/*
 * Copyright (C) 2011,2013 Colin Walters <walters@verbum.org>
 *
 * SPDX-License-Identifier: LGPL-2.0+
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library. If not, see <https://www.gnu.org/licenses/>.
 */

#include "config.h"

#include "ostree-core-private.h"
#include "ostree-repo-private.h"
#include "otutil.h"
#include "ot-fs-utils.h"

/* This is polymorphic in @collection_id: if non-%NULL, @refs will be treated as of
 * type OstreeCollectionRef ↦ checksum. Otherwise, it will be treated as of type
 * refspec ↦ checksum. */
static gboolean
add_ref_to_set (const char       *remote,
                const char       *collection_id,
                int               base_fd,
                const char       *path,
                GHashTable       *refs,
                GCancellable     *cancellable,
                GError          **error)
{
  g_return_val_if_fail (remote == NULL || collection_id == NULL, FALSE);

  gsize len;
  char *contents = glnx_file_get_contents_utf8_at (base_fd, path, &len, cancellable, error);
  if (!contents)
    return FALSE;

  g_strchomp (contents);

  if (collection_id == NULL)
    {
      g_autoptr(GString) refname = g_string_new ("");
      if (remote)
        {
          g_string_append (refname, remote);
          g_string_append_c (refname, ':');
        }
      g_string_append (refname, path);
      g_hash_table_insert (refs, g_string_free (g_steal_pointer (&refname), FALSE), contents);
    }
  else
    {
      g_hash_table_insert (refs, ostree_collection_ref_new (collection_id, path), contents);
    }

  return TRUE;
}

static gboolean
write_checksum_file_at (OstreeRepo   *self,
                        int dfd,
                        const char *name,
                        const char *sha256,
                        GCancellable *cancellable,
                        GError **error)
{
  if (!ostree_validate_checksum_string (sha256, error))
    return FALSE;

  if (ostree_validate_checksum_string (name, NULL))
    return glnx_throw (error, "Rev name '%s' looks like a checksum", name);

  if (!*name)
    return glnx_throw (error, "Invalid empty ref name");

  const char *lastslash = strrchr (name, '/');

  if (lastslash)
    {
      char *parent = strdupa (name);
      parent[lastslash - name] = '\0';

      if (!glnx_shutil_mkdir_p_at (dfd, parent, 0777, cancellable, error))
        return FALSE;
    }

  {
    size_t l = strlen (sha256);
    char *bufnl = alloca (l + 2);
    g_autoptr(GError) temp_error = NULL;

    memcpy (bufnl, sha256, l);
    bufnl[l] = '\n';
    bufnl[l+1] = '\0';

    if (!_ostree_repo_file_replace_contents (self, dfd, name, (guint8*)bufnl, l + 1,
                                             cancellable, &temp_error))
      {
        if (g_error_matches (temp_error, G_IO_ERROR, G_IO_ERROR_IS_DIRECTORY))
          {
            g_autoptr(GHashTable) refs = NULL;
            GHashTableIter hashiter;
            gpointer hashkey, hashvalue;

            g_clear_error (&temp_error);

            /* FIXME: Conflict detection needs to be extended to collection–refs
             * using ostree_repo_list_collection_refs(). */
            if (!ostree_repo_list_refs (self, name, &refs, cancellable, error))
              return FALSE;

            g_hash_table_iter_init (&hashiter, refs);

            while ((g_hash_table_iter_next (&hashiter, &hashkey, &hashvalue)))
              {
                if (strcmp (name, (char *)hashkey) != 0)
                  return glnx_throw (error, "Conflict: %s exists under %s when attempting write", (char*)hashkey, name);
              }

            if (!glnx_shutil_rm_rf_at (dfd, name, cancellable, error))
              return FALSE;

            if (!_ostree_repo_file_replace_contents (self, dfd, name, (guint8*)bufnl, l + 1,
                                                     cancellable, error))
              return FALSE;
          }
        else
          {
            g_propagate_error (error, g_steal_pointer (&temp_error));
            return FALSE;
          }
      }
  }

  return TRUE;
}

static gboolean
find_ref_in_remotes (OstreeRepo         *self,
                     const char         *rev,
                     int                *out_fd,
                     GError            **error)
{
  g_auto(GLnxDirFdIterator) dfd_iter = { 0, };
  glnx_autofd int ret_fd = -1;

  if (!glnx_dirfd_iterator_init_at (self->repo_dir_fd, "refs/remotes", TRUE, &dfd_iter, error))
    return FALSE;

  while (TRUE)
    {
      struct dirent *dent = NULL;
      glnx_autofd int remote_dfd = -1;

      if (!glnx_dirfd_iterator_next_dent_ensure_dtype (&dfd_iter, &dent, NULL, error))
        return FALSE;
      if (dent == NULL)
        break;

      if (dent->d_type != DT_DIR)
        continue;

      if (!glnx_opendirat (dfd_iter.fd, dent->d_name, TRUE, &remote_dfd, error))
        return FALSE;

      if (!ot_openat_ignore_enoent (remote_dfd, rev, &ret_fd, error))
        return FALSE;

      if (ret_fd != -1)
        break;
    }

  *out_fd = ret_fd; ret_fd = -1;
  return TRUE;
}

static gboolean
resolve_refspec (OstreeRepo     *self,
                 const char     *remote,
                 const char     *ref,
                 gboolean        allow_noent,
                 gboolean        fallback_remote,
                 char          **out_rev,
                 GError        **error);

static gboolean
resolve_refspec_fallback (OstreeRepo     *self,
                          const char     *remote,
                          const char     *ref,
                          gboolean        allow_noent,
                          gboolean        fallback_remote,
                          char          **out_rev,
                          GCancellable   *cancellable,
                          GError        **error)
{
  g_autofree char *ret_rev = NULL;

  if (self->parent_repo)
    {
      if (!resolve_refspec (self->parent_repo, remote, ref, allow_noent,
                            fallback_remote, &ret_rev, error))
        return FALSE;
    }
  else if (!allow_noent)
    {
      g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND,
                   "Refspec '%s%s%s' not found",
                   remote ? remote : "",
                   remote ? ":" : "",
                   ref);
      return FALSE;
    }

  ot_transfer_out_value (out_rev, &ret_rev);
  return TRUE;
}

static gboolean
resolve_refspec (OstreeRepo     *self,
                 const char     *remote,
                 const char     *ref,
                 gboolean        allow_noent,
                 gboolean        fallback_remote,
                 char          **out_rev,
                 GError        **error)
{
  __attribute__((unused)) GCancellable *cancellable = NULL;
  g_autofree char *ret_rev = NULL;
  glnx_autofd int target_fd = -1;

  g_return_val_if_fail (ref != NULL, FALSE);

