builder-git.c

/* builder-git.c
 *
 * Copyright (C) 2015 Red Hat, Inc
 *
 * This file 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 file 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 program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Authors:
 *       Alexander Larsson <alexl@redhat.com>
 */

#include "config.h"

#include <string.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/statfs.h>

#include "builder-utils.h"

#include "builder-git.h"
#include "builder-utils.h"
#include "builder-flatpak-utils.h"

static gboolean
git (GFile   *dir,
     char   **output,
     GSubprocessFlags flags,
     GError **error,
     ...)
{
  gboolean res;
  va_list ap;

  va_start (ap, error);
  res = flatpak_spawn (dir, output, flags, error, "git", ap);
  va_end (ap);

  return res;
}

static gboolean
cp (GError **error,
     ...)
{
  gboolean res;
  va_list ap;

  va_start (ap, error);
  res = flatpak_spawn (NULL, NULL, 0, error, "cp", ap);
  va_end (ap);

  return res;
}

static gboolean
git_get_version (GError **error,
                 int *major,
                 int *minor,
                 int *micro,
                 int *extra)
{
  g_autofree char *output = NULL;
  char *p;

  *major = *minor = *micro = *extra = 0;

  if (!git (NULL, &output, 0, error,
            "--version", NULL))
    return FALSE;

  /* Trim trailing whitespace */
  g_strchomp (output);

  if (!g_str_has_prefix (output, "git version "))
    return flatpak_fail (error, "Unexpected git --version output");

  p = output + strlen ("git version ");

  *major = strtol (p, &p, 10);
  while (*p == '.')
    p++;
  *minor = strtol (p, &p, 10);
  while (*p == '.')
    p++;
  *micro = strtol (p, &p, 10);
  while (*p == '.')
    p++;
  *extra = strtol (p, &p, 10);
  while (*p == '.')
    p++;

  return TRUE;
}

static gboolean
git_has_version (int major,
                 int minor,
                 int micro,
                 int extra)
{
  g_autoptr(GError) error = NULL;
  int git_major, git_minor, git_micro, git_extra;

  if (!git_get_version (&error, &git_major, &git_minor, &git_micro, &git_extra))
    {
      g_warning ("Failed to get git version: %s\n", error->message);
      return FALSE;
    }

  g_debug ("Git version: %d.%d.%d.%d", git_major, git_minor, git_micro, git_extra);

  if (git_major > major)
    return TRUE;
  if (git_major < major)
    return FALSE;
  /* git_major == major */

  if (git_minor > minor)
    return TRUE;
  if (git_minor < minor)
    return FALSE;
  /* git_minor == minor */

  if (git_micro > micro)
    return TRUE;
  if (git_micro < micro)
    return FALSE;
  /* git_micro == micro */

  if (git_extra > extra)
    return TRUE;
  if (git_extra < extra)
    return FALSE;
  /* git_extra == extra */

  return TRUE;
}

static gboolean
git_version_supports_fsck_and_shallow (void)
{
  return git_has_version (1,8,3,2);
}

static gboolean
git_version_supports_fetch_from_shallow (void)
{
  return git_has_version (1,9,0,0);
}

static gboolean
git_repo_is_shallow (GFile *repo_dir)
{
  g_autoptr(GFile) shallow_file = g_file_get_child (repo_dir, "shallow");
  if (g_file_query_exists (shallow_file, NULL))
    return TRUE;

  return FALSE;
}

static GHashTable *
git_ls_remote (GFile *repo_dir,
               const char *remote,
               GError **error)
{
  g_autofree char *output = NULL;
  g_autoptr(GHashTable) refs = NULL;
  g_auto(GStrv) lines = NULL;
  int i;

  if (!git (repo_dir, &output, 0, error,
            "ls-remote", remote, NULL))
    return NULL;

  refs = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_free);
  lines = g_strsplit (output, "\n", -1);
  for (i = 0; lines[i] != NULL; i++)
    {
      g_autofree char **line = g_strsplit (lines[i], "\t", 2);
      if (line[0] != NULL && line[1] != NULL)
        g_hash_table_insert (refs, line[1], line[0]);
    }

