text: /* histfile.c - functions to manipulate the history file. */
  
  /* Copyright (C) 1989-2003 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 (__TANDEM)
  #  include <floss.h>
  #endif
  
  #if defined (HAVE_CONFIG_H)
  #  include <config.h>
  #endif
  
  #include <stdio.h>
  
  #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
  
  #if defined (__EMX__) || defined (__CYGWIN__)
  #  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 non-zero, we write timestamps to the history file in history_do_write() */
  int history_write_timestamps = 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)
  
  /* 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)
       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 (home == 0)
      {
        home = ".";
        home_len = 1;
      }
    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);
  }
  
  /* 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)
       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 (filename, from, to)
       const char *filename;
       int from, to;
  {
    register char *line_start, *line_end, *p;
    char *input, *buffer, *bufend, *last_ts;
    int file, current_line, chars_read;
    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
  
    buffer = last_ts = (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)
      {
        errno = overflow_errno;
        goto error_and_exit;
      }
  
  #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;
    current_line = 0;
  
    /* 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')
        {
  	if (line_end - 1 >= line_start && *(line_end - 1) == '\r')
  	  *(line_end - 1) = '\0';
  	else
  	  *line_end = '\0';
  
  	if (*line_start)
  	  {
  	    if (HIST_TIMESTAMP_START(line_start) == 0)
  	      {
  		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;
        }
  
    FREE (input);
  #ifndef HISTORY_USE_MMAP
    FREE (buffer);
  #else
    munmap (buffer, file_size);
  #endif
  
    return (0);
  }
  
  /* Truncate the history file FNAME, leaving only LINES trailing lines.
     If FNAME is NULL, then use ~/.history.  Returns 0 on success, errno
     on failure. */
  int
  history_truncate_file (fname, lines)
       const char *fname;
       int lines;
  {
    char *buffer, *filename, *bp, *bp1;		/* bp1 == bp+1 */
    int file, chars_read, rv;
    struct stat finfo;
    size_t file_size;
  
    buffer = (char *)NULL;
    filename = history_filename (fname);
    file = open (filename, O_RDONLY|O_BINARY, 0666);
    rv = 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;
      }
  
    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)
      {
        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;
      }
  
    /* 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 && ((file = open (filename, O_WRONLY|O_TRUNC|O_BINARY, 0600)) != -1))
      {
        write (file, bp, chars_read - (bp - buffer));
  
  #if defined (__BEOS__)
        /* BeOS ignores O_TRUNC. */
        ftruncate (file, chars_read - (bp - buffer));
  #endif
  
        close (file);
      }
  
   truncate_exit:
  
    FREE (buffer);
  
    free (filename);
    return rv;
  }
  
  /* 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)
       const char *filename;
       int nelements, overwrite;
  {
    register int i;
    char *output;
    int file, mode, rv;
  #ifdef HISTORY_USE_MMAP
    size_t cursize;
  
    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
    output = history_filename (filename);
    rv = 0;
  
    if ((file = open (output, mode, 0600)) == -1)
      {
        FREE (output);
        return (errno);
      }
  
  #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;
  	FREE (output);
  	close (file);
  	return rv;
        }
  #else    
      buffer = (char *)malloc (buffer_size);
      if (buffer == 0)
        {
        	rv = errno;
  	FREE (output);
  	close (file);
  	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, 0) != 0 || munmap (buffer, buffer_size) != 0)
        rv = errno;
  #else
      if (write (file, buffer, buffer_size) < 0)
        rv = errno;
      free (buffer);
  #endif
    }
  
    close (file);
  
    FREE (output);
  
    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 (nelements, filename)
       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 (filename)
       const char *filename;
  {
    return (history_do_write (filename, history_length, HISTORY_OVERWRITE));
  }
  