Avoid some core dumps in X session management

Derived from a bug report by Nicolas Richard in:
http://bugs.gnu.org/20191#20
* xsmfns.c (smc_save_yourself_CB): Don't dump core if
invocation-name is not a string.  Initialize user-login-name if it
is not already initialized, and don't dump core if it is not a
string.
(create_client_leader_window): Don't dump core if x-resource-name
and x-resource-class are not both strings.
(x_session_initialize): Don't dump core if x-session-previous-id,
invocation-directory, and invocation-name are not strings.

1 files changed, 33 insertions, 24 deletions

diff --git a/src/xsmfns.c b/src/xsmfns.c
index 0e635d38ec6..375b51c4466 100644
--- a/src/xsmfns.c
+++ b/src/xsmfns.c
@@ -168,7 +168,6 @@ smc_save_yourself_CB (SmcConn smcConn,
   int val_idx = 0, vp_idx = 0;
   int props_idx = 0;
   int i;
-  char *cwd = get_current_dir_name ();
   char *smid_opt, *chdir_opt = NULL;
 
   /* How to start a new instance of Emacs.  */
@@ -181,27 +180,34 @@ smc_save_yourself_CB (SmcConn smcConn,
   props[props_idx]->vals[0].value = emacs_program;
   ++props_idx;
 
-  /* The name of the program.  */
-  props[props_idx] = &prop_ptr[props_idx];
-  props[props_idx]->name = xstrdup (SmProgram);
-  props[props_idx]->type = xstrdup (SmARRAY8);
-  props[props_idx]->num_vals = 1;
-  props[props_idx]->vals = &values[val_idx++];
-  props[props_idx]->vals[0].length = SBYTES (Vinvocation_name);
-  props[props_idx]->vals[0].value = SDATA (Vinvocation_name);
-  ++props_idx;
+  if (STRINGP (Vinvocation_name))
+    {
+      /* The name of the program.  */
+      props[props_idx] = &prop_ptr[props_idx];
+      props[props_idx]->name = xstrdup (SmProgram);
+      props[props_idx]->type = xstrdup (SmARRAY8);
+      props[props_idx]->num_vals = 1;
+      props[props_idx]->vals = &values[val_idx++];
+      props[props_idx]->vals[0].length = SBYTES (Vinvocation_name);
+      props[props_idx]->vals[0].value = SDATA (Vinvocation_name);
+      ++props_idx;
+    }
 
   /* User id.  */
-  props[props_idx] = &prop_ptr[props_idx];
-  props[props_idx]->name = xstrdup (SmUserID);
-  props[props_idx]->type = xstrdup (SmARRAY8);
-  props[props_idx]->num_vals = 1;
-  props[props_idx]->vals = &values[val_idx++];
-  props[props_idx]->vals[0].length = SBYTES (Vuser_login_name);
-  props[props_idx]->vals[0].value = SDATA (Vuser_login_name);
-  ++props_idx;
-
+  Lisp_Object user_login_name = Fuser_login_name (Qnil);
+  if (STRINGP (user_login_name))
+    {
+      props[props_idx] = &prop_ptr[props_idx];
+      props[props_idx]->name = xstrdup (SmUserID);
+      props[props_idx]->type = xstrdup (SmARRAY8);
+      props[props_idx]->num_vals = 1;
+      props[props_idx]->vals = &values[val_idx++];
+      props[props_idx]->vals[0].length = SBYTES (user_login_name);
+      props[props_idx]->vals[0].value = SDATA (user_login_name);
+      ++props_idx;
+    }
 
+  char *cwd = get_current_dir_name ();
   if (cwd)
     {
       props[props_idx] = &prop_ptr[props_idx];
@@ -372,6 +378,7 @@ create_client_leader_window (struct x_display_info *dpyinfo, char *client_ID)
                            -1, -1, 1, 1,
                            CopyFromParent, CopyFromParent, CopyFromParent);
 
+  validate_x_resource_name ();
   class_hints.res_name = SSDATA (Vx_resource_name);
   class_hints.res_class = SSDATA (Vx_resource_class);
   XSetClassHint (dpyinfo->display, w, &class_hints);
@@ -402,22 +409,24 @@ x_session_initialize (struct x_display_info *dpyinfo)
 
   /* Check if we where started by the session manager.  If so, we will
      have a previous id.  */
-  if (! NILP (Vx_session_previous_id) && STRINGP (Vx_session_previous_id))
+  if (STRINGP (Vx_session_previous_id))
     previous_id = SSDATA (Vx_session_previous_id);
 
   /* Construct the path to the Emacs program.  */
-  if (! NILP (Vinvocation_directory))
+  if (STRINGP (Vinvocation_directory))
     name_len += SBYTES (Vinvocation_directory);
-  name_len += SBYTES (Vinvocation_name);
+  if (STRINGP (Vinvocation_name))
+    name_len += SBYTES (Vinvocation_name);
 
   /* This malloc will not be freed, but it is only done once, and hopefully
      not very large   */
   emacs_program = xmalloc (name_len + 1);
   char *z = emacs_program;
 
-  if (! NILP (Vinvocation_directory))
+  if (STRINGP (Vinvocation_directory))
     z = lispstpcpy (z, Vinvocation_directory);
-  lispstpcpy (z, Vinvocation_name);
+  if (STRINGP (Vinvocation_name))
+    lispstpcpy (z, Vinvocation_name);
 
   /* The SM protocol says all callbacks are mandatory, so set up all
      here and in the mask passed to SmcOpenConnection.  */