Adding upstream version 5.0.upstream/5.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 791 insertions, 0 deletions

diff --git a/lib/readline/histfile.c b/lib/readline/histfile.c
new file mode 100644
index 0000000..dc64bde
--- /dev/null
+++ b/lib/readline/histfile.c
@@ -0,0 +1,791 @@
+/* histfile.c - functions to manipulate the history file. */
+
+/* Copyright (C) 1989-2018 Free Software Foundation, Inc.
+
+   This file contains the GNU History Library (History), a set of
+   routines for managing the text of previously typed lines.
+
+   History is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   History is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with History.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/* The goal is to make the implementation transparent, so that you
+   don't have to know what data types are used, just what functions
+   you can call.  I think I have done that. */
+
+#define READLINE_LIBRARY
+
+#if defined (__TANDEM)
+#  include <floss.h>
+#endif
+
+#if defined (HAVE_CONFIG_H)
+#  include <config.h>
+#endif
+
+#include <stdio.h>
+
+#if defined (HAVE_LIMITS_H)
+#  include <limits.h>
+#endif
+
+#include <sys/types.h>
+#if ! defined (_MINIX) && defined (HAVE_SYS_FILE_H)
+#  include <sys/file.h>
+#endif
+#include "posixstat.h"
+#include <fcntl.h>
+
+#if defined (HAVE_STDLIB_H)
+#  include <stdlib.h>
+#else
+#  include "ansi_stdlib.h"
+#endif /* HAVE_STDLIB_H */
+
+#if defined (HAVE_UNISTD_H)
+#  include <unistd.h>
+#endif
+
+#include <ctype.h>
+
+#if defined (__EMX__)
+#  undef HAVE_MMAP
+#endif
+
+#ifdef HISTORY_USE_MMAP
+#  include <sys/mman.h>
+
+#  ifdef MAP_FILE
+#    define MAP_RFLAGS	(MAP_FILE|MAP_PRIVATE)
+#    define MAP_WFLAGS	(MAP_FILE|MAP_SHARED)
+#  else
+#    define MAP_RFLAGS	MAP_PRIVATE
+#    define MAP_WFLAGS	MAP_SHARED
+#  endif
+
+#  ifndef MAP_FAILED
+#    define MAP_FAILED	((void *)-1)
+#  endif
+
+#endif /* HISTORY_USE_MMAP */
+
+/* If we're compiling for __EMX__ (OS/2) or __CYGWIN__ (cygwin32 environment
+   on win 95/98/nt), we want to open files with O_BINARY mode so that there
+   is no \n -> \r\n conversion performed.  On other systems, we don't want to
+   mess around with O_BINARY at all, so we ensure that it's defined to 0. */
+#if defined (__EMX__) || defined (__CYGWIN__)
+#  ifndef O_BINARY
+#    define O_BINARY 0
+#  endif
+#else /* !__EMX__ && !__CYGWIN__ */
+#  undef O_BINARY
+#  define O_BINARY 0
+#endif /* !__EMX__ && !__CYGWIN__ */
+
+#include <errno.h>
+#if !defined (errno)
+extern int errno;
+#endif /* !errno */
+
+#include "history.h"
+#include "histlib.h"
+
+#include "rlshell.h"
+#include "xmalloc.h"
+
+#if !defined (PATH_MAX)
+#  define PATH_MAX	1024	/* default */
+#endif
+
+extern void _hs_append_history_line PARAMS((int, const char *));
+
+/* history file version; currently unused */
+int history_file_version = 1;
+
+/* If non-zero, we write timestamps to the history file in history_do_write() */
+int history_write_timestamps = 0;
+
+/* If non-zero, we assume that a history file that starts with a timestamp
+   uses timestamp-delimited entries and can include multi-line history
+   entries. Used by read_history_range */
+int history_multiline_entries = 0;
+
+/* Immediately after a call to read_history() or read_history_range(), this
+   will return the number of lines just read from the history file in that
+   call. */
+int history_lines_read_from_file = 0;
+
+/* Immediately after a call to write_history() or history_do_write(), this