  return g_steal_pointer (&refs);
}

static char *
lookup_full_ref (GHashTable *refs, const char *ref)
{
  int i;
  const char *prefixes[] = {
    "",
    "refs/",
    "refs/tags/",
    "refs/heads/"
  };
  GHashTableIter iter;
  gpointer key, value;

  for (i = 0; i < G_N_ELEMENTS(prefixes); i++)
    {
      g_autofree char *full_ref = g_strconcat (prefixes[i], ref, NULL);
      if (g_hash_table_contains (refs, full_ref))
        return g_steal_pointer (&full_ref);
    }

  g_hash_table_iter_init (&iter, refs);
  while (g_hash_table_iter_next (&iter, &key, &value))
    {
      const char *key_ref = key;
      const char *commit = value;

      if (g_str_has_prefix (key_ref, "refs/") &&
          g_ascii_strncasecmp (commit, ref, strlen (ref)) == 0)
        {
          char *full_ref = g_strdup (key_ref);
          if (g_str_has_suffix (full_ref, "^{}"))
            full_ref[strlen (full_ref) - 3] = 0;
          return full_ref;
        }
    }

  return NULL;
}

static GFile *
git_get_mirror_dir (const char     *url_or_path,
                    BuilderContext *context)
{
  g_autoptr(GFile) git_dir = NULL;
  g_autofree char *filename = NULL;
  g_autofree char *git_dir_path = NULL;

  git_dir = g_file_get_child (builder_context_get_state_dir (context),
                              "git");

  git_dir_path = g_file_get_path (git_dir);
  g_mkdir_with_parents (git_dir_path, 0755);

  /* Technically a path isn't a uri but if it's absolute it should still be unique. */
  filename = builder_uri_to_filename (url_or_path);
  return g_file_get_child (git_dir, filename);
}

static char *
git_get_current_commit (GFile          *repo_dir,
                        const char     *branch,
                        gboolean        ensure_commit,
                        BuilderContext *context,
                        GError        **error)
{
  char *output = NULL;
  g_autofree char *arg = NULL;

  if (ensure_commit)
    arg = g_strconcat (branch, "^{commit}", NULL);
  else
    arg = g_strdup (branch);

  if (!git (repo_dir, &output, 0, error,
            "rev-parse", arg, NULL))
    return NULL;

  /* Trim trailing whitespace */
  g_strchomp (output);

  return output;
}

char *
builder_git_get_current_commit (const char     *repo_location,
                                const char     *branch,
                                gboolean        ensure_commit,
                                BuilderContext *context,
                                GError        **error)
{
  g_autoptr(GFile) mirror_dir = NULL;

  mirror_dir = git_get_mirror_dir (repo_location, context);
  return git_get_current_commit (mirror_dir, branch, ensure_commit, context, error);
}

static char *
make_absolute (const char *orig_parent, const char *orig_relpath, GError **error)
{
  g_autofree char *parent = g_strdup (orig_parent);
  const char *relpath = orig_relpath;
  char *start;
  char *parent_path;

  if (!g_str_has_prefix (relpath, "../"))
    return g_strdup (orig_relpath);

  if (parent[strlen (parent) - 1] == '/')
    parent[strlen (parent) - 1] = 0;

  if ((start = strstr (parent, "://")))
    start = start + 3;
  else
    start = parent;

  parent_path = strchr (start, '/');
  if (parent_path == NULL)
    {
      g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED, "Invalid uri or path %s", orig_parent);
      return NULL;
    }

  while (g_str_has_prefix (relpath, "../"))
    {
      char *last_slash = strrchr (parent_path, '/');
      if (last_slash == NULL)
        {
          g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED, "Invalid relative path %s for uri or path %s", orig_relpath, orig_parent);
          return NULL;
        }
      relpath += 3;
      *last_slash = 0;
    }

  return g_strconcat (parent, "/", relpath, NULL);
}

static gboolean
git_mirror_submodules (const char     *repo_location,
                       const char     *destination_path,
                       gboolean        shallow,
                       FlatpakGitMirrorFlags flags,
                       GFile          *mirror_dir,
                       const char     *revision,
                       BuilderContext *context,
                       GError        **error)
{
  g_autoptr(GKeyFile) key_file = g_key_file_new ();
  g_autofree gchar *rev_parse_output = NULL;
  g_autofree gchar *submodule_data = NULL;
  g_autofree gchar **submodules = NULL;
  g_autofree gchar *gitmodules = g_strconcat (revision, ":.gitmodules", NULL);
  gsize num_submodules;

