/* vi:set ts=8 sts=4 sw=4:
 *
 * VIM - Vi IMproved	by Bram Moolenaar
 *
 * Do ":help uganda"  in Vim to read copying and usage conditions.
 * Do ":help credits" in Vim to see a list of people who contributed.
 * See README.txt for an overview of the Vim source code.
 */

/*
 * misc1.c: functions that didn't seem to fit elsewhere
 */

#include <string.h>

#include "vim.h"
#include "version_defs.h"
#include "misc1.h"
#include "charset.h"
#include "diff.h"
#include "edit.h"
#include "eval.h"
#include "ex_cmds.h"
#include "ex_docmd.h"
#include "ex_getln.h"
#include "fileio.h"
#include "fold.h"
#include "getchar.h"
#include "indent.h"
#include "indent_c.h"
#include "main.h"
#include "mark.h"
#include "mbyte.h"
#include "memline.h"
#include "memory.h"
#include "message.h"
#include "misc2.h"
#include "garray.h"
#include "move.h"
#include "option.h"
#include "os_unix.h"
#include "path.h"
#include "quickfix.h"
#include "regexp.h"
#include "screen.h"
#include "search.h"
#include "tag.h"
#include "term.h"
#include "ui.h"
#include "undo.h"
#include "window.h"
#include "os/os.h"
#include "os/shell.h"
static char_u *vim_version_dir(char_u *vimdir);
static char_u *remove_tail(char_u *p, char_u *pend, char_u *name);
static void init_users(void);

/* All user names (for ~user completion as done by shell). */
static garray_T ga_users;

/*
 * open_line: Add a new line below or above the current line.
 *
 * For VREPLACE mode, we only add a new line when we get to the end of the
 * file, otherwise we just start replacing the next line.
 *
 * Caller must take care of undo.  Since VREPLACE may affect any number of
 * lines however, it may call u_save_cursor() again when starting to change a
 * new line.
 * "flags": OPENLINE_DELSPACES	delete spaces after cursor
 *	    OPENLINE_DO_COM	format comments
 *	    OPENLINE_KEEPTRAIL	keep trailing spaces
 *	    OPENLINE_MARKFIX	adjust mark positions after the line break
 *	    OPENLINE_COM_LIST	format comments with list or 2nd line indent
 *
 * "second_line_indent": indent for after ^^D in Insert mode or if flag
 *			  OPENLINE_COM_LIST
 *
 * Return TRUE for success, FALSE for failure
 */
int 
open_line (
    int dir,                        /* FORWARD or BACKWARD */
    int flags,
    int second_line_indent
)
{
  char_u      *saved_line;              /* copy of the original line */
  char_u      *next_line = NULL;        /* copy of the next line */
  char_u      *p_extra = NULL;          /* what goes to next line */
  int less_cols = 0;                    /* less columns for mark in new line */
  int less_cols_off = 0;                /* columns to skip for mark adjust */
  pos_T old_cursor;                     /* old cursor position */
  int newcol = 0;                       /* new cursor column */
  int newindent = 0;                    /* auto-indent of the new line */
  int n;
  int trunc_line = FALSE;               /* truncate current line afterwards */
  int retval = FALSE;                   /* return value, default is FAIL */
  int extra_len = 0;                    /* length of p_extra string */
  int lead_len;                         /* length of comment leader */
  char_u      *lead_flags;      /* position in 'comments' for comment leader */
  char_u      *leader = NULL;           /* copy of comment leader */
  char_u      *allocated = NULL;        /* allocated memory */
#if defined(FEAT_SMARTINDENT) || defined(FEAT_VREPLACE) || defined(FEAT_LISP) \
  || defined(FEAT_CINDENT) || defined(FEAT_COMMENTS)
  char_u      *p;
#endif
  int saved_char = NUL;                 /* init for GCC */
  pos_T       *pos;
  int do_si = (!p_paste && curbuf->b_p_si
               && !curbuf->b_p_cin
               );
  int no_si = FALSE;                    /* reset did_si afterwards */
  int first_char = NUL;                 /* init for GCC */
  int vreplace_mode;
  int did_append;                       /* appended a new line */
  int saved_pi = curbuf->b_p_pi;           /* copy of preserveindent setting */

  /*
   * make a copy of the current line so we can mess with it
   */
  saved_line = vim_strsave(ml_get_curline());
  if (saved_line == NULL)           /* out of memory! */
    return FALSE;

  if (State & VREPLACE_FLAG) {
    /*
     * With VREPLACE we make a copy of the next line, which we will be
     * starting to replace.  First make the new line empty and let vim play
     * with the indenting and comment leader to its heart's content.  Then
     * we grab what it ended up putting on the new line, put back the
     * original line, and call ins_char() to put each new character onto
     * the line, replacing what was there before and pushing the right
     * stuff onto the replace stack.  -- webb.
     */
    if (curwin->w_cursor.lnum < orig_line_count)
      next_line = vim_strsave(ml_get(curwin->w_cursor.lnum + 1));
    else
      next_line = vim_strsave((char_u *)"");
    if (next_line == NULL)          /* out of memory! */
      goto theend;

    /*
     * In VREPLACE mode, a NL replaces the rest of the line, and starts
     * replacing the next line, so push all of the characters left on the
     * line onto the replace stack.  We'll push any other characters that
     * might be replaced at the start of the next line (due to autoindent
     * etc) a bit later.
     */
    replace_push(NUL);      /* Call twice because BS over NL expects it */
    replace_push(NUL);
    p = saved_line + curwin->w_cursor.col;
    while (*p != NUL) {
      if (has_mbyte)
        p += replace_push_mb(p);
      else
        replace_push(*p++);
    }
    saved_line[curwin->w_cursor.col] = NUL;
  }

  if ((State & INSERT)
      && !(State & VREPLACE_FLAG)
      ) {
    p_extra = saved_line + curwin->w_cursor.col;
    if (do_si) {                /* need first char after new line break */
      p = skipwhite(p_extra);
      first_char = *p;
    }
    extra_len = (int)STRLEN(p_extra);
    saved_char = *p_extra;
    *p_extra = NUL;
  }

  u_clearline();                /* cannot do "U" command when adding lines */
  did_si = FALSE;
  ai_col = 0;

  /*
   * If we just did an auto-indent, then we didn't type anything on
   * the prior line, and it should be truncated.  Do this even if 'ai' is not
   * set because automatically inserting a comment leader also sets did_ai.
   */
  if (dir == FORWARD && did_ai)
    trunc_line = TRUE;

  /*
   * If 'autoindent' and/or 'smartindent' is set, try to figure out what
   * indent to use for the new line.
   */
  if (curbuf->b_p_ai
      || do_si
      ) {
    /*
     * count white space on current line
     */
    newindent = get_indent_str(saved_line, (int)curbuf->b_p_ts);
    if (newindent == 0 && !(flags & OPENLINE_COM_LIST))
      newindent = second_line_indent;       /* for ^^D command in insert mode */