+   will return the number of lines just written to the history file in that
+   call.  This also works with history_truncate_file. */
+int history_lines_written_to_file = 0;
+
+/* Does S look like the beginning of a history timestamp entry?  Placeholder
+   for more extensive tests. */
+#define HIST_TIMESTAMP_START(s)		(*(s) == history_comment_char && isdigit ((unsigned char)(s)[1]) )
+
+static char *history_backupfile PARAMS((const char *));
+static char *history_tempfile PARAMS((const char *));
+static int histfile_backup PARAMS((const char *, const char *));
+static int histfile_restore PARAMS((const char *, const char *));
+
+/* Return the string that should be used in the place of this
+   filename.  This only matters when you don't specify the
+   filename to read_history (), or write_history (). */
+static char *
+history_filename (const char *filename)
+{
+  char *return_val;
+  const char *home;
+  int home_len;
+
+  return_val = filename ? savestring (filename) : (char *)NULL;
+
+  if (return_val)
+    return (return_val);
+  
+  home = sh_get_env_value ("HOME");
+#if defined (_WIN32)
+  if (home == 0)
+    home = sh_get_env_value ("APPDATA");
+#endif
+
+  if (home == 0)
+    return (NULL);
+  else
+    home_len = strlen (home);
+
+  return_val = (char *)xmalloc (2 + home_len + 8); /* strlen(".history") == 8 */
+  strcpy (return_val, home);
+  return_val[home_len] = '/';
+#if defined (__MSDOS__)
+  strcpy (return_val + home_len + 1, "_history");
+#else
+  strcpy (return_val + home_len + 1, ".history");
+#endif
+
+  return (return_val);
+}
+
+static char *
+history_backupfile (const char *filename)
+{
+  const char *fn;
+  char *ret, linkbuf[PATH_MAX+1];
+  size_t len;
+  ssize_t n;
+  struct stat fs;
+
+  fn = filename;  
+#if defined (HAVE_READLINK)
+  /* Follow symlink to avoid backing up symlink itself; call will fail if
+     not a symlink */
+  if ((n = readlink (filename, linkbuf, sizeof (linkbuf) - 1)) > 0)
+    {
+      linkbuf[n] = '\0';
+      fn = linkbuf;
+    }
+#endif
+      
+  len = strlen (fn);
+  ret = xmalloc (len + 2);
+  strcpy (ret, fn);
+  ret[len] = '-';
+  ret[len+1] = '\0';
+  return ret;
+}
+  
+static char *
+history_tempfile (const char *filename)
+{
+  const char *fn;
+  char *ret, linkbuf[PATH_MAX+1];
+  size_t len;
+  ssize_t n;
+  struct stat fs;
+  int pid;
+
+  fn = filename;  
+#if defined (HAVE_READLINK)
+  /* Follow symlink so tempfile created in the same directory as any symlinked
+     history file; call will fail if not a symlink */
+  if ((n = readlink (filename, linkbuf, sizeof (linkbuf) - 1)) > 0)
+    {
+      linkbuf[n] = '\0';
+      fn = linkbuf;
+    }
+#endif
+      
+  len = strlen (fn);
+  ret = xmalloc (len + 11);
+  strcpy (ret, fn);
+
+  pid = (int)getpid ();
+
+  /* filename-PID.tmp */
+  ret[len] = '-';
+  ret[len+1] = (pid / 10000 % 10) + '0';
+  ret[len+2] = (pid / 1000 % 10) + '0';
+  ret[len+3] = (pid / 100 % 10) + '0';
+  ret[len+4] = (pid / 10 % 10) + '0';
+  ret[len+5] = (pid % 10) + '0';
+  strcpy (ret + len + 6, ".tmp");
+
+  return ret;
+}
+  
+/* Add the contents of FILENAME to the history list, a line at a time.
+   If FILENAME is NULL, then read from ~/.history.  Returns 0 if
+   successful, or errno if not. */
+int
+read_history (const char *filename)
+{
+  return (read_history_range (filename, 0, -1));
+}
+
+/* Read a range of lines from FILENAME, adding them to the history list.
