sysroot/deploy: Some cleanup to decl-after-stmt/return FALSE style

And fd-relative. I also introduced some helpers here which I'll use later in
more invasive patches.

Closes: #742
Approved by: jlebon

src/libotutil/ot-fs-utils.c

@@ -25,6 +25,16 @@
 #include <sys/xattr.h>
 #include <gio/gunixinputstream.h>
 
+/* Convert a fd-relative path to a GFile* - use
+ * for legacy code.
+ */
+GFile *
+ot_fdrel_to_gfile (int dfd, const char *path)
+{
+  g_autofree char *abspath = glnx_fdrel_abspath (dfd, path);
+  return g_file_new_for_path (abspath);
+}
+
 int
 ot_opendirat (int dfd, const char *path, gboolean follow)
 {
@@ -205,6 +215,30 @@ ot_ensure_unlinked_at (int dfd,
   return TRUE;
 }
 
+gboolean
+ot_query_exists_at (int dfd, const char *path,
+                    gboolean *out_exists,
+                    GError **error)
+{
+  struct stat stbuf;
+  gboolean ret_exists;
+
+  if (fstatat (dfd, path, &stbuf, AT_SYMLINK_NOFOLLOW) < 0)
+    {
+      if (errno != ENOENT)
+        {
+          glnx_set_error_from_errno (error);
+          return FALSE;
+        }
+      ret_exists = FALSE;
+    }
+  else
+    ret_exists = TRUE;
+
+  *out_exists = ret_exists;
+  return TRUE;
+}
+
 gboolean
 ot_openat_ignore_enoent (int dfd,
                          const char *path,

src/libotutil/ot-fs-utils.h

@@ -24,6 +24,8 @@
 
 G_BEGIN_DECLS
 
+GFile * ot_fdrel_to_gfile (int dfd, const char *path);
+
 int ot_opendirat (int dfd, const char *path, gboolean follow);
 gboolean ot_gopendirat (int             dfd,
                         const char     *path,
@@ -57,6 +59,11 @@ gboolean ot_openat_read_stream (int             dfd,
                                 GCancellable   *cancellable,
                                 GError        **error);
 
+
+gboolean ot_query_exists_at (int dfd, const char *path,
+                             gboolean *out_exists,
+                             GError **error);
+
 gboolean ot_ensure_unlinked_at (int dfd,
                                 const char *path,
                                 GError **error);