system-name's returned value can vary

Also, the system-name variable is now obsolete.
Fixes Bug#19438.
* doc/lispref/os.texi (System Environment):
* etc/NEWS: Document this.
* doc/misc/efaq.texi:
(Displaying the current file name in the titlebar):
* lisp/desktop.el (desktop-save-frameset):
* lisp/dnd.el (dnd-get-local-file-uri):
* lisp/gnus/message.el (message-make-fqdn):
* lisp/gnus/nnvirtual.el (nnvirtual-retrieve-headers)
(nnvirtual-update-xref-header):
* lisp/nxml/rng-uri.el (rng-uri-file-name-1):
* lisp/org/org-clock.el (org-clock-save):
* src/filelock.c (current_lock_owner):
* src/xrdb.c (get_environ_db):
* src/xterm.c (same_x_server):
* src/xterm.c (x_term_init):
Prefer (system-name) to system-name, and avoid naming
locals 'system-name'.
* doc/misc/smtpmail.texi (Server workarounds): Fix grammar.
* lisp/startup.el (system-name): Now an obsolete variable.
* src/editfns.c (cached_system_name): New static var.
(init_and_cache_system_name): New function.
(init_editfns, Fsystem_name): Use it.
(syms_of_editfns): Initialize it and Vsystem_name to the same value.
* src/sysdep.c [HAVE_SOCKETS]: Don't include <sys/socket.h>, <netdb.h>.
(h_errno) [TRY_AGAIN && !HAVE_H_ERRNO]: Remove decl.
(init_system_name) [HAVE_SOCKETS]: Don't canonicalize the name.
Don't create a new string if the current value is already correct.

1 files changed, 7 insertions, 5 deletions

diff --git a/src/xterm.c b/src/xterm.c
index 130174dff19..892562bd612 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -10497,8 +10497,9 @@ static bool
 same_x_server (const char *name1, const char *name2)
 {
   bool seen_colon = false;
-  const char *system_name = SSDATA (Vsystem_name);
-  ptrdiff_t system_name_length = SBYTES (Vsystem_name);
+  Lisp_Object sysname = Fsystem_name ();
+  const char *system_name = SSDATA (sysname);
+  ptrdiff_t system_name_length = SBYTES (sysname);
   ptrdiff_t length_until_period = 0;
 
   while (system_name[length_until_period] != 0
@@ -10890,14 +10891,15 @@ x_term_init (Lisp_Object display_name, char *xrm_option, char *resource_name)
 #endif
 
   lim = min (PTRDIFF_MAX, SIZE_MAX) - sizeof "@";
-  if (lim - SBYTES (Vinvocation_name) < SBYTES (Vsystem_name))
+  Lisp_Object system_name = Fsystem_name ();
+  if (lim - SBYTES (Vinvocation_name) < SBYTES (system_name))
     memory_full (SIZE_MAX);
   dpyinfo->x_id = ++x_display_id;
   dpyinfo->x_id_name = xmalloc (SBYTES (Vinvocation_name)
-				+ SBYTES (Vsystem_name) + 2);
+				+ SBYTES (system_name) + 2);
   char *nametail = lispstpcpy (dpyinfo->x_id_name, Vinvocation_name);
   *nametail++ = '@';
-  lispstpcpy (nametail, Vsystem_name);
+  lispstpcpy (nametail, system_name);
 
   /* Figure out which modifier bits mean what.  */
   x_find_modifier_meanings (dpyinfo);