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/* histfile.c - functions to manipulate the history file. */

/* Copyright (C) 1989, 1992 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, 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.

   The GNU General Public License is often shipped with GNU software, and

   is generally kept in a file called COPYING or LICENSE.  If you do not

   have a copy of the license, write to the Free Software Foundation,

   59 Temple Place, Suite 330, Boston, MA 02111 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. */

#define READLINE_LIBRARY

#if defined (HAVE_CONFIG_H)

#  include <config.h>

#endif

#include <stdio.h>

#include <sys/types.h>

#ifndef _MINIX

#  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

#if defined (HAVE_STRING_H)

#  include <string.h>

#else

#  include <strings.h>

#endif /* !HAVE_STRING_H */

/* 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"

/* 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, *home;

  int home_len;

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

  if (return_val)

    return (return_val);

  home = get_env_value ("HOME");

  if (home == 0)

    {

      home = ".";

      home_len = 1;

    }

  else

    home_len = strlen (home);

  return_val = 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);

}

/* 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;

  int file, current_line, chars_read;

  struct stat finfo;

  size_t file_size;

  buffer = (char *)NULL;

  input = history_filename (filename);

  file = open (input, O_RDONLY|O_BINARY, 0666);

  if ((file < 0) || (fstat (file, &finfo) == -1))

    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)

    {

#if defined (EFBIG)

      errno = EFBIG;

#endif

      goto error_and_exit;

    }

  buffer = xmalloc (file_size + 1);

  chars_read = read (file, buffer, file_size);

  if (chars_read < 0)

    {

  error_and_exit:

      if (file >= 0)

        close (file);

      FREE (input);

      FREE (buffer);

      return (errno);

    }

  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. */

  line_start = line_end = current_line = 0;

  /* Skip lines until we are at FROM. */

  while (line_start < chars_read && current_line < from)

    {

      for (line_end = line_start; line_end < chars_read; 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 < chars_read; 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;

      }

  FREE (input);

  FREE (buffer);

  return (0);

}

/* Truncate the history file FNAME, leaving only LINES trailing lines.

   If FNAME is NULL, then use ~/.history. */

int

history_truncate_file (fname, lines)

     char *fname;

     int lines;

{

  register int i;

  int file, chars_read;

  char *buffer, *filename;

  struct stat finfo;

  size_t file_size;

  buffer = (char *)NULL;

  filename = history_filename (fname);

  file = open (filename, O_RDONLY|O_BINARY, 0666);

  if (file == -1 || fstat (file, &finfo) == -1)

    goto truncate_exit;

  /* Don't try to truncate non-regular files. */

  if (S_ISREG(finfo.st_mode) == 0)

    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)

      errno = EFBIG;

#endif

      goto truncate_exit;

    }

  buffer = xmalloc (file_size + 1);

  chars_read = read (file, buffer, file_size);

  close (file);

  if (chars_read <= 0)

    goto truncate_exit;

  /* Count backwards from the end of buffer until we have passed

     LINES lines. */

  for (i = chars_read - 1; lines && i; i--)

    {

      if (buffer[i] == '\n')

        lines--;

    }

  /* 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 ( ; i; i--)

    if (buffer[i] == '\n')

      {

        i++;

        break;

      }

  /* Write only if there are more lines in the file than we want to

     truncate to. */

  if (i && ((file = open (filename, O_WRONLY|O_TRUNC|O_BINARY, 0600)) != -1))

    {

      write (file, buffer + i, chars_read - i);

#if defined (__BEOS__)

      /* BeOS ignores O_TRUNC. */

      ftruncate (file, chars_read - i);

#endif

      close (file);

    }

 truncate_exit:

  FREE (buffer);

  free (filename);

  return 0;

}

/* Workhorse function for writing history.  Writes 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 (filename, nelements, overwrite)

     char *filename;

     int nelements, overwrite;

{

  register int i;

  char *output;

  int file, mode;

  mode = overwrite ? O_WRONLY|O_CREAT|O_TRUNC|O_BINARY : O_WRONLY|O_APPEND|O_BINARY;

  output = history_filename (filename);

  if ((file = open (output, mode, 0600)) == -1)

    {

      FREE (output);

      return (errno);

    }

  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++)

      buffer_size += 1 + strlen (the_history[i]->line);

    /* Allocate the buffer, and fill it. */

    buffer = xmalloc (buffer_size);

    for (j = 0, i = history_length - nelements; i < history_length; i++)

      {

        strcpy (buffer + j, the_history[i]->line);

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

        buffer[j++] = '\n';

      }

    write (file, buffer, buffer_size);

    free (buffer);

  }

  close (file);

  FREE (output);

  return (0);

}

/* 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 (nelements, filename)

     int nelements;

     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 (filename)

     char *filename;

{

  return (history_do_write (filename, history_length, HISTORY_OVERWRITE));

}