Move lldb/test to lldb/packages/Python/lldbsuite/test.

This is the conclusion of an effort to get LLDB's Python code
structured into a bona-fide Python package.  This has a number
of benefits, but most notably the ability to more easily share
Python code between different but related pieces of LLDB's Python
infrastructure (for example, `scripts` can now share code with
`test`).

llvm-svn: 251532

14 files changed, 547 insertions, 0 deletions

diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/Makefile b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/Makefile
new file mode 100644
index 00000000000..cbac629c7b5
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/Makefile
@@ -0,0 +1,24 @@
+LEVEL := ../../make
+
+LIB_PREFIX := loadunload_
+
+LD_EXTRAS := -L. -l$(LIB_PREFIX)d -ldl
+C_SOURCES := main.c
+
+include $(LEVEL)/Makefile.rules
+
+.PHONY:
+a.out: lib_a lib_b lib_c lib_d hidden_lib_d
+
+lib_%:
+	$(MAKE) -f $*.mk
+
+hidden_lib_d:
+	$(MAKE) -C hidden
+
+clean::
+	$(MAKE) -f a.mk clean
+	$(MAKE) -f b.mk clean
+	$(MAKE) -f c.mk clean
+	$(MAKE) -f d.mk clean
+	$(MAKE) -C hidden clean
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/TestLoadUnload.py b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/TestLoadUnload.py
new file mode 100644
index 00000000000..29f6effeeff
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/TestLoadUnload.py
@@ -0,0 +1,315 @@
+"""
+Test that breakpoint by symbol name works correctly with dynamic libs.
+"""
+
+from __future__ import print_function
+
+import use_lldb_suite
+
+import os, time
+import re
+import lldb
+from lldbtest import *
+import lldbutil
+
+@skipIfWindows # Windows doesn't have dlopen and friends, dynamic libraries work differently
+class LoadUnloadTestCase(TestBase):
+
+    def getCategories (self):
+        return ['basic_process']
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    def setUp(self):
+        # Call super's setUp().
+        TestBase.setUp(self)
+        # Find the line number to break for main.cpp.
+        self.line = line_number('main.c',
+                                '// Set break point at this line for test_lldb_process_load_and_unload_commands().')
+        self.line_d_function = line_number('d.c',
+                                           '// Find this line number within d_dunction().')
+        if not self.platformIsDarwin():
+            if not lldb.remote_platform and "LD_LIBRARY_PATH" in os.environ:
+                self.runCmd("settings set target.env-vars " + self.dylibPath + "=" + os.environ["LD_LIBRARY_PATH"] + ":" + os.getcwd())
+            else:
+                if lldb.remote_platform:
+                    wd = lldb.remote_platform.GetWorkingDirectory()
+                else:
+                    wd = os.getcwd()
+                self.runCmd("settings set target.env-vars " + self.dylibPath + "=" + wd)
+
+    def copy_shlibs_to_remote(self, hidden_dir=False):
+        """ Copies the shared libs required by this test suite to remote.
+        Does nothing in case of non-remote platforms.
+        """
+        if lldb.remote_platform:
+            cwd = os.getcwd()
+            shlibs = ['libloadunload_a.so', 'libloadunload_b.so',
+                      'libloadunload_c.so', 'libloadunload_d.so']
+            wd = lldb.remote_platform.GetWorkingDirectory()
+            for f in shlibs:
+                err = lldb.remote_platform.Put(
+                    lldb.SBFileSpec(os.path.join(cwd, f)),
+                    lldb.SBFileSpec(os.path.join(wd, f)))
+                if err.Fail():
+                    raise RuntimeError(
+                        "Unable copy '%s' to '%s'.\n>>> %s" %
+                        (f, wd, err.GetCString()))
+            if hidden_dir:
+                shlib = 'libloadunload_d.so'
+                hidden_dir = os.path.join(wd, 'hidden')
+                hidden_file = os.path.join(hidden_dir, shlib)
+                err = lldb.remote_platform.MakeDirectory(hidden_dir)
+                if err.Fail():
+                    raise RuntimeError(
+                        "Unable to create a directory '%s'." % hidden_dir)
+                err = lldb.remote_platform.Put(
+                    lldb.SBFileSpec(os.path.join(cwd, 'hidden', shlib)),
+                    lldb.SBFileSpec(hidden_file))
+                if err.Fail():
+                    raise RuntimeError(
+                        "Unable copy 'libloadunload_d.so' to '%s'.\n>>> %s" %
+                        (wd, err.GetCString()))
+
+    @skipIfFreeBSD # llvm.org/pr14424 - missing FreeBSD Makefiles/testcase support
+    @not_remote_testsuite_ready
+    @skipIfWindows # Windows doesn't have dlopen and friends, dynamic libraries work differently
+    def test_modules_search_paths(self):
+        """Test target modules list after loading a different copy of the library libd.dylib, and verifies that it works with 'target modules search-paths add'."""
