Use INT_ADD_WRAPV etc. to check integer overflow

* src/alloc.c (xnmalloc, xnrealloc, xpalloc, Fmake_string):
* src/buffer.c (record_overlay_string, overlay_strings):
* src/casefiddle.c (casify_object):
* src/ccl.c (Fccl_execute_on_string):
* src/character.c (char_width, c_string_width, lisp_string_width)
(count_size_as_multibyte, string_escape_byte8):
* src/coding.c (coding_alloc_by_realloc, produce_chars):
* src/data.c (arith_driver):
* src/dispnew.c (realloc_glyph_pool, init_display):
* src/editfns.c (styled_format):
* src/fns.c (Ffillarray):
* src/ftfont.c (ftfont_shape_by_flt):
* src/gnutls.c (gnutls_hex_string):
* src/gtkutil.c (get_utf8_string):
* src/image.c (x_to_xcolors, x_detect_edges, png_load_body):
* src/keymap.c (Fkey_description):
* src/lisp.h (SAFE_ALLOCA_LISP):
* src/term.c (encode_terminal_code):
* src/tparam.c (tparam1):
* src/xselect.c (x_property_data_to_lisp):
* src/xsmfns.c (smc_save_yourself_CB):
* src/xterm.c (x_term_init):
When checking for integer overflow, prefer INT_MULTIPLY_WRAPV to
more-complicated code involving division and/or
INT_MULTIPLY_OVERFLOW, and similarly for INT_ADD_WRAPV and
subtraction and/or INT_ADD_OVERFLOW.
* src/casefiddle.c (casify_object): Simplify multibyte size check.
* src/character.c: Remove some obsolete ‘#ifdef emacs’s.
* src/data.c (arith_driver): Also check for division overflow,
as that’s now possible given that the accumulator can now contain
any Emacs integer.
* src/lisp.h (lisp_word_count): Remove; no longer used.

1 files changed, 4 insertions, 5 deletions

diff --git a/src/xterm.c b/src/xterm.c
index 5e9c16b8af4..5756378bd3a 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -11773,7 +11773,6 @@ x_term_init (Lisp_Object display_name, char *xrm_option, char *resource_name)
   struct terminal *terminal;
   struct x_display_info *dpyinfo;
   XrmDatabase xrdb;
-  ptrdiff_t lim;
 
   block_input ();
 
@@ -11974,13 +11973,13 @@ x_term_init (Lisp_Object display_name, char *xrm_option, char *resource_name)
   XSetAfterFunction (x_current_display, x_trace_wire);
 #endif
 
-  lim = min (PTRDIFF_MAX, SIZE_MAX) - sizeof "@";
   Lisp_Object system_name = Fsystem_name ();
-  if (lim - SBYTES (Vinvocation_name) < SBYTES (system_name))
+  ptrdiff_t nbytes;
+  if (INT_ADD_WRAPV (SBYTES (Vinvocation_name), SBYTES (system_name) + 2,
+		     &nbytes))
     memory_full (SIZE_MAX);
   dpyinfo->x_id = ++x_display_id;
-  dpyinfo->x_id_name = xmalloc (SBYTES (Vinvocation_name)
-				+ SBYTES (system_name) + 2);
+  dpyinfo->x_id_name = xmalloc (nbytes);
   char *nametail = lispstpcpy (dpyinfo->x_id_name, Vinvocation_name);
   *nametail++ = '@';
   lispstpcpy (nametail, system_name);