Add --follow-name option.

NEWS.VER

@@ -15,6 +15,9 @@
 
  Major changes between "less" versions 409 and @@VERSION@@
 
+* New --follow-name option makes F command follow the name of a file
+ rather than the file descriptor if an open file is renamed.
+
 * Make searching with -i/-I work correctly with non-ASCII text.
 
 * Fix DJGPP build.

ch.c

@@ -21,6 +21,12 @@
 #include <windows.h>
 #endif
 
+#if HAVE_STAT_INO
+#include <sys/stat.h>
+extern dev_t curr_ino;
+extern ino_t curr_dev;
+#endif
+
 typedef POSITION BLOCKNUM;
 
 public int ignore_eoi;
@@ -98,6 +104,8 @@ static int maxbufs = -1;
 extern int autobuf;
 extern int sigs;
 extern int secure;
+extern int screen_trashed;
+extern int follow_mode;
 extern constant char helpdata[];
 extern constant int size_helpdata;
 extern IFILE curr_ifile;
@@ -276,6 +284,28 @@ fch_get()
 #endif
 #endif
  slept = TRUE;
+
+#if HAVE_STAT_INO
+ if (follow_mode == FOLLOW_NAME)
+ {
+ struct stat st;
+ int r = stat(get_filename(curr_ifile), &st);
+ long diff = 0;
+ if (r == 0)
+ {
+ diff = st.st_ino - curr_ino;
+ if (diff == 0)
+ diff = st.st_dev - curr_dev;
+ }
+ if (diff)
+ {
+ /* screen_trashed=2 makes make_display 
+ * reopen the file. */
+ screen_trashed = 2;
+ return (EOI);
+ }
+ }
+#endif
  }
  if (sigs)
  return (EOI);

command.c

@@ -551,6 +551,21 @@ mca_char(c)
  return (MCA_MORE);
 }
 
+/*
+ * Discard any buffered file data.
+ */
+ static void
+clear_buffers()
+{
+ if (!(ch_getflags() & CH_CANSEEK))
+ return;
+ ch_flush();
+ clr_linenum();
+#if HILITE_SEARCH
+ clr_hilite();
+#endif
+}
+
 /*
  * Make sure the screen is displayed.
  */
@@ -577,6 +592,8 @@ make_display()
  int save_top_scroll;
  save_top_scroll = top_scroll;
  top_scroll = 1;
+ if (screen_trashed == 2)
+ reopen_curr_ifile();
  repaint();
  top_scroll = save_top_scroll;
  }
@@ -1148,14 +1165,7 @@ commands()
  * Flush buffers, then repaint screen.
  * Don't flush the buffers on a pipe!
  */
- if (ch_getflags() & CH_CANSEEK)
- {
- ch_flush();
- clr_linenum();
-#if HILITE_SEARCH
- clr_hilite();
-#endif
- }
+ clear_buffers();
  /* FALLTHRU */
  case A_REPAINT:
  /*
@@ -1257,7 +1267,8 @@ commands()
 /*
  * Define abbreviation for a commonly used sequence below.
  */
-#define DO_SEARCH() if (number <= 0) number = 1; \
+#define DO_SEARCH() \
+ if (number <= 0) number = 1; \
  mca_search(); \
  cmd_exec(); \
  multi_search((char *)NULL, (int) number);

configure.ac

@@ -197,6 +197,8 @@ AH_TEMPLATE([HAVE_VOID],
  [Define HAVE_VOID if your compiler supports the "void" type.])
 AH_TEMPLATE([HAVE_CONST],
  [Define HAVE_CONST if your compiler supports the "const" modifier.])
+AH_TEMPLATE([HAVE_STAT_INO],
+ [Define HAVE_STAT_INO if your struct stat has st_ino and st_dev.])
 AH_TEMPLATE([HAVE_TIME_T],
  [Define HAVE_TIME_T if your system supports the "time_t" type.])
 AH_TEMPLATE([HAVE_STRERROR],
@@ -241,6 +243,11 @@ AC_TRY_COMPILE(, [const int foo = 0;],
 AC_MSG_CHECKING(for time_t)
 AC_TRY_COMPILE([#include <time.h>], [time_t t = 0;],
  [AC_MSG_RESULT(yes); AC_DEFINE(HAVE_TIME_T)], [AC_MSG_RESULT(no)])
+AC_MSG_CHECKING(for st_ino in struct stat)
+AC_TRY_COMPILE([#include <sys/types.h>
+#include <sys/stat.h>],
+ [struct stat s; dev_t dev = s.st_dev; ino_t ino = s.st_ino;],
+ [AC_MSG_RESULT(yes); AC_DEFINE(HAVE_STAT_INO)], [AC_MSG_RESULT(no)])
 
 # Checks for library functions.
 AC_TYPE_SIGNAL

edit.c

@@ -10,6 +10,9 @@
 
 
 #include "less.h"
+#if HAVE_STAT
+#include <sys/stat.h>
+#endif
 
 public int fd0 = 0;
 
@@ -36,6 +39,11 @@ extern int force_logfile;
 extern char *namelogfile;
 #endif
 
+#if HAVE_STAT_INO
+public dev_t curr_ino;
+public ino_t curr_dev;
+#endif
+
 char *curr_altfilename = NULL;
 static void *curr_altpipe;
 
@@ -178,6 +186,9 @@ close_file()
  curr_altfilename = NULL;
  }
  curr_ifile = NULL_IFILE;
+#if HAVE_STAT_INO
+ curr_ino = curr_dev = 0;
+#endif
 }
 
 /*
@@ -360,7 +371,6 @@ edit_ifile(ifile)
  }
  }
  }
- free(qopen_filename);
 