+
+        # Invoke the default build rule.
+        self.build()
+
+        if self.platformIsDarwin():
+            dylibName = 'libloadunload_d.dylib'
+        else:
+            dylibName = 'libloadunload_d.so'
+
+        # The directory with the dynamic library we did not link to.
+        new_dir = os.path.join(os.getcwd(), "hidden")
+
+        old_dylib = os.path.join(os.getcwd(), dylibName)
+        new_dylib = os.path.join(new_dir, dylibName)
+
+        exe = os.path.join(os.getcwd(), "a.out")
+        self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
+
+        self.expect("target modules list",
+            substrs = [old_dylib])
+        #self.expect("target modules list -t 3",
+        #    patterns = ["%s-[^-]*-[^-]*" % self.getArchitecture()])
+        # Add an image search path substitution pair.
+        self.runCmd("target modules search-paths add %s %s" % (os.getcwd(), new_dir))
+
+        self.expect("target modules search-paths list",
+            substrs = [os.getcwd(), new_dir])
+
+        self.expect("target modules search-paths query %s" % os.getcwd(), "Image search path successfully transformed",
+            substrs = [new_dir])
+
+        # Obliterate traces of libd from the old location.
+        os.remove(old_dylib)
+        # Inform (DY)LD_LIBRARY_PATH of the new path, too.
+        env_cmd_string = "settings set target.env-vars " + self.dylibPath + "=" + new_dir
+        if self.TraceOn():
+            print("Set environment to: ", env_cmd_string)
+        self.runCmd(env_cmd_string)
+        self.runCmd("settings show target.env-vars")
+
+        remove_dyld_path_cmd = "settings remove target.env-vars " + self.dylibPath
+        self.addTearDownHook(lambda: self.dbg.HandleCommand(remove_dyld_path_cmd))
+
+        self.runCmd("run")
+
+        self.expect("target modules list", "LLDB successfully locates the relocated dynamic library",
+            substrs = [new_dylib])
+
+    @skipIfFreeBSD # llvm.org/pr14424 - missing FreeBSD Makefiles/testcase support
+    @skipUnlessListedRemote(['android'])
+    @expectedFailureAndroid # wrong source file shows up for hidden library
+    @skipIfWindows # Windows doesn't have dlopen and friends, dynamic libraries work differently
+    def test_dyld_library_path(self):
+        """Test (DY)LD_LIBRARY_PATH after moving libd.dylib, which defines d_function, somewhere else."""
+
+        # Invoke the default build rule.
+        self.build()
+        self.copy_shlibs_to_remote(hidden_dir=True)
+
+        exe = os.path.join(os.getcwd(), "a.out")
+        self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
+
+        if self.platformIsDarwin():
+            dylibName = 'libloadunload_d.dylib'
+            dsymName = 'libloadunload_d.dylib.dSYM'
+        else:
+            dylibName = 'libloadunload_d.so'
+
+        # The directory to relocate the dynamic library and its debugging info.
+        special_dir = "hidden"
+        if lldb.remote_platform:
+            wd = lldb.remote_platform.GetWorkingDirectory()
+        else:
+            wd = os.getcwd()
+
+        old_dir = wd
+        new_dir = os.path.join(wd, special_dir)
+        old_dylib = os.path.join(old_dir, dylibName)
+
+        remove_dyld_path_cmd = "settings remove target.env-vars " + self.dylibPath
+        self.addTearDownHook(lambda: self.dbg.HandleCommand(remove_dyld_path_cmd))
+
+        # For now we don't track (DY)LD_LIBRARY_PATH, so the old library will be in
+        # the modules list.
+        self.expect("target modules list",
+                    substrs = [os.path.basename(old_dylib)],
+                    matching=True)
+
+        lldbutil.run_break_set_by_file_and_line (self, "d.c", self.line_d_function, num_expected_locations=1)
+        # After run, make sure the non-hidden library is picked up.