    /*
     * Do smart indenting.
     * In insert/replace mode (only when dir == FORWARD)
     * we may move some text to the next line. If it starts with '{'
     * don't add an indent. Fixes inserting a NL before '{' in line
     *	"if (condition) {"
     */
    if (!trunc_line && do_si && *saved_line != NUL
        && (p_extra == NULL || first_char != '{')) {
      char_u  *ptr;
      char_u last_char;

      old_cursor = curwin->w_cursor;
      ptr = saved_line;
      if (flags & OPENLINE_DO_COM)
        lead_len = get_leader_len(ptr, NULL, FALSE, TRUE);
      else
        lead_len = 0;
      if (dir == FORWARD) {
        /*
         * Skip preprocessor directives, unless they are
         * recognised as comments.
         */
        if (
          lead_len == 0 &&
          ptr[0] == '#') {
          while (ptr[0] == '#' && curwin->w_cursor.lnum > 1)
            ptr = ml_get(--curwin->w_cursor.lnum);
          newindent = get_indent();
        }
        if (flags & OPENLINE_DO_COM)
          lead_len = get_leader_len(ptr, NULL, FALSE, TRUE);
        else
          lead_len = 0;
        if (lead_len > 0) {
          /*
           * This case gets the following right:
           *	    \*
           *	     * A comment (read '\' as '/').
           *	     *\
           * #define IN_THE_WAY
           *	    This should line up here;
           */
          p = skipwhite(ptr);
          if (p[0] == '/' && p[1] == '*')
            p++;
          if (p[0] == '*') {
            for (p++; *p; p++) {
              if (p[0] == '/' && p[-1] == '*') {
                /*
                 * End of C comment, indent should line up
                 * with the line containing the start of
                 * the comment
                 */
                curwin->w_cursor.col = (colnr_T)(p - ptr);
                if ((pos = findmatch(NULL, NUL)) != NULL) {
                  curwin->w_cursor.lnum = pos->lnum;
                  newindent = get_indent();
                }
              }
            }
          }
        } else {      /* Not a comment line */
          /* Find last non-blank in line */
          p = ptr + STRLEN(ptr) - 1;
          while (p > ptr && vim_iswhite(*p))
            --p;
          last_char = *p;

          /*
           * find the character just before the '{' or ';'
           */
          if (last_char == '{' || last_char == ';') {
            if (p > ptr)
              --p;
            while (p > ptr && vim_iswhite(*p))
              --p;
          }
          /*
           * Try to catch lines that are split over multiple
           * lines.  eg:
           *	    if (condition &&
           *			condition) {
           *		Should line up here!
           *	    }
           */
          if (*p == ')') {
            curwin->w_cursor.col = (colnr_T)(p - ptr);
            if ((pos = findmatch(NULL, '(')) != NULL) {
              curwin->w_cursor.lnum = pos->lnum;
              newindent = get_indent();
              ptr = ml_get_curline();
            }
          }
          /*
           * If last character is '{' do indent, without
           * checking for "if" and the like.
           */
          if (last_char == '{') {
            did_si = TRUE;              /* do indent */
            no_si = TRUE;               /* don't delete it when '{' typed */
          }
          /*
           * Look for "if" and the like, use 'cinwords'.
           * Don't do this if the previous line ended in ';' or
           * '}'.
           */
          else if (last_char != ';' && last_char != '}'
                   && cin_is_cinword(ptr))
            did_si = TRUE;
        }
      } else { /* dir == BACKWARD */
                 /*
                  * Skip preprocessor directives, unless they are
                  * recognised as comments.
                  */
        if (
          lead_len == 0 &&
          ptr[0] == '#') {
          int was_backslashed = FALSE;

          while ((ptr[0] == '#' || was_backslashed) &&
                 curwin->w_cursor.lnum < curbuf->b_ml.ml_line_count) {
            if (*ptr && ptr[STRLEN(ptr) - 1] == '\\')
              was_backslashed = TRUE;
            else
              was_backslashed = FALSE;
            ptr = ml_get(++curwin->w_cursor.lnum);
          }
          if (was_backslashed)
            newindent = 0;                  /* Got to end of file */
          else
            newindent = get_indent();
        }
        p = skipwhite(ptr);
        if (*p == '}')              /* if line starts with '}': do indent */
          did_si = TRUE;
        else                        /* can delete indent when '{' typed */
          can_si_back = TRUE;
      }
      curwin->w_cursor = old_cursor;
    }
    if (do_si)
      can_si = TRUE;

    did_ai = TRUE;
  }

  /*
   * Find out if the current line starts with a comment leader.
   * This may then be inserted in front of the new line.
   */
  end_comment_pending = NUL;
  if (flags & OPENLINE_DO_COM)
    lead_len = get_leader_len(saved_line, &lead_flags, dir == BACKWARD, TRUE);
  else
    lead_len = 0;
  if (lead_len > 0) {
    char_u  *lead_repl = NULL;              /* replaces comment leader */
    int lead_repl_len = 0;                  /* length of *lead_repl */
    char_u lead_middle[COM_MAX_LEN];        /* middle-comment string */
    char_u lead_end[COM_MAX_LEN];           /* end-comment string */
    char_u  *comment_end = NULL;            /* where lead_end has been found */
    int extra_space = FALSE;                /* append extra space */
    int current_flag;
    int require_blank = FALSE;              /* requires blank after middle */
    char_u  *p2;

    /*
     * If the comment leader has the start, middle or end flag, it may not
     * be used or may be replaced with the middle leader.
     */
    for (p = lead_flags; *p && *p != ':'; ++p) {
      if (*p == COM_BLANK) {
        require_blank = TRUE;
        continue;
      }
      if (*p == COM_START || *p == COM_MIDDLE) {
        current_flag = *p;
        if (*p == COM_START) {
          /*
           * Doing "O" on a start of comment does not insert leader.
           */
          if (dir == BACKWARD) {
            lead_len = 0;
            break;
          }

          /* find start of middle part */
          (void)copy_option_part(&p, lead_middle, COM_MAX_LEN, ",");
          require_blank = FALSE;
        }

        /*
         * Isolate the strings of the middle and end leader.
         */
        while (*p && p[-1] != ':') {            /* find end of middle flags */
          if (*p == COM_BLANK)
            require_blank = TRUE;
          ++p;
        }
        (void)copy_option_part(&p, lead_middle, COM_MAX_LEN, ",");

        while (*p && p[-1] != ':') {            /* find end of end flags */
          /* Check whether we allow automatic ending of comments */
          if (*p == COM_AUTO_END)
            end_comment_pending = -1;             /* means we want to set it */
          ++p;
        }
        n = copy_option_part(&p, lead_end, COM_MAX_LEN, ",");

        if (end_comment_pending == -1)          /* we can set it now */
          end_comment_pending = lead_end[n - 1];

        /*
         * If the end of the comment is in the same line, don't use
         * the comment leader.
         */
        if (dir == FORWARD) {
          for (p = saved_line + lead_len; *p; ++p)
            if (STRNCMP(p, lead_end, n) == 0) {
              comment_end = p;
              lead_len = 0;
              break;
            }
        }

