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, 4 deletions

diff --git a/src/casefiddle.c b/src/casefiddle.c
index 8755353240a..b94ea8e212e 100644
--- a/src/casefiddle.c
+++ b/src/casefiddle.c
@@ -114,15 +114,15 @@ casify_object (enum case_action flag, Lisp_Object obj)
       ptrdiff_t i, i_byte, size = SCHARS (obj);
       int len;
       USE_SAFE_ALLOCA;
-      ptrdiff_t o_size = (size < STRING_BYTES_BOUND / MAX_MULTIBYTE_LENGTH
-                          ? size * MAX_MULTIBYTE_LENGTH
-                          : STRING_BYTES_BOUND);
+      ptrdiff_t o_size;
+      if (INT_MULTIPLY_WRAPV (size, MAX_MULTIBYTE_LENGTH, &o_size))
+        o_size = PTRDIFF_MAX;
       unsigned char *dst = SAFE_ALLOCA (o_size);
       unsigned char *o = dst;
 
       for (i = i_byte = 0; i < size; i++, i_byte += len)
         {
-          if (o_size - (o - dst) < MAX_MULTIBYTE_LENGTH)
+          if (o_size - MAX_MULTIBYTE_LENGTH < o - dst)
             string_overflow ();
           c = STRING_CHAR_AND_LENGTH (SDATA (obj) + i_byte, len);
           if (inword && flag != CASE_CAPITALIZE_UP)