  /* The submodule update will fetch from this repo */
  flags |= FLATPAK_GIT_MIRROR_FLAGS_WILL_FETCH_FROM;

  if (!git (mirror_dir, &rev_parse_output, 0, NULL, "rev-parse", "--verify", "--quiet", gitmodules, NULL))
    return TRUE;

  if (git (mirror_dir, &submodule_data, 0, NULL, "show", gitmodules, NULL))
    {
      if (!g_key_file_load_from_data (key_file, submodule_data, -1,
                                      G_KEY_FILE_NONE, error))
        return FALSE;

      submodules = g_key_file_get_groups (key_file, &num_submodules);

      int i;
      for (i = 0; i < num_submodules; i++)
        {
          g_autofree gchar *submodule = NULL;
          g_autofree gchar *path = NULL;
          g_autofree gchar *relative_url = NULL;
          g_autofree gchar *absolute_url = NULL;
          g_autofree gchar *ls_tree = NULL;
          g_auto(GStrv) lines = NULL;
          g_auto(GStrv) words = NULL;

          submodule = submodules[i];

          if (!g_str_has_prefix (submodule, "submodule \""))
            continue;

          path = g_key_file_get_string (key_file, submodule, "path", error);
          if (path == NULL)
            return FALSE;
          /* Remove any trailing whitespace */
          g_strchomp (path);

          relative_url = g_key_file_get_string (key_file, submodule, "url", error);
          /* Remove any trailing whitespace */
          g_strchomp (relative_url);
          absolute_url = make_absolute (repo_location, relative_url, error);
          if (absolute_url == NULL)
            return FALSE;

          if (!git (mirror_dir, &ls_tree, 0, error, "ls-tree", revision, path, NULL))
            return FALSE;

          lines = g_strsplit (g_strstrip (ls_tree), "\n", 0);
          /* There can be path in the .gitmodules file that are not submodules. */
          if (g_strv_length (lines) != 1)
            continue;

          words = g_strsplit_set (lines[0], " \t", 4);

          if (g_strcmp0 (words[0], "160000") != 0)
            continue;

          g_debug ("mirror submodule %s at revision %s\n", absolute_url, words[2]);
          if (shallow)
            {
              if (!builder_git_shallow_mirror_ref (absolute_url, destination_path, flags, words[2], context, error))
                return FALSE;
            }
          else
            {
              if (!builder_git_mirror_repo (absolute_url, destination_path, flags, words[2], context, error))
                return FALSE;
            }
        }
    }

  return TRUE;
}

/* This mirrors the repo given by repo_location in a local
   directory. It tries to mirror only "ref", in a shallow way.
   However, this only works if ref is a tag or branch, or
   a commit id that is currently at the tip of a remote ref.
   If it is just a random commit id then we're forced to do
   a deep fetch of the entire remote repo.
*/
gboolean
builder_git_mirror_repo (const char     *repo_location,
                         const char     *destination_path,
                         FlatpakGitMirrorFlags flags,
                         const char     *ref,
                         BuilderContext *context,
                         GError        **error)
{
  g_autoptr(GFile) cache_mirror_dir = NULL;
  g_autoptr(GFile) mirror_dir = NULL;
  g_autoptr(GFile) real_mirror_dir = NULL;
  g_autoptr(FlatpakTempDir) tmp_mirror_dir = NULL;
  g_autofree char *current_commit = NULL;
  g_autoptr(GHashTable) refs = NULL;
  gboolean already_exists = FALSE;
  gboolean created = FALSE;
  gboolean was_shallow = FALSE;
  gboolean do_disable_shallow = FALSE;
  gboolean update = (flags & FLATPAK_GIT_MIRROR_FLAGS_UPDATE) != 0;
  gboolean disable_fsck = (flags & FLATPAK_GIT_MIRROR_FLAGS_DISABLE_FSCK) != 0;

  gboolean git_supports_fsck_and_shallow = git_version_supports_fsck_and_shallow ();

