertion is violated, it'll tell you what assertion failed but completely lacks any context:
example: example.c:9: main: Assertion `i == 3' failed.
This is better:
Assertion failed insist.c:7 in main(), insist(i == 3): Something went wrong, wanted i == 3, got 4
The main difference here is that there's context about what failed. A message for humans looking to debug this. This is especially important on Linux these days because every distro I've used recently hates sysadmins and hates debugging - all libraries are stripped of debug symbols and coredumps are disabled by default.

What's the usage look like?

#include "insist.h"

int main() {
  int i = 4;
  //assert(i == 3);
  insist(i == 3, "Something went wrong, wanted i == 3, got %d", i);
  return 0;
I also added a special 'return' version of this, 'insist_return' that lets you do error checking and early aborting like this:
insist_return(fd >= 0, START_FAILURE,
              "socket() returned %d, an error: %s", fd, strerror(errno));
Works just like insist() except returns START_FAILURE if 'fd > 0' is false and additionally logs the error formatted above.

Code here: insist.h

xdotool 2.20110530release

It's been about 8 months since the last xdotool release, and I think it's long overdue! This release has a ton of new feature and fixes.

Download: xdotool-2.20110530.1.tar.gz

As usual, if you find problems or have feature requests, please file bugs or send an email to the list.

Changelist since previous announcement:

  - New set_window feature: --urgency. This lets you set the urgency flag on a
    window Window managers will interpret this as something about your window
    needing attention. It might flash in the taskbar, pop up, or other.
    Original patch and suggestion by ervandew.
  - New function: xdo_window_seturgency (see above)
  - Hack in OS X support as it is missing a proper clock_gettime.
    Should fix
    Reported by
  - Add support for typing UTF-8 characters. Patch from Joseph Krahn.
  - Make all output call fflush to send data immediately (for pipes). Reported
    by Andreas Wagner on the mailing list.
  - Make 'get_desktop_viewport' output usable with 'set_desktop_viewport'
  - You can now make 'libxdo.a' for embedding libxdo into your binary
    (Requested by psc on the mailing list).
  - Fixed a typing bug where the keymap changes unnecessarily 
  - Should now build cleanly in C++ environments (Reported by psc on the
    mailing list)
  - bugfix: xdotool should use command names first before trying file scripts. 
    See for original report.
  - Add a 'sleep' command. (Requested by Joseph Krahn via mailing list)
  - Add --relative flag to windowmve. (Requested by Anthony Thyssen via mailing
  - Add --desktop flag to the search command. This lets you search for windows
    on specific desktop. Requires a window manager that supports multiple
    desktops in a way that EWMH supports.
  - Add --limit flag to search. This allows you to break the search early after
    a certain number of matches. (Requested by Anthony Thyssen)
  - New command 'getwindowgeometry' for fetching window position and size
    (Requested by Anthony Thyssen via mailing list)
  - Add --sync flag to search command; blocks until results are found.
    xdotool will search every 0.5 seconds for results.
  - windowmove can now move windows along an axis. Give literal 'x' or 'y'
    instead of a coordinate and it uses the current position. (Requested by
    etnlIcarus via mailing list)
  - Add '--args N' and '--terminator TERMINATOR' to the 'exec' command.
    Default terminator unless specified (or --args is) is ':' (Requested by
    Joseph Krahn and Henning Bekel via mailing list)
  - set_desktop now supports --relative flag (+N or -N to move relative)
    (Requested by Anthony Thyssen)
  - The mouse cursor now changes during 'xdotool selectwindow' (Requested by
    Anthony Thyssen via mailing list)
  - Added '--args N' and '--terminator TERMINATOR' to the 'type' command.
  - Add 'getdisplaygeometry' command for querying the size of your screen.
    (Requested by @rrwo via twitter)
  - Add xdo_get_viewport_dimensions function.

xdotool 2.20101012 release

New xdotool for your enjoyment. Lots of features and bug fixes. Huge thanks to folks who sent in bug reports, patches, or ideas. This version should be ABI compatible to the previous release. All tests are passing (270 tests, 2838 assertions).


Major changes:

  • New commands: behave_screen_edge, windowminimize, exec
  • Add static build ('make xdotool.static')
  • Add 'restore' feature to 'mousemove'.
  • Improvements to xdotool 'script' behavior. Patch from Henning Bekel.

