Allow control-X to interrupt F command loop.

configure.ac

@@ -274,7 +274,7 @@ AC_TRY_COMPILE([], [int f(int a) { return a; }],
 
 # Checks for library functions.
 AC_TYPE_SIGNAL
-AC_CHECK_FUNCS([fsync popen _setjmp sigprocmask sigsetmask snprintf stat system fchmod realpath])
+AC_CHECK_FUNCS([fsync poll popen _setjmp sigprocmask sigsetmask snprintf stat system fchmod realpath])
 
 # AC_CHECK_FUNCS may not work for inline functions, so test these separately.
 AC_MSG_CHECKING(for memcpy)

less.nro.VER

@@ -117,6 +117,8 @@ Normally this command would be used when already at the end of the file.
 It is a way to monitor the tail of a file which is growing
 while it is being viewed.
 (The behavior is similar to the "tail \-f" command.)
+To stop waiting for more data, enter the interrupt character (usually ^C).
+On some systems you can also use ^X.
 .IP "ESC-F"
 Like F, but as soon as a line is found which matches
 the last search pattern, the terminal bell is rung

linenum.c

@@ -241,6 +241,8 @@ longish(VOID_PARAM)
  static void
 abort_long(VOID_PARAM)
 {
+ if (loopcount >= 0)
+ return;
  if (linenums == OPT_ONPLUS)
  /*
  * We were displaying line numbers, so need to repaint.
@@ -301,6 +303,7 @@ find_linenum(pos)
 #if HAVE_TIME
  startime = get_time();
 #endif
+ loopcount = 0;
  if (p == &anchor || pos - p->prev->pos < p->pos - pos)
  {
  /*
@@ -309,7 +312,6 @@ find_linenum(pos)
  p = p->prev;
  if (ch_seek(p->pos))
  return (0);
- loopcount = 0;
  for (linenum = p->line, cpos = p->pos; cpos < pos; linenum++)
  {
  /*
@@ -341,7 +343,6 @@ find_linenum(pos)
  */
  if (ch_seek(p->pos))
  return (0);
- loopcount = 0;
  for (linenum = p->line, cpos = p->pos; cpos > pos; linenum--)
  {
  /*
@@ -361,7 +362,7 @@ find_linenum(pos)
  */
  add_lnum(linenum, cpos);
  }
-
+ loopcount = 0;
  return (linenum);
 }
 

os.c

@@ -25,6 +25,9 @@
 #if HAVE_VALUES_H
 #include <values.h>
 #endif
+#if HAVE_POLL
+#include <poll.h>
+#endif
 
 /*
  * BSD setjmp() saves (and longjmp() restores) the signal mask.
@@ -46,6 +49,10 @@ public int reading;
 static jmp_buf read_label;
 
 extern int sigs;
+extern int ignore_eoi;
+#if !MSDOS_COMPILER
+extern int tty;
+#endif
 
 /*
  * Like read() system call, but is deliberately interruptible.
@@ -119,6 +126,25 @@ iread(fd, buf, len)
  if (select(fd+1, &readfds, 0, 0, 0) == -1)
  return (-1);
  }
+#endif
+#if HAVE_POLL && !MSDOS_COMPILER
+ if (ignore_eoi)
+ {
+ struct pollfd poll_tty = { tty, POLLIN, 0 };
+ n = poll(&poll_tty, 1, 0);
+ if (n > 0)
+ {
+ if (poll_tty.revents & POLLIN)
+ {
+ n = read(tty, buf, 1);
+ if (n > 0 && buf[0] == CONTROL('X'))
+ {
+ sigs |= S_INTERRUPT;
+ return (READ_INTR);
+ }
+ }
+ }
+ }
 #endif
  n = read(fd, buf, len);
 #if 1
@@ -128,7 +154,6 @@ iread(fd, buf, len)
  * start returning 0 forever, instead of -1.
  */
  {
- extern int ignore_eoi;
  if (!ignore_eoi)
  {
  static int consecutive_nulls = 0;

version.c

@@ -895,7 +895,8 @@ v567 11/25/20 Fix typo.
 v568 11/29/20 Fix some hyperlink bugs; add ^W search modifier
  (thanks to Arminius); allow Makefile.aut to use Python 
  instead of Perl (thanks to Charlie Lin).
-v569 Allow multiple & filters (thanks to Mattias Johansson).
+v569 Allow multiple & filters (thanks to Mattias Johansson),
+ allow ^X to exit F command.
 */
 
 char version[] = "569x";