        /*
         * Doing "o" on a start of comment inserts the middle leader.
         */
        if (lead_len > 0) {
          if (current_flag == COM_START) {
            lead_repl = lead_middle;
            lead_repl_len = (int)STRLEN(lead_middle);
          }

          /*
           * If we have hit RETURN immediately after the start
           * comment leader, then put a space after the middle
           * comment leader on the next line.
           */
          if (!vim_iswhite(saved_line[lead_len - 1])
              && ((p_extra != NULL
                   && (int)curwin->w_cursor.col == lead_len)
                  || (p_extra == NULL
                      && saved_line[lead_len] == NUL)
                  || require_blank))
            extra_space = TRUE;
        }
        break;
      }
      if (*p == COM_END) {
        /*
         * Doing "o" on the end of a comment does not insert leader.
         * Remember where the end is, might want to use it to find the
         * start (for C-comments).
         */
        if (dir == FORWARD) {
          comment_end = skipwhite(saved_line);
          lead_len = 0;
          break;
        }

        /*
         * Doing "O" on the end of a comment inserts the middle leader.
         * Find the string for the middle leader, searching backwards.
         */
        while (p > curbuf->b_p_com && *p != ',')
          --p;
        for (lead_repl = p; lead_repl > curbuf->b_p_com
             && lead_repl[-1] != ':'; --lead_repl)
          ;
        lead_repl_len = (int)(p - lead_repl);

        /* We can probably always add an extra space when doing "O" on
         * the comment-end */
        extra_space = TRUE;

        /* Check whether we allow automatic ending of comments */
        for (p2 = p; *p2 && *p2 != ':'; p2++) {
          if (*p2 == COM_AUTO_END)
            end_comment_pending = -1;             /* means we want to set it */
        }
        if (end_comment_pending == -1) {
          /* Find last character in end-comment string */
          while (*p2 && *p2 != ',')
            p2++;
          end_comment_pending = p2[-1];
        }
        break;
      }
      if (*p == COM_FIRST) {
        /*
         * Comment leader for first line only:	Don't repeat leader
         * when using "O", blank out leader when using "o".
         */
        if (dir == BACKWARD)
          lead_len = 0;
        else {
          lead_repl = (char_u *)"";
          lead_repl_len = 0;
        }
        break;
      }
    }
    if (lead_len) {
      /* allocate buffer (may concatenate p_extra later) */
      leader = alloc(lead_len + lead_repl_len + extra_space + extra_len
          + (second_line_indent > 0 ? second_line_indent : 0) + 1);
      allocated = leader;                   /* remember to free it later */

      vim_strncpy(leader, saved_line, lead_len);

      /*
       * Replace leader with lead_repl, right or left adjusted
       */
      if (lead_repl != NULL) {
        int c = 0;
        int off = 0;

        for (p = lead_flags; *p != NUL && *p != ':'; ) {
          if (*p == COM_RIGHT || *p == COM_LEFT)
            c = *p++;
          else if (VIM_ISDIGIT(*p) || *p == '-')
            off = getdigits(&p);
          else
            ++p;
        }
        if (c == COM_RIGHT) {            /* right adjusted leader */
          /* find last non-white in the leader to line up with */
          for (p = leader + lead_len - 1; p > leader
               && vim_iswhite(*p); --p)
            ;
          ++p;

          /* Compute the length of the replaced characters in
           * screen characters, not bytes. */
          {
            int repl_size = vim_strnsize(lead_repl,
                lead_repl_len);
            int old_size = 0;
            char_u  *endp = p;
            int l;

            while (old_size < repl_size && p > leader) {
              mb_ptr_back(leader, p);
              old_size += ptr2cells(p);
            }
            l = lead_repl_len - (int)(endp - p);
            if (l != 0)
              memmove(endp + l, endp,
                  (size_t)((leader + lead_len) - endp));
            lead_len += l;
          }
          memmove(p, lead_repl, (size_t)lead_repl_len);
          if (p + lead_repl_len > leader + lead_len)
            p[lead_repl_len] = NUL;

          /* blank-out any other chars from the old leader. */
          while (--p >= leader) {
            int l = mb_head_off(leader, p);

            if (l > 1) {
              p -= l;
              if (ptr2cells(p) > 1) {
                p[1] = ' ';
                --l;
              }
              memmove(p + 1, p + l + 1,
                  (size_t)((leader + lead_len) - (p + l + 1)));
              lead_len -= l;
              *p = ' ';
            } else if (!vim_iswhite(*p))
              *p = ' ';
          }
        } else {                        /* left adjusted leader */
          p = skipwhite(leader);
          /* Compute the length of the replaced characters in
           * screen characters, not bytes. Move the part that is
           * not to be overwritten. */
          {
            int repl_size = vim_strnsize(lead_repl,
                lead_repl_len);
            int i;
            int l;

            for (i = 0; p[i] != NUL && i < lead_len; i += l) {
              l = (*mb_ptr2len)(p + i);
              if (vim_strnsize(p, i + l) > repl_size)
                break;
            }
            if (i != lead_repl_len) {
              memmove(p + lead_repl_len, p + i,
                  (size_t)(lead_len - i - (p - leader)));
              lead_len += lead_repl_len - i;
            }
          }
          memmove(p, lead_repl, (size_t)lead_repl_len);

          /* Replace any remaining non-white chars in the old
           * leader by spaces.  Keep Tabs, the indent must
           * remain the same. */
          for (p += lead_repl_len; p < leader + lead_len; ++p)
            if (!vim_iswhite(*p)) {
              /* Don't put a space before a TAB. */
              if (p + 1 < leader + lead_len && p[1] == TAB) {
                --lead_len;
                memmove(p, p + 1,
                    (leader + lead_len) - p);
              } else {
                int l = (*mb_ptr2len)(p);

                if (l > 1) {
                  if (ptr2cells(p) > 1) {
                    /* Replace a double-wide char with
                     * two spaces */
                    --l;
                    *p++ = ' ';
                  }
                  memmove(p + 1, p + l,
                      (leader + lead_len) - p);
                  lead_len -= l - 1;
                }
                *p = ' ';
              }
            }
          *p = NUL;
        }

        /* Recompute the indent, it may have changed. */
        if (curbuf->b_p_ai
            || do_si
            )
          newindent = get_indent_str(leader, (int)curbuf->b_p_ts);

        /* Add the indent offset */
        if (newindent + off < 0) {
          off = -newindent;
          newindent = 0;
        } else
          newindent += off;

        /* Correct trailing spaces for the shift, so that
         * alignment remains equal. */
        while (off > 0 && lead_len > 0
               && leader[lead_len - 1] == ' ') {
          /* Don't do it when there is a tab before the space */
          if (vim_strchr(skipwhite(leader), '\t') != NULL)
            break;
          --lead_len;
          --off;
        }

        /* If the leader ends in white space, don't add an
         * extra space */
        if (lead_len > 0 && vim_iswhite(leader[lead_len - 1]))
          extra_space = FALSE;
        leader[lead_len] = NUL;
      }

      if (extra_space) {
        leader[lead_len++] = ' ';
        leader[lead_len] = NUL;
      }

      newcol = lead_len;