Cool tool: With the new screen edge behavior, added examples/ This takes a selected window (by click) and hides it until the mouse hits the left-side of the screen. The window will hide again when the mouse leaves the window; the window will be full-height and slide in from the left. When hiding it, it will slide left, off of the screen. If you run this and want to restore the window, just ctrl+c the script, rerun it, and hit ctrl+c again before clicking on a new window.

As usual, if you find problems or have feature requests, please file bugs or send an email to the list.

Changelist since previous announcement:

  - New command: 'windowminimize' for minimizing windows.
  - New command: 'behave_screen_edge' to attach commands to edge and corner activities.
    For example, to lock your screen when the mouse hits the top-right corner
    for more than 2 seconds:
      xdotool behave_screen_edge --delay 2000 top-right exec xscreensaver-command -lock
    'xscreensaver-command' comes with the xscreensaver package.
  - New command: 'exec' for executing commands. Useful with behave_screen_edge.
  - Bug fix: Catch pointer grab failures in selectwindow (xdo_window_select)
    and abort if we can't grab it and report an error message.
  - Add  --delay and --repeat flags to click. This allows you to easily
    double-click (or more) in a single command. Requested by meenakshi sundaram
    via the mailing list.
  - Add new option to mouse move 'restore'. This will restore the mouse position
    to the last known position prior to the most recent move. That is:
      xdotool mousemove 0 0 mousemove restore
    the above will move the mouse to 0,0 then move the mouse back to the
    position it was before. Requested by luc le rumeur and suffian amjad on the
    mailing list.
  - Add 'static' and 'install-static' targets. Requested by Anthony
    Thyssen on the mailing list.
  - Fix bug in xdotool getmouselocation that didn't search for the client window
  - New function: xdo_mousewindow, which lets you get the window the mouse is
    currently over.
  - New function: xdo_mouselocation2, which is an extended version of
    xdo_mouselocation and includes the window the mouse is currently over.
  - New function: xdo_window_minimize, which minimizes a window.
  - Add patch from Henning Bekel that greatly improves xdotool's script
    feature. Scripts now no longer invoke /bin/sh for each line, but instead
    build a command chain to execute. Further, positional arguments ($1, $2,
    etc) and environment variables ($FOO, $WINDOWID, etc) work as expected
    despite the removal of /bin/sh.

xdotool 2.20100601 release

Thanks to some early testing and feedback from the previous xdotool release, I've put together a new release that fixes a few minor problems.

Download: xdotool-2.20100601.2912.tar.gz

As usual, if you find problems or have feature requests, please file bugs or send an email to the list.

Changelist since previous announcement:

  - Add --sync and --clearmodifiers support to mousemove_relative
  - Fix bug in mousemove_relative --polar (Reported by Paul S via mailing list)
  - Change polar coordinates to be 'north'-oriented (0 is up, 90 is right...)
    (Requested by Paul S via mailing list)
  - Changed xdotool search flags. '--title' now means '--name' to match the
    window name (shown in the window manager title bar for the window).
    --title still works, but you will get a warning about deprecation.
  - Walked through all commands and tried to make sure the manpage reflects
    reality and has more detail where needed.

  - Skip certain tests when the requirements aren't met (ie; no such window manager, etc)
    Reported by Daniel Kahn Gillmor.

xdotool 2.20100524 release

New xdotool for your enjoyment.


Major changes:

  • xdotool getmouselocation now supports --shell for outputting something you can simply eval into your shell
  • Added 'sync' support to several commands. The --sync flag, if supported, will wait until the requested operation has completed before exiting.
  • Added --polar (polar coordinate) support to mousemove
  • Fixed some keymap bugs

As usual, if you find problems or have feature requests, please file bugs or send an email to the list.