  /* We intentionally don't allow a ref that looks like a checksum */
  if (ostree_validate_checksum_string (ref, NULL))
    {
      ret_rev = g_strdup (ref);
    }
  else if (self->in_transaction)
    {
      const char *refspec;

      if (remote != NULL)
        refspec = glnx_strjoina (remote, ":", ref);
      else
        refspec = ref;

      g_mutex_lock (&self->txn_lock);
      if (self->txn.refs)
        ret_rev = g_strdup (g_hash_table_lookup (self->txn.refs, refspec));
      g_mutex_unlock (&self->txn_lock);
    }

  if (ret_rev != NULL)
    {
      ot_transfer_out_value (out_rev, &ret_rev);
      return TRUE;
    }

  if (remote != NULL)
    {
      const char *remote_ref = glnx_strjoina ("refs/remotes/", remote, "/", ref);

      if (!ot_openat_ignore_enoent (self->repo_dir_fd, remote_ref, &target_fd, error))
        return FALSE;
    }
  else
    {
      const char *local_ref = glnx_strjoina ("refs/heads/", ref);

      if (!ot_openat_ignore_enoent (self->repo_dir_fd, local_ref, &target_fd, error))
        return FALSE;

      if (target_fd == -1 && fallback_remote)
        {
          local_ref = glnx_strjoina ("refs/remotes/", ref);

          if (!ot_openat_ignore_enoent (self->repo_dir_fd, local_ref, &target_fd, error))
            return FALSE;

          if (target_fd == -1)
            {
              if (!find_ref_in_remotes (self, ref, &target_fd, error))
                return FALSE;
            }
        }
    }

  if (target_fd != -1)
    {
      ret_rev = glnx_fd_readall_utf8 (target_fd, NULL, NULL, error);
      if (!ret_rev)
        {
          g_prefix_error (error, "Couldn't open ref '%s': ", ref);
          return FALSE;
        }

      g_strchomp (ret_rev);
      if (!ostree_validate_checksum_string (ret_rev, error))
        return FALSE;
    }
  else
    {
      if (!resolve_refspec_fallback (self, remote, ref, allow_noent, fallback_remote,
                                     &ret_rev, cancellable, error))
        return FALSE;
    }

  ot_transfer_out_value (out_rev, &ret_rev);
  return TRUE;
}

/**
 * ostree_repo_resolve_partial_checksum:
 * @self: Repo
 * @refspec: A refspec
 * @full_checksum (out) (transfer full): A full checksum corresponding to the truncated ref given
 * @error: Error
 *
 * Look up the existing refspec checksums.  If the given ref is a unique truncated beginning
 * of a valid checksum it will return that checksum in the parameter @full_checksum
 */
static gboolean
ostree_repo_resolve_partial_checksum (OstreeRepo   *self,
                                      const char   *refspec,
                                      char        **full_checksum,
                                      GError      **error)
{
  static const char hexchars[] = "0123456789abcdef";
  g_autofree char *ret_rev = NULL;

  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);

  /* If the input is longer than OSTREE_SHA256_STRING_LEN chars or contains non-hex chars,
     don't bother looking for it as an object */
  const gsize off = strspn (refspec, hexchars);
  if (off > OSTREE_SHA256_STRING_LEN || refspec[off] != '\0')
    return TRUE;

  /* this looks through all objects and adds them to the ref_list if:
     a) they are a commit object AND
     b) the obj checksum starts with the partual checksum defined by "refspec" */
  g_autoptr(GHashTable) ref_list = NULL;
  if (!ostree_repo_list_commit_objects_starting_with (self, refspec, &ref_list, NULL, error))
    return FALSE;

  guint length = g_hash_table_size (ref_list);

  GHashTableIter hashiter;
  gpointer key, value;
  GVariant *first_commit = NULL;
  g_hash_table_iter_init (&hashiter, ref_list);
  if (g_hash_table_iter_next (&hashiter, &key, &value))
    first_commit = (GVariant*) key;

  OstreeObjectType objtype;
  const char *checksum = NULL;
  if (first_commit)
    ostree_object_name_deserialize (first_commit, &checksum, &objtype);

  /* length more than one - multiple commits match partial refspec: is not unique */
  if (length > 1)
    return glnx_throw (error, "Refspec %s not unique", refspec);
  /* length is 1 - a single matching commit gives us our revision */
  else if (length == 1)
    ret_rev = g_strdup (checksum);

  /* Note: if length is 0, then code will return TRUE
     because there is no error, but it will return full_checksum = NULL
     to signal to continue parsing */

  ot_transfer_out_value (full_checksum, &ret_rev);
  return TRUE;
}

static gboolean
_ostree_repo_resolve_rev_internal (OstreeRepo     *self,
                                   const char     *refspec,
                                   gboolean        allow_noent,
                                   gboolean        fallback_remote,
                                   char          **out_rev,
                                   GError        **error)
{
  g_autofree char *ret_rev = NULL;

  g_return_val_if_fail (refspec != NULL, FALSE);

  if (ostree_validate_checksum_string (refspec, NULL))
    {
      ret_rev = g_strdup (refspec);
    }
  else if (!ostree_repo_resolve_partial_checksum (self, refspec, &ret_rev, error))
    return FALSE;

  if (!ret_rev)
    {
      if (error != NULL && *error != NULL)
        return FALSE;