      /*
       * if a new indent will be set below, remove the indent that
       * is in the comment leader
       */
      if (newindent
          || did_si
          ) {
        while (lead_len && vim_iswhite(*leader)) {
          --lead_len;
          --newcol;
          ++leader;
        }
      }

      did_si = can_si = FALSE;
    } else if (comment_end != NULL) {
      /*
       * We have finished a comment, so we don't use the leader.
       * If this was a C-comment and 'ai' or 'si' is set do a normal
       * indent to align with the line containing the start of the
       * comment.
       */
      if (comment_end[0] == '*' && comment_end[1] == '/' &&
          (curbuf->b_p_ai
           || do_si
          )) {
        old_cursor = curwin->w_cursor;
        curwin->w_cursor.col = (colnr_T)(comment_end - saved_line);
        if ((pos = findmatch(NULL, NUL)) != NULL) {
          curwin->w_cursor.lnum = pos->lnum;
          newindent = get_indent();
        }
        curwin->w_cursor = old_cursor;
      }
    }
  }

  /* (State == INSERT || State == REPLACE), only when dir == FORWARD */
  if (p_extra != NULL) {
    *p_extra = saved_char;              /* restore char that NUL replaced */

    /*
     * When 'ai' set or "flags" has OPENLINE_DELSPACES, skip to the first
     * non-blank.
     *
     * When in REPLACE mode, put the deleted blanks on the replace stack,
     * preceded by a NUL, so they can be put back when a BS is entered.
     */
    if (REPLACE_NORMAL(State))
      replace_push(NUL);            /* end of extra blanks */
    if (curbuf->b_p_ai || (flags & OPENLINE_DELSPACES)) {
      while ((*p_extra == ' ' || *p_extra == '\t')
             && (!enc_utf8
                 || !utf_iscomposing(utf_ptr2char(p_extra + 1)))
             ) {
        if (REPLACE_NORMAL(State))
          replace_push(*p_extra);
        ++p_extra;
        ++less_cols_off;
      }
    }
    if (*p_extra != NUL)
      did_ai = FALSE;               /* append some text, don't truncate now */

    /* columns for marks adjusted for removed columns */
    less_cols = (int)(p_extra - saved_line);
  }

  if (p_extra == NULL)
    p_extra = (char_u *)"";                 /* append empty line */

  /* concatenate leader and p_extra, if there is a leader */
  if (lead_len) {
    if (flags & OPENLINE_COM_LIST && second_line_indent > 0) {
      int i;
      int padding = second_line_indent
                    - (newindent + (int)STRLEN(leader));

      /* Here whitespace is inserted after the comment char.
       * Below, set_indent(newindent, SIN_INSERT) will insert the
       * whitespace needed before the comment char. */
      for (i = 0; i < padding; i++) {
        STRCAT(leader, " ");
        less_cols--;
        newcol++;
      }
    }
    STRCAT(leader, p_extra);
    p_extra = leader;
    did_ai = TRUE;          /* So truncating blanks works with comments */
    less_cols -= lead_len;
  } else
    end_comment_pending = NUL;      /* turns out there was no leader */

  old_cursor = curwin->w_cursor;
  if (dir == BACKWARD)
    --curwin->w_cursor.lnum;
  if (!(State & VREPLACE_FLAG) || old_cursor.lnum >= orig_line_count) {
    if (ml_append(curwin->w_cursor.lnum, p_extra, (colnr_T)0, FALSE)
        == FAIL)
      goto theend;
    /* Postpone calling changed_lines(), because it would mess up folding
     * with markers. */
    mark_adjust(curwin->w_cursor.lnum + 1, (linenr_T)MAXLNUM, 1L, 0L);
    did_append = TRUE;
  } else {
    /*
     * In VREPLACE mode we are starting to replace the next line.
     */
    curwin->w_cursor.lnum++;
    if (curwin->w_cursor.lnum >= Insstart.lnum + vr_lines_changed) {
      /* In case we NL to a new line, BS to the previous one, and NL
       * again, we don't want to save the new line for undo twice.
       */
      (void)u_save_cursor();                        /* errors are ignored! */
      vr_lines_changed++;
    }
    ml_replace(curwin->w_cursor.lnum, p_extra, TRUE);
    changed_bytes(curwin->w_cursor.lnum, 0);
    curwin->w_cursor.lnum--;
    did_append = FALSE;
  }

  if (newindent
      || did_si
      ) {
    ++curwin->w_cursor.lnum;
    if (did_si) {
      int sw = (int)get_sw_value(curbuf);

      if (p_sr)
        newindent -= newindent % sw;
      newindent += sw;
    }
    /* Copy the indent */
    if (curbuf->b_p_ci) {
      (void)copy_indent(newindent, saved_line);

      /*
       * Set the 'preserveindent' option so that any further screwing
       * with the line doesn't entirely destroy our efforts to preserve
       * it.  It gets restored at the function end.
       */
      curbuf->b_p_pi = TRUE;
    } else
      (void)set_indent(newindent, SIN_INSERT);
    less_cols -= curwin->w_cursor.col;

    ai_col = curwin->w_cursor.col;

    /*
     * In REPLACE mode, for each character in the new indent, there must
     * be a NUL on the replace stack, for when it is deleted with BS
     */
    if (REPLACE_NORMAL(State))
      for (n = 0; n < (int)curwin->w_cursor.col; ++n)
        replace_push(NUL);
    newcol += curwin->w_cursor.col;
    if (no_si)
      did_si = FALSE;
  }

  /*
   * In REPLACE mode, for each character in the extra leader, there must be
   * a NUL on the replace stack, for when it is deleted with BS.
   */
  if (REPLACE_NORMAL(State))
    while (lead_len-- > 0)
      replace_push(NUL);

  curwin->w_cursor = old_cursor;

  if (dir == FORWARD) {
    if (trunc_line || (State & INSERT)) {
      /* truncate current line at cursor */
      saved_line[curwin->w_cursor.col] = NUL;
      /* Remove trailing white space, unless OPENLINE_KEEPTRAIL used. */
      if (trunc_line && !(flags & OPENLINE_KEEPTRAIL))
        truncate_spaces(saved_line);
      ml_replace(curwin->w_cursor.lnum, saved_line, FALSE);
      saved_line = NULL;
      if (did_append) {
        changed_lines(curwin->w_cursor.lnum, curwin->w_cursor.col,
            curwin->w_cursor.lnum + 1, 1L);
        did_append = FALSE;

        /* Move marks after the line break to the new line. */
        if (flags & OPENLINE_MARKFIX)
          mark_col_adjust(curwin->w_cursor.lnum,
              curwin->w_cursor.col + less_cols_off,
              1L, (long)-less_cols);
      } else
        changed_bytes(curwin->w_cursor.lnum, curwin->w_cursor.col);
    }