Changelist since previous announcement:

  - Add --sync flag to many commands. This flag will make any supporting command
    block until the operation completes. For example, a 'windowmove --sync' will
    only exit once the window has moved. Commands supported:
    * windowactivate
    * windowfocus
    * windowmap
    * windowmove
    * windowunmap
  - Fix
    Multiple keyboard layouts are now supported better. Added unit tests
    to ensure consistency in typing across releases.
  - Added polar coordinate support to mouse movement. 'mousemove' and
    'mousemove_relative' support this. Flag is --polar. 'x' becomes angle (degrees)
    and 'y' becomes distance. The default origin is screen center. If you specify
    a window (to mousemove) then the origin is the center of that window.
    Requested by Paul S on the xdotool-users mailing list.
  - internal: Reworked testing to be less flakey
  - internal: split commands into one per C file
  - API changes that required a version bump.
    * xdo_keysequence and friends now take a delay.
  - New libxdo functions:
    * xdo_window_wait_for_map_state
    * xdo_window_wait_for_active
    * xdo_get_window_location
    * xdo_window_wait_for_focus

  - Add support for searching classnames (not just class)
  - Support switched xkbmaps. We do this by checking if the keycode found for a keysym
    has that keysym as the first or second (normal or with shift-key) mapping, if not
    we pretend we didn't find it and request it be bound as if the keysym wasn't mapped
    to any key.

    This is a hack to avoid knowing what other modifiers are required to type
    keysyms mapped at indexes 2 or beyond (0 is normal, 1 is shift, 2 and beyond
    are unknown).
    Verified fixes this:
    Should fix some of this:
  - Add --shell flag to getmouselocation. This will output data you can safely
    eval in your shell.
  - Add platform detection for Darwin when building.
    Should fix:

  - Fix bug in search where --name wasn't working. Test written to cover this.

  - Bug fixes only this release
  - Rewrote tests to use ruby and will now test against Xvfb and Xephyr using:
    no window manager, openbox, and then gnome.
  - Fix build problems on Arch linux (or gentoo?)
  - Fix searching for only visible windows.
  - Fix xdotool search flags: --title, --name, --class
  - Add include for keysym.h to fix compile errors reported on the mailing

xdotool 1.20100302 release

Thanks to some early testing and feedback from the previous xdotool release, I've put together a new release that fixes a few minor problems.

Download: xdotool-1.20100302.2708.tar.gz

As usual, if you find problems or have feature requests, please file bugs or send an email to the list.

Changelist since previous announcement:

  - Some test fixes suggested by Daniel Kahn Gillmor
  - Don't use isatty(0) anymore as it isn't totally reliable in determining if
    we should try to read from stdin.

  - Minor libxdo patch to avoid exporting unnecessary symbols (Daniel Kahn Gillmor)
  - Minor Makefile fix to only link libxdo (and not xdotool) against libX11 and
    libXtst (also Daniel Kahn Gillmor)
  - Some test cleanup patches by Daniel Kahn Gillmor
  - Fixed the 'type hello' test that would fail sometimes when run in Xephyr.
  - Fix a minor bug in xdo_window_setclass that incorrectly aborts when
    XGetClassHint fails.

grok 20091103 release

Lots of changes since the last announced release. Grok should get some more activity now that I'm actually using it in a few places. If you find bugs or have feature requests, please file them on googlecode issue tracker (see below)

The largest changes are:

  • we ship with Ruby and C API.
  • lots of new testing code.
  • we now use tokyocabinet internally instead of bdb.
Grok documentation:
File bugs/features:

This release has all tests passing in these configurations:

  • FreeBSD 7.1. tokyocabinet 1.4.30, pcre 8.00, libevent 1.4.12
  • Ubuntu 9.04. tokyocabinet 1.4.35, pcre 7.8-2, libevent 1.3e-3
  • CentOS 5.3. tokyocabinet 1.4.9-1, pcre 7.8-2, libevent 1.1a-3.2.1
Thanks to Pete Fritchman, grok also ships with an RPM spec so you can 'rpmbuild -tb grok-20091103.tar.gz' for simple build and deployment. The spec builds grok, grok-devel, and grok-ruby.

I'm using this version of grok myself with good success. It's also being used in the new logstash (log indexing tool) project for doing log parsing.

Full changelist since the last announced release:

 - New: ruby bindings are now really supported.
 - Change 'WORD' pattern to be word bounded (\b)
 - Move grok-patterns to patterns/base
 - update rpm spec to install patterns/base in /usr/share/grok

 - Add a bunch of tests, mostly in ruby, to exercise grok. This uncovered a
   few bugs which are fixed.
   All tests currently pass (both CUnit and Ruby Test::Unit) on:
   * FreeBSD 7.1. tokyocabinet 1.4.30, pcre 8.00, libevent 1.4.12
   * Ubuntu 9.04. tokyocabinet 1.4.35, pcre 7.8-2, libevent 1.3e-3
   * CentOS 5.3. tokyocabinet 1.4.9-1, pcre 7.8-2, libevent 1.1a-3.2.1
 - When making strings in ruby, we now make them tainted per ruby C docs.
 - "Too many replacements" error will now occur if you have cyclic patterns,
   such as defining 'FOO' to be '%{FOO}'. Max replacements is 500.