+   Start reading at the FROM'th line and end at the TO'th.  If FROM
+   is zero, start at the beginning.  If TO is less than FROM, read
+   until the end of the file.  If FILENAME is NULL, then read from
+   ~/.history.  Returns 0 if successful, or errno if not. */
+int
+read_history_range (const char *filename, int from, int to)
+{
+  register char *line_start, *line_end, *p;
+  char *input, *buffer, *bufend, *last_ts;
+  int file, current_line, chars_read, has_timestamps, reset_comment_char;
+  struct stat finfo;
+  size_t file_size;
+#if defined (EFBIG)
+  int overflow_errno = EFBIG;
+#elif defined (EOVERFLOW)
+  int overflow_errno = EOVERFLOW;
+#else
+  int overflow_errno = EIO;
+#endif
+
+  history_lines_read_from_file = 0;
+
+  buffer = last_ts = (char *)NULL;
+  input = history_filename (filename);
+  file = input ? open (input, O_RDONLY|O_BINARY, 0666) : -1;
+
+  if ((file < 0) || (fstat (file, &finfo) == -1))
+    goto error_and_exit;
+
+  if (S_ISREG (finfo.st_mode) == 0)
+    {
+#ifdef EFTYPE
+      errno = EFTYPE;
+#else
+      errno = EINVAL;
+#endif
+      goto error_and_exit;
+    }
+
+  file_size = (size_t)finfo.st_size;
+
+  /* check for overflow on very large files */
+  if (file_size != finfo.st_size || file_size + 1 < file_size)
+    {
+      errno = overflow_errno;
+      goto error_and_exit;
+    }
+
+  if (file_size == 0)
+    {
+      free (input);
+      return 0;	/* don't waste time if we don't have to */
+    }
+
+#ifdef HISTORY_USE_MMAP
+  /* We map read/write and private so we can change newlines to NULs without
+     affecting the underlying object. */
+  buffer = (char *)mmap (0, file_size, PROT_READ|PROT_WRITE, MAP_RFLAGS, file, 0);
+  if ((void *)buffer == MAP_FAILED)
+    {
+      errno = overflow_errno;
+      goto error_and_exit;
+    }
+  chars_read = file_size;
+#else
+  buffer = (char *)malloc (file_size + 1);
+  if (buffer == 0)
+    {
+      errno = overflow_errno;
+      goto error_and_exit;
+    }
+
+  chars_read = read (file, buffer, file_size);
+#endif
+  if (chars_read < 0)
+    {
+  error_and_exit:
+      if (errno != 0)
+	chars_read = errno;
+      else
+	chars_read = EIO;
+      if (file >= 0)
+	close (file);
+
+      FREE (input);
+#ifndef HISTORY_USE_MMAP
+      FREE (buffer);
+#endif
+
+      return (chars_read);
+    }
+
+  close (file);
+
+  /* Set TO to larger than end of file if negative. */
+  if (to < 0)
+    to = chars_read;
+
+  /* Start at beginning of file, work to end. */
+  bufend = buffer + chars_read;
+  *bufend = '\0';		/* null-terminate buffer for timestamp checks */
+  current_line = 0;
+
+  /* Heuristic: the history comment character rarely changes, so assume we
+     have timestamps if the buffer starts with `#[:digit:]' and temporarily
+     set history_comment_char so timestamp parsing works right */
+  reset_comment_char = 0;
+  if (history_comment_char == '\0' && buffer[0] == '#' && isdigit ((unsigned char)buffer[1]))
+    {
+      history_comment_char = '#';
+      reset_comment_char = 1;
+    }
+
+  has_timestamps = HIST_TIMESTAMP_START (buffer);
+  history_multiline_entries += has_timestamps && history_write_timestamps;  
+
+  /* Skip lines until we are at FROM. */
+  for (line_start = line_end = buffer; line_end < bufend && current_line < from; line_end++)
+    if (*line_end == '\n')
+      {
+      	p = line_end + 1;
+      	/* If we see something we think is a timestamp, continue with this
+	   line.  We should check more extensively here... */
+	if (HIST_TIMESTAMP_START(p) == 0)
+	  current_line++;
+	line_start = p;
+      }
+
+  /* If there are lines left to gobble, then gobble them now. */
+  for (line_end = line_start; line_end < bufend; line_end++)
+    if (*line_end == '\n')
