[gnome-builder] terminal: learn to discover the shell from the host passwd

[Christian Hergert <chergert src gnome org>]

commit 74818ae4a9714cc967f790920cf82af045cf6dd3
Author: Christian Hergert <chergert redhat com>
Date:   Fri Sep 16 12:10:45 2016 -0700

    terminal: learn to discover the shell from the host passwd
    
    We need to discover the users preferred shell from the host as the shell
    will not be propagated to the flatpak runtime. Which makes sense since that
    shell might not be available in the runtime anyway.
    
    Normally, vte would look at getpwent() info for the shell, but we can just
    as easily shell out to the host system to discover it from /etc/passwd and
    fallback to /bin/sh when that doesn't work.

 plugins/terminal/gb-terminal-view.c |   52 +++++++++++++++++++++++++++++++----
 1 files changed, 46 insertions(+), 6 deletions(-)
---
diff --git a/plugins/terminal/gb-terminal-view.c b/plugins/terminal/gb-terminal-view.c
index fc6741e..4f57f29 100644
--- a/plugins/terminal/gb-terminal-view.c
+++ b/plugins/terminal/gb-terminal-view.c
@@ -41,6 +41,7 @@ enum {
 };
 
 static GParamSpec *properties [LAST_PROP];
+static gchar *cached_shell;
 
 /* TODO: allow palette to come from gnome-terminal. */
 static const GdkRGBA solarized_palette[] =
@@ -72,6 +73,43 @@ static void gb_terminal_view_connect_terminal (GbTerminalView *self,
 static void gb_terminal_respawn               (GbTerminalView *self,
                                                VteTerminal    *terminal);
 
+static const gchar *
+gb_terminal_view_discover_shell (GCancellable  *cancellable,
+                                 GError       **error)
+{
+  g_autoptr(IdeSubprocessLauncher) launcher = NULL;
+  g_autoptr(IdeSubprocess) subprocess = NULL;
+  g_autofree gchar *command = NULL;
+  g_autofree gchar *stdout_buf = NULL;
+
+  g_assert (!cancellable || G_IS_CANCELLABLE (cancellable));
+
+  if (cached_shell == NULL)
+    return cached_shell;
+
+  command = g_strdup_printf ("sh -c 'cat /etc/passwd | grep ^%s: | cut -f 7 -d :'",
+                             g_get_user_name ());
+
+  launcher = ide_subprocess_launcher_new (G_SUBPROCESS_FLAGS_STDOUT_PIPE);
+  ide_subprocess_launcher_set_run_on_host (launcher, TRUE);
+  ide_subprocess_launcher_set_clear_env (launcher, FALSE);
+  ide_subprocess_launcher_set_cwd (launcher, g_get_home_dir ());
+  ide_subprocess_launcher_push_argv (launcher, command);
+
+  subprocess = ide_subprocess_launcher_spawn_sync (launcher, cancellable, error);
+
+  if (subprocess == NULL)
+    return NULL;
+
+  if (!ide_subprocess_communicate_utf8 (subprocess, NULL, cancellable, &stdout_buf, NULL, error))
+    return NULL;
+
+  if (!ide_str_empty0 (stdout_buf) && stdout_buf[0] == '/')
+    cached_shell = g_steal_pointer (&stdout_buf);
+
+  return cached_shell;
+}
+
 static void
 gb_terminal_view_wait_cb (GObject      *object,
                           GAsyncResult *result,
@@ -131,7 +169,7 @@ gb_terminal_respawn (GbTerminalView *self,
   g_autoptr(IdeSubprocess) subprocess = NULL;
   g_autoptr(IdeSubprocessLauncher) launcher = NULL;
   g_autofree gchar *workpath = NULL;
-  g_autofree gchar *shell = NULL;
+  const gchar *shell;
   GtkWidget *toplevel;
   GError *error = NULL;
   IdeContext *context;
@@ -164,8 +202,12 @@ gb_terminal_respawn (GbTerminalView *self,
   workdir = ide_vcs_get_working_directory (vcs);
   workpath = g_file_get_path (workdir);
 
-  args = g_ptr_array_new_with_free_func (g_free);
-  g_ptr_array_add (args, vte_get_user_shell ());
+  shell = gb_terminal_view_discover_shell (NULL, NULL);
+  if (shell == NULL)
+    shell = vte_get_user_shell ();
+
+  args = g_ptr_array_new ();
+  g_ptr_array_add (args, (gchar *)shell);
   g_ptr_array_add (args, NULL);
 
   pty = vte_terminal_pty_new_sync (terminal,
@@ -205,9 +247,7 @@ gb_terminal_respawn (GbTerminalView *self,
   ide_subprocess_launcher_take_stderr_fd (launcher, dup (tty_fd));
   ide_subprocess_launcher_setenv (launcher, "TERM", "xterm-256color", TRUE);
   ide_subprocess_launcher_setenv (launcher, "INSIDE_GNOME_BUILDER", PACKAGE_VERSION, TRUE);
-
-  if (shell != NULL)
-    ide_subprocess_launcher_setenv (launcher, "SHELL", shell, TRUE);
+  ide_subprocess_launcher_setenv (launcher, "SHELL", shell, TRUE);
 
   subprocess = ide_subprocess_launcher_spawn_sync (launcher, NULL, &error);
   if (subprocess == NULL)