  cache_mirror_dir = git_get_mirror_dir (repo_location, context);

  if (destination_path != NULL)
    {
      g_autofree char *file_name = g_file_get_basename (cache_mirror_dir);
      g_autofree char *destination_file_path = g_build_filename (destination_path,
                                                                 file_name,
                                                                 NULL);
      mirror_dir = g_file_new_for_path (destination_file_path);
    }
  else
    mirror_dir = g_object_ref (cache_mirror_dir);

  if (!g_file_query_exists (mirror_dir, NULL))
    {
      g_autofree char *tmpdir = g_strconcat (flatpak_file_get_path_cached (mirror_dir), "-XXXXXX", NULL);

      if (g_mkdtemp_full (tmpdir, 0755) == NULL)
        return flatpak_fail (error, "Can't create temporary directory");

      tmp_mirror_dir = g_file_new_for_path (tmpdir);
      real_mirror_dir = g_steal_pointer (&mirror_dir);
      mirror_dir = g_object_ref (tmp_mirror_dir);

      if (!git (NULL, NULL, 0, error,
                "init", "--bare",
                (char *)flatpak_file_get_path_cached (mirror_dir), NULL))
        return FALSE;

      if (!git (mirror_dir, NULL, 0, error,
                "remote", "add", "--mirror=fetch", "origin",
                repo_location, NULL))
        return FALSE;

      created = TRUE;
    }

  was_shallow = git_repo_is_shallow (mirror_dir);

  if (git (mirror_dir, NULL, G_SUBPROCESS_FLAGS_STDERR_SILENCE, NULL,
           "cat-file", "-e", ref, NULL))
    already_exists = TRUE;

  do_disable_shallow = (flags & FLATPAK_GIT_MIRROR_FLAGS_DISABLE_SHALLOW) != 0;

  /* If we ever pulled non-shallow, then keep doing so, because
     otherwise old git clients break */
  if (!created && !was_shallow)
    do_disable_shallow = TRUE;

  /* Older versions of git can't fetch from shallow repos, so for
     those, always clone deeply anything we will later fetch from.
     (This is typically submodules and regular repos if we're bundling
     sources) */
  if ((flags & FLATPAK_GIT_MIRROR_FLAGS_WILL_FETCH_FROM) != 0 &&
      !git_version_supports_fetch_from_shallow ())
    {
      do_disable_shallow = TRUE;
    }

    {
      g_autofree char *full_ref = NULL;
      g_autoptr(GFile) cached_git_dir = NULL;
      g_autofree char *origin = NULL;
      g_autoptr(GFile) alternates = NULL;
      g_autofree char *cache_filename = NULL;

      if (real_mirror_dir)
        cache_filename = g_file_get_basename (real_mirror_dir);
      else
        cache_filename = g_file_get_basename (mirror_dir);

      /* If we're doing a regular download, look for cache sources */
      if (destination_path == NULL)
        cached_git_dir = builder_context_find_in_sources_dirs (context, "git", cache_filename, NULL);
      else
        cached_git_dir = g_object_ref (cache_mirror_dir);

      /* If the ref already exists (it may not with a shallow mirror
       * if it has changed) and we're not updating, only pull from
       * cache to avoid network i/o. */
      if (already_exists && !update)
        {
          if (cached_git_dir)
            origin = g_file_get_uri (cached_git_dir);
          else if (!created)
            return TRUE;
        }

      if (origin == NULL)
        origin = g_strdup ("origin");

      refs = git_ls_remote (mirror_dir, origin, error);
      if (refs == NULL)
        return FALSE;

      if (update && cached_git_dir)
        {
          const char *data = flatpak_file_get_path_cached (cached_git_dir);
          /* If we're updating, use the cache as a source of git objects */
          alternates = g_file_resolve_relative_path (mirror_dir, "objects/info/alternates");
          if (!g_file_replace_contents (alternates,
                                        data, strlen (data),
                                        NULL, FALSE,
                                        G_FILE_CREATE_REPLACE_DESTINATION,
                                        NULL, NULL, error))
            return FALSE;
        }

      if (!git (mirror_dir, NULL, 0, error,
                "config", "transfer.fsckObjects", (disable_fsck || (!git_supports_fsck_and_shallow && !do_disable_shallow)) ? "0" : "1", NULL))
        return FALSE;

      if (!do_disable_shallow)
        full_ref = lookup_full_ref (refs, ref);
      if (full_ref)
        {
          g_autofree char *full_ref_mapping = g_strdup_printf ("+%s:%s", full_ref, full_ref);

          g_print ("Fetching git repo %s, ref %s\n", repo_location, full_ref);
          if (!git (mirror_dir, NULL, 0, error,
                    "fetch", "-p", "--no-recurse-submodules", "--depth=1", "-f",
                    origin, full_ref_mapping, NULL))
            return FALSE;