+      {
+	/* Change to allow Windows-like \r\n end of line delimiter. */
+	if (line_end > line_start && line_end[-1] == '\r')
+	  line_end[-1] = '\0';
+	else
+	  *line_end = '\0';
+
+	if (*line_start)
+	  {
+	    if (HIST_TIMESTAMP_START(line_start) == 0)
+	      {
+	      	if (last_ts == NULL && history_length > 0 && history_multiline_entries)
+		  _hs_append_history_line (history_length - 1, line_start);
+		else
+		  add_history (line_start);
+		if (last_ts)
+		  {
+		    add_history_time (last_ts);
+		    last_ts = NULL;
+		  }
+	      }
+	    else
+	      {
+		last_ts = line_start;
+		current_line--;
+	      }
+	  }
+
+	current_line++;
+
+	if (current_line >= to)
+	  break;
+
+	line_start = line_end + 1;
+      }
+
+  history_lines_read_from_file = current_line;
+  if (reset_comment_char)
+    history_comment_char = '\0';
+
+  FREE (input);
+#ifndef HISTORY_USE_MMAP
+  FREE (buffer);
+#else
+  munmap (buffer, file_size);
+#endif
+
+  return (0);
+}
+
+/* Save FILENAME to BACK, handling case where FILENAME is a symlink
+   (e.g., ~/.bash_history -> .histfiles/.bash_history.$HOSTNAME) */
+static int
+histfile_backup (const char *filename, const char *back)
+{
+#if defined (HAVE_READLINK)
+  char linkbuf[PATH_MAX+1];
+  ssize_t n;
+
+  /* Follow to target of symlink to avoid renaming symlink itself */
+  if ((n = readlink (filename, linkbuf, sizeof (linkbuf) - 1)) > 0)
+    {
+      linkbuf[n] = '\0';
+      return (rename (linkbuf, back));
+    }
+#endif
+  return (rename (filename, back));
+}
+
+/* Restore ORIG from BACKUP handling case where ORIG is a symlink
+   (e.g., ~/.bash_history -> .histfiles/.bash_history.$HOSTNAME) */
+static int
+histfile_restore (const char *backup, const char *orig)
+{
+#if defined (HAVE_READLINK)
+  char linkbuf[PATH_MAX+1];
+  ssize_t n;
+
+  /* Follow to target of symlink to avoid renaming symlink itself */
+  if ((n = readlink (orig, linkbuf, sizeof (linkbuf) - 1)) > 0)
+    {
+      linkbuf[n] = '\0';
+      return (rename (backup, linkbuf));
+    }
+#endif
+  return (rename (backup, orig));
+}
+
+/* Truncate the history file FNAME, leaving only LINES trailing lines.
+   If FNAME is NULL, then use ~/.history.  Writes a new file and renames
+   it to the original name.  Returns 0 on success, errno on failure. */
+int
+history_truncate_file (const char *fname, int lines)
+{
+  char *buffer, *filename, *tempname, *bp, *bp1;		/* bp1 == bp+1 */
+  int file, chars_read, rv, orig_lines, exists, r;
+  struct stat finfo;
+  size_t file_size;
+
+  history_lines_written_to_file = 0;
+
+  buffer = (char *)NULL;
+  filename = history_filename (fname);
+  tempname = 0;
+  file = filename ? open (filename, O_RDONLY|O_BINARY, 0666) : -1;
+  rv = exists = 0;
+
+  /* Don't try to truncate non-regular files. */
+  if (file == -1 || fstat (file, &finfo) == -1)
+    {
+      rv = errno;
+      if (file != -1)
+	close (file);
+      goto truncate_exit;
+    }
+  exists = 1;
+
+  if (S_ISREG (finfo.st_mode) == 0)
+    {
+      close (file);
+#ifdef EFTYPE
+      rv = EFTYPE;
+#else
+      rv = EINVAL;
+#endif
+      goto truncate_exit;
+    }
+
+  file_size = (size_t)finfo.st_size;
+
+  /* check for overflow on very large files */
+  if (file_size != finfo.st_size || file_size + 1 < file_size)
+    {
+      close (file);
+#if defined (EFBIG)
+      rv = errno = EFBIG;
+#elif defined (EOVERFLOW)
+      rv = errno = EOVERFLOW;
+#else
+      rv = errno = EINVAL;
+#endif
+      goto truncate_exit;
+    }
+
+  buffer = (char *)malloc (file_size + 1);
+  if (buffer == 0)
+    {
+      rv = errno;
+      close (file);
+      goto truncate_exit;
+    }
+
+  chars_read = read (file, buffer, file_size);
+  close (file);
+
