From e828765d01313acddcf17279b6b43ae9f777f2a4 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Wed, 27 Feb 2019 01:14:27 -0800
Subject: DEFVAR_INT variables are now intmax_t
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Formerly they were fixnums, which led to problems when dealing
with values that might not fit on 32-bit platforms, such as
string-chars-consed or floats_consed.  64-bit counters should
be good enough for these (for a while, anyway...).
While we’re at it, fix some unlikely integer overflow bugs
that have been in the code for a while.
* lib-src/make-docfile.c (write_globals):
* src/data.c (do_symval_forwarding, store_symval_forwarding):
* src/eval.c (restore_stack_limits, call_debugger):
* src/frame.h (struct frame.cost_calculation_baud_rate):
* src/keyboard.c (last_auto_save, bind_polling_period, read_char):
* src/lisp.h (struct Lisp_Intfwd.intvar):
* src/lread.c (defvar_int):
* src/pdumper.c (dump_fwd_int):
* src/thread.h (struct thread_state.m_lisp_eval_depth):
* src/undo.c (truncate_undo_list):
* src/xselect.c (wait_for_property_change)
(x_get_foreign_selection):
* src/xterm.c (x_emacs_to_x_modifiers):
DEFVAR_INT variables now have the C type intmax_t, not EMACS_INT.
* src/data.c (store_symval_forwarding):
* src/gnutls.c (Fgnutls_boot):
* src/keyboard.c (bind_polling_period):
* src/macros.c (pop_kbd_macro, Fexecute_kbd_macro):
* src/undo.c (truncate_undo_list):
Allow any integer that fits into intmax_t, instead of
requiring it to be a Lisp fixnum.
* src/dispnew.c (update_window):
* src/frame.c (x_figure_window_size):
* src/gnutls.c (init_gnutls_functions)
(emacs_gnutls_handle_error):
* src/keyboard.c (make_lisp_event):
* src/nsterm.m (ns_dumpglyphs_image):
* src/profiler.c (make_log):
* src/scroll.c (calculate_scrolling)
(calculate_direct_scrolling):
* src/termcap.c (tputs):
* src/xterm.c (x_draw_image_relief):
Avoid implementation-defined behavior on conversion of
out-of-range integers.
* src/eval.c (when_entered_debugger): Now intmax_t.
(max_ensure_room): New function, that avoids signed integer overflow.
(call_debugger, signal_or_quit): Use it.
* src/fileio.c (Fdo_auto_save):
* src/keyboard.c (make_lisp_event):
* src/term.c (calculate_costs):
* src/xdisp.c (build_desired_tool_bar_string)
(hscroll_window_tree, try_scrolling, decode_mode_spec)
(x_produce_glyphs):
Avoid signed integer overflow.
* src/lisp.h (clip_to_bounds): Generalize to intmax_t.
* src/pdumper.c (dump_emacs_reloc_immediate_emacs_int): Remove, ...
(dump_emacs_reloc_immediate_intmax_t): ... replacing with this
function.  All uses changed.
* src/profiler.c (make_log): Omit args.  All callers changed.
* src/termcap.c: Include stdlib.h, for atoi.
Include intprops.h.
* src/window.c (sanitize_next_screen_context_lines): New function.
(window_scroll_pixel_based, window_scroll_line_based):
Use it to avoid signed integer overflow.
---
 src/scroll.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

(limited to 'src/scroll.c')

diff --git a/src/scroll.c b/src/scroll.c
index e523a19ab89..8eda510945f 100644
--- a/src/scroll.c
+++ b/src/scroll.c
@@ -107,10 +107,8 @@ calculate_scrolling (struct frame *frame,
   /* Discourage long scrolls on fast lines.
      Don't scroll nearly a full frame height unless it saves
      at least 1/4 second.  */
-  int extra_cost = baud_rate / (10 * 4 * frame_total_lines);
-
-  if (baud_rate <= 0)
-    extra_cost = 1;
+  int extra_cost
+    = clip_to_bounds (1, baud_rate / (10 * 4) / frame_total_lines, INT_MAX / 2);
 
   /* initialize the top left corner of the matrix */
   matrix->writecost = 0;
@@ -446,10 +444,8 @@ calculate_direct_scrolling (struct frame *frame,
   /* Discourage long scrolls on fast lines.
      Don't scroll nearly a full frame height unless it saves
      at least 1/4 second.  */
-  int extra_cost = baud_rate / (10 * 4 * frame_total_lines);
-
-  if (baud_rate <= 0)
-    extra_cost = 1;
+  int extra_cost
+    = clip_to_bounds (1, baud_rate / (10 * 4) / frame_total_lines, INT_MAX / 2);
 
   /* Overhead of setting the scroll window, plus the extra
      cost of scrolling by a distance of one.  The extra cost is
-- 
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