spawn: Rework spawning

The old spawning code was copied from glib, and used a thread to
make the synchronous variant into an asynchronous one. This had the
problem that fork(3p) was called from the worker thread, not the
calling (main) thread.

The new code replaces this with a two-stage approach where the
fork takes place on the calling thread, and only the async wait
for the child error is done in a worker thread.

This also unifies the sync and async spawn variants to use
the exact same code, only called in one or two stages.

This also removes calls to setenv/unsetenv from the child setup
code, which are not safe to do there. Instead, the environment
is prepared in advance and used via execve(2).

Fixes: https://gitlab.gnome.org/GNOME/vte/-/issues/118

1 files changed, 22 insertions, 10 deletions

diff --git a/src/vtespawn.hh b/src/vtespawn.hh
index 89c752be..855394e6 100644
--- a/src/vtespawn.hh
+++ b/src/vtespawn.hh
@@ -22,13 +22,25 @@
 
 #include <glib.h>
 
-gboolean vte_spawn_async_cancellable (const gchar          *working_directory,
-                                      gchar               **argv,
-                                      gchar               **envp,
-                                      GSpawnFlags           flags,
-                                      GSpawnChildSetupFunc  child_setup,
-                                      gpointer              user_data,
-                                      GPid                 *child_pid,
-                                      gint                  timeout,
-                                      GPollFD              *pollfd,
-                                      GError              **error);
+void _vte_cloexec_from(int fd);
+
+char** _vte_merge_envv(char** envp,
+                       char const* cwd,
+                       bool inherit);
+
+int _vte_execute(char const* file,
+                 char** argv,
+                 char** envp,
+                 bool search_path,
+                 bool search_path_from_envp);
+
+bool _vte_read_ints(int     fd,
+                    int*    buf,
+                    int     n_ints_in_buf,
+                    int    *n_ints_read,
+                    int     timeout,
+                    GPollFD *cancellable_pollfd,
+                    GError **error);
+
+void _vte_write_err (int fd,
+                     int msg);