	  /* It turns out that older versions of git (at least 2.7.4)
	   * cannot check out a commit unless a real tag/branch points
	   * to it, which is not the case for e.g. gitbug pull requests.
	   * So, to make this work we fake a branch for these cases.
	   * See https://github.com/flatpak/flatpak/issues/1133
	   */
	  if (!g_str_has_prefix (full_ref, "refs/heads") &&
	      !g_str_has_prefix (full_ref, "refs/tags"))
	    {
	      g_autofree char *fake_ref = g_strdup_printf ("refs/heads/flatpak-builder-internal/%s", full_ref);
	      g_autofree char *peeled_full_ref = g_strdup_printf ("%s^{}", full_ref);

	      if (!git (mirror_dir, NULL, 0, NULL,
			"update-ref", fake_ref, peeled_full_ref, NULL))
		return FALSE;
	    }
        }
      else if (!already_exists || do_disable_shallow)
        /* We don't fetch everything if it already exists (and we're not disabling shallow), because
           since it failed to resolve to full_ref it is a commit id
           which can't change and thus need no updates */
        {
          g_print ("Fetching full git repo %s\n", repo_location);
          if (!git (mirror_dir, NULL, 0, error,
                    "fetch", "-f", "-p", "--no-recurse-submodules", "--tags", origin, "*:*",
                    was_shallow ? "--unshallow" : NULL,
                    NULL))
            return FALSE;
        }

      if (alternates)
        {
          g_autoptr(GError) local_error = NULL;

          /* Ensure we copy the files from the cache, to be safe if the extra source changes */
          if (!git (mirror_dir, NULL, 0, error,
                    "repack", "-a", "-d", NULL))
            return FALSE;

          if (!g_file_delete (alternates, NULL, &local_error) &&
              !g_error_matches (local_error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND))
            g_debug ("Error deleting alternates file: %s", local_error->message);
        }
    }

  if (real_mirror_dir)
    {
      if (!flatpak_file_rename (mirror_dir, real_mirror_dir, NULL, error))
        return FALSE;
      g_clear_object (&mirror_dir);
      mirror_dir = g_steal_pointer (&real_mirror_dir);
    }

  if (flags & FLATPAK_GIT_MIRROR_FLAGS_MIRROR_SUBMODULES)
    {
      current_commit = git_get_current_commit (mirror_dir, ref, FALSE, context, error);
      if (current_commit == NULL)
        return FALSE;

      if (!git_mirror_submodules (repo_location, destination_path, FALSE, flags,
                                  mirror_dir, current_commit, context, error))
        return FALSE;
    }

  return TRUE;
}

/* In contrast with builder_git_mirror_repo this always does a shallow
   mirror. However, it only works for sources that are local, because
   it handles the case builder_git_mirror_repo fails at by creating refs
   in the source repo. */
gboolean
builder_git_shallow_mirror_ref (const char     *repo_location,
                                const char     *destination_path,
                                FlatpakGitMirrorFlags flags,
                                const char     *ref,
                                BuilderContext *context,
                                GError        **error)
{
  g_autoptr(GFile) cache_mirror_dir = NULL;
  g_autoptr(GFile) mirror_dir = NULL;
  g_autofree char *current_commit = NULL;
  g_autofree char *file_name = NULL;
  g_autofree char *destination_file_path = NULL;
  g_autofree char *full_ref = NULL;
  g_autofree char *full_ref_colon_full_ref = NULL;

  cache_mirror_dir = git_get_mirror_dir (repo_location, context);

  file_name = g_file_get_basename (cache_mirror_dir);
  destination_file_path = g_build_filename (destination_path,
                                            file_name,
                                            NULL);
  mirror_dir = g_file_new_for_path (destination_file_path);

