history.c

早期freebsd实现

/* History.c -- standalone history library */

/* Copyright (C) 1989, 1991 Free Software Foundation, Inc.

   This file contains the GNU History Library (the Library), a set of
   routines for managing the text of previously typed lines.

   The Library 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 2 of the License, or
   (at your option) any later version.

   The Library 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 this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */

/* 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. */

/* Remove these declarations when we have a complete libgnu.a. */
#if !defined (STATIC_MALLOC)
extern char *xmalloc (), *xrealloc ();
#else
static char *xmalloc (), *xrealloc ();
#endif

#include "sysdep.h"
#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#ifndef	NO_SYS_FILE
#include <sys/file.h>
#endif
#include <sys/stat.h>
#include <fcntl.h>

#include "history.h"

#ifndef savestring
#define savestring(x) (char *)strcpy (xmalloc (1 + strlen (x)), (x))
#endif

#ifndef whitespace
#define whitespace(c) (((c) == ' ') || ((c) == '\t'))
#endif

#ifndef digit
#define digit(c)  ((c) >= '0' && (c) <= '9')
#endif

#ifndef member
#define member(c, s) ((c) ? index ((s), (c)) : 0)
#endif

/* **************************************************************** */
/*								    */
/*			History Functions			    */
/*								    */
/* **************************************************************** */

/* An array of HIST_ENTRY.  This is where we store the history. */
static HIST_ENTRY **the_history = (HIST_ENTRY **)NULL;

/* Non-zero means that we have enforced a limit on the amount of
   history that we save. */
int history_stifled = 0;

/* If HISTORY_STIFLED is non-zero, then this is the maximum number of
   entries to remember. */
int max_input_history;

/* The current location of the interactive history pointer.  Just makes
   life easier for outside callers. */
static int history_offset = 0;

/* The number of strings currently stored in the input_history list. */
int history_length = 0;

/* The current number of slots allocated to the input_history. */
static int history_size = 0;

/* The number of slots to increase the_history by. */
#define DEFAULT_HISTORY_GROW_SIZE 50

/* The character that represents the start of a history expansion
   request.  This is usually `!'. */
char history_expansion_char = '!';

/* The character that invokes word substitution if found at the start of
   a line.  This is usually `^'. */
char history_subst_char = '^';

/* During tokenization, if this character is seen as the first character
   of a word, then it, and all subsequent characters upto a newline are
   ignored.  For a Bourne shell, this should be '#'.  Bash special cases
   the interactive comment character to not be a comment delimiter. */
char history_comment_char = '\0';

/* The list of characters which inhibit the expansion of text if found
   immediately following history_expansion_char. */
char *history_no_expand_chars = " \t\n\r=";

/* The logical `base' of the history array.  It defaults to 1. */
int history_base = 1;

/* Begin a session in which the history functions might be used.  This
   initializes interactive variables. */
void
using_history ()
{
  history_offset = history_length;
}

/* Return the number of bytes that the primary history entries are using.
   This just adds up the lengths of the_history->lines. */
int
history_total_bytes ()
{
  register int i, result;

  result = 0;

  for (i = 0; the_history && the_history[i]; i++)
    result += strlen (the_history[i]->line);

  return (result);
}

/* Place STRING at the end of the history list.  The data field
   is  set to NULL. */
void
add_history (string)
     char *string;
{
  HIST_ENTRY *temp;

  if (history_stifled && (history_length == max_input_history))
    {
      register int i;

      /* If the history is stifled, and history_length is zero,
	 and it equals max_input_history, we don't save items. */
      if (!history_length)
	return;

      /* If there is something in the slot, then remove it. */
      if (the_history[0])
	{
	  free (the_history[0]->line);
	  free (the_history[0]);
	}

      for (i = 0; i < history_length; i++)
	the_history[i] = the_history[i + 1];

      history_base++;

    }
  else
    {
      if (!history_size)
	{
	  the_history = (HIST_ENTRY **)
	    xmalloc ((history_size = DEFAULT_HISTORY_GROW_SIZE)
		     * sizeof (HIST_ENTRY *));
	  history_length = 1;