    /*
     * Put the cursor on the new line.  Careful: the scrollup() above may
     * have moved w_cursor, we must use old_cursor.
     */
    curwin->w_cursor.lnum = old_cursor.lnum + 1;
  }
  if (did_append)
    changed_lines(curwin->w_cursor.lnum, 0, curwin->w_cursor.lnum, 1L);

  curwin->w_cursor.col = newcol;
  curwin->w_cursor.coladd = 0;

  /*
   * In VREPLACE mode, we are handling the replace stack ourselves, so stop
   * fixthisline() from doing it (via change_indent()) by telling it we're in
   * normal INSERT mode.
   */
  if (State & VREPLACE_FLAG) {
    vreplace_mode = State;      /* So we know to put things right later */
    State = INSERT;
  } else
    vreplace_mode = 0;
  /*
   * May do lisp indenting.
   */
  if (!p_paste
      && leader == NULL
      && curbuf->b_p_lisp
      && curbuf->b_p_ai) {
    fixthisline(get_lisp_indent);
    p = ml_get_curline();
    ai_col = (colnr_T)(skipwhite(p) - p);
  }
  /*
   * May do indenting after opening a new line.
   */
  if (!p_paste
      && (curbuf->b_p_cin
          || *curbuf->b_p_inde != NUL
          )
      && in_cinkeys(dir == FORWARD
          ? KEY_OPEN_FORW
          : KEY_OPEN_BACK, ' ', linewhite(curwin->w_cursor.lnum))) {
    do_c_expr_indent();
    p = ml_get_curline();
    ai_col = (colnr_T)(skipwhite(p) - p);
  }
  if (vreplace_mode != 0)
    State = vreplace_mode;

  /*
   * Finally, VREPLACE gets the stuff on the new line, then puts back the
   * original line, and inserts the new stuff char by char, pushing old stuff
   * onto the replace stack (via ins_char()).
   */
  if (State & VREPLACE_FLAG) {
    /* Put new line in p_extra */
    p_extra = vim_strsave(ml_get_curline());
    if (p_extra == NULL)
      goto theend;

    /* Put back original line */
    ml_replace(curwin->w_cursor.lnum, next_line, FALSE);

    /* Insert new stuff into line again */
    curwin->w_cursor.col = 0;
    curwin->w_cursor.coladd = 0;
    ins_bytes(p_extra);         /* will call changed_bytes() */
    vim_free(p_extra);
    next_line = NULL;
  }

  retval = TRUE;                /* success! */
theend:
  curbuf->b_p_pi = saved_pi;
  vim_free(saved_line);
  vim_free(next_line);
  vim_free(allocated);
  return retval;
}

/*
 * get_leader_len() returns the length in bytes of the prefix of the given
 * string which introduces a comment.  If this string is not a comment then
 * 0 is returned.
 * When "flags" is not NULL, it is set to point to the flags of the recognized
 * comment leader.
 * "backward" must be true for the "O" command.
 * If "include_space" is set, include trailing whitespace while calculating the
 * length.
 */
int get_leader_len(char_u *line, char_u **flags, int backward, int include_space)
{
  int i, j;
  int result;
  int got_com = FALSE;
  int found_one;
  char_u part_buf[COM_MAX_LEN];         /* buffer for one option part */
  char_u      *string;                  /* pointer to comment string */
  char_u      *list;
  int middle_match_len = 0;
  char_u      *prev_list;
  char_u      *saved_flags = NULL;

  result = i = 0;
  while (vim_iswhite(line[i]))      /* leading white space is ignored */
    ++i;

  /*
   * Repeat to match several nested comment strings.
   */
  while (line[i] != NUL) {
    /*
     * scan through the 'comments' option for a match
     */
    found_one = FALSE;
    for (list = curbuf->b_p_com; *list; ) {
      /* Get one option part into part_buf[].  Advance "list" to next
       * one.  Put "string" at start of string.  */
      if (!got_com && flags != NULL)
        *flags = list;              /* remember where flags started */
      prev_list = list;
      (void)copy_option_part(&list, part_buf, COM_MAX_LEN, ",");
      string = vim_strchr(part_buf, ':');
      if (string == NULL)           /* missing ':', ignore this part */
        continue;
      *string++ = NUL;              /* isolate flags from string */

      /* If we found a middle match previously, use that match when this
       * is not a middle or end. */
      if (middle_match_len != 0
          && vim_strchr(part_buf, COM_MIDDLE) == NULL
          && vim_strchr(part_buf, COM_END) == NULL)
        break;

      /* When we already found a nested comment, only accept further
       * nested comments. */
      if (got_com && vim_strchr(part_buf, COM_NEST) == NULL)
        continue;

      /* When 'O' flag present and using "O" command skip this one. */
      if (backward && vim_strchr(part_buf, COM_NOBACK) != NULL)
        continue;

      /* Line contents and string must match.
       * When string starts with white space, must have some white space
       * (but the amount does not need to match, there might be a mix of
       * TABs and spaces). */
      if (vim_iswhite(string[0])) {
        if (i == 0 || !vim_iswhite(line[i - 1]))
          continue;            /* missing white space */
        while (vim_iswhite(string[0]))
          ++string;
      }
      for (j = 0; string[j] != NUL && string[j] == line[i + j]; ++j)
        ;
      if (string[j] != NUL)
        continue;          /* string doesn't match */

      /* When 'b' flag used, there must be white space or an
       * end-of-line after the string in the line. */
      if (vim_strchr(part_buf, COM_BLANK) != NULL
          && !vim_iswhite(line[i + j]) && line[i + j] != NUL)
        continue;

      /* We have found a match, stop searching unless this is a middle
       * comment. The middle comment can be a substring of the end
       * comment in which case it's better to return the length of the
       * end comment and its flags.  Thus we keep searching with middle
       * and end matches and use an end match if it matches better. */
      if (vim_strchr(part_buf, COM_MIDDLE) != NULL) {
        if (middle_match_len == 0) {
          middle_match_len = j;
          saved_flags = prev_list;
        }
        continue;
      }
      if (middle_match_len != 0 && j > middle_match_len)
        /* Use this match instead of the middle match, since it's a
         * longer thus better match. */
        middle_match_len = 0;

      if (middle_match_len == 0)
        i += j;
      found_one = TRUE;
      break;
    }

    if (middle_match_len != 0) {
      /* Use the previously found middle match after failing to find a
       * match with an end. */
      if (!got_com && flags != NULL)
        *flags = saved_flags;
      i += middle_match_len;
      found_one = TRUE;
    }

    /* No match found, stop scanning. */
    if (!found_one)
      break;

    result = i;

    /* Include any trailing white space. */
    while (vim_iswhite(line[i]))
      ++i;

    if (include_space)
      result = i;

    /* If this comment doesn't nest, stop here. */
    got_com = TRUE;
    if (vim_strchr(part_buf, COM_NEST) == NULL)
      break;
  }
  return result;
}

