Revamp quitting and fix infloops

This fixes some infinite loops that cannot be quitted out of,
e.g., (defun foo () (nth most-positive-fixnum '#1=(1 . #1#)))
when byte-compiled and when run under X.  See:
http://lists.gnu.org/archive/html/emacs-devel/2017-01/msg00577.html
This also attempts to keep the performance improvements I recently
added, as much as possible under the constraint that the infloops
must be caught.  In some cases this fixes infloop bugs recently
introduced when I removed immediate_quit.
* src/alloc.c (Fmake_list):
Use rarely_quit, not maybe_quit, for speed in the usual case.
* src/bytecode.c (exec_byte_code):
* src/editfns.c (Fcompare_buffer_substrings):
* src/fns.c (Fnthcdr):
* src/syntax.c (scan_words, skip_chars, skip_syntaxes)
(Fbackward_prefix_chars):
Use rarely_quit so that users can C-g out of long loops.
* src/callproc.c (call_process_cleanup, call_process):
* src/fileio.c (read_non_regular, Finsert_file_contents):
* src/indent.c (compute_motion):
* src/syntax.c (scan_words, Fforward_comment):
Remove now-unnecessary maybe_quit calls.
* src/callproc.c (call_process):
* src/doc.c (get_doc_string, Fsnarf_documentation):
* src/fileio.c (Fcopy_file, read_non_regular, Finsert_file_contents):
* src/lread.c (safe_to_load_version):
* src/sysdep.c (system_process_attributes) [GNU_LINUX]:
Use emacs_read_quit instead of emacs_read in places where
C-g handling is safe.
* src/eval.c (maybe_quit): Move comment here from lisp.h.
* src/fileio.c (Fcopy_file, e_write):
Use emacs_write_quit instead of emacs_write_sig in places where
C-g handling is safe.
* src/filelock.c (create_lock_file): Use emacs_write, not
plain write, as emacs_write no longer has a problem.
(read_lock_data): Use emacs_read, not read, as emacs_read
no longer has a problem.
* src/fns.c (rarely_quit): Move to lisp.h and rename to
incr_rarely_quit.  All uses changed..
* src/fns.c (Fmemq, Fmemql, Fassq, Frassq, Fplist_put, Fplist_member):
* src/indent.c (compute_motion):
* src/syntax.c (find_defun_start, back_comment, forw_comment)
(Fforward_comment, scan_lists, scan_sexps_forward):
Use incr_rarely_quit so that users can C-g out of long loops.
* src/fns.c (Fnconc): Move incr_rarely_quit call to within
inner loop, so that it catches C-g there too.
* src/keyboard.c (tty_read_avail_input): Remove commented-out
and now-obsolete code dealing with interrupts.
* src/lisp.h (rarely_quit, incr_rarely_quit): New functions,
the latter moved here from fns.c and renamed from rarely_quit.
(emacs_read_quit, emacs_write_quit): New decls.
* src/search.c (find_newline, search_buffer, find_newline1):
Add maybe_quit to catch C-g.
* src/sysdep.c (get_child_status): Always invoke maybe_quit
if interruptible, so that the caller need not bother.
(emacs_nointr_read, emacs_read_quit, emacs_write_quit):
New functions.
(emacs_read): Rewrite in terms of emacs_nointr_read.
Do not handle C-g or signals; that is now for emacs_read_quit.
(emacs_full_write): Replace PROCESS_SIGNALS two-way arg
with INTERRUPTIBLE three-way arg.  All uses changed.

1 files changed, 23 insertions, 32 deletions

diff --git a/src/fileio.c b/src/fileio.c
index a109737240f..38400623793 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -2030,9 +2030,9 @@ permissions.  */)
     {
       char buf[MAX_ALLOCA];
       ptrdiff_t n;
-      for (newsize = 0; 0 < (n = emacs_read (ifd, buf, sizeof buf));
+      for (newsize = 0; 0 < (n = emacs_read_quit (ifd, buf, sizeof buf));
            newsize += n)
-        if (emacs_write_sig (ofd, buf, n) != n)
+        if (emacs_write_quit (ofd, buf, n) != n)
           report_file_error ("Write error", newname);
       if (n < 0)
         report_file_error ("Read error", file);
@@ -3396,13 +3396,10 @@ decide_coding_unwind (Lisp_Object unwind_data)
 static Lisp_Object
 read_non_regular (Lisp_Object state)
 {
-  int nbytes;
-
-  maybe_quit ();
-  nbytes = emacs_read (XSAVE_INTEGER (state, 0),
-                       ((char *) BEG_ADDR + PT_BYTE - BEG_BYTE
-                        + XSAVE_INTEGER (state, 1)),
-                       XSAVE_INTEGER (state, 2));
+  int nbytes = emacs_read_quit (XSAVE_INTEGER (state, 0),
+                                ((char *) BEG_ADDR + PT_BYTE - BEG_BYTE
+                                 + XSAVE_INTEGER (state, 1)),
+                                XSAVE_INTEGER (state, 2));
   /* Fast recycle this object for the likely next call.  */
   free_misc (state);
   return make_number (nbytes);
@@ -3746,17 +3743,17 @@ by calling `format-decode', which see.  */)
               int nread;
 
