Port to GLnxTmpfile

There's lots of mechanically replacing `OtTmpFile` with `GLnxTmpfile`;
the biggest changes are in the commit path.  Symlink commits are now
very clearly separated from regular files.  Symlinks are `OtCleanupUnlinkat`,
and regular files are `GLnxTmpfile`.

The commit codepath separates those as `_ostree_repo_commit_path_final()` and
`_ostree_repo_commit_tmpf_final()`. A nice aspect of all of this is that they
both *consume* the temporary on success. This avoids an extra spurious
`unlink()` call.

One of the biggest bits of code motion is in `commit_loose_regfile_object()`,
which no longer needs to care about symlinks. For the most parth though it's
just removing conditionals.

Update submodule: libglnx

Closes: #958
Approved by: jlebon

src/libotutil/ot-fs-utils.c

@@ -25,61 +25,6 @@
 #include <sys/xattr.h>
 #include <gio/gunixinputstream.h>
 
-/* Before https://github.com/GNOME/libglnx/commit/9929adc, the libglnx
- * tmpfile API made it hard to clean up tmpfiles in failure cases.
- * it's API breaking. Carry the fix here until we're ready to fully port.
- */
-void
-ot_tmpfile_clear (OtTmpfile *tmpf)
-{
-  if (!tmpf->initialized)
-    return;
-  if (tmpf->fd == -1)
-    return;
-  (void) close (tmpf->fd);
-  /* If ->path is set, we're likely aborting due to an error. Clean it up */
-  if (tmpf->path)
-    {
-      (void) unlinkat (tmpf->src_dfd, tmpf->path, 0);
-      g_free (tmpf->path);
-    }
-}
-
-gboolean
-ot_open_tmpfile_linkable_at (int dfd,
-                             const char *subpath,
-                             int flags,
-                             OtTmpfile *out_tmpf,
-                             GError **error)
-{
-  if (!glnx_open_tmpfile_linkable_at (dfd, subpath, flags, &out_tmpf->fd, &out_tmpf->path, error))
-    return FALSE;
-  out_tmpf->initialized = TRUE;
-  out_tmpf->src_dfd = dfd;
-  return TRUE;
-}
-
-gboolean
-ot_link_tmpfile_at (OtTmpfile *tmpf,
-                    GLnxLinkTmpfileReplaceMode mode,
-                    int target_dfd,
-                    const char *target,
-                    GError **error)
-{
-  g_return_val_if_fail (tmpf->initialized, FALSE);
-  glnx_fd_close int fd = glnx_steal_fd (&tmpf->fd);
-  if (!glnx_link_tmpfile_at (tmpf->src_dfd, mode, fd, tmpf->path,
-                             target_dfd, target, error))
-    {
-      if (tmpf->path)
-        (void) unlinkat (tmpf->src_dfd, tmpf->path, 0);
-      tmpf->initialized = FALSE;
-      return FALSE;
-    }
-  tmpf->initialized = FALSE;
-  return TRUE;
-}
-
 /* Convert a fd-relative path to a GFile* - use
  * for legacy code.
  */
@@ -213,9 +158,8 @@ ot_dfd_iter_init_allow_noent (int dfd,
       *out_exists = FALSE;
       return TRUE;
     }
-  if (!glnx_dirfd_iterator_init_take_fd (fd, dfd_iter, error))
+  if (!glnx_dirfd_iterator_init_take_fd (&fd, dfd_iter, error))
     return FALSE;
-  fd = -1;
   *out_exists = TRUE;
   return TRUE;
 }

src/libotutil/ot-fs-utils.h

@@ -25,31 +25,6 @@
 
 G_BEGIN_DECLS
 
-/* This is a copy of https://github.com/GNOME/libglnx/pull/46 until we
- * can do a full port; see https://github.com/ostreedev/ostree/pull/861 */
-typedef struct {
-  gboolean initialized;
-  int src_dfd;
-  int fd;
-  char *path;
-} OtTmpfile;
-void ot_tmpfile_clear (OtTmpfile *tmpf);
-G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(OtTmpfile, ot_tmpfile_clear);
-
-gboolean
-ot_open_tmpfile_linkable_at (int dfd,
-                             const char *subpath,
-                             int flags,
-                             OtTmpfile *out_tmpf,
-                             GError **error);
-gboolean
-ot_link_tmpfile_at (OtTmpfile *tmpf,
-                    GLnxLinkTmpfileReplaceMode flags,
-                    int target_dfd,
-                    const char *target,
-                    GError **error);
-
-
 /* A little helper to call unlinkat() as a cleanup
  * function.  Mostly only necessary to handle
  * deletion of temporary symlinks.
@@ -76,7 +51,6 @@ ot_cleanup_unlinkat (OtCleanupUnlinkat *cleanup)
 }
 G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(OtCleanupUnlinkat, ot_cleanup_unlinkat);
 
-
 GFile * ot_fdrel_to_gfile (int dfd, const char *path);
 
 gboolean ot_readlinkat_gfile_info (int             dfd,