  /*
  * Get the new ifile.
@@ -384,11 +394,24 @@ edit_ifile(ifile)
 #if LOGFILE
  if (namelogfile != NULL && is_tty)
  use_logfile(namelogfile);
+#endif
+#if HAVE_STAT_INO
+ {
+ struct stat statbuf;
+ int r = stat(qopen_filename, &statbuf);
+ if (r == 0)
+ {
+ curr_ino = statbuf.st_ino;
+ curr_dev = statbuf.st_dev;
+ }
+else abort();
+ }
 #endif
  if (every_first_cmd != NULL)
  ungetsc(every_first_cmd);
  }
 
+ free(qopen_filename);
  no_display = !any_display;
  flush();
  any_display = TRUE;
@@ -657,6 +680,14 @@ reedit_ifile(save_ifile)
  quit(QUIT_ERROR);
 }
 
+ public void
+reopen_curr_ifile()
+{
+ IFILE save_ifile = save_curr_ifile();
+ close_file();
+ reedit_ifile(save_ifile);
+}
+
 /*
  * Edit standard input.
  */

less.h

@@ -474,6 +474,9 @@ struct textlist
 #define QUIT_ERROR 1
 #define QUIT_SAVED_STATUS (-1)
 
+#define FOLLOW_DESC 0
+#define FOLLOW_NAME 1
+
 /* filestate flags */
 #define CH_CANSEEK 001
 #define CH_KEEPOPEN 002

less.nro.VER

@@ -799,11 +799,6 @@ Disables sending the termcap initialization and deinitialization strings
 to the terminal.
 This is sometimes desirable if the deinitialization string does
 something unnecessary, like clearing the screen.
-.IP "\-\-no-keypad"
-Disables sending the keypad initialization and deinitialization strings
-to the terminal.
-This is sometimes useful if the keypad strings make the numeric
-keypad behave in an undesirable manner.
 .IP "\-y\fIn\fP or \-\-max-forw-scroll=\fIn\fP"
 Specifies a maximum number of lines to scroll forward.
 If it is necessary to scroll forward more than \fIn\fP lines,
@@ -847,6 +842,23 @@ Specifies the default number of positions to scroll horizontally
 in the RIGHTARROW and LEFTARROW commands.
 If the number specified is zero, it sets the default number of
 positions to one half of the screen width.
+.IP "\-\-no-keypad"
+Disables sending the keypad initialization and deinitialization strings
+to the terminal.
+This is sometimes useful if the keypad strings make the numeric
+keypad behave in an undesirable manner.
+.IP "\-\-follow-name"
+Normally, if the input file is renamed while an F command is executing, 
+.I less
+will continue to display the contents of the original file despite
+its name change.
+If \-\-follow-name is specified, during an F command
+.I less
+will periodically attempt to reopen the file by name.
+If the reopen succeeds, which means that a new file has been created 
+with the same name as the original (now renamed) file, 
+.I less
+will display the contents of that new file.
 .IP \-\-
 A command line argument of "\-\-" marks the end of option arguments.
 Any arguments following this are interpreted as filenames.

line.c

@@ -1046,16 +1046,18 @@ pdone(endline)
  linebuf[curr] = '\n';
  attr[curr] = AT_NORMAL;
  curr++;
- } else if (ignaw && !auto_wrap && column >= sc_width)
+ } 
+ else if (ignaw && !auto_wrap && column >= sc_width)
  {
  /*
  * Big horrible kludge.
  * No-wrap terminals are too hard to deal with when they get in
  * the state where a full screen width of characters have been 
  * output but the cursor is sitting on the right edge instead
- * of at the start of the next line. So after we output a
- * full line, we output an extra space and backspace to force 
- * the cursor to the next line.
+ * of at the start of the next line. 
+ * So after we output a full line, we output an extra 
+ * space and backspace to force the cursor to the 
+ * beginning of the next line, like a sane terminal.
  */
  linebuf[curr] = ' '; 
  attr[curr++] = AT_NORMAL;

opttbl.c

@@ -50,7 +50,8 @@ public int shift_count; /* Number of positions to shift horizontally */
 public int status_col; /* Display a status column */
 public int use_lessopen; /* Use the LESSOPEN filter */
 public int quit_on_intr; /* Quit on interrupt */
-public int oldbot; /* Old bottom of screen behavior */
+public int follow_mode; /* F cmd Follows file desc or file name? */
+public int oldbot; /* Old bottom of screen behavior {{REMOVE}} */
 #if HILITE_SEARCH
 public int hilite_search; /* Highlight matched search patterns? */
 #endif
@@ -113,6 +114,7 @@ static struct optname query_optname = { "help", NULL };
 static struct optname pound_optname = { "shift", NULL };
 static struct optname keypad_optname = { "no-keypad", NULL };
 static struct optname oldbot_optname = { "old-bot", NULL };
+static struct optname follow_optname = { "follow-name", NULL };
 
 
 /*
@@ -440,6 +442,14 @@ static struct loption option[] =
  NULL
  }
  },
+ { '.', &follow_optname,
+ BOOL, FOLLOW_DESC, &follow_mode, NULL,
+ {
+ "F command Follows file descriptor",
+ "F command Follows file name",
+ NULL
+ }
+ },
  { '\0', NULL, NOVAR, 0, NULL, NULL, { NULL, NULL, NULL } }
 };
 

version.c

@@ -700,6 +700,7 @@ v411 11/6/07 Fix case-insensitive searching with non-ASCII text.
 v412 11/6/07 Use symbolic SEEK constants.
 v413 11/6/07 Fix search highlight bug with non-ASCII text.
 v414 11/6/07 Fix display bug with no-wrap terminals.
+v415 11/14/07 Add --follow-name option.
 */
 
-char version[] = "414";
+char version[] = "415";