  if (!g_file_query_exists (mirror_dir, NULL))
    {
      if (!git (NULL, NULL, 0, error,
                "init", "--bare", destination_file_path, NULL))
        return FALSE;
      if (!git (mirror_dir, NULL, 0, error,
                "remote", "add", "--mirror=fetch", "origin",
                (char *)flatpak_file_get_path_cached (cache_mirror_dir), NULL))
        return FALSE;
    }

  if (!git (cache_mirror_dir, &full_ref, 0, error,
            "rev-parse", "--symbolic-full-name", ref, NULL))
    return FALSE;

  /* Trim trailing whitespace */
  g_strchomp (full_ref);

  if (*full_ref == 0)
    {
      g_autofree char *peeled_ref = g_strdup_printf ("%s^{}", ref);

      g_free (full_ref);
      /* We can't pull the commit id, so we create a ref we can pull */
      full_ref = g_strdup_printf ("refs/heads/flatpak-builder-internal/commit/%s", ref);
      if (!git (cache_mirror_dir, NULL, 0, error,
                "update-ref", full_ref, peeled_ref, NULL))
        return FALSE;
    }

  full_ref_colon_full_ref = g_strdup_printf ("%s:%s", full_ref, full_ref);
  if (!git (mirror_dir, NULL, 0, error,
            "fetch", "--depth", "1", "origin", full_ref_colon_full_ref, NULL))
    return FALSE;

  /* Always mirror submodules */
  current_commit = git_get_current_commit (mirror_dir, ref, FALSE, context, error);
  if (current_commit == NULL)
    return FALSE;

  if (flags & FLATPAK_GIT_MIRROR_FLAGS_MIRROR_SUBMODULES)
    {
      if (!git_mirror_submodules (repo_location, destination_path, TRUE,
                                  flags | FLATPAK_GIT_MIRROR_FLAGS_DISABLE_FSCK,
                                  mirror_dir, current_commit, context, error))
        return FALSE;
    }

  return TRUE;
}

static gboolean
git_extract_submodule (const char     *repo_location,
                       GFile          *checkout_dir,
                       const char     *revision,
                       BuilderContext *context,
                       GError        **error)
{
  g_autoptr(GKeyFile) key_file = g_key_file_new ();
  g_autofree gchar *rev_parse_output = NULL;
  g_autofree gchar *submodule_data = NULL;
  g_autofree gchar **submodules = NULL;
  g_autofree gchar *gitmodules = g_strconcat (revision, ":.gitmodules", NULL);
  gsize num_submodules;

  if (!git (checkout_dir, &rev_parse_output, 0, NULL, "rev-parse", "--verify", "--quiet", gitmodules, NULL))
    return TRUE;

  if (git (checkout_dir, &submodule_data, 0, NULL, "show", gitmodules, NULL))
    {
      if (!g_key_file_load_from_data (key_file, submodule_data, -1,
                                      G_KEY_FILE_NONE, error))
        return FALSE;

      submodules = g_key_file_get_groups (key_file, &num_submodules);

      int i;
      for (i = 0; i < num_submodules; i++)
        {
          g_autofree gchar *submodule = NULL;
          g_autofree gchar *name = NULL;
          g_autofree gchar *update_method = NULL;
          g_autofree gchar *path = NULL;
          g_autofree gchar *relative_url = NULL;
          g_autofree gchar *absolute_url = NULL;
          g_autofree gchar *ls_tree = NULL;
          g_auto(GStrv) lines = NULL;
          g_auto(GStrv) words = NULL;
          g_autoptr(GFile) mirror_dir = NULL;
          g_autoptr(GFile) child_dir = NULL;
          g_autofree gchar *mirror_dir_as_url = NULL;
          g_autofree gchar *option = NULL;
          gsize len;

          submodule = submodules[i];
          len = strlen (submodule);

          if (!g_str_has_prefix (submodule, "submodule \""))
            continue;

          name = g_strndup (submodule + 11, len - 12);