/*
 * Return the offset at which the last comment in line starts. If there is no
 * comment in the whole line, -1 is returned.
 *
 * When "flags" is not null, it is set to point to the flags describing the
 * recognized comment leader.
 */
int get_last_leader_offset(char_u *line, char_u **flags)
{
  int result = -1;
  int i, j;
  int lower_check_bound = 0;
  char_u      *string;
  char_u      *com_leader;
  char_u      *com_flags;
  char_u      *list;
  int found_one;
  char_u part_buf[COM_MAX_LEN];         /* buffer for one option part */

  /*
   * Repeat to match several nested comment strings.
   */
  i = (int)STRLEN(line);
  while (--i >= lower_check_bound) {
    /*
     * scan through the 'comments' option for a match
     */
    found_one = FALSE;
    for (list = curbuf->b_p_com; *list; ) {
      char_u *flags_save = list;

      /*
       * Get one option part into part_buf[].  Advance list to next one.
       * put string at start of string.
       */
      (void)copy_option_part(&list, part_buf, COM_MAX_LEN, ",");
      string = vim_strchr(part_buf, ':');
      if (string == NULL) {     /* If everything is fine, this cannot actually
                                 * happen. */
        continue;
      }
      *string++ = NUL;          /* Isolate flags from string. */
      com_leader = string;

      /*
       * Line contents and string must match.
       * When string starts with white space, must have some white space
       * (but the amount does not need to match, there might be a mix of
       * TABs and spaces).
       */
      if (vim_iswhite(string[0])) {
        if (i == 0 || !vim_iswhite(line[i - 1]))
          continue;
        while (vim_iswhite(string[0]))
          ++string;
      }
      for (j = 0; string[j] != NUL && string[j] == line[i + j]; ++j)
        /* do nothing */;
      if (string[j] != NUL)
        continue;

      /*
       * When 'b' flag used, there must be white space or an
       * end-of-line after the string in the line.
       */
      if (vim_strchr(part_buf, COM_BLANK) != NULL
          && !vim_iswhite(line[i + j]) && line[i + j] != NUL) {
        continue;
      }

      /*
       * We have found a match, stop searching.
       */
      found_one = TRUE;

      if (flags)
        *flags = flags_save;
      com_flags = flags_save;

      break;
    }

    if (found_one) {
      char_u part_buf2[COM_MAX_LEN];            /* buffer for one option part */
      int len1, len2, off;

      result = i;
      /*
       * If this comment nests, continue searching.
       */
      if (vim_strchr(part_buf, COM_NEST) != NULL)
        continue;

      lower_check_bound = i;

      /* Let's verify whether the comment leader found is a substring
       * of other comment leaders. If it is, let's adjust the
       * lower_check_bound so that we make sure that we have determined
       * the comment leader correctly.
       */

      while (vim_iswhite(*com_leader))
        ++com_leader;
      len1 = (int)STRLEN(com_leader);

      for (list = curbuf->b_p_com; *list; ) {
        char_u *flags_save = list;

        (void)copy_option_part(&list, part_buf2, COM_MAX_LEN, ",");
        if (flags_save == com_flags)
          continue;
        string = vim_strchr(part_buf2, ':');
        ++string;
        while (vim_iswhite(*string))
          ++string;
        len2 = (int)STRLEN(string);
        if (len2 == 0)
          continue;

        /* Now we have to verify whether string ends with a substring
         * beginning the com_leader. */
        for (off = (len2 > i ? i : len2); off > 0 && off + len1 > len2; ) {
          --off;
          if (!STRNCMP(string + off, com_leader, len2 - off)) {
            if (i - off < lower_check_bound)
              lower_check_bound = i - off;
          }
        }
      }
    }
  }
  return result;
}

/*
 * Return the number of window lines occupied by buffer line "lnum".
 */
int plines(linenr_T lnum)
{
  return plines_win(curwin, lnum, TRUE);
}

int 
plines_win (
    win_T *wp,
    linenr_T lnum,
    int winheight                  /* when TRUE limit to window height */
)
{
  /* Check for filler lines above this buffer line.  When folded the result
   * is one line anyway. */
  return plines_win_nofill(wp, lnum, winheight) + diff_check_fill(wp, lnum);
}

int plines_nofill(linenr_T lnum)
{
  return plines_win_nofill(curwin, lnum, TRUE);
}

int 
plines_win_nofill (
    win_T *wp,
    linenr_T lnum,
    int winheight                  /* when TRUE limit to window height */
)
{
  int lines;

  if (!wp->w_p_wrap)
    return 1;

  if (wp->w_width == 0)
    return 1;

  /* A folded lines is handled just like an empty line. */
  /* NOTE: Caller must handle lines that are MAYBE folded. */
  if (lineFolded(wp, lnum) == TRUE)
    return 1;

  lines = plines_win_nofold(wp, lnum);
  if (winheight > 0 && lines > wp->w_height)
    return (int)wp->w_height;
  return lines;
}

/*
 * Return number of window lines physical line "lnum" will occupy in window
 * "wp".  Does not care about folding, 'wrap' or 'diff'.
 */
int plines_win_nofold(win_T *wp, linenr_T lnum)
{
  char_u      *s;
  long col;
  int width;

  s = ml_get_buf(wp->w_buffer, lnum, FALSE);
  if (*s == NUL)                /* empty line */
    return 1;
  col = win_linetabsize(wp, s, (colnr_T)MAXCOL);

  /*
   * If list mode is on, then the '$' at the end of the line may take up one
   * extra column.
   */
  if (wp->w_p_list && lcs_eol != NUL)
    col += 1;

  /*
   * Add column offset for 'number', 'relativenumber' and 'foldcolumn'.
   */
  width = W_WIDTH(wp) - win_col_off(wp);
  if (width <= 0)
    return 32000;
  if (col <= width)
    return 1;
  col -= width;
  width += win_col_off2(wp);
  return (col + (width - 1)) / width + 1;
}

/*
 * Like plines_win(), but only reports the number of physical screen lines
 * used from the start of the line to the given column number.
 */
int plines_win_col(win_T *wp, linenr_T lnum, long column)
{
  long col;
  char_u      *s;
  int lines = 0;
  int width;

  /* Check for filler lines above this buffer line.  When folded the result
   * is one line anyway. */
  lines = diff_check_fill(wp, lnum);

  if (!wp->w_p_wrap)
    return lines + 1;

  if (wp->w_width == 0)
    return lines + 1;

  s = ml_get_buf(wp->w_buffer, lnum, FALSE);

  col = 0;
  while (*s != NUL && --column >= 0) {
    col += win_lbr_chartabsize(wp, s, (colnr_T)col, NULL);
    mb_ptr_adv(s);
  }

  /*
   * If *s is a TAB, and the TAB is not displayed as ^I, and we're not in
   * INSERT mode, then col must be adjusted so that it represents the last
   * screen position of the TAB.  This only fixes an error when the TAB wraps
   * from one screen line to the next (when 'columns' is not a multiple of
   * 'ts') -- webb.
   */
  if (*s == TAB && (State & NORMAL) && (!wp->w_p_list || lcs_tab1))
    col += win_lbr_chartabsize(wp, s, (colnr_T)col, NULL) - 1;

