[gnome-builder] libide/foundry: fix FD arguments to flatpak-spawn

[Christian Hergert <chergert src gnome org>]

commit 7e47a719d897a282ae7354776d757667c88918a2
Author: Christian Hergert <chergert redhat com>
Date:   Sat Sep 24 12:20:41 2022 -0700

    libide/foundry: fix FD arguments to flatpak-spawn
    
    The main thing here is that we need to extract the FDs before we merge
    down the FD map, otherwise they'll always be -1.
    
    Additionally, we need to skip FD's 0/1/2 since flatpak-spawn will handle
    that for us already since we're not setting up PTYs.

 src/libide/foundry/ide-run-context.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)
---
diff --git a/src/libide/foundry/ide-run-context.c b/src/libide/foundry/ide-run-context.c
index 121cd3072..ba4db940b 100644
--- a/src/libide/foundry/ide-run-context.c
+++ b/src/libide/foundry/ide-run-context.c
@@ -294,9 +294,6 @@ ide_run_context_host_handler (IdeRunContext       *self,
 
   if ((length = ide_unix_fd_map_get_length (unix_fd_map)))
     {
-      if (!ide_run_context_merge_unix_fd_map (self, unix_fd_map, error))
-        return FALSE;
-
       for (guint i = 0; i < length; i++)
         {
           int source_fd;
@@ -304,9 +301,18 @@ ide_run_context_host_handler (IdeRunContext       *self,
 
           source_fd = ide_unix_fd_map_peek (unix_fd_map, i, &dest_fd);
 
+          if (dest_fd < STDERR_FILENO)
+            continue;
+
+          g_debug ("Mapping Builder FD %d to target FD %d via flatpak-spawn",
+                   source_fd, dest_fd);
+
           if (source_fd != -1 && dest_fd != -1)
             ide_run_context_append_formatted (self, "--forward-fd=%d", dest_fd);
         }
+
+      if (!ide_run_context_merge_unix_fd_map (self, unix_fd_map, error))
+        return FALSE;
     }
 
   /* Now append the arguments */