               if (st.st_size <= (1024 * 4))
-                nread = emacs_read (fd, read_buf, 1024 * 4);
+                nread = emacs_read_quit (fd, read_buf, 1024 * 4);
               else
                 {
-                  nread = emacs_read (fd, read_buf, 1024);
+                  nread = emacs_read_quit (fd, read_buf, 1024);
                   if (nread == 1024)
                     {
                       int ntail;
                       if (lseek (fd, - (1024 * 3), SEEK_END) < 0)
                         report_file_error ("Setting file position",
                                            orig_filename);
-                      ntail = emacs_read (fd, read_buf + nread, 1024 * 3);
+                      ntail = emacs_read_quit (fd, read_buf + nread, 1024 * 3);
                       nread = ntail < 0 ? ntail : nread + ntail;
                     }
                 }
@@ -3861,14 +3858,11 @@ by calling `format-decode', which see.  */)
             report_file_error ("Setting file position", orig_filename);
         }
 
-      maybe_quit ();
       /* Count how many chars at the start of the file
          match the text at the beginning of the buffer.  */
-      while (1)
+      while (true)
         {
-          int nread, bufpos;
-
-          nread = emacs_read (fd, read_buf, sizeof read_buf);
+          int nread = emacs_read_quit (fd, read_buf, sizeof read_buf);
           if (nread < 0)
             report_file_error ("Read error", orig_filename);
           else if (nread == 0)
@@ -3890,7 +3884,7 @@ by calling `format-decode', which see.  */)
               break;
             }
 
-          bufpos = 0;
+          int bufpos = 0;
           while (bufpos < nread && same_at_start < ZV_BYTE
                  && FETCH_BYTE (same_at_start) == read_buf[bufpos])
             same_at_start++, bufpos++;
@@ -3910,7 +3904,7 @@ by calling `format-decode', which see.  */)
           del_range_1 (same_at_start, same_at_end, 0, 0);
           goto handled;
         }
-      maybe_quit ();
+
       /* Count how many chars at the end of the file
          match the text at the end of the buffer.  But, if we have
          already found that decoding is necessary, don't waste time.  */
@@ -3932,7 +3926,8 @@ by calling `format-decode', which see.  */)
           total_read = nread = 0;
           while (total_read < trial)
             {
-              nread = emacs_read (fd, read_buf + total_read, trial - total_read);
+              nread = emacs_read_quit (fd, read_buf + total_read,
+                                       trial - total_read);
               if (nread < 0)
                 report_file_error ("Read error", orig_filename);
               else if (nread == 0)
@@ -4058,16 +4053,13 @@ by calling `format-decode', which see.  */)
       inserted = 0;             /* Bytes put into CONVERSION_BUFFER so far.  */
       unprocessed = 0;          /* Bytes not processed in previous loop.  */
 
-      while (1)
+      while (true)
         {
           /* Read at most READ_BUF_SIZE bytes at a time, to allow
              quitting while reading a huge file.  */
 
-          /* Allow quitting out of the actual I/O.  */
-          maybe_quit ();
-          this = emacs_read (fd, read_buf + unprocessed,
-                             READ_BUF_SIZE - unprocessed);
-
+          this = emacs_read_quit (fd, read_buf + unprocessed,
+                                  READ_BUF_SIZE - unprocessed);
           if (this <= 0)
             break;
 
@@ -4281,11 +4273,10 @@ by calling `format-decode', which see.  */)
             /* Allow quitting out of the actual I/O.  We don't make text
                part of the buffer until all the reading is done, so a C-g
                here doesn't do any harm.  */
-            maybe_quit ();
-            this = emacs_read (fd,
-                               ((char *) BEG_ADDR + PT_BYTE - BEG_BYTE
-                                + inserted),
-                               trytry);
+            this = emacs_read_quit (fd,
+                                    ((char *) BEG_ADDR + PT_BYTE - BEG_BYTE
+                                     + inserted),
+                                    trytry);
           }
 
         if (this <= 0)
@@ -5398,7 +5389,7 @@ e_write (int desc, Lisp_Object string, ptrdiff_t start, ptrdiff_t end,
                        : (STRINGP (coding->dst_object)
                           ? SSDATA (coding->dst_object)
                           : (char *) BYTE_POS_ADDR (coding->dst_pos_byte)));
-          coding->produced -= emacs_write_sig (desc, buf, coding->produced);
+          coding->produced -= emacs_write_quit (desc, buf, coding->produced);
 
           if (coding->raw_destination)
             {