	}
      else
	{
	  if (history_length == (history_size - 1))
	    {
	      the_history = (HIST_ENTRY **)
		xrealloc (the_history,
			  ((history_size += DEFAULT_HISTORY_GROW_SIZE)
			   * sizeof (HIST_ENTRY *)));
	  }
	  history_length++;
	}
    }

  temp = (HIST_ENTRY *)xmalloc (sizeof (HIST_ENTRY));
  temp->line = savestring (string);
  temp->data = (char *)NULL;

  the_history[history_length] = (HIST_ENTRY *)NULL;
  the_history[history_length - 1] = temp;
}

/* Make the history entry at WHICH have LINE and DATA.  This returns
   the old entry so you can dispose of the data.  In the case of an
   invalid WHICH, a NULL pointer is returned. */
HIST_ENTRY *
replace_history_entry (which, line, data)
     int which;
     char *line;
     char *data;
{
  HIST_ENTRY *temp = (HIST_ENTRY *)xmalloc (sizeof (HIST_ENTRY));
  HIST_ENTRY *old_value;

  if (which >= history_length)
    return ((HIST_ENTRY *)NULL);

  old_value = the_history[which];

  temp->line = savestring (line);
  temp->data = data;
  the_history[which] = temp;

  return (old_value);
}

/* Returns the magic number which says what history element we are
   looking at now.  In this implementation, it returns history_offset. */
int
where_history ()
{
  return (history_offset);
}

/* Search the history for STRING, starting at history_offset.
   If DIRECTION < 0, then the search is through previous entries, else
   through subsequent.  If ANCHORED is non-zero, the string must
   appear at the beginning of a history line, otherwise, the string
   may appear anywhere in the line.  If the string is found, then
   current_history () is the history entry, and the value of this
   function is the offset in the line of that history entry that the
   string was found in.  Otherwise, nothing is changed, and a -1 is
   returned. */

#define ANCHORED_SEARCH 1
#define NON_ANCHORED_SEARCH 0

static int
history_search_internal (string, direction, anchored)
     char *string;
     int direction, anchored;
{
  register int i = history_offset;
  register int reverse = (direction < 0);
  register char *line;
  register int index;
  int string_len = strlen (string);

  /* Take care of trivial cases first. */

  if (!history_length || ((i == history_length) && !reverse))
    return (-1);

  if (reverse && (i == history_length))
    i--;

  while (1)
    {
      /* Search each line in the history list for STRING. */

      /* At limit for direction? */
      if ((reverse && i < 0) ||
	  (!reverse && i == history_length))
	return (-1);

      line = the_history[i]->line;
      index = strlen (line);

      /* If STRING is longer than line, no match. */
      if (string_len > index)
	goto next_line;

      /* Handle anchored searches first. */
      if (anchored == ANCHORED_SEARCH)
	{
	  if (strncmp (string, line, string_len) == 0)
	    {
	      history_offset = i;
	      return (0);
	    }

	  goto next_line;
	}

      /* Do substring search. */
      if (reverse)
	{
	  index -= string_len;

	  while (index >= 0)
	    {
	      if (strncmp (string, line + index, string_len) == 0)
		{
		  history_offset = i;
		  return (index);
		}
	      index--;
	    }
	}
      else
	{
	  register int limit = index - string_len + 1;
	  index = 0;

	  while (index < limit)
	    {
	      if (strncmp (string, line + index, string_len) == 0)
		{
		  history_offset = i;
		  return (index);
		}
	      index++;
	    }
	}
    next_line:
      if (reverse)
	i--;
      else
	i++;
    }
}

/* Do a non-anchored search for STRING through the history in DIRECTION. */
int
history_search (string, direction)
     char *string;
     int direction;
{
  return (history_search_internal (string, direction, NON_ANCHORED_SEARCH));
}

/* Do an anchored search for string through the history in DIRECTION. */
int
history_search_prefix (string, direction)
     char *string;
     int direction;
{
  return (history_search_internal (string, direction, ANCHORED_SEARCH));
}

/* Remove history element WHICH from the history.  The removed
   element is returned to you so you can free the line, data,
   and containing structure. */
HIST_ENTRY *
remove_history (which)
     int which;
{
  HIST_ENTRY *return_value;

  if (which >= history_length || !history_length)
    return_value = (HIST_ENTRY *)NULL;
  else
    {
      register int i;
      return_value = the_history[which];

      for (i = which; i < history_length; i++)
	the_history[i] = the_history[i + 1];

      history_length--;
    }

  return (return_value);
}

/* Stifle the history list, remembering only MAX number of lines. */
void
stifle_history (max)
     int max;
{
  if (max < 0)
    max = 0;
  if (history_length > max)
    {
      register int i, j;