+        self.expect("run", substrs=["return", "700"])
+
+        self.runCmd("continue")
+
+        # Add the hidden directory first in the search path.
+        env_cmd_string = ("settings set target.env-vars %s=%s" %
+                          (self.dylibPath, new_dir))
+        if not self.platformIsDarwin():
+            env_cmd_string += ":" + wd
+        self.runCmd(env_cmd_string)
+
+        # This time, the hidden library should be picked up.
+        self.expect("run", substrs=["return", "12345"])
+
+    @skipIfFreeBSD # llvm.org/pr14424 - missing FreeBSD Makefiles/testcase support
+    @skipUnlessListedRemote(['android'])
+    @expectedFailureAndroid # dlopen and dlclose prefixed with "__dl_" on android causing JIT compilation issues
+    @skipIfWindows # Windows doesn't have dlopen and friends, dynamic libraries work differently
+    def test_lldb_process_load_and_unload_commands(self):
+        """Test that lldb process load/unload command work correctly."""
+
+        # Invoke the default build rule.
+        self.build()
+        self.copy_shlibs_to_remote()
+
+        exe = os.path.join(os.getcwd(), "a.out")
+        self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
+
+        # Break at main.c before the call to dlopen().
+        # Use lldb's process load command to load the dylib, instead.
+
+        lldbutil.run_break_set_by_file_and_line (self, "main.c", self.line, num_expected_locations=1, loc_exact=True)
+
+        self.runCmd("run", RUN_SUCCEEDED)
+
+        if lldb.remote_platform:
+            shlib_dir = lldb.remote_platform.GetWorkingDirectory()
+        else:
+            shlib_dir = self.mydir
+        # Make sure that a_function does not exist at this point.
+        self.expect("image lookup -n a_function", "a_function should not exist yet",
+                    error=True, matching=False,
+            patterns = ["1 match found .* %s" % shlib_dir])
+
+        if lldb.remote_platform:
+            dylibName = os.path.join(shlib_dir, 'libloadunload_a.so')
+        elif self.platformIsDarwin():
+            dylibName = 'libloadunload_a.dylib'
+        else:
+            dylibName = 'libloadunload_a.so'
+
+        # Use lldb 'process load' to load the dylib.
+        self.expect("process load %s" % dylibName, "%s loaded correctly" % dylibName,
+            patterns = ['Loading "%s".*ok' % dylibName,
+                        'Image [0-9]+ loaded'])
+
+        # Search for and match the "Image ([0-9]+) loaded" pattern.
+        output = self.res.GetOutput()
+        pattern = re.compile("Image ([0-9]+) loaded")
+        for l in output.split(os.linesep):
+            #print("l:", l)
+            match = pattern.search(l)
+            if match:
+                break
+        index = match.group(1)
+
+        # Now we should have an entry for a_function.
+        self.expect("image lookup -n a_function", "a_function should now exist",
+            patterns = ["1 match found .*%s" % shlib_dir])
+
+        # Use lldb 'process unload' to unload the dylib.
+        self.expect("process unload %s" % index, "%s unloaded correctly" % dylibName,
+            patterns = ["Unloading .* with index %s.*ok" % index])
+
+        self.runCmd("process continue")
+
+    @skipIfFreeBSD # llvm.org/pr14424 - missing FreeBSD Makefiles/testcase support
+    @skipUnlessListedRemote(['android'])
+    def test_load_unload(self):
+        """Test breakpoint by name works correctly with dlopen'ing."""
+
+        # Invoke the default build rule.
+        self.build()
+        self.copy_shlibs_to_remote()
+
+        exe = os.path.join(os.getcwd(), "a.out")
+        self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
+
+        # Break by function name a_function (not yet loaded).
+        lldbutil.run_break_set_by_symbol (self, "a_function", num_expected_locations=0)
+
+        self.runCmd("run", RUN_SUCCEEDED)
+
+        # The stop reason of the thread should be breakpoint and at a_function.
+        self.expect("thread list", STOPPED_DUE_TO_BREAKPOINT,
+            substrs = ['stopped',
+                       'a_function',
+                       'stop reason = breakpoint'])
+
+        # The breakpoint should have a hit count of 1.
