tests/c-api: Test that the library can really be loaded with dlopen.

Answer is yes, but it was good to know.

.gitignore

@@ -483,6 +483,7 @@ Makefile.in
 /tests/c-api/test-config
 /tests/c-api/test-create-handle
 /tests/c-api/test-debug-to-file
+/tests/c-api/test-dlopen
 /tests/c-api/test-environment
 /tests/c-api/test-event-string
 /tests/c-api/test*.img

configure.ac

@@ -581,6 +581,13 @@ AC_ARG_WITH([extra-packages],
     [EXTRA_PACKAGES=])
 AC_SUBST([EXTRA_PACKAGES])
 
+dnl Check for libdl/dlopen (optional - only used to test if the library
+dnl can be used with libdl).
+AC_CHECK_LIB([dl],[dlopen],[have_libdl=yes],[have_libdl=no])
+AC_CHECK_HEADERS([dlfcn.h],[have_dlfcn=yes],[have_dlfcn=no])
+AM_CONDITIONAL([HAVE_LIBDL],
+               [test "x$have_libdl" = "xyes" && test "x$have_dlfcn" = "xyes"])
+
 dnl Check for rpcgen and XDR library.  rpcgen is optional.
 AC_CHECK_PROG([RPCGEN],[rpcgen],[rpcgen],[no])
 AM_CONDITIONAL([HAVE_RPCGEN],[test "x$RPCGEN" != "xno"])

tests/c-api/Makefile.am

@@ -38,11 +38,16 @@ check_PROGRAMS = \
 	test-environment \
 	test-pwd \
 	test-event-string
+if HAVE_LIBDL
+check_PROGRAMS += \
+	test-dlopen
+endif
 
 TESTS = \
 	tests \
 	test-just-header \
 	test-create-handle \
+	test-dlopen \
 	test-config \
 	test-add-drive-opts \
 	test-last-errno \
@@ -52,6 +57,10 @@ TESTS = \
 	test-debug-to-file \
 	test-environment \
 	test-event-string
+if HAVE_LIBDL
+TESTS += \
+	test-dlopen
+endif
 
 if HAVE_CXX
 check_PROGRAMS += test-just-header-cxx
@@ -130,6 +139,17 @@ test_create_handle_CFLAGS = \
 test_create_handle_LDADD = \
 	$(top_builddir)/src/libguestfs.la
 
+if HAVE_LIBDL
+test_dlopen_SOURCES = test-dlopen.c
+test_dlopen_CPPFLAGS = \
+	-I$(top_srcdir)/src -I$(top_builddir)/src
+test_dlopen_CFLAGS = \
+	$(WARN_CFLAGS) $(WERROR_CFLAGS) \
+	-DLIBRARY=\"$(top_builddir)/src/.libs/libguestfs.so.0\"
+test_dlopen_LDADD = \
+	-ldl
+endif
+
 test_config_SOURCES = test-config.c
 test_config_CPPFLAGS = \
 	-I$(top_srcdir)/src -I$(top_builddir)/src

tests/c-api/test-dlopen.c

@@ -0,0 +1,94 @@
+/* libguestfs
+ * Copyright (C) 2014 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/* Test the library can be loaded and unloaded using dlopen etc. */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <dlfcn.h>
+
+/* We don't need the <guestfs.h> header file here. */
+typedef struct guestfs_h guestfs_h;
+
+typedef guestfs_h *(*guestfs_create_t) (void);
+typedef const char * (*guestfs_get_program_t) (guestfs_h *);
+typedef void (*guestfs_close_t) (guestfs_h *);
+
+#ifndef LIBRARY
+#error "-DLIBRARY was not defined"
+#endif
+
+static void *
+read_symbol (void *lib, const char *symbol)
+{
+  void *symval;
+  const char *err;
+
+  dlerror (); /* Clear error indicator. */
+  symval = dlsym (lib, symbol);
+  if ((err = dlerror ()) != NULL) {
+    fprintf (stderr, "could not read symbol: %s: %s\n", symbol, err);
+    exit (EXIT_FAILURE);
+  }
+  return symval;
+}
+
+int
+main (int argc, char *argv[])
+{
+  void *lib;
+  guestfs_create_t guestfs_create;
+  guestfs_get_program_t guestfs_get_program;
+  guestfs_close_t guestfs_close;
+  guestfs_h *g;
+
+  if (access (LIBRARY, X_OK) == -1) {
+    fprintf (stderr, "test skipped because %s cannot be accessed: %m\n",
+             LIBRARY);
+    exit (77);
+  }
+
+  lib = dlopen (LIBRARY, RTLD_LAZY);
+  if (lib == NULL) {
+    fprintf (stderr, "could not open %s: %s\n", LIBRARY, dlerror ());
+    exit (EXIT_FAILURE);
+  }
+
+  guestfs_create = read_symbol (lib, "guestfs_create");
+  guestfs_get_program = read_symbol (lib, "guestfs_get_program");
+  guestfs_close = read_symbol (lib, "guestfs_close");
+
+  g = guestfs_create ();
+  if (g == NULL) {
+    fprintf (stderr, "failed to create handle\n");
+    exit (EXIT_FAILURE);
+  }
+  printf ("program = %s\n", guestfs_get_program (g));
+
+  guestfs_close (g);
+
+  if (dlclose (lib) != 0) {
+    fprintf (stderr, "could not close %s: %s\n", LIBRARY, dlerror ());
+    exit (EXIT_FAILURE);
+  }
+
+  exit (EXIT_SUCCESS);
+}