 - Make 'grok' main take a config for an argument.
 - Add grok rpm spec.
 - Updated Makefile to work on Linux and FreeBSD without modification.
 - Fixed bug introduced in 20091022 where capture_by_(name,subname) didn't
   work properly.
 - Add default values for match {} grok.conf blocks:
   shell: stdout
   reaction: "%{@LINE}"
 - Have grok exit nonzero if there were no reactions executed, akin to grep(1)
   not matching anything. 'reactions' are important here; matches with no
   reaction will not count as a reaction.

 - Fix libgrok accidentally sharing it's parser/lexer functions. Turns out,
   libgrok doesn't actually need to parse the grok.conf, so we don't build
   against it anymore for the library.

 - Convert to using tokyocabinet instead of berkeley db.
   * Berkeley DB isn't easy to target across platforms (4.x versions vary
     wildly in bugs)
   * tokyo cabinet should be faster
   * tokyo cabinet is less code to write, and slightly more readable in the
     author's opinion.
   * we don't have to serialize with xdr anymore

 - include pregenerated bison/flex output since gnu flex varies much from
 non-gnu flex, and many important platforms don't have gnu flex available
 easily from packages (freebsd, centos, etc) but come with the other flex.

 No functional changes.

Oniguruma - named capture example

For whatever reason, I decided to play with oniguruma tonight (a newish regular expression library). I'm considering an effort to port some of grok's functionality to C or C++ for speed reasons. Doing it in C++ would require me to re-learn C++.

The docs are pretty complete, but not very helpful with respect to examples. I wasn't able to find very many useful examples on google, but the API docs are quite good. What wasn't answered by the docs was answered by reading header files. Excellent.

The result of this adventure is this:

# regex: ^(?<test>.*?)( (?<word2>.*))?$
# input: "hello there"

% gcc -I/usr/local/include -L/usr/local/lib -lonig oniguruma_named_captures.c
% ./a.out "hello there"
word2 = there
test = hello
% ./a.out "foobarbazfizz"
word2 = 
test = foobarbazfizz

Download the code

Soekris net4501 GPIO on FreeBSD 7.0

I finally picked up some small parts (leds, breadboard, leads, multimeter) from Fry's to start work on my universal remote project. Yes, I know you can buy universal remotes. I want to learn more electronics, so why not use this as a starter project?

Since my Soekris box is now free of it's router duties, I can use it for this project. To do this, I'll need two pieces: an infrared receiver, and an infrared emitter. I bought an infrared emitter led today, and I just need to buy a receiver online (they're like $2).

Before getting there, I needed to learn how to drive the GPIO ports on the net4501.

It was pretty simple to do, nd after hooking up a few wires I had an LED that blinked after a few hours of reading and hacking. The code itself was trivial to write, I just had to learn how to talk to the GPIO ports.

After writing the blinking code, I decided the next step was clearly to add fading to the LED. This is commonly done with PWM (pulse-width modulation). Apple made this technique famous with its "breathing" LED lights on the monitors and laptops when the devices were in sleep mode.

At any rate, I have successfully written code that makes both the error led and the PIO5 (GPIO 0) pin "breathe".

Download glow.c

Overriding shared library functions

Long story short...

File: 'connect.over' contains

#include <netinet/in.h>

override(`connect', `
    // code to inject before the connect() call is actually made
Output is '' which overrides libc's connect function.
% LD_PRELOAD=./ nc 80
stream connect: fd=3 host=
% LD_PRELOAD=./ nc -u 53 
dgram connect: fd=3 host=
% LD_PRELOAD=./ ssh scorn           
stream connect: fd=3 host=
stream connect: fd=4 host=
scorn(~) %
The output by nc was due to my function above outputting this.

The strange ssh connection on fd=4 above is seemingly due to ssh calling connect() on a tty? fstat says:

jls      ssh         3221    4 /dev        122 crw--w----   ttypd rw
inode 122 on /dev is /dev/ttypd.