      if (g_str_has_suffix (refspec, "^"))
        {
          g_autofree char *parent_refspec = NULL;
          g_autofree char *parent_rev = NULL;
          g_autoptr(GVariant) commit = NULL;

          parent_refspec = g_strdup (refspec);
          parent_refspec[strlen(parent_refspec) - 1] = '\0';

          if (!ostree_repo_resolve_rev (self, parent_refspec, allow_noent, &parent_rev, error))
            return FALSE;

          if (!ostree_repo_load_variant (self, OSTREE_OBJECT_TYPE_COMMIT, parent_rev,
                                         &commit, error))
            return FALSE;

          if (!(ret_rev = ostree_commit_get_parent (commit)))
            return glnx_throw (error, "Commit %s has no parent", parent_rev);
        }
      else
        {
          g_autofree char *remote = NULL;
          g_autofree char *ref = NULL;

          if (!ostree_parse_refspec (refspec, &remote, &ref, error))
            return FALSE;

          if (!resolve_refspec (self, remote, ref, allow_noent,
                                fallback_remote, &ret_rev, error))
            return FALSE;
        }
    }

  ot_transfer_out_value (out_rev, &ret_rev);
  return TRUE;
}

/**
 * ostree_repo_resolve_rev:
 * @self: Repo
 * @refspec: A refspec
 * @allow_noent: Do not throw an error if refspec does not exist
 * @out_rev: (out) (nullable) (transfer full): A checksum,or %NULL if @allow_noent is true and it does not exist
 * @error: Error
 *
 * Look up the given refspec, returning the checksum it references in
 * the parameter @out_rev. Will fall back on remote directory if cannot
 * find the given refspec in local.
 */
gboolean
ostree_repo_resolve_rev (OstreeRepo     *self,
                         const char     *refspec,
                         gboolean        allow_noent,
                         char          **out_rev,
                         GError        **error)
{
  return _ostree_repo_resolve_rev_internal (self, refspec, allow_noent, TRUE, out_rev, error);
}

/**
 * ostree_repo_resolve_rev_ext:
 * @self: Repo
 * @refspec: A refspec
 * @allow_noent: Do not throw an error if refspec does not exist
 * @flags: Options controlling behavior
 * @out_rev: (out) (nullable) (transfer full): A checksum,or %NULL if @allow_noent is true and it does not exist
 * @error: Error
 *
 * Look up the given refspec, returning the checksum it references in
 * the parameter @out_rev. Differently from ostree_repo_resolve_rev(),
 * this will not fall back to searching through remote repos if a
 * local ref is specified but not found.
 *
 * The flag %OSTREE_REPO_RESOLVE_REV_EXT_LOCAL_ONLY is implied so
 * using it has no effect.
 *
 * Since: 2016.7
 */
gboolean
ostree_repo_resolve_rev_ext (OstreeRepo                    *self,
                             const char                    *refspec,
                             gboolean                       allow_noent,
                             OstreeRepoResolveRevExtFlags   flags,
                             char                         **out_rev,
                             GError                       **error)
{
  return _ostree_repo_resolve_rev_internal (self, refspec, allow_noent, FALSE, out_rev, error);
}

/**
 * ostree_repo_resolve_collection_ref:
 * @self: an #OstreeRepo
 * @ref: a collection–ref to resolve
 * @allow_noent: %TRUE to not throw an error if @ref doesn’t exist
 * @flags: options controlling behaviour
 * @out_rev: (out) (transfer full) (optional) (nullable): return location for
 *    the checksum corresponding to @ref, or %NULL if @allow_noent is %TRUE and
 *    the @ref could not be found
 * @cancellable: (nullable): a #GCancellable, or %NULL
 * @error: return location for a #GError, or %NULL
 *
 * Look up the checksum for the given collection–ref, returning it in @out_rev.
 * This will search through the mirrors and remote refs.
 *
 * If @allow_noent is %TRUE and the given @ref cannot be found, %TRUE will be
 * returned and @out_rev will be set to %NULL. If @allow_noent is %FALSE and
 * the given @ref cannot be found, a %G_IO_ERROR_NOT_FOUND error will be
 * returned.
 *
 * If you want to check only local refs, not remote or mirrored ones, use the
 * flag %OSTREE_REPO_RESOLVE_REV_EXT_LOCAL_ONLY. This is analogous to using
 * ostree_repo_resolve_rev_ext() but for collection-refs.
 *
 * Returns: %TRUE on success, %FALSE on failure
 * Since: 2018.6
 */
gboolean
ostree_repo_resolve_collection_ref (OstreeRepo                    *self,
                                    const OstreeCollectionRef     *ref,
                                    gboolean                       allow_noent,
                                    OstreeRepoResolveRevExtFlags   flags,
                                    char                         **out_rev,
                                    GCancellable                  *cancellable,
                                    GError                       **error)
{
  g_autofree char *ret_contents = NULL;

  g_return_val_if_fail (OSTREE_IS_REPO (self), FALSE);
  g_return_val_if_fail (ref != NULL, FALSE);
  g_return_val_if_fail (ref->collection_id != NULL && ref->ref_name != NULL, FALSE);
  g_return_val_if_fail (cancellable == NULL || G_IS_CANCELLABLE (cancellable), FALSE);
  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);

  /* Check for the ref in the current transaction in case it hasn't been
   * written to disk, to match the behavior of ostree_repo_resolve_rev() */
  if (self->in_transaction)
    {
      g_mutex_lock (&self->txn_lock);
      if (self->txn.collection_refs)
        {
          const char *repo_collection_id = ostree_repo_get_collection_id (self);
          /* If the collection ID doesn't match it's a remote ref */
          if (!(flags & OSTREE_REPO_RESOLVE_REV_EXT_LOCAL_ONLY) ||
              repo_collection_id == NULL ||
              g_strcmp0 (repo_collection_id, ref->collection_id) == 0)
            {
              ret_contents = g_strdup (g_hash_table_lookup (self->txn.collection_refs, ref));
            }
         }
      g_mutex_unlock (&self->txn_lock);
    }