+  if (chars_read <= 0)
+    {
+      rv = (chars_read < 0) ? errno : 0;
+      goto truncate_exit;
+    }
+
+  orig_lines = lines;
+  /* Count backwards from the end of buffer until we have passed
+     LINES lines.  bp1 is set funny initially.  But since bp[1] can't
+     be a comment character (since it's off the end) and *bp can't be
+     both a newline and the history comment character, it should be OK. */
+  for (bp1 = bp = buffer + chars_read - 1; lines && bp > buffer; bp--)
+    {
+      if (*bp == '\n' && HIST_TIMESTAMP_START(bp1) == 0)
+	lines--;
+      bp1 = bp;
+    }
+
+  /* If this is the first line, then the file contains exactly the
+     number of lines we want to truncate to, so we don't need to do
+     anything.  It's the first line if we don't find a newline between
+     the current value of i and 0.  Otherwise, write from the start of
+     this line until the end of the buffer. */
+  for ( ; bp > buffer; bp--)
+    {
+      if (*bp == '\n' && HIST_TIMESTAMP_START(bp1) == 0)
+        {
+	  bp++;
+	  break;
+        }
+      bp1 = bp;
+    }
+
+  /* Write only if there are more lines in the file than we want to
+     truncate to. */
+  if (bp <= buffer)
+    {
+      rv = 0;
+      /* No-op if LINES == 0 at this point */
+      history_lines_written_to_file = orig_lines - lines;
+      goto truncate_exit;
+    }
+
+  tempname = history_tempfile (filename);
+
+  if ((file = open (tempname, O_WRONLY|O_CREAT|O_TRUNC|O_BINARY, 0600)) != -1)
+    {
+      if (write (file, bp, chars_read - (bp - buffer)) < 0)
+	rv = errno;
+
+      if (close (file) < 0 && rv == 0)
+	rv = errno;
+    }
+  else
+    rv = errno;
+
+ truncate_exit:
+  FREE (buffer);
+
+  history_lines_written_to_file = orig_lines - lines;
+
+  if (rv == 0 && filename && tempname)
+    rv = histfile_restore (tempname, filename);
+
+  if (rv != 0)
+    {
+      if (tempname)
+	unlink (tempname);
+      history_lines_written_to_file = 0;
+    }
+
+#if defined (HAVE_CHOWN)
+  /* Make sure the new filename is owned by the same user as the old.  If one
+     user is running this, it's a no-op.  If the shell is running after sudo
+     with a shared history file, we don't want to leave the history file
+     owned by root. */
+  if (rv == 0 && exists)
+    r = chown (filename, finfo.st_uid, finfo.st_gid);
+#endif
+
+  xfree (filename);
+  FREE (tempname);
+
+  return rv;
+}
+
+/* Workhorse function for writing history.  Writes the last NELEMENT entries
+   from the history list to FILENAME.  OVERWRITE is non-zero if you
+   wish to replace FILENAME with the entries. */
+static int
+history_do_write (const char *filename, int nelements, int overwrite)
+{
+  register int i;
+  char *output, *tempname, *histname;
+  int file, mode, rv, exists;
+  struct stat finfo;
+#ifdef HISTORY_USE_MMAP
+  size_t cursize;
+
+  history_lines_written_to_file = 0;
+
+  mode = overwrite ? O_RDWR|O_CREAT|O_TRUNC|O_BINARY : O_RDWR|O_APPEND|O_BINARY;
+#else
+  mode = overwrite ? O_WRONLY|O_CREAT|O_TRUNC|O_BINARY : O_WRONLY|O_APPEND|O_BINARY;
+#endif
+  histname = history_filename (filename);
+  exists = histname ? (stat (histname, &finfo) == 0) : 0;
+
+  tempname = (overwrite && exists && S_ISREG (finfo.st_mode)) ? history_tempfile (histname) : 0;
+  output = tempname ? tempname : histname;
+
+  file = output ? open (output, mode, 0600) : -1;
+  rv = 0;
+
+  if (file == -1)
+    {
+      rv = errno;
+      FREE (histname);
+      FREE (tempname);
+      return (rv);
+    }
+
+#ifdef HISTORY_USE_MMAP
+  cursize = overwrite ? 0 : lseek (file, 0, SEEK_END);
+#endif
+
+  if (nelements > history_length)
+    nelements = history_length;
+
+  /* Build a buffer of all the lines to write, and write them in one syscall.