+        self.expect("breakpoint list -f", BREAKPOINT_HIT_ONCE,
+            substrs = [' resolved, hit count = 1'])
+
+        # Issue the 'contnue' command.  We should stop agaian at a_function.
+        # The stop reason of the thread should be breakpoint and at a_function.
+        self.runCmd("continue")
+
+        # rdar://problem/8508987
+        # The a_function breakpoint should be encountered twice.
+        self.expect("thread list", STOPPED_DUE_TO_BREAKPOINT,
+            substrs = ['stopped',
+                       'a_function',
+                       'stop reason = breakpoint'])
+
+        # The breakpoint should have a hit count of 2.
+        self.expect("breakpoint list -f", BREAKPOINT_HIT_ONCE,
+            substrs = [' resolved, hit count = 2'])
+
+    @skipIfFreeBSD # llvm.org/pr14424 - missing FreeBSD Makefiles/testcase support
+    @skipUnlessListedRemote(['android'])
+    @skipIfWindows # Windows doesn't have dlopen and friends, dynamic libraries work differently
+    def test_step_over_load (self):
+        """Test stepping over code that loads a shared library works correctly."""
+
+        # Invoke the default build rule.
+        self.build()
+        self.copy_shlibs_to_remote()
+
+        exe = os.path.join(os.getcwd(), "a.out")
+        self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
+
+        # Break by function name a_function (not yet loaded).
+        lldbutil.run_break_set_by_file_and_line (self, "main.c", self.line, num_expected_locations=1, loc_exact=True)
+
+        self.runCmd("run", RUN_SUCCEEDED)
+
+        # The stop reason of the thread should be breakpoint and at a_function.
+        self.expect("thread list", STOPPED_DUE_TO_BREAKPOINT,
+            substrs = ['stopped',
+                       'stop reason = breakpoint'])
+
+        self.runCmd("thread step-over", "Stepping over function that loads library")
+        
+        # The stop reason should be step end.
+        self.expect("thread list", "step over succeeded.", 
+            substrs = ['stopped',
+                      'stop reason = step over'])
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/a.c b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/a.c
new file mode 100644
index 00000000000..9d4711772dd
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/a.c
@@ -0,0 +1,15 @@
+//===-- a.c -----------------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+extern int b_function ();
+
+int
+a_function ()
+{
+    return b_function ();
+}
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/a.mk b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/a.mk
new file mode 100644
index 00000000000..a5c37561daa
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/a.mk
@@ -0,0 +1,21 @@
+LEVEL := ../../make
+
+LIB_PREFIX := loadunload_
+
+CFLAGS_EXTRAS := -fPIC
+LD_EXTRAS := -L. -l$(LIB_PREFIX)b
+
+DYLIB_NAME := $(LIB_PREFIX)a
+DYLIB_C_SOURCES := a.c
+DYLIB_ONLY := YES
+
+include $(LEVEL)/Makefile.rules
+
+.PHONY:
+$(DYLIB_FILENAME): lib_b
+
+lib_b:
+	$(MAKE) -f b.mk
+
+clean::
+	$(MAKE) -f b.mk clean
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/b.c b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/b.c
new file mode 100644
index 00000000000..6c629323655
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/b.c
@@ -0,0 +1,13 @@
+//===-- b.c -----------------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+int
+b_function ()
+{
+  return 500;
+}
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/b.mk b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/b.mk
new file mode 100644
index 00000000000..956dc37cb3f
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/b.mk
@@ -0,0 +1,9 @@
+LEVEL := ../../make
+
+LIB_PREFIX := loadunload_
+
+DYLIB_NAME := $(LIB_PREFIX)b
+DYLIB_C_SOURCES := b.c
+DYLIB_ONLY := YES
+
+include $(LEVEL)/Makefile.rules
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/c.c b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/c.c
new file mode 100644
index 00000000000..b1778b462d0
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/c.c
@@ -0,0 +1,13 @@
+//===-- c.c -----------------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+int
+c_function ()
+{
+    return 600;
+}
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/c.mk b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/c.mk
new file mode 100644
index 00000000000..ebb5ce15787
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/c.mk
@@ -0,0 +1,9 @@
+LEVEL := ../../make
+
+LIB_PREFIX := loadunload_
+
+DYLIB_NAME := $(LIB_PREFIX)c
+DYLIB_C_SOURCES := c.c
+DYLIB_ONLY := YES
+
+include $(LEVEL)/Makefile.rules
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/cmds.txt b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/cmds.txt
new file mode 100644
index 00000000000..1e4b198dc0d
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/cmds.txt
@@ -0,0 +1,2 @@
+breakpoint set -n a_function
+run
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/d.c b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/d.c
new file mode 100644
index 00000000000..6e5f0623101
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/d.c
@@ -0,0 +1,13 @@
+//===-- c.c -----------------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+int
+d_function ()
+{ // Find this line number within d_dunction().