  /* Check for the ref on disk in the repo */
  if (ret_contents == NULL)
    {
      g_autoptr(GHashTable) refs = NULL;  /* (element-type OstreeCollectionRef utf8) */
      OstreeRepoListRefsExtFlags list_refs_flags;

      if (flags & OSTREE_REPO_RESOLVE_REV_EXT_LOCAL_ONLY)
        list_refs_flags = OSTREE_REPO_LIST_REFS_EXT_EXCLUDE_REMOTES | OSTREE_REPO_LIST_REFS_EXT_EXCLUDE_MIRRORS;
      else
        list_refs_flags = OSTREE_REPO_LIST_REFS_EXT_NONE;

      if (!ostree_repo_list_collection_refs (self, ref->collection_id, &refs,
                                             list_refs_flags, cancellable, error))
        return FALSE;

      ret_contents = g_strdup (g_hash_table_lookup (refs, ref));
    }

  /* Check for the ref in the parent repo */
  if (ret_contents == NULL && self->parent_repo != NULL)
    {
      if (!ostree_repo_resolve_collection_ref (self->parent_repo,
                                               ref,
                                               TRUE,
                                               flags,
                                               &ret_contents,
                                               cancellable,
                                               error))
        return FALSE;
    }

  if (ret_contents == NULL && !allow_noent)
    {
      g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND,
                   "Collection–ref (%s, %s) not found",
                   ref->collection_id, ref->ref_name);
      return FALSE;
    }

  if (out_rev != NULL)
    *out_rev = g_steal_pointer (&ret_contents);
  return TRUE;
}

static gboolean
enumerate_refs_recurse (OstreeRepo    *repo,
                        const char    *remote,
                        OstreeRepoListRefsExtFlags flags,
                        const char    *collection_id,
                        int            base_dfd,
                        GString       *base_path,
                        int            child_dfd,
                        const char    *path,
                        GHashTable    *refs,
                        GCancellable  *cancellable,
                        GError       **error)
{
  g_auto(GLnxDirFdIterator) dfd_iter = { 0, };
  const gboolean aliases_only = (flags & OSTREE_REPO_LIST_REFS_EXT_ALIASES) > 0;

  if (!glnx_dirfd_iterator_init_at (child_dfd, path, FALSE, &dfd_iter, error))
    return FALSE;

  while (TRUE)
    {
      guint len = base_path->len;
      struct dirent *dent = NULL;

      if (!glnx_dirfd_iterator_next_dent_ensure_dtype (&dfd_iter, &dent, cancellable, error))
        return FALSE;
      if (dent == NULL)
        break;

      /* https://github.com/ostreedev/ostree/issues/1285
       * Ignore any files that don't appear to be valid fragments; e.g.
       * Red Hat has a tool that drops .rsync_info files into each
       * directory it syncs.
       **/
      if (!_ostree_validate_ref_fragment (dent->d_name, NULL))
        continue;

      g_string_append (base_path, dent->d_name);

      if (dent->d_type == DT_DIR)
        {
          g_string_append_c (base_path, '/');

          if (!enumerate_refs_recurse (repo, remote, flags, collection_id, base_dfd, base_path,
                                       dfd_iter.fd, dent->d_name,
                                       refs, cancellable, error))
            return FALSE;
        }
      else
        {
          if (aliases_only && dent->d_type == DT_LNK)
            {
              g_autofree char *target = glnx_readlinkat_malloc (base_dfd, base_path->str,
                                                                cancellable, error);
              const char *resolved_target = target;
              if (!target)
                return FALSE;
              while (g_str_has_prefix (resolved_target, "../"))
                resolved_target += 3;
              g_hash_table_insert (refs, g_strdup (base_path->str), g_strdup (resolved_target));
            }
          else if ((!aliases_only && dent->d_type == DT_REG) || dent->d_type == DT_LNK)
            {
              if (!add_ref_to_set (remote, collection_id, base_dfd, base_path->str, refs,
                                   cancellable, error))
                return FALSE;
            }
        }

      g_string_truncate (base_path, len);
    }

  return TRUE;
}

static gboolean
_ostree_repo_list_refs_internal (OstreeRepo       *self,
                                 gboolean         cut_prefix,
                                 OstreeRepoListRefsExtFlags flags,
                                 const char       *refspec_prefix,
                                 GHashTable      **out_all_refs,
                                 GCancellable     *cancellable,
                                 GError          **error)
{
  GLNX_AUTO_PREFIX_ERROR ("Listing refs", error);

  g_autofree char *remote = NULL;
  g_autofree char *ref_prefix = NULL;

  g_autoptr(GHashTable) ret_all_refs = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_free);
  if (refspec_prefix)
    {
      struct stat stbuf;
      const char *prefix_path;
      const char *path;

      /* special-case "<remote>:" and "<remote>:.", which ostree_parse_refspec won't like */
      if (g_str_has_suffix (refspec_prefix, ":") ||
          g_str_has_suffix (refspec_prefix, ":."))
        {
          const char *colon = strrchr (refspec_prefix, ':');
          g_autofree char *r = g_strndup (refspec_prefix, colon - refspec_prefix);
          if (ostree_validate_remote_name (r, NULL))
            {
              remote = g_steal_pointer (&r);
              ref_prefix = g_strdup (".");
            }
        }

      if (!ref_prefix)
        {
          if (!ostree_parse_refspec (refspec_prefix, &remote, &ref_prefix, error))
            return FALSE;
        }

      if (!(flags & OSTREE_REPO_LIST_REFS_EXT_EXCLUDE_REMOTES) && remote)
        {
          prefix_path = glnx_strjoina ("refs/remotes/", remote, "/");
          path = glnx_strjoina (prefix_path, ref_prefix);
        }
      else
        {
          prefix_path = "refs/heads/";
          path = glnx_strjoina (prefix_path, ref_prefix);
        }

      if (!glnx_fstatat_allow_noent (self->repo_dir_fd, path, &stbuf, 0, error))
        return FALSE;
      if (errno == 0)
        {
          if (S_ISDIR (stbuf.st_mode))
            {
              glnx_autofd int base_fd = -1;
              g_autoptr(GString) base_path = g_string_new ("");
              if (!cut_prefix)
                g_string_printf (base_path, "%s/", ref_prefix);

