portal: Remap --env-fd into child process's fd space

Just because we can allocate a new, unused fd in the portal's fd space, that doesn't mean that fd number is going to be unused in the child process's fd space: we might need to remap it. Resolves: #4286 Fixes: aeb6a7a "portal: Convert --env in extra-args into --env-fd" Signed-off-by: Simon McVittie <[email protected]>
flatpak · May 25, 2021 · 526dae9 · 526dae9
1 parent a09d07f
commit 526dae9
Showing 1 changed file with 10 additions and 2 deletions.
diff --git a/portal/flatpak-portal.c b/portal/flatpak-portal.c
@@ -1092,6 +1092,7 @@ handle_spawn (PortalFlatpak *object,
 
  if (env_string->len > 0)
  {
+ FdMapEntry fd_map_entry;
  g_auto(GLnxTmpfile) env_tmpf = { 0, };
 
  if (!flatpak_buffer_to_sealed_memfd_or_tmpfile (&env_tmpf, "environ",
@@ -1103,9 +1104,16 @@ handle_spawn (PortalFlatpak *object,
  }
 
  env_fd = glnx_steal_fd (&env_tmpf.fd);
- child_setup_data.env_fd = env_fd;
+
+ /* Use a fd that hasn't been used yet. We might have to reshuffle
+ * fd_map_entry.to, a bit later. */
+ fd_map_entry.from = env_fd;
+ fd_map_entry.to = ++max_fd;
+ fd_map_entry.final = fd_map_entry.to;
+ g_array_append_val (fd_map, fd_map_entry);
+
  g_ptr_array_add (flatpak_argv,
- g_strdup_printf ("--env-fd=%d", env_fd));
+ g_strdup_printf ("--env-fd=%d", fd_map_entry.final));
  }
 
  for (i = 0; unset_env != NULL && unset_env[i] != NULL; i++)