+    return 700;
+}
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/d.mk b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/d.mk
new file mode 100644
index 00000000000..437c1507e20
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/d.mk
@@ -0,0 +1,11 @@
+LEVEL := ../../make
+
+LIB_PREFIX := loadunload_
+
+DYLIB_EXECUTABLE_PATH := $(CURDIR)
+
+DYLIB_NAME := $(LIB_PREFIX)d
+DYLIB_C_SOURCES := d.c
+DYLIB_ONLY := YES
+
+include $(LEVEL)/Makefile.rules
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/hidden/Makefile b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/hidden/Makefile
new file mode 100644
index 00000000000..09aa39b378e
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/hidden/Makefile
@@ -0,0 +1,9 @@
+LEVEL := ../../../make
+
+LIB_PREFIX := loadunload_
+
+DYLIB_NAME := $(LIB_PREFIX)d
+DYLIB_C_SOURCES := d.c
+DYLIB_ONLY := YES
+
+include $(LEVEL)/Makefile.rules
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/hidden/d.c b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/hidden/d.c
new file mode 100644
index 00000000000..f20aa095f2f
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/hidden/d.c
@@ -0,0 +1,13 @@
+//===-- c.c -----------------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+int
+d_function ()
+{ // Find this line number within d_dunction().
+    return 12345;
+}
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/main.c b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/main.c
new file mode 100644
index 00000000000..bff9a317606
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/load_unload/main.c
@@ -0,0 +1,80 @@
+//===-- main.c --------------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+#include <stdio.h>
+#include <dlfcn.h>
+#include <limits.h>
+#include <string.h>
+#include <unistd.h>
+#include <libgen.h>
+#include <stdlib.h>
+
+int
+main (int argc, char const *argv[])
+{
+#if defined (__APPLE__)
+    const char *a_name = "@executable_path/libloadunload_a.dylib";
+    const char *c_name = "@executable_path/libloadunload_c.dylib";
+#else
+    const char *a_name = "libloadunload_a.so";
+    const char *c_name = "libloadunload_c.so";
+#endif
+    void *a_dylib_handle = NULL;
+    void *c_dylib_handle = NULL;
+    int (*a_function) (void);
+
+    a_dylib_handle = dlopen (a_name, RTLD_NOW); // Set break point at this line for test_lldb_process_load_and_unload_commands().
+    if (a_dylib_handle == NULL)
+    {
+        fprintf (stderr, "%s\n", dlerror());
+        exit (1);
+    }
+
+    a_function = (int (*) ()) dlsym (a_dylib_handle, "a_function");
+    if (a_function == NULL)
+    {
+        fprintf (stderr, "%s\n", dlerror());
+        exit (2);
+    }
+    printf ("First time around, got: %d\n", a_function ());
+    dlclose (a_dylib_handle);
+
+    c_dylib_handle = dlopen (c_name, RTLD_NOW);
+    if (c_dylib_handle == NULL)
+    {
+        fprintf (stderr, "%s\n", dlerror());
+        exit (3);
+    }
+    a_function = (int (*) ()) dlsym (c_dylib_handle, "c_function");
+    if (a_function == NULL)
+    {
+        fprintf (stderr, "%s\n", dlerror());
+        exit (4);
+    }
+
+    a_dylib_handle = dlopen (a_name, RTLD_NOW);
+    if (a_dylib_handle == NULL)
+    {
+        fprintf (stderr, "%s\n", dlerror());
+        exit (5);
+    }
+
+    a_function = (int (*) ()) dlsym (a_dylib_handle, "a_function");
+    if (a_function == NULL)
+    {
+        fprintf (stderr, "%s\n", dlerror());
+        exit (6);
+    }
+    printf ("Second time around, got: %d\n", a_function ());
+    dlclose (a_dylib_handle);
+
+    int d_function(void);
+    printf ("d_function returns: %d\n", d_function());
+
+    return 0;
+}