              if (!glnx_opendirat (self->repo_dir_fd, cut_prefix ? path : prefix_path, TRUE, &base_fd, error))
                return FALSE;

              if (!enumerate_refs_recurse (self, remote, flags, NULL, base_fd, base_path,
                                           base_fd, cut_prefix ? "." : ref_prefix,
                                           ret_all_refs, cancellable, error))
                return FALSE;
            }
          else
            {
              glnx_autofd int prefix_dfd = -1;

              if (!glnx_opendirat (self->repo_dir_fd, prefix_path, TRUE, &prefix_dfd, error))
                return FALSE;

              if (!add_ref_to_set (remote, NULL, prefix_dfd, ref_prefix, ret_all_refs,
                                   cancellable, error))
                return FALSE;
            }
        }
    }
  else
    {
      g_auto(GLnxDirFdIterator) dfd_iter = { 0, };
      g_autoptr(GString) base_path = g_string_new ("");
      glnx_autofd int refs_heads_dfd = -1;

      if (!glnx_opendirat (self->repo_dir_fd, "refs/heads", TRUE, &refs_heads_dfd, error))
        return FALSE;

      if (!enumerate_refs_recurse (self, NULL, flags, NULL, refs_heads_dfd, base_path,
                                   refs_heads_dfd, ".",
                                   ret_all_refs, cancellable, error))
        return FALSE;

      if (!(flags & OSTREE_REPO_LIST_REFS_EXT_EXCLUDE_REMOTES))
        {
          g_string_truncate (base_path, 0);

          if (!glnx_dirfd_iterator_init_at (self->repo_dir_fd, "refs/remotes", TRUE, &dfd_iter, error))
            return FALSE;

          while (TRUE)
            {
              struct dirent *dent;
              glnx_autofd int remote_dfd = -1;

              if (!glnx_dirfd_iterator_next_dent_ensure_dtype (&dfd_iter, &dent, cancellable, error))
                return FALSE;
              if (!dent)
                break;

              if (dent->d_type != DT_DIR)
                continue;

              if (!glnx_opendirat (dfd_iter.fd, dent->d_name, TRUE, &remote_dfd, error))
                return FALSE;

              if (!enumerate_refs_recurse (self, dent->d_name, flags, NULL, remote_dfd, base_path,
                                           remote_dfd, ".",
                                           ret_all_refs,
                                           cancellable, error))
                return FALSE;
            }
        }
    }

  ot_transfer_out_value (out_all_refs, &ret_all_refs);
  return TRUE;
}

/**
 * ostree_repo_list_refs:
 * @self: Repo
 * @refspec_prefix: (allow-none): Only list refs which match this prefix
 * @out_all_refs: (out) (element-type utf8 utf8) (transfer container):
 *    Mapping from refspec to checksum
 * @cancellable: Cancellable
 * @error: Error
 *
 * If @refspec_prefix is %NULL, list all local and remote refspecs,
 * with their current values in @out_all_refs.  Otherwise, only list
 * refspecs which have @refspec_prefix as a prefix.
 *
 * @out_all_refs will be returned as a mapping from refspecs (including the
 * remote name) to checksums. If @refspec_prefix is non-%NULL, it will be
 * removed as a prefix from the hash table keys.
 */
gboolean
ostree_repo_list_refs (OstreeRepo       *self,
                       const char       *refspec_prefix,
                       GHashTable      **out_all_refs,
                       GCancellable     *cancellable,
                       GError          **error)
{
  return _ostree_repo_list_refs_internal (self, TRUE,
                                          OSTREE_REPO_LIST_REFS_EXT_NONE,
                                          refspec_prefix, out_all_refs,
                                          cancellable, error);
}

/**
 * ostree_repo_list_refs_ext:
 * @self: Repo
 * @refspec_prefix: (allow-none): Only list refs which match this prefix
 * @out_all_refs: (out) (element-type utf8 utf8) (transfer container):
 *    Mapping from refspec to checksum
 * @flags: Options controlling listing behavior
 * @cancellable: Cancellable
 * @error: Error
 *
 * If @refspec_prefix is %NULL, list all local and remote refspecs,
 * with their current values in @out_all_refs.  Otherwise, only list
 * refspecs which have @refspec_prefix as a prefix.
 *
 * @out_all_refs will be returned as a mapping from refspecs (including the
 * remote name) to checksums. Differently from ostree_repo_list_refs(), the
 * @refspec_prefix will not be removed from the refspecs in the hash table.
 *
 * Since: 2016.4
 */
gboolean
ostree_repo_list_refs_ext (OstreeRepo                 *self,
                           const char                 *refspec_prefix,
                           GHashTable                 **out_all_refs,
                           OstreeRepoListRefsExtFlags flags,
                           GCancellable               *cancellable,
                           GError                     **error)
{
  return _ostree_repo_list_refs_internal (self, FALSE, flags,
                                          refspec_prefix, out_all_refs,
                                          cancellable, error);
}

/**
 * ostree_repo_remote_list_refs:
 * @self: Repo
 * @remote_name: Name of the remote.
 * @out_all_refs: (out) (element-type utf8 utf8) (transfer container):
 *    Mapping from ref to checksum
 * @cancellable: Cancellable
 * @error: Error
 *
 */
gboolean
ostree_repo_remote_list_refs (OstreeRepo       *self,
                              const char       *remote_name,
                              GHashTable      **out_all_refs,
                              GCancellable     *cancellable,
                              GError          **error)
{
  g_autoptr(GBytes) summary_bytes = NULL;
  g_autoptr(GHashTable) ret_all_refs = NULL;

  if (!ostree_repo_remote_fetch_summary (self, remote_name,
                                         &summary_bytes, NULL,
                                         cancellable, error))
    return FALSE;

  if (summary_bytes == NULL)
    {
      return glnx_throw (error, "Remote refs not available; server has no summary file");
    }
  else
    {
      g_autoptr(GVariant) summary = NULL;
      g_autoptr(GVariant) ref_map = NULL;
      GVariantIter iter;
      GVariant *child;
      ret_all_refs = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_free);