+     Suggested by Peter Ho (peter@robosts.oxford.ac.uk). */
+  {
+    HIST_ENTRY **the_history;	/* local */
+    register int j;
+    int buffer_size;
+    char *buffer;
+
+    the_history = history_list ();
+    /* Calculate the total number of bytes to write. */
+    for (buffer_size = 0, i = history_length - nelements; i < history_length; i++)
+#if 0
+      buffer_size += 2 + HISTENT_BYTES (the_history[i]);
+#else
+      {
+	if (history_write_timestamps && the_history[i]->timestamp && the_history[i]->timestamp[0])
+	  buffer_size += strlen (the_history[i]->timestamp) + 1;
+	buffer_size += strlen (the_history[i]->line) + 1;
+      }
+#endif
+
+    /* Allocate the buffer, and fill it. */
+#ifdef HISTORY_USE_MMAP
+    if (ftruncate (file, buffer_size+cursize) == -1)
+      goto mmap_error;
+    buffer = (char *)mmap (0, buffer_size, PROT_READ|PROT_WRITE, MAP_WFLAGS, file, cursize);
+    if ((void *)buffer == MAP_FAILED)
+      {
+mmap_error:
+	rv = errno;
+	close (file);
+	if (tempname)
+	  unlink (tempname);
+	FREE (histname);
+	FREE (tempname);
+	return rv;
+      }
+#else    
+    buffer = (char *)malloc (buffer_size);
+    if (buffer == 0)
+      {
+      	rv = errno;
+	close (file);
+	if (tempname)
+	  unlink (tempname);
+	FREE (histname);
+	FREE (tempname);
+	return rv;
+      }
+#endif
+
+    for (j = 0, i = history_length - nelements; i < history_length; i++)
+      {
+	if (history_write_timestamps && the_history[i]->timestamp && the_history[i]->timestamp[0])
+	  {
+	    strcpy (buffer + j, the_history[i]->timestamp);
+	    j += strlen (the_history[i]->timestamp);
+	    buffer[j++] = '\n';
+	  }
+	strcpy (buffer + j, the_history[i]->line);
+	j += strlen (the_history[i]->line);
+	buffer[j++] = '\n';
+      }
+
+#ifdef HISTORY_USE_MMAP
+    if (msync (buffer, buffer_size, MS_ASYNC) != 0 || munmap (buffer, buffer_size) != 0)
+      rv = errno;
+#else
+    if (write (file, buffer, buffer_size) < 0)
+      rv = errno;
+    xfree (buffer);
+#endif
+  }
+
+  history_lines_written_to_file = nelements;
+
+  if (close (file) < 0 && rv == 0)
+    rv = errno;
+
+  if (rv == 0 && histname && tempname)
+    rv = histfile_restore (tempname, histname);
+
+  if (rv != 0)
+    {
+      if (tempname)
+	unlink (tempname);
+      history_lines_written_to_file = 0;
+    }
+
+#if defined (HAVE_CHOWN)
+  /* Make sure the new filename is owned by the same user as the old.  If one
+     user is running this, it's a no-op.  If the shell is running after sudo
+     with a shared history file, we don't want to leave the history file
+     owned by root. */
+  if (rv == 0 && exists)
+    mode = chown (histname, finfo.st_uid, finfo.st_gid);
+#endif
+
+  FREE (histname);
+  FREE (tempname);
+
+  return (rv);
+}
+
+/* Append NELEMENT entries to FILENAME.  The entries appended are from
+   the end of the list minus NELEMENTs up to the end of the list. */
+int
+append_history (int nelements, const char *filename)
+{
+  return (history_do_write (filename, nelements, HISTORY_APPEND));
+}
+
+/* Overwrite FILENAME with the current history.  If FILENAME is NULL,
+   then write the history list to ~/.history.  Values returned
+   are as in read_history ().*/
+int
+write_history (const char *filename)
+{
+  return (history_do_write (filename, history_length, HISTORY_OVERWRITE));
+}