Use SAFE_ALLOCA etc. to avoid unbounded stack allocation.

This follows up on the recent thread in emacs-devel on alloca; see:
http://lists.gnu.org/archive/html/emacs-devel/2014-09/msg00042.html
This patch also cleans up alloca-related glitches noted while
examining the code looking for unbounded alloca.
* alloc.c (listn):
* callproc.c (init_callproc):
Rewrite to avoid need for alloca.
* buffer.c (mouse_face_overlay_overlaps)
(report_overlay_modification):
* buffer.h (GET_OVERLAYS_AT):
* coding.c (make_subsidiaries):
* doc.c (Fsnarf_documentation):
* editfns.c (Fuser_full_name):
* fileio.c (Ffile_name_directory, Fexpand_file_name)
(search_embedded_absfilename, Fsubstitute_in_file_name):
* fns.c (Fmake_hash_table):
* font.c (font_vconcat_entity_vectors, font_update_drivers):
* fontset.c (fontset_pattern_regexp, Ffontset_info):
* frame.c (Fmake_terminal_frame, x_set_frame_parameters)
(xrdb_get_resource, x_get_resource_string):
* ftfont.c (ftfont_get_charset, ftfont_check_otf, ftfont_drive_otf):
* ftxfont.c (ftxfont_draw):
* image.c (xbm_load, xpm_load, jpeg_load_body):
* keyboard.c (echo_add_key, menu_bar_items, tool_bar_items):
* keymap.c (Fdescribe_buffer_bindings, describe_map):
* lread.c (openp):
* menu.c (digest_single_submenu, find_and_call_menu_selection)
(find_and_return_menu_selection):
* print.c (PRINTFINISH):
* process.c (Fformat_network_address):
* scroll.c (do_scrolling, do_direct_scrolling, scrolling_1):
* search.c (search_buffer, Fmatch_data, Fregexp_quote):
* sound.c (wav_play, au_play):
* syntax.c (skip_chars):
* term.c (tty_menu_activate, tty_menu_show):
* textprop.c (get_char_property_and_overlay):
* window.c (Fset_window_configuration):
* xdisp.c (safe__call, next_overlay_change, vmessage)
(compute_overhangs_and_x, draw_glyphs, note_mouse_highlight):
* xfaces.c (face_at_buffer_position):
* xmenu.c (x_menu_show):
Use SAFE_ALLOCA etc. instead of plain alloca, since the
allocation size isn't bounded.
* callint.c (Fcall_interactively): Redo memory_full check
so that it can be done at compile-time on some platforms.
* coding.c (MAX_LOOKUP_MAX): New constant.
(get_translation_table): Use it.
* callproc.c (call_process): Use SAFE_NALLOCA instead of
SAFE_ALLOCA, to catch integer overflows on size calculation.
(exec_failed) [!DOS_NT]: New function.
(child_setup) [!DOS_NT]: Use it.
* editfns.c (Ftranspose_regions):
Hoist USE_SAFE_ALLOC + SAFE_FREE out of 'if'.
* editfns.c (check_translation):
Allocate larger buffers on the heap.
* eval.c (internal_lisp_condition_case):
Check for MAX_ALLOCA overflow.
* fns.c (sort_vector): Use SAFE_ALLOCA_LISP rather than Fmake_vector.
(Fbase64_encode_region, Fbase64_decode_region):
Avoid unnecessary calls to SAFE_FREE before 'error'.
* buffer.c (mouse_face_overlay_overlaps):
* editfns.c (Fget_pos_property, check_translation):
* eval.c (Ffuncall):
* font.c (font_unparse_xlfd, font_find_for_lface):
* ftfont.c (ftfont_drive_otf):
* keyboard.c (echo_add_key, read_decoded_event_from_main_queue)
(menu_bar_items, tool_bar_items):
* sound.c (Fplay_sound_internal):
* xdisp.c (load_overlay_strings, dump_glyph_row):
Use an ordinary auto buffer rather than alloca, since the
allocation size is fixed and small.
* ftfont.c: Include <c-strcase.h>.
(matching_prefix): New function.
(get_adstyle_property): Use it, to avoid need for alloca.
* keyboard.c (echo_add_key):
* keymap.c (describe_map): Use ptrdiff_t, not int.
* keyboard.c (echo_add_key): Prefer sizeof to strlen.
* keymap.c (Fdescribe_buffer_bindings): Use SBYTES, not SCHARS,
when counting bytes.
* lisp.h (xlispstrdupa): Remove, replacing with ...
(SAFE_ALLOCA_STRING): ... new macro with different API.
This fixes a portability problem, namely, alloca result
passed to another function.  All uses changed.
(SAFE_ALLOCA, SAFE_ALLOCA_LISP): Check for MAX_ALLOCA,
not MAX_ALLOCA - 1.
* regex.c (REGEX_USE_SAFE_ALLOCA, REGEX_SAFE_FREE)
(REGEX_ALLOCATE): New macros.
(REGEX_REALLOCATE, REGEX_ALLOCATE_STACK, REGEX_REALLOCATE_STACK)
(REGEX_FREE_STACK, FREE_VARIABLES, re_match_2_internal):
Use them.
* xdisp.c (message3): Use SAFE_ALLOCA_STRING rather than doing it
by hand.
(decode_mode_spec_coding): Store directly into buf rather than
into an alloca temporary and copying the temporary to the buf.

