tests: add tool for observing the profile of a given command

Using gdb in batch mode, put a breakpoint on _start and spawn the
process.  Then using the built-in python interpreter print the
confinement label on the process and terminate everything.

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>

.image-garden.mk

@@ -19,6 +19,7 @@ packages:
 - dosfstools
 - flake8
 - flex
+- gdb
 - gettext
 - libdbus-1-dev
 - libpam0g-dev
@@ -57,6 +58,7 @@ packages:
 - flex
 - gcc
 - gcc-c++
+- gdb
 - gettext
 - gobject-introspection
 - libtool
@@ -88,6 +90,7 @@ packages:
 - dejagnu
 - dosfstools
 - flex
+- gdb
 - gettext
 - libstdc++-static
 - libtool

tests/bin/actual-profile-of

@@ -0,0 +1,9 @@
+#!/bin/sh
+exec gdb \
+	--quiet \
+	--batch \
+	--eval-command='set breakpoint pending on' \
+	--eval-command='break _start' \
+	--eval-command='run' \
+	--eval-command='python import os; os.fdopen(3, "wt").write(open("/proc/{}/attr/current".format(gdb.selected_inferior().pid), "rt").read())' \
+	"$@" 3>/dev/stdout 1>/dev/null 2>/dev/null