test-doc-portal: Check for FUSE support more thoroughly

Some CI pipelines do the build as root, which means /dev/fuse is
writable, but if we do not have appropriate permissions then we cannot
actually mount FUSE filesystems.

Signed-off-by: Simon McVittie <smcv@debian.org>

Gbp-Pq: Name test-doc-portal-Check-for-FUSE-support-more-thoroughly.patch

3 files changed, 84 insertions, 23 deletions

diff --git a/document-portal/document-portal-fuse.c b/document-portal/document-portal-fuse.c
index 2705402..f1935ec 100644
--- a/document-portal/document-portal-fuse.c
+++ b/document-portal/document-portal-fuse.c
@@ -2537,7 +2537,8 @@ xdp_fuse_init (GError **error)
   main_ch = fuse_mount (path, &args);
   if (main_ch == NULL)
     {
-      g_set_error (error, XDG_DESKTOP_PORTAL_ERROR, XDG_DESKTOP_PORTAL_ERROR_FAILED, "Can't mount fuse fs");
+      g_set_error (error, XDG_DESKTOP_PORTAL_ERROR, XDG_DESKTOP_PORTAL_ERROR_FAILED,
+                   "Can't mount fuse fs on %s: %s", path, g_strerror (errno));
       return FALSE;
     }
 
diff --git a/tests/Makefile.am.inc b/tests/Makefile.am.inc
index fcc6a76..7418b69 100644
--- a/tests/Makefile.am.inc
+++ b/tests/Makefile.am.inc
@@ -13,10 +13,11 @@ testdb_LDADD = \
 	$(NULL)
 testdb_SOURCES = tests/testdb.c	$(DB_SOURCES)
 
-test_doc_portal_CFLAGS = $(AM_CFLAGS) $(BASE_CFLAGS)
+test_doc_portal_CFLAGS = $(AM_CFLAGS) $(BASE_CFLAGS) $(FUSE_CFLAGS)
 test_doc_portal_LDADD = \
 	$(AM_LDADD) \
 	$(BASE_LIBS) \
+	$(FUSE_LIBS) \
 	$(NULL)
 test_doc_portal_SOURCES = tests/test-doc-portal.c
 nodist_test_doc_portal_SOURCES = document-portal/document-portal-dbus.c
diff --git a/tests/test-doc-portal.c b/tests/test-doc-portal.c
index 10b9b5d..fb199d3 100644
--- a/tests/test-doc-portal.c
+++ b/tests/test-doc-portal.c
@@ -11,6 +11,10 @@
 
 #include <gio/gio.h>
 #include <gio/gunixfdlist.h>
+#include <glib/gstdio.h>
+
+#define FUSE_USE_VERSION 26
+#include <fuse_lowlevel.h>
 
 #include "document-portal/document-portal-dbus.h"
 
@@ -22,7 +26,7 @@ GTestDBus *dbus;
 GDBusConnection *session_bus;
 XdpDbusDocuments *documents;
 char *mountpoint;
-static gboolean have_fuse;
+static gchar *cannot_use_fuse = NULL;
 
 static gboolean
 set_contents_trunc (const gchar  *filename,
@@ -352,9 +356,9 @@ test_create_doc (void)
   const char *basename = "a-file";
   GError *error = NULL;
 
-  if (!have_fuse)
+  if (cannot_use_fuse != NULL)
     {
-      g_test_skip ("this test requires FUSE");
+      g_test_skip (cannot_use_fuse);
       return;
     }
 
@@ -467,9 +471,9 @@ test_recursive_doc (void)
   g_autofree char *path = NULL;
   g_autofree char *app_path = NULL;
 
-  if (!have_fuse)
+  if (cannot_use_fuse != NULL)
     {
-      g_test_skip ("this test requires FUSE");
+      g_test_skip (cannot_use_fuse);
       return;
     }
 
@@ -509,9 +513,9 @@ test_create_docs (void)
   const char *basenames[] = { "doc1", "doc2" };
   int i;
 
