# Introduction

Sometimes installing the debug packages for gtk and glib isn't quite enough.
(For instance, if the artifacts from -O2 are driving you bonkers in gdb, you
might want to rebuild with -O0.)
Here's how to build from source and use your local version without installing it.

## 32-bit systems

On Ubuntu, to download and build glib and gtk suitable for debugging:

1. If you don't have a gpg key yet, generate one with gpg --gen-key.

2. Create file ~/.devscripts containing DEBSIGN\_KEYID=yourkey, e.g.
DEBSIGN\_KEYID=CC91A262
(See http://www.debian.org/doc/maint-guide/ch-build.en.html

3. If you're on a 32 bit system, do:
```
#!/bin/sh
set -x
set -e
# Workaround for "E: Build-dependencies for glib2.0 could not be satisfied"
# See also https://bugs.launchpad.net/ubuntu/+source/apt/+bug/245068
sudo apt-get install libgamin-dev
sudo apt-get build-dep glib2.0 gtk+2.0
rm -rf ~/mylibs
mkdir ~/mylibs
cd ~/mylibs
apt-get source glib2.0 gtk+2.0
cd glib2.0*
DEB_BUILD_OPTIONS="nostrip noopt debug" debuild
cd ../gtk+2.0*
DEB_BUILD_OPTIONS="nostrip noopt debug" debuild
```
This should take about an hour.  If it gets stuck waiting for a zombie,
you may have to kill its closest parent (the makefile uses subshells,
and bash seems to get confused).  When I did this, it continued successfully.

At the very end, it will prompt you for the passphrase for your gpg key.

Then, to run an app with those libraries, do e.g.
```
export LD_LIBRARY_PATH=$HOME/mylibs/gtk+2.0-2.16.1/debian/install/shared/usr/lib:$HOME/mylibs/gtk+2.0-2.20.1/debian/install/shared/usr/lib
```

gdb ignores that variable, so in the debugger, you would have to do something like
```
set solib-search-path $HOME/mylibs/gtk+2.0-2.16.1/debian/install/shared/usr/lib:$HOME/mylibs/gtk+2.0-2.20.1/debian/install/shared/usr/lib
```

See also http://sources.redhat.com/gdb/current/onlinedocs/gdb_17.html

## 64-bit systems

If you're on a 64 bit systems, you can do the above on a 32
bit system, and copy the result.  Or try one of the following:

### Building your own GTK

```
apt-get source glib-2.0 gtk+-2.0

export CFLAGS='-m32 -g'
export LDFLAGS=-L/usr/lib32
export LD_LIBRARY_PATH=/work/32/lib
export PKG_CONFIG_PATH=/work/32/lib/pkgconfig

# glib
setarch i386 ./configure --prefix=/work/32 --enable-debug=yes

# gtk
setarch i386 ./configure --prefix=/work/32 --enable-debug=yes --without-libtiff
```


### ia32-libs
_Note: Evan tried this and didn't get any debug libs at the end._

Or you could try this instead:
```
#!/bin/sh
set -x
set -e
sudo apt-get build-dep ia32-libs
rm -rf ~/mylibs
mkdir ~/mylibs
cd ~/mylibs
apt-get source ia32-libs
cd ia32-libs*
DEB_BUILD_OPTIONS="nostrip noopt debug" debuild
```

By default, this just grabs and unpacks prebuilt libraries; see
ia32-libs-2.7ubuntu6/fetch-and-build which documents a BUILD
variable which would force actual building.
This would take way longer, since it builds dozens of libraries.
I haven't tried it yet.

#### Possible Issues

debuild may fail with
```
gpg: [stdin]: clearsign failed: secret key not available
debsign: gpg error occurred!  Aborting....
```
if you forget to create ~/.devscripts with the right contents.

The build may fail with a "FAIL: abicheck.sh" if gold is your system
linker.  Use ld instead.