Fixes: debbugs:18410

1 files changed, 10 insertions, 14 deletions

diff --git a/src/fns.c b/src/fns.c
index 6cc5cef95df..260bc4e3a12 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -1992,17 +1992,14 @@ sort_vector (Lisp_Object vector, Lisp_Object predicate)
     return;
   ptrdiff_t halflen = len >> 1;
   Lisp_Object *tmp;
-  Lisp_Object tmpvec = Qnil;
-  struct gcpro gcpro1, gcpro2, gcpro3;
-  GCPRO3 (vector, predicate, tmpvec);
-  if (halflen < MAX_ALLOCA / word_size)
-    tmp = alloca (halflen * word_size);
-  else
-    {
-      tmpvec = Fmake_vector (make_number (halflen), make_number (0));
-      tmp = XVECTOR (tmpvec)->contents;
-    }
+  struct gcpro gcpro1, gcpro2;
+  GCPRO2 (vector, predicate);
+  USE_SAFE_ALLOCA;
+  SAFE_ALLOCA_LISP (tmp, halflen);
+  for (ptrdiff_t i = 0; i < halflen; i++)
+    tmp[i] = make_number (0);
   sort_vector_inplace (predicate, len, XVECTOR (vector)->contents, tmp);
+  SAFE_FREE ();
   UNGCPRO;
 }
 
@@ -3289,7 +3286,6 @@ into shorter lines.  */)
   if (encoded_length < 0)
     {
       /* The encoding wasn't possible. */
-      SAFE_FREE ();
       error ("Multibyte character in data for base64 encoding");
     }
 
@@ -3434,7 +3430,6 @@ If the region can't be decoded, signal an error and don't modify the buffer.  */
   if (decoded_length < 0)
     {
       /* The decoding wasn't possible. */
-      SAFE_FREE ();
       error ("Invalid base64 data");
     }
 
@@ -4581,12 +4576,12 @@ usage: (make-hash-table &rest KEYWORD-ARGS)  */)
 {
   Lisp_Object test, size, rehash_size, rehash_threshold, weak;
   struct hash_table_test testdesc;
-  char *used;
   ptrdiff_t i;
+  USE_SAFE_ALLOCA;
 
   /* The vector `used' is used to keep track of arguments that
      have been consumed.  */
-  used = alloca (nargs * sizeof *used);
+  char *used = SAFE_ALLOCA (nargs * sizeof *used);
   memset (used, 0, nargs * sizeof *used);
 
   /* See if there's a `:test TEST' among the arguments.  */
@@ -4653,6 +4648,7 @@ usage: (make-hash-table &rest KEYWORD-ARGS)  */)
     if (!used[i])
       signal_error ("Invalid argument list", args[i]);
 
+  SAFE_FREE ();
   return make_hash_table (testdesc, size, rehash_size, rehash_threshold, weak);
 }