      summary = g_variant_new_from_bytes (OSTREE_SUMMARY_GVARIANT_FORMAT,
                                          summary_bytes, FALSE);

      ref_map = g_variant_get_child_value (summary, 0);

      g_variant_iter_init (&iter, ref_map);
      while ((child = g_variant_iter_next_value (&iter)) != NULL)
        {
          const char *ref_name = NULL;
          g_autoptr(GVariant) csum_v = NULL;
          char tmp_checksum[OSTREE_SHA256_STRING_LEN+1];

          g_variant_get_child (child, 0, "&s", &ref_name);

          if (ref_name != NULL)
            {
              g_variant_get_child (child, 1, "(t@aya{sv})", NULL, &csum_v, NULL);

              const guchar *csum_bytes = ostree_checksum_bytes_peek_validate (csum_v, error);
              if (csum_bytes == NULL)
                return FALSE;

              ostree_checksum_inplace_from_bytes (csum_bytes, tmp_checksum);

              g_hash_table_insert (ret_all_refs,
                                   g_strdup (ref_name),
                                   g_strdup (tmp_checksum));
            }

          g_variant_unref (child);
        }
    }

  ot_transfer_out_value (out_all_refs, &ret_all_refs);
  return TRUE;
}

static gboolean
remote_list_collection_refs_process_refs (OstreeRepo   *self,
                                          const gchar  *remote_name,
                                          const gchar  *summary_collection_id,
                                          GVariant     *summary_refs,
                                          GHashTable   *ret_all_refs,
                                          GError      **error)
{
  gsize j, n;

  for (j = 0, n = g_variant_n_children (summary_refs); j < n; j++)
    {
      const guchar *csum_bytes;
      g_autoptr(GVariant) ref_v = NULL, csum_v = NULL;
      gchar tmp_checksum[OSTREE_SHA256_STRING_LEN + 1];
      const gchar *ref_name;

      /* Check the ref name. */
      ref_v = g_variant_get_child_value (summary_refs, j);
      g_variant_get_child (ref_v, 0, "&s", &ref_name);

      if (!ostree_validate_rev (ref_name, error))
        return FALSE;

      /* Check the commit checksum. */
      g_variant_get_child (ref_v, 1, "(t@ay@a{sv})", NULL, &csum_v, NULL);

      csum_bytes = ostree_checksum_bytes_peek_validate (csum_v, error);
      if (csum_bytes == NULL)
        return FALSE;

      ostree_checksum_inplace_from_bytes (csum_bytes, tmp_checksum);

      g_hash_table_insert (ret_all_refs,
                           ostree_collection_ref_new (summary_collection_id, ref_name),
                           g_strdup (tmp_checksum));
    }

  return TRUE;
}

/**
 * ostree_repo_remote_list_collection_refs:
 * @self: Repo
 * @remote_name: Name of the remote.
 * @out_all_refs: (out) (element-type OstreeCollectionRef utf8) (transfer container):
 *    Mapping from collection–ref to checksum
 * @cancellable: Cancellable
 * @error: Error
 *
 * List refs advertised by @remote_name, including refs which are part of
 * collections. If the repository at @remote_name has a collection ID set, its
 * refs will be returned with that collection ID; otherwise, they will be returned
 * with a %NULL collection ID in each #OstreeCollectionRef key in @out_all_refs.
 * Any refs for other collections stored in the repository will also be returned.
 * No filtering is performed.
 *
 * Since: 2018.6
 */
gboolean
ostree_repo_remote_list_collection_refs (OstreeRepo    *self,
                                         const char    *remote_name,
                                         GHashTable   **out_all_refs,
                                         GCancellable  *cancellable,
                                         GError       **error)
{
  g_autoptr(GBytes) summary_bytes = NULL;
  g_autoptr(GHashTable) ret_all_refs = NULL;  /* (element-type OstreeCollectionRef utf8) */
  g_autoptr(GVariant) summary_v = NULL;
  g_autoptr(GVariant) additional_metadata_v = NULL;
  g_autoptr(GVariant) summary_refs = NULL;
  const char *summary_collection_id;
  g_autoptr(GVariantIter) summary_collection_map = NULL;

  if (!ostree_repo_remote_fetch_summary (self, remote_name,
                                         &summary_bytes, NULL,
                                         cancellable, error))
    return FALSE;

  if (summary_bytes == NULL)
    return glnx_throw (error, "Remote refs not available; server has no summary file");

  ret_all_refs = g_hash_table_new_full (ostree_collection_ref_hash,
                                        ostree_collection_ref_equal,
                                        (GDestroyNotify) ostree_collection_ref_free,
                                        g_free);

  summary_v = g_variant_new_from_bytes (OSTREE_SUMMARY_GVARIANT_FORMAT,
                                        summary_bytes, FALSE);
  additional_metadata_v = g_variant_get_child_value (summary_v, 1);

  /* List the refs in the main map. */
  if (!g_variant_lookup (additional_metadata_v, OSTREE_SUMMARY_COLLECTION_ID, "&s", &summary_collection_id))
    summary_collection_id = NULL;

  summary_refs = g_variant_get_child_value (summary_v, 0);

  if (!remote_list_collection_refs_process_refs (self, remote_name,
                                                summary_collection_id, summary_refs,
                                                ret_all_refs, error))
    return FALSE;