      /* This loses because we cannot free the data. */
      for (i = 0; i < (history_length - max); i++)
	{
	  free (the_history[i]->line);
	  free (the_history[i]);
	}
      history_base = i;
      for (j = 0, i = history_length - max; j < max; i++, j++)
	the_history[j] = the_history[i];
      the_history[j] = (HIST_ENTRY *)NULL;
      history_length = j;
    }
  history_stifled = 1;
  max_input_history = max;
}

/* Stop stifling the history.  This returns the previous amount the history
 was stifled by.  The value is positive if the history was stifled, negative
 if it wasn't. */
int
unstifle_history ()
{
  int result = max_input_history;
  if (history_stifled)
    {
      result = - result;
      history_stifled = 0;
    }
  return (result);
}

/* 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 (filename)
     char *filename;
{
  char *return_val = filename ? savestring (filename) : (char *)NULL;

  if (!return_val)
    {
      char *home = (char *)getenv ("HOME");
      if (!home) home = ".";
      return_val = (char *)xmalloc (2 + strlen (home) + strlen (".history"));
      sprintf (return_val, "%s/.history", home);
    }
  return (return_val);
}

/* 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 (filename)
     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 (filename, from, to)
     char *filename;
     int from, to;
{
  register int line_start, line_end;
  char *input, *buffer = (char *)NULL;
  int file, current_line;
  struct stat finfo;
  extern int errno;

  input = history_filename (filename);
  file = open (input, O_RDONLY, 0666);

  if ((file < 0) ||
      (stat (input, &finfo) == -1))
    goto error_and_exit;

  buffer = (char *)xmalloc (finfo.st_size + 1);

  if (read (file, buffer, finfo.st_size) != finfo.st_size)
  error_and_exit:
    {
      if (file >= 0)
	close (file);

      if (buffer)
	free (buffer);

      return (errno);
    }

  close (file);

  /* Set TO to larger than end of file if negative. */
  if (to < 0)
    to = finfo.st_size;

  /* Start at beginning of file, work to end. */
  line_start = line_end = current_line = 0;

  /* Skip lines until we are at FROM. */
  while (line_start < finfo.st_size && current_line < from)
    {
      for (line_end = line_start; line_end < finfo.st_size; line_end++)
	if (buffer[line_end] == '\n')
	  {
	    current_line++;
	    line_start = line_end + 1;
	    if (current_line == from)
	      break;
	  }
    }

  /* If there are lines left to gobble, then gobble them now. */
  for (line_end = line_start; line_end < finfo.st_size; line_end++)
    if (buffer[line_end] == '\n')
      {
	buffer[line_end] = '\0';

	if (buffer[line_start])
	  add_history (buffer + line_start);

	current_line++;

	if (current_line >= to)
	  break;

	line_start = line_end + 1;
      }
  return (0);
}

/* Truncate the history file FNAME, leaving only LINES trailing lines.
   If FNAME is NULL, then use ~/.history. */
history_truncate_file (fname, lines)
     char *fname;
     register int lines;
{
  register int i;
  int file;
  char *buffer = (char *)NULL, *filename;
  struct stat finfo;

  filename = history_filename (fname);
  if (stat (filename, &finfo) == -1)
    goto truncate_exit;

  file = open (filename, O_RDONLY, 0666);

  if (file == -1)
    goto truncate_exit;

  buffer = (char *)xmalloc (finfo.st_size + 1);
  read (file, buffer, finfo.st_size);
  close (file);

  /* Count backwards from the end of buffer until we have passed
     LINES lines. */
  for (i = finfo.st_size; lines && i; i--)
    {
      if (buffer[i] == '\n')
	lines--;
    }

  /* If there are fewer lines in the file than we want to truncate to,
     then we are all done. */
  if (!i)
    goto truncate_exit;

  /* Otherwise, write from the start of this line until the end of the
     buffer. */
  for (--i; i; i--)
    if (buffer[i] == '\n')
      {
	i++;
	break;
      }

  file = open (filename, O_WRONLY | O_TRUNC | O_CREAT, 0666);
  if (file == -1)