Change OstreeFetcher to be dirfd-relative

This is a noticeable cleanup, and fixes another big user of GFile* in
performance/security sensitive codepaths.

I'm specifically making this change because the static deltas code was
leaking temporary files, and cleaning that up nicely would be best if
we were fd relative.

src/libostree/ostree-repo-pull.c

@@ -29,11 +29,14 @@
 #include "ostree-metalink.h"
 #include "otutil.h"
 
+#include <gio/gunixinputstream.h>
+
 #define OSTREE_REPO_PULL_CONTENT_PRIORITY  (OSTREE_FETCHER_DEFAULT_PRIORITY)
 #define OSTREE_REPO_PULL_METADATA_PRIORITY (OSTREE_REPO_PULL_CONTENT_PRIORITY - 100)
 
 typedef struct {
   OstreeRepo   *repo;
+  int           tmpdir_dfd;
   OstreeRepoPullFlags flags;
   char         *remote_name;
   OstreeRepoMode remote_mode;
@@ -569,7 +572,7 @@ content_fetch_on_complete (GObject        *object,
   gs_unref_variant GVariant *xattrs = NULL;
   gs_unref_object GInputStream *file_in = NULL;
   gs_unref_object GInputStream *object_input = NULL;
-  gs_unref_object GFile *temp_path = NULL;
+  gs_free char *temp_path = NULL;
   const char *checksum;
   OstreeObjectType objtype;
 
@@ -582,12 +585,12 @@ content_fetch_on_complete (GObject        *object,
 
   g_debug ("fetch of %s complete", ostree_object_to_string (checksum, objtype));
   
-  if (!ostree_content_file_parse (TRUE, temp_path, FALSE,
-                                  &file_in, &file_info, &xattrs,
-                                  cancellable, error))
+  if (!ostree_content_file_parse_at (TRUE, pull_data->tmpdir_dfd, temp_path, FALSE,
+                                     &file_in, &file_info, &xattrs,
+                                     cancellable, error))
     {
       /* If it appears corrupted, delete it */
-      (void) gs_file_unlink (temp_path, NULL, NULL);
+      (void) unlinkat (pull_data->tmpdir_dfd, temp_path, 0);
       goto out;
     }
 
@@ -595,7 +598,7 @@ content_fetch_on_complete (GObject        *object,
    * a reference to the fd.  If we fail to write later, then
    * the temp space will be cleaned up.
    */
-  (void) gs_file_unlink (temp_path, NULL, NULL);
+  (void) unlinkat (pull_data->tmpdir_dfd, temp_path, 0);
 
   if (!ostree_raw_file_to_content_stream (file_in, file_info, xattrs,
                                           &object_input, &length,
@@ -677,11 +680,12 @@ meta_fetch_on_complete (GObject           *object,
   FetchObjectData *fetch_data = user_data;
   OtPullData *pull_data = fetch_data->pull_data;
   gs_unref_variant GVariant *metadata = NULL;
-  gs_unref_object GFile *temp_path = NULL;
+  gs_free char *temp_path = NULL;
   const char *checksum;
   OstreeObjectType objtype;
   GError *local_error = NULL;
   GError **error = &local_error;
+  gs_fd_close int fd = -1;
 
   ostree_object_name_deserialize (fetch_data->object, &checksum, &objtype);
   g_debug ("fetch of %s%s complete", ostree_object_to_string (checksum, objtype),
@@ -702,14 +706,21 @@ meta_fetch_on_complete (GObject           *object,
       goto out;
     }
 
+  fd = openat (pull_data->tmpdir_dfd, temp_path, O_RDONLY | O_CLOEXEC);
+  if (fd == -1)
+    {
+      gs_set_error_from_errno (error, errno);
+      goto out;
+    }
+
   if (fetch_data->is_detached_meta)
     {
-      if (!ot_util_variant_map (temp_path, G_VARIANT_TYPE ("a{sv}"),
-                                FALSE, &metadata, error))
+      if (!ot_util_variant_map_fd (fd, 0, G_VARIANT_TYPE ("a{sv}"),
+                                   FALSE, &metadata, error))
         goto out;
 
       /* Now delete it, see comment in corresponding content fetch path */
-      (void) gs_file_unlink (temp_path, NULL, NULL);
+      (void) unlinkat (pull_data->tmpdir_dfd, temp_path, 0);
 
       if (!ostree_repo_write_commit_detached_metadata (pull_data->repo, checksum, metadata,
                                                        pull_data->cancellable, error))
@@ -719,11 +730,11 @@ meta_fetch_on_complete (GObject           *object,
     }
   else
     {
-      if (!ot_util_variant_map (temp_path, ostree_metadata_variant_type (objtype),
-                                FALSE, &metadata, error))
+      if (!ot_util_variant_map_fd (fd, 0, ostree_metadata_variant_type (objtype),
+                                   FALSE, &metadata, error))
         goto out;
 