  /* List the refs in the collection map. */
  if (!g_variant_lookup (additional_metadata_v, OSTREE_SUMMARY_COLLECTION_MAP, "a{sa(s(taya{sv}))}", &summary_collection_map))
    summary_collection_map = NULL;

  while (summary_collection_map != NULL &&
         g_variant_iter_loop (summary_collection_map, "{&s@a(s(taya{sv}))}", &summary_collection_id, &summary_refs))
    {
      if (!remote_list_collection_refs_process_refs (self, remote_name,
                                                     summary_collection_id, summary_refs,
                                                     ret_all_refs, error))
        return FALSE;
    }

  ot_transfer_out_value (out_all_refs, &ret_all_refs);
  return TRUE;
}

static char *
relative_symlink_to (const char *relpath,
                     const char *target)
{
  g_assert (*relpath);
  g_assert (*target && *target != '/');

  g_autoptr(GString) buf = g_string_new ("");

  while (TRUE)
    {
      const char *slash = strchr (relpath, '/');
      if (!slash)
        break;
      relpath = slash + 1;
      g_string_append (buf, "../");
    }

  g_string_append (buf, target);

  return g_string_free (g_steal_pointer (&buf), FALSE);
}

/* May specify @rev or @alias */
gboolean
_ostree_repo_write_ref (OstreeRepo                 *self,
                        const char                 *remote,
                        const OstreeCollectionRef  *ref,
                        const char                 *rev,
                        const char                 *alias,
                        GCancellable               *cancellable,
                        GError                    **error)
{
  glnx_autofd int dfd = -1;

  g_return_val_if_fail (remote == NULL || ref->collection_id == NULL, FALSE);
  g_return_val_if_fail (!(rev != NULL && alias != NULL), FALSE);

  if (remote != NULL && !ostree_validate_remote_name (remote, error))
    return FALSE;
  if (ref->collection_id != NULL && !ostree_validate_collection_id (ref->collection_id, error))
    return FALSE;
  if (!ostree_validate_rev (ref->ref_name, error))
    return FALSE;

  if (remote == NULL &&
      (ref->collection_id == NULL || g_strcmp0 (ref->collection_id, ostree_repo_get_collection_id (self)) == 0))
    {
      if (!glnx_opendirat (self->repo_dir_fd, "refs/heads", TRUE,
                           &dfd, error))
        return FALSE;
    }
  else if (remote == NULL && ref->collection_id != NULL)
    {
      glnx_autofd int refs_mirrors_dfd = -1;

      /* refs/mirrors might not exist in older repositories, so create it. */
      if (!glnx_shutil_mkdir_p_at_open (self->repo_dir_fd, "refs/mirrors", 0777,
                                        &refs_mirrors_dfd, cancellable, error))
        return FALSE;

      if (rev != NULL)
        {
          /* Ensure we have a dir for the collection */
          if (!glnx_shutil_mkdir_p_at (refs_mirrors_dfd, ref->collection_id, 0777, cancellable, error))
            return FALSE;
        }

      dfd = glnx_opendirat_with_errno (refs_mirrors_dfd, ref->collection_id, TRUE);
      if (dfd < 0 && (errno != ENOENT || rev != NULL))
        return glnx_throw_errno_prefix (error, "Opening mirrors/ dir %s", ref->collection_id);
    }
  else
    {
      glnx_autofd int refs_remotes_dfd = -1;

      if (!glnx_opendirat (self->repo_dir_fd, "refs/remotes", TRUE,
                           &refs_remotes_dfd, error))
        return FALSE;

      if (rev != NULL)
        {
          /* Ensure we have a dir for the remote */
          if (!glnx_shutil_mkdir_p_at (refs_remotes_dfd, remote, 0777, cancellable, error))
            return FALSE;
        }

      dfd = glnx_opendirat_with_errno (refs_remotes_dfd, remote, TRUE);
      if (dfd < 0 && (errno != ENOENT || rev != NULL))
        return glnx_throw_errno_prefix (error, "Opening remotes/ dir %s", remote);
    }

  if (rev == NULL && alias == NULL)
    {
      if (dfd >= 0)
        {
          if (!ot_ensure_unlinked_at (dfd, ref->ref_name, error))
            return FALSE;
        }
    }
  else if (rev != NULL)
    {
      if (!write_checksum_file_at (self, dfd, ref->ref_name, rev, cancellable, error))
        return FALSE;
    }
  else if (alias != NULL)
    {
      const char *lastslash = strrchr (ref->ref_name, '/');

      if (lastslash)
        {
          char *parent = strdupa (ref->ref_name);
          parent[lastslash - ref->ref_name] = '\0';

          if (!glnx_shutil_mkdir_p_at (dfd, parent, DEFAULT_DIRECTORY_MODE, cancellable, error))
            return FALSE;
        }

      g_autofree char *reltarget = relative_symlink_to (ref->ref_name, alias);
      g_autofree char *tmplink = NULL;
      if (!_ostree_make_temporary_symlink_at (self->tmp_dir_fd, reltarget,
                                              &tmplink, cancellable, error))
        return FALSE;
      if (!glnx_renameat (self->tmp_dir_fd, tmplink, dfd, ref->ref_name, error))
        return FALSE;
    }

  if (!_ostree_repo_update_mtime (self, error))
    return FALSE;

  /* Update the summary after updating the mtime so the summary doesn't look
   * out of date */
  if (!self->in_transaction && !_ostree_repo_maybe_regenerate_summary (self, cancellable, error))
    return FALSE;

  return TRUE;
}

gboolean
_ostree_repo_update_refs (OstreeRepo        *self,
                          GHashTable        *refs,  /* (element-type utf8 utf8) */
                          GCancellable      *cancellable,
                          GError           **error)
{
  GLNX_HASH_TABLE_FOREACH_KV (refs, const char*, refspec, const char*, rev)
    {
      g_autofree char *remote = NULL;
      g_autofree char *ref_name = NULL;
      if (!ostree_parse_refspec (refspec, &remote, &ref_name, error))
        return FALSE;

      const OstreeCollectionRef ref = { NULL, ref_name };
      if (!_ostree_repo_write_ref (self, remote, &ref, rev, NULL,
                                   cancellable, error))
        return FALSE;
    }

  return TRUE;
}

gboolean
_ostree_repo_update_collection_refs (OstreeRepo        *self,
                                     GHashTable        *refs,  /* (element-type OstreeCollectionRef utf8) */
                                     GCancellable      *cancellable,
                                     GError           **error)
{
  GHashTableIter hash_iter;
  gpointer key, value;

  g_hash_table_iter_init (&hash_iter, refs);
  while (g_hash_table_iter_next (&hash_iter, &key, &value))
    {
      const OstreeCollectionRef *ref = key;
      const char *rev = value;

