From 1726e150f4f4d5649a9a774eee7bb55b55d6b675 Mon Sep 17 00:00:00 2001
From: Simon McVittie <smcv@collabora.com>
Date: Sat, 19 Mar 2022 11:16:46 +0000
Subject: [PATCH] tests: Call openpty (if available) without using dlsym

The SONAME of libutil varies between architectures, so the logic to find
the SONAME of libutil was only correct for native builds (Linux on
Linux), not for cross-builds. The regular expression was also not
sufficiently broad to match the SONAME used on the alpha architecture,
which is apparently libutil.so.1.1.

Instead of screen-scraping the output of ldconfig and using that to
dlopen the library that contains openpty, it seems more reliable to
emit a link-time reference to openpty and let the linker do its job.
It's also less code.

Bug-Debian: https://bugs.debian.org/1007946
Signed-off-by: Simon McVittie <smcv@collabora.com>
---
 gio/tests/meson.build | 28 ++++++++++++++--------------
 gio/tests/pollable.c  | 36 ++++++++++++++----------------------
 2 files changed, 28 insertions(+), 36 deletions(-)

diff --git a/gio/tests/meson.build b/gio/tests/meson.build
index c825b0cd7..56a04cce1 100644
--- a/gio/tests/meson.build
+++ b/gio/tests/meson.build
@@ -12,20 +12,20 @@ test_c_args = [
   '-UG_DISABLE_ASSERT',
 ]
 
-# workaround for https://github.com/mesonbuild/meson/issues/6880
-if build_machine.system() == 'linux'
-  libutil_name = 'libutil'
-  libutil = run_command('sh', '-c',
-    '''ldconfig -p | grep -o "[[:space:]]@0@\.so\(\.[0-9]\+\)\?\b"'''
-    .format(libutil_name), check: false).stdout().strip().split('\n')
+libutil_dep = dependency('', required : false)
 
-  if libutil.length() > 0
-      message('Found libutil as @0@'.format(libutil[0]))
-      test_c_args += '-DLIBUTIL_SONAME="@0@"'.format(libutil[0])
-  else
-      warning('libutil not found')
-  endif # libutil.length() > 0
-endif # build_machine.system() == 'linux'
+if cc.has_header('pty.h')
+  have_openpty = cc.has_function('openpty', prefix : '#include <pty.h>')
+
+  if host_machine.system() == 'linux' and not have_openpty
+    libutil_dep = cc.find_library('util', required : false)
+    have_openpty = cc.has_function('openpty', dependencies : libutil_dep, prefix : '#include <pty.h>')
+  endif
+
+  if have_openpty
+    test_c_args += '-DHAVE_OPENPTY'
+  endif
+endif
 
 if host_machine.system() == 'windows'
   common_gio_tests_deps += [iphlpapi_dep, winsock2, cc.find_library ('secur32')]
@@ -91,7 +91,7 @@ gio_tests = {
   'network-monitor' : {},
   'network-monitor-race' : {},
   'permission' : {},
-  'pollable' : {'dependencies' : [libdl_dep]},
+  'pollable' : {'dependencies' : [libutil_dep]},
   'power-profile-monitor' : {},
   'proxy-test' : {},
   'readwrite' : {},
diff --git a/gio/tests/pollable.c b/gio/tests/pollable.c
index 516d7f4e4..97c26c25d 100644
--- a/gio/tests/pollable.c
+++ b/gio/tests/pollable.c
@@ -22,12 +22,20 @@
 #include <glib/gstdio.h>
 
 #ifdef G_OS_UNIX
-#include <dlfcn.h>
 #include <fcntl.h>
+#ifdef HAVE_OPENPTY
+#include <pty.h>
+#endif
 #include <gio/gunixinputstream.h>
 #include <gio/gunixoutputstream.h>
 #endif
 
+/* openpty() is non-standard and might not be available on all kernels
+ * and libc implementations, but glibc on Linux definitely has it */
+#if defined(__linux__) && defined(__GNUC__) && !defined(HAVE_OPENPTY)
+#error Should have been able to find openpty on GNU/Linux
+#endif
+
 GMainLoop *loop;
 GPollableInputStream *in;
 GOutputStream *out;
@@ -185,31 +193,19 @@ test_pollable_unix_pipe (void)
 static void
 test_pollable_unix_pty (void)
 {
-  int (*openpty_impl) (int *, int *, char *, void *, void *);
+#ifdef HAVE_OPENPTY
   int a, b, status;
-#ifdef LIBUTIL_SONAME
-  void *handle;
 #endif
 
   g_test_summary ("Test that PTYs are considered pollable");
 
-#ifdef LIBUTIL_SONAME
-  handle = dlopen (LIBUTIL_SONAME, RTLD_GLOBAL | RTLD_LAZY);
-  g_assert_nonnull (handle);
-#endif
+#ifdef HAVE_OPENPTY
+  status = openpty (&a, &b, NULL, NULL, NULL);
 
-  openpty_impl = dlsym (RTLD_DEFAULT, "openpty");
-  if (openpty_impl == NULL)
-    {
-      g_test_skip ("System does not support openpty()");
-      goto close_libutil;
-    }
-
-  status = openpty_impl (&a, &b, NULL, NULL, NULL);
   if (status == -1)
     {
       g_test_skip ("Unable to open PTY");
-      goto close_libutil;
+      return;
     }
 
   in = G_POLLABLE_INPUT_STREAM (g_unix_input_stream_new (a, TRUE));
@@ -222,12 +218,8 @@ test_pollable_unix_pty (void)
 
   close (a);
   close (b);
-
-close_libutil:
-#ifdef LIBUTIL_SONAME
-  dlclose (handle);
 #else
-  return;
+  g_test_skip ("openpty not found");
 #endif
 }