-      (void) gs_file_unlink (temp_path, NULL, NULL);
+      (void) unlinkat (pull_data->tmpdir_dfd, temp_path, 0);
 
       /* Write the commitpartial file now while we're still fetching data */
       if (objtype == OSTREE_OBJECT_TYPE_COMMIT)
@@ -797,12 +808,13 @@ static_deltapart_fetch_on_complete (GObject           *object,
   FetchStaticDeltaData *fetch_data = user_data;
   OtPullData *pull_data = fetch_data->pull_data;
   gs_unref_variant GVariant *metadata = NULL;
-  gs_unref_object GFile *temp_path = NULL;
+  gs_free char *temp_path = NULL;
   gs_unref_object GInputStream *in = NULL;
   gs_free char *actual_checksum = NULL;
   gs_free guint8 *csum = NULL;
   GError *local_error = NULL;
   GError **error = &local_error;
+  gs_fd_close int fd = -1;
 
   g_debug ("fetch static delta part %s complete", fetch_data->expected_checksum);
 
@@ -810,10 +822,14 @@ static_deltapart_fetch_on_complete (GObject           *object,
   if (!temp_path)
     goto out;
 
-  in = (GInputStream*)g_file_read (temp_path, pull_data->cancellable, error);
-  if (!in)
-    goto out;
-  
+  fd = openat (pull_data->tmpdir_dfd, temp_path, O_RDONLY | O_CLOEXEC);
+  if (fd == -1)
+    {
+      gs_set_error_from_errno (error, errno);
+      goto out;
+    }
+  in = g_unix_input_stream_new (fd, FALSE);
+
   /* TODO - consider making async */
   if (!ot_gio_checksum_stream (in, &csum, pull_data->cancellable, error))
     goto out;
@@ -832,10 +848,14 @@ static_deltapart_fetch_on_complete (GObject           *object,
   (void) g_input_stream_close (in, NULL, NULL);
 
   {
-    gs_unref_bytes GBytes *delta_data
-      = gs_file_map_readonly (temp_path, pull_data->cancellable, error);
-    if (!delta_data)
+    GMappedFile *mfile = NULL;
+    gs_unref_bytes GBytes *delta_data = NULL;
+
+    mfile = g_mapped_file_new_from_fd (fd, FALSE, error);
+    if (!mfile)
       goto out;
+    delta_data = g_mapped_file_get_bytes (mfile);
+    g_mapped_file_unref (mfile);
 
     _ostree_static_delta_part_execute_async (pull_data->repo,
                                              fetch_data->objects,
@@ -1610,8 +1630,8 @@ ostree_repo_pull_with_options (OstreeRepo             *self,
   if (tls_permissive)
     fetcher_flags |= OSTREE_FETCHER_FLAGS_TLS_PERMISSIVE;
 
-  pull_data->fetcher = _ostree_fetcher_new (pull_data->repo->tmp_dir,
-                                           fetcher_flags);
+  pull_data->tmpdir_dfd = pull_data->repo->tmp_dir_fd;
+  pull_data->fetcher = _ostree_fetcher_new (pull_data->tmpdir_dfd, fetcher_flags);
   requested_refs_to_fetch = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_free);
   commits_to_fetch = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, NULL);
 
@@ -1711,9 +1731,10 @@ ostree_repo_pull_with_options (OstreeRepo             *self,
     }
   else
     {
-      gs_unref_object GFile *metalink_data = NULL;
+      gs_free char *metalink_data = NULL;
       SoupURI *metalink_uri = soup_uri_new (metalink_url_str);
       SoupURI *target_uri = NULL;
+      gs_fd_close int fd = -1;
       
       if (!metalink_uri)
         {
@@ -1741,8 +1762,15 @@ ostree_repo_pull_with_options (OstreeRepo             *self,
         soup_uri_set_path (pull_data->base_uri, repo_base);
       }
 
-      if (!ot_util_variant_map (metalink_data, OSTREE_SUMMARY_GVARIANT_FORMAT, FALSE,
-                                &pull_data->summary, error))
+      fd = openat (pull_data->tmpdir_dfd, metalink_data, O_RDONLY | O_CLOEXEC);
+      if (fd == -1)
+        {
+          gs_set_error_from_errno (error, errno);
+          goto out;
+        }
+
+      if (!ot_util_variant_map_fd (fd, 0, OSTREE_SUMMARY_GVARIANT_FORMAT, FALSE,
+                                   &pull_data->summary, error))
         goto out;
     }