khorben's Place

Debian sarge packages for some DeforaOS software

Mon May 14 01:16:24 CEST 2007

Ok, so before I go ahead and put it somewhere on www.defora.org (probably in the packages page), here is something I invite you to play with:

deb http://ftp.defora.org/debian sarge defora
deb-src http://ftp.defora.org/debian sarge defora

which you can directly include to your /etc/apt/sources.list if you are running Debian sarge.

You can safely replace "http" with "ftp" if you prefer.

The packages available so far are libsystem0, libsystem-dev, init, probe, and gputty.

I promise to write some documentation for all of this as soon as I can.

Update: yes, this will be available for etch when this machine gets an update.

Note for C/C++ developers and code auditors

Thu May 3 19:56:35 CEST 2007

Duh. I was lurking on fefe's web site this evening, and I stumbled upon GCC bug #30475 (and associated thread on GCC's mailing-list). I won't add my own comment here, but just try to summarize the essential.

The following integer overflow detection code:

1  signed int a = INT_MAX;
2  signed int b = 1;
3  
4  	if(a + b <= 0)
5  		exit(1); //integer overflow detection

is not correct. The C standard apparently says that signed integer overflows are undefined. This sort of security check code consequently breaks portability of the code, or at least cannot be proven correct.

Moreover, it seems the newest versions of GCC (>= 4.1) may optimize it out by default (e.g. even without specifying -O).

This definitely deserves the attention of developers and code auditors. There is probably a lot of code out there that may look safe but is not. Read more about it there.

Some good practices in Gtk+ programming

Wed May 2 21:43:49 CEST 2007

Not that I'm a Gtk+ guru, but there are a number of non-obvious things that may break if you don't pay attention:

call gtk_init() before getopt()
convert filenames to UTF-8 before use with g_filename_to_utf8()
call g_object_unref() whenever you have internally allocated something, used it somewhere and don't need it elsewhere (this is never obvious, check the documentation)
use extra variables to avoid macro expansions like GTK_TYPE() all the time (it improves readability too)
check in the documentation if the functions you are using exist in every version available, and otherwise make good use of GTK_CHECK_VERSION(); write alternative code whenever possible (it's often easy, and many users stuck with old Debian, Ubuntu or Solaris systems will thank you)

I said I'd never blog