  /*
   * Add column offset for 'number', 'relativenumber', 'foldcolumn', etc.
   */
  width = W_WIDTH(wp) - win_col_off(wp);
  if (width <= 0)
    return 9999;

  lines += 1;
  if (col > width)
    lines += (col - width) / (width + win_col_off2(wp)) + 1;
  return lines;
}

int plines_m_win(win_T *wp, linenr_T first, linenr_T last)
{
  int count = 0;

  while (first <= last) {
    int x;

    /* Check if there are any really folded lines, but also included lines
     * that are maybe folded. */
    x = foldedCount(wp, first, NULL);
    if (x > 0) {
      ++count;              /* count 1 for "+-- folded" line */
      first += x;
    } else {
      if (first == wp->w_topline)
        count += plines_win_nofill(wp, first, TRUE) + wp->w_topfill;
      else
        count += plines_win(wp, first, TRUE);
      ++first;
    }
  }
  return count;
}

/*
 * Insert string "p" at the cursor position.  Stops at a NUL byte.
 * Handles Replace mode and multi-byte characters.
 */
void ins_bytes(char_u *p)
{
  ins_bytes_len(p, (int)STRLEN(p));
}

#if defined(FEAT_VREPLACE) || defined(FEAT_INS_EXPAND) \
  || defined(FEAT_COMMENTS) || defined(FEAT_MBYTE) || defined(PROTO)
/*
 * Insert string "p" with length "len" at the cursor position.
 * Handles Replace mode and multi-byte characters.
 */
void ins_bytes_len(char_u *p, int len)
{
  int i;
  int n;

  if (has_mbyte)
    for (i = 0; i < len; i += n) {
      if (enc_utf8)
        /* avoid reading past p[len] */
        n = utfc_ptr2len_len(p + i, len - i);
      else
        n = (*mb_ptr2len)(p + i);
      ins_char_bytes(p + i, n);
    }
  else
    for (i = 0; i < len; ++i)
      ins_char(p[i]);
}
#endif

/*
 * Insert or replace a single character at the cursor position.
 * When in REPLACE or VREPLACE mode, replace any existing character.
 * Caller must have prepared for undo.
 * For multi-byte characters we get the whole character, the caller must
 * convert bytes to a character.
 */
void ins_char(int c)
{
  char_u buf[MB_MAXBYTES + 1];
  int n;

  n = (*mb_char2bytes)(c, buf);

  /* When "c" is 0x100, 0x200, etc. we don't want to insert a NUL byte.
   * Happens for CTRL-Vu9900. */
  if (buf[0] == 0)
    buf[0] = '\n';

  ins_char_bytes(buf, n);
}

void ins_char_bytes(char_u *buf, int charlen)
{
  int c = buf[0];
  int newlen;                   /* nr of bytes inserted */
  int oldlen;                   /* nr of bytes deleted (0 when not replacing) */
  char_u      *p;
  char_u      *newp;
  char_u      *oldp;
  int linelen;                  /* length of old line including NUL */
  colnr_T col;
  linenr_T lnum = curwin->w_cursor.lnum;
  int i;

  /* Break tabs if needed. */
  if (virtual_active() && curwin->w_cursor.coladd > 0)
    coladvance_force(getviscol());

  col = curwin->w_cursor.col;
  oldp = ml_get(lnum);
  linelen = (int)STRLEN(oldp) + 1;

  /* The lengths default to the values for when not replacing. */
  oldlen = 0;
  newlen = charlen;

  if (State & REPLACE_FLAG) {
    if (State & VREPLACE_FLAG) {
      colnr_T new_vcol = 0;             /* init for GCC */
      colnr_T vcol;
      int old_list;

      /*
       * Disable 'list' temporarily, unless 'cpo' contains the 'L' flag.
       * Returns the old value of list, so when finished,
       * curwin->w_p_list should be set back to this.
       */
      old_list = curwin->w_p_list;
      if (old_list && vim_strchr(p_cpo, CPO_LISTWM) == NULL)
        curwin->w_p_list = FALSE;

      /*
       * In virtual replace mode each character may replace one or more
       * characters (zero if it's a TAB).  Count the number of bytes to
       * be deleted to make room for the new character, counting screen
       * cells.  May result in adding spaces to fill a gap.
       */
      getvcol(curwin, &curwin->w_cursor, NULL, &vcol, NULL);
      new_vcol = vcol + chartabsize(buf, vcol);
      while (oldp[col + oldlen] != NUL && vcol < new_vcol) {
        vcol += chartabsize(oldp + col + oldlen, vcol);
        /* Don't need to remove a TAB that takes us to the right
         * position. */
        if (vcol > new_vcol && oldp[col + oldlen] == TAB)
          break;
        oldlen += (*mb_ptr2len)(oldp + col + oldlen);
        /* Deleted a bit too much, insert spaces. */
        if (vcol > new_vcol)
          newlen += vcol - new_vcol;
      }
      curwin->w_p_list = old_list;
    } else if (oldp[col] != NUL)  {
      /* normal replace */
      oldlen = (*mb_ptr2len)(oldp + col);
    }


    /* Push the replaced bytes onto the replace stack, so that they can be
     * put back when BS is used.  The bytes of a multi-byte character are
     * done the other way around, so that the first byte is popped off
     * first (it tells the byte length of the character). */
    replace_push(NUL);
    for (i = 0; i < oldlen; ++i) {
      if (has_mbyte)
        i += replace_push_mb(oldp + col + i) - 1;
      else
        replace_push(oldp[col + i]);
    }
  }

  newp = (char_u *) xmalloc((size_t)(linelen + newlen - oldlen));

  /* Copy bytes before the cursor. */
  if (col > 0)
    memmove(newp, oldp, (size_t)col);

  /* Copy bytes after the changed character(s). */
  p = newp + col;
  memmove(p + newlen, oldp + col + oldlen,
      (size_t)(linelen - col - oldlen));

  /* Insert or overwrite the new character. */
  memmove(p, buf, charlen);
  i = charlen;

  /* Fill with spaces when necessary. */
  while (i < newlen)
    p[i++] = ' ';

  /* Replace the line in the buffer. */
  ml_replace(lnum, newp, FALSE);

  /* mark the buffer as changed and prepare for displaying */
  changed_bytes(lnum, col);

  /*
   * If we're in Insert or Replace mode and 'showmatch' is set, then briefly
   * show the match for right parens and braces.
   */
  if (p_sm && (State & INSERT)
      && msg_silent == 0
      && !ins_compl_active()
      ) {
    if (has_mbyte)
      showmatch(mb_ptr2char(buf));
    else
      showmatch(c);
  }

  if (!p_ri || (State & REPLACE_FLAG)) {
    /* Normal insert: move cursor right */
    curwin->w_cursor.col += charlen;
  }
  /*
   * TODO: should try to update w_row here, to avoid recomputing it later.
   */
}

