testsuite: Add check for shared memory

Created a test process test_shm that allocates a shared memory
segment and prints the segment ID. pmap testsuite runs pmap to
check that the segment is found.

The value returned by shmget() is the same value that is printed
in the fifth column /proc/<PID>/maps

Signed-off-by: Craig Small <csmall@dropbear.xyz>

testsuite/config/unix.exp

@@ -186,6 +186,27 @@ proc make_testproc { } {
     set testproc2_pid [ exec $testproc_path & ]
 }
 
+proc make_testshm_proc { } {
+    global testshmproc_pid testshm_spawnid topdir shmid
+
+    set testshm_realpath "${topdir}/lib/test_shm"
+
+    set testshmproc_pid [ spawn $testshm_realpath ]
+    set testshmproc_spawnid $spawn_id
+    expect {
+	-i $testshmproc_spawnid
+	-re "^SHMID: (\\d+)" { set shmid $expect_out(1,string) }
+	default { fail "spawning testshm" }
+    }
+
+}
+
+proc kill_testshm_proc { } {
+    global testshmproc_pid
+
+    kill_process $testshmproc_pid
+}
+
 proc kill_testproc { } {
     global testproc_path testproc1_pid testproc2_pid