-  if (!have_fuse)
+  if (cannot_use_fuse != NULL)
     {
-      g_test_skip ("this test requires FUSE");
+      g_test_skip (cannot_use_fuse);
       return;
     }
 
@@ -582,9 +586,9 @@ test_add_named (void)
   GError *error = NULL;
   gboolean res;
 
-  if (!have_fuse)
+  if (cannot_use_fuse != NULL)
     {
-      g_test_skip ("this test requires FUSE");
+      g_test_skip (cannot_use_fuse);
       return;
     }
 
@@ -696,23 +700,78 @@ test_add_named (void)
   assert_doc_not_exist (id1, basename1, "com.test.App2");
 }
 
+/*
+ * If we cannot use FUSE, set cannot_use_fuse and return %FALSE.
+ */
+static gboolean
+check_fuse (void)
+{
+  g_autofree gchar *fusermount = NULL;
+  g_autofree gchar *path = NULL;
+  char *argv[] = { "xdp-fuse-test" };
+  struct fuse_args args = FUSE_ARGS_INIT (G_N_ELEMENTS (argv), argv);
+  struct fuse_chan *chan = NULL;
+  g_autoptr(GError) error = NULL;
+
+  if (cannot_use_fuse != NULL)
+    return FALSE;
+
+  if (access ("/dev/fuse", W_OK) != 0)
+    {
+      cannot_use_fuse = g_strdup_printf ("access /dev/fuse: %s",
+                                         g_strerror (errno));
+      return FALSE;
+    }
+
+  fusermount = g_find_program_in_path ("fusermount");
+
+  if (fusermount == NULL)
+    {
+      cannot_use_fuse = g_strdup ("fusermount not found in PATH");
+      return FALSE;
+    }
+
+  if (!g_file_test (fusermount, G_FILE_TEST_IS_EXECUTABLE))
+    {
+      cannot_use_fuse = g_strdup_printf ("%s not executable", fusermount);
+      return FALSE;
+    }
+
+  path = g_dir_make_tmp ("xdp-test.XXXXXX", &error);
+  g_assert_no_error (error);
+
+  chan = fuse_mount (path, &args);
+
+  if (chan == NULL)
+    {
+      cannot_use_fuse = g_strdup_printf ("fuse_mount: %s",
+                                         g_strerror (errno));
+      return FALSE;
+    }
+
+  g_test_message ("Successfully set up test FUSE fs on %s", path);
+
+  fuse_unmount (path, chan);
+
+  if (g_rmdir (path) != 0)
+    g_error ("rmdir %s: %s", path, g_strerror (errno));
+
+  return TRUE;
+}
+
 static void
 global_setup (void)
 {
   gboolean inited;
-  g_autofree gchar *fusermount = NULL;
   GError *error = NULL;
   g_autofree gchar *services = NULL;
   int fd;
 
-  fusermount = g_find_program_in_path ("fusermount");
-  /* cache result so subsequent tests can be marked as skipped */
-  have_fuse = (access ("/dev/fuse", W_OK) == 0 &&
-               fusermount != NULL &&
-               g_file_test (fusermount, G_FILE_TEST_IS_EXECUTABLE));
-
-  if (!have_fuse)
-    return;
+  if (!check_fuse ())
+    {
+      g_assert_cmpstr (cannot_use_fuse, !=, NULL);
+      return;
+    }
 
   g_mkdtemp (outdir);
   g_print ("outdir: %s\n", outdir);
@@ -805,7 +864,7 @@ global_teardown (void)
   g_autoptr(GFile) outdir_file = g_file_new_for_path (outdir);
   int res, i;
 
-  if (!have_fuse)
+  if (cannot_use_fuse != NULL)
     return;
 
   res = stat (by_app_dir, &buf);
@@ -858,9 +917,9 @@ global_teardown (void)
 static void
 test_version (void)
 {
-  if (!have_fuse)
+  if (cannot_use_fuse != NULL)
     {
-      g_test_skip ("this test requires FUSE");
+      g_test_skip (cannot_use_fuse);
       return;
     }