          /* Skip any submodules that are disabled (have the update method set to "none")
             Only check if the command succeeds. If it fails, the update method is not set. */
          update_method = g_key_file_get_string (key_file, submodule, "update", NULL);
          if (g_strcmp0 (update_method, "none") == 0)
            continue;

          path = g_key_file_get_string (key_file, submodule, "path", error);
          if (path == NULL)
            return FALSE;
          /* Remove any trailing whitespace */
          g_strchomp (path);

          relative_url = g_key_file_get_string (key_file, submodule, "url", error);
          absolute_url = make_absolute (repo_location, relative_url, error);
          if (absolute_url == NULL)
            return FALSE;

          if (!git (checkout_dir, &ls_tree, 0, error, "ls-tree", revision, path, NULL))
            return FALSE;

          lines = g_strsplit (g_strstrip (ls_tree), "\n", 0);
          /* There can be path in the .gitmodules file that are not submodules. */
          if (g_strv_length (lines) != 1)
            continue;

          words = g_strsplit_set (lines[0], " \t", 4);

          if (g_strcmp0 (words[0], "160000") != 0)
            continue;

          mirror_dir = git_get_mirror_dir (absolute_url, context);
          mirror_dir_as_url = g_file_get_uri (mirror_dir);
          option = g_strdup_printf ("submodule.%s.url", name);

          if (!git (checkout_dir, NULL, 0, error,
                    "config", option, mirror_dir_as_url, NULL))
            return FALSE;

          if (!git (checkout_dir, NULL, 0, error,
                    "-c", "protocol.file.allow=always", "submodule", "update", "--init", path, NULL))
            return FALSE;

          child_dir = g_file_resolve_relative_path (checkout_dir, path);

          if (!git_extract_submodule (absolute_url, child_dir, words[2], context, error))
            return FALSE;
        }
    }

  return TRUE;
}

gboolean
builder_git_checkout (const char     *repo_location,
                      const char     *branch,
                      GFile          *dest,
                      BuilderContext *context,
                      FlatpakGitMirrorFlags mirror_flags,
                      GError        **error)
{
  g_autoptr(GFile) mirror_dir = NULL;
  g_autofree char *mirror_dir_path = NULL;
  g_autofree char *dest_path = NULL;
  g_autofree char *dest_path_git = NULL;

  mirror_dir = git_get_mirror_dir (repo_location, context);

  mirror_dir_path = g_file_get_path (mirror_dir);
  dest_path = g_file_get_path (dest);
  dest_path_git = g_build_filename (dest_path, ".git", NULL);

  g_mkdir_with_parents (dest_path, 0755);

  if (!cp (error,
           "-al",
           mirror_dir_path, dest_path_git, NULL))
    return FALSE;

  /* Then we need to convert to regular */
  if (!git (dest, NULL, 0, error,
            "config", "--bool", "core.bare", "false", NULL))
    return FALSE;

  if (!git (dest, NULL, 0, error,
            "checkout", branch, NULL))
    return FALSE;

  if (mirror_flags & FLATPAK_GIT_MIRROR_FLAGS_MIRROR_SUBMODULES)
    if (!git_extract_submodule (repo_location, dest, branch, context, error))
      return FALSE;

  return TRUE;
}

char *
builder_git_get_default_branch (const char *repo_location)
{
  g_auto(GStrv) parts = NULL;
  g_autofree char *output = NULL;
  g_autoptr(GError) error = NULL;

  if (!git (NULL, &output, 0, &error,
            "ls-remote", "--symref", repo_location, "HEAD", NULL))
    return g_strdup ("master");

  /* Example output:
   * $ git ls-remote --symref http://gitlab.gnome.org/GNOME/evince.git HEAD
   * warning: redirigiendo a https://gitlab.gnome.org/GNOME/evince.git/
   * ref: refs/heads/main	HEAD
   * 7a5ceb841874bef4b91282eee1025b0335a21795	HEAD
   */
  parts = g_strsplit (output, "\t", 1);
  if (g_strv_length (parts) > 1 && g_str_has_prefix (parts[1], "HEAD") &&
      g_strstr_len (parts[0], -1, "ref: "))
    {
      char *branch = strrchr (parts[0], '/');
      if (branch != NULL)
        return g_strdup (branch + 1);
    }

  g_debug ("Failed to auto-detect default branch from git output");
  return g_strdup ("master");
}