      if (!_ostree_repo_write_ref (self, NULL, ref, rev, NULL,
                                   cancellable, error))
        return FALSE;
    }

  return TRUE;
}

/**
 * ostree_repo_list_collection_refs:
 * @self: Repo
 * @match_collection_id: (nullable): If non-%NULL, only list refs from this collection
 * @out_all_refs: (out) (element-type OstreeCollectionRef utf8) (transfer container):
 *    Mapping from collection–ref to checksum
 * @flags: Options controlling listing behavior
 * @cancellable: Cancellable
 * @error: Error
 *
 * List all local, mirrored, and remote refs, mapping them to the commit
 * checksums they currently point to in @out_all_refs. If @match_collection_id
 * is specified, the results will be limited to those with an equal collection
 * ID.
 *
 * #OstreeCollectionRefs are guaranteed to be returned with their collection ID
 * set to a non-%NULL value; so no refs from `refs/heads` will be listed if no
 * collection ID is configured for the repository
 * (ostree_repo_get_collection_id()).
 *
 * If you want to exclude refs from `refs/remotes`, use
 * %OSTREE_REPO_LIST_REFS_EXT_EXCLUDE_REMOTES in @flags. Similarly use
 * %OSTREE_REPO_LIST_REFS_EXT_EXCLUDE_MIRRORS to exclude refs from
 * `refs/mirrors`.
 *
 * Returns: %TRUE on success, %FALSE otherwise
 * Since: 2018.6
 */
gboolean
ostree_repo_list_collection_refs (OstreeRepo                 *self,
                                  const char                 *match_collection_id,
                                  GHashTable                 **out_all_refs,
                                  OstreeRepoListRefsExtFlags flags,
                                  GCancellable               *cancellable,
                                  GError                     **error)
{
  GLNX_AUTO_PREFIX_ERROR ("Listing refs", error);

  g_return_val_if_fail (OSTREE_IS_REPO (self), FALSE);
  g_return_val_if_fail (cancellable == NULL || G_IS_CANCELLABLE (cancellable), FALSE);
  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);

  if (match_collection_id != NULL && !ostree_validate_collection_id (match_collection_id, error))
    return FALSE;

  g_autoptr(GPtrArray) refs_dirs = g_ptr_array_new ();
  if (!(flags & OSTREE_REPO_LIST_REFS_EXT_EXCLUDE_MIRRORS))
    g_ptr_array_add (refs_dirs, "refs/mirrors");
  if (!(flags & OSTREE_REPO_LIST_REFS_EXT_EXCLUDE_REMOTES))
    g_ptr_array_add (refs_dirs, "refs/remotes");
  g_ptr_array_add (refs_dirs, NULL);

  g_autoptr(GHashTable) ret_all_refs = NULL;

  ret_all_refs = g_hash_table_new_full (ostree_collection_ref_hash,
                                        ostree_collection_ref_equal,
                                        (GDestroyNotify) ostree_collection_ref_free,
                                        g_free);

  g_autoptr(GString) base_path = g_string_new ("");

  const gchar *main_collection_id = ostree_repo_get_collection_id (self);

  if (main_collection_id != NULL &&
      (match_collection_id == NULL || g_strcmp0 (match_collection_id, main_collection_id) == 0))
    {
      glnx_autofd int refs_heads_dfd = -1;

      if (!glnx_opendirat (self->repo_dir_fd, "refs/heads", TRUE, &refs_heads_dfd, error))
        return FALSE;

      if (!enumerate_refs_recurse (self, NULL, flags,
                                   main_collection_id, refs_heads_dfd, base_path,
                                   refs_heads_dfd, ".",
                                   ret_all_refs, cancellable, error))
        return FALSE;
    }

  g_string_truncate (base_path, 0);

  for (const char **iter = (const char **)refs_dirs->pdata; iter && *iter; iter++)
    {
      const char *refs_dir = *iter;
      gboolean refs_dir_exists = FALSE;
      g_auto(GLnxDirFdIterator) dfd_iter = { 0, };

      if (!ot_dfd_iter_init_allow_noent (self->repo_dir_fd, refs_dir,
                                         &dfd_iter, &refs_dir_exists, error))
        return FALSE;

      while (refs_dir_exists)
        {
          struct dirent *dent;
          glnx_autofd int subdir_fd = -1;
          const gchar *current_collection_id;
          g_autofree gchar *remote_collection_id = NULL;

          if (!glnx_dirfd_iterator_next_dent_ensure_dtype (&dfd_iter, &dent, cancellable, error))
            return FALSE;
          if (!dent)
            break;

          if (dent->d_type != DT_DIR)
            continue;

          if (g_strcmp0 (refs_dir, "refs/mirrors") == 0)
            {
              if (match_collection_id != NULL && g_strcmp0 (match_collection_id, dent->d_name) != 0)
                continue;
              else
                current_collection_id = dent->d_name;
            }
          else /* refs_dir = "refs/remotes" */
            {
              g_autoptr(GError) local_error = NULL;
              if (!ostree_repo_get_remote_option (self, dent->d_name, "collection-id",
                                                  NULL, &remote_collection_id, &local_error) ||
                  !ostree_validate_collection_id (remote_collection_id, &local_error))
                {
                  g_debug ("Ignoring remote ‘%s’ due to no valid collection ID being configured for it: %s",
                           dent->d_name, local_error->message);
                  g_clear_error (&local_error);
                  continue;
                }

              if (match_collection_id != NULL && g_strcmp0 (match_collection_id, remote_collection_id) != 0)
                continue;
              else
                current_collection_id = remote_collection_id;
            }

          if (!glnx_opendirat (dfd_iter.fd, dent->d_name, TRUE, &subdir_fd, error))
            return FALSE;

          if (!enumerate_refs_recurse (self, NULL, flags,
                                       current_collection_id, subdir_fd, base_path,
                                       subdir_fd, ".",
                                       ret_all_refs,
                                       cancellable, error))
            return FALSE;
        }
    }

  ot_transfer_out_value (out_all_refs, &ret_all_refs);
  return TRUE;
}