/*
 * Insert a string at the cursor position.
 * Note: Does NOT handle Replace mode.
 * Caller must have prepared for undo.
 */
void ins_str(char_u *s)
{
  char_u      *oldp, *newp;
  int newlen = (int)STRLEN(s);
  int oldlen;
  colnr_T col;
  linenr_T lnum = curwin->w_cursor.lnum;

  if (virtual_active() && curwin->w_cursor.coladd > 0)
    coladvance_force(getviscol());

  col = curwin->w_cursor.col;
  oldp = ml_get(lnum);
  oldlen = (int)STRLEN(oldp);

  newp = (char_u *) xmalloc((size_t)(oldlen + newlen + 1));
  if (col > 0)
    memmove(newp, oldp, (size_t)col);
  memmove(newp + col, s, (size_t)newlen);
  memmove(newp + col + newlen, oldp + col, (size_t)(oldlen - col + 1));
  ml_replace(lnum, newp, FALSE);
  changed_bytes(lnum, col);
  curwin->w_cursor.col += newlen;
}

/*
 * Delete one character under the cursor.
 * If "fixpos" is TRUE, don't leave the cursor on the NUL after the line.
 * Caller must have prepared for undo.
 *
 * return FAIL for failure, OK otherwise
 */
int del_char(int fixpos)
{
  if (has_mbyte) {
    /* Make sure the cursor is at the start of a character. */
    mb_adjust_cursor();
    if (*ml_get_cursor() == NUL)
      return FAIL;
    return del_chars(1L, fixpos);
  }
  return del_bytes(1L, fixpos, TRUE);
}

/*
 * Like del_bytes(), but delete characters instead of bytes.
 */
int del_chars(long count, int fixpos)
{
  long bytes = 0;
  long i;
  char_u      *p;
  int l;

  p = ml_get_cursor();
  for (i = 0; i < count && *p != NUL; ++i) {
    l = (*mb_ptr2len)(p);
    bytes += l;
    p += l;
  }
  return del_bytes(bytes, fixpos, TRUE);
}

/*
 * Delete "count" bytes under the cursor.
 * If "fixpos" is TRUE, don't leave the cursor on the NUL after the line.
 * Caller must have prepared for undo.
 *
 * return FAIL for failure, OK otherwise
 */
int 
del_bytes (
    long count,
    int fixpos_arg,
    int use_delcombine                  /* 'delcombine' option applies */
)
{
  char_u      *oldp, *newp;
  colnr_T oldlen;
  linenr_T lnum = curwin->w_cursor.lnum;
  colnr_T col = curwin->w_cursor.col;
  int was_alloced;
  long movelen;
  int fixpos = fixpos_arg;

  oldp = ml_get(lnum);
  oldlen = (int)STRLEN(oldp);

  /*
   * Can't do anything when the cursor is on the NUL after the line.
   */
  if (col >= oldlen)
    return FAIL;

  /* If 'delcombine' is set and deleting (less than) one character, only
   * delete the last combining character. */
  if (p_deco && use_delcombine && enc_utf8
      && utfc_ptr2len(oldp + col) >= count) {
    int cc[MAX_MCO];
    int n;

    (void)utfc_ptr2char(oldp + col, cc);
    if (cc[0] != NUL) {
      /* Find the last composing char, there can be several. */
      n = col;
      do {
        col = n;
        count = utf_ptr2len(oldp + n);
        n += count;
      } while (UTF_COMPOSINGLIKE(oldp + col, oldp + n));
      fixpos = 0;
    }
  }

  /*
   * When count is too big, reduce it.
   */
  movelen = (long)oldlen - (long)col - count + 1;   /* includes trailing NUL */
  if (movelen <= 1) {
    /*
     * If we just took off the last character of a non-blank line, and
     * fixpos is TRUE, we don't want to end up positioned at the NUL,
     * unless "restart_edit" is set or 'virtualedit' contains "onemore".
     */
    if (col > 0 && fixpos && restart_edit == 0
        && (ve_flags & VE_ONEMORE) == 0
        ) {
      --curwin->w_cursor.col;
      curwin->w_cursor.coladd = 0;
      if (has_mbyte)
        curwin->w_cursor.col -=
          (*mb_head_off)(oldp, oldp + curwin->w_cursor.col);
    }
    count = oldlen - col;
    movelen = 1;
  }

  /*
   * If the old line has been allocated the deletion can be done in the
   * existing line. Otherwise a new line has to be allocated.
   */
  was_alloced = ml_line_alloced();          /* check if oldp was allocated */
  if (was_alloced)
    newp = oldp;                            /* use same allocated memory */
  else {                                    /* need to allocate a new line */
    newp = alloc((unsigned)(oldlen + 1 - count));
    if (newp == NULL)
      return FAIL;
    memmove(newp, oldp, (size_t)col);
  }
  memmove(newp + col, oldp + col + count, (size_t)movelen);
  if (!was_alloced)
    ml_replace(lnum, newp, FALSE);

  /* mark the buffer as changed and prepare for displaying */
  changed_bytes(lnum, curwin->w_cursor.col);

  return OK;
}

/*
 * Delete from cursor to end of line.
 * Caller must have prepared for undo.
 *
 * return FAIL for failure, OK otherwise
 */
int 
truncate_line (
    int fixpos                 /* if TRUE fix the cursor position when done */
)
{
  char_u      *newp;
  linenr_T lnum = curwin->w_cursor.lnum;
  colnr_T col = curwin->w_cursor.col;

  if (col == 0)
    newp = vim_strsave((char_u *)"");
  else
    newp = vim_strnsave(ml_get(lnum), col);

  if (newp == NULL)
    return FAIL;

  ml_replace(lnum, newp, FALSE);

  /* mark the buffer as changed and prepare for displaying */
  changed_bytes(lnum, curwin->w_cursor.col);

  /*
   * If "fixpos" is TRUE we don't want to end up positioned at the NUL.
   */
  if (fixpos && curwin->w_cursor.col > 0)
    --curwin->w_cursor.col;

  return OK;
}

/*
 * Delete "nlines" lines at the cursor.
 * Saves the lines for undo first if "undo" is TRUE.
 */
void 
del_lines (
    long nlines,                    /* number of lines to delete */
    int undo                       /* if TRUE, prepare for undo */
)
{
  long n;
  linenr_T first = curwin->w_cursor.lnum;

  if (nlines <= 0)
    return;

  /* save the deleted lines for undo */
  if (undo && u_savedel(first, nlines) == FAIL)
    return;

  for (n = 0; n < nlines; ) {
    if (curbuf->b_ml.ml_flags & ML_EMPTY)           /* nothing to delete */
      break;

    ml_delete(first, TRUE);
    ++n;

    /* If we delete the last line in the file, stop */
    if (first > curbuf->b_ml.ml_line_count)
      break;
  }

  /* Correct the cursor position before calling deleted_lines_mark(), it may
   * trigger a callback to display the cursor. */
  curwin->w_cursor.col = 0;
  check_cursor_lnum();

  /* adjust marks, mark the buffer as changed and prepare for displaying */
  deleted_lines_mark(first, n);
}

int gchar_pos(pos_T *pos)
{
  char_u      *ptr = ml_get_pos(pos);

  if (has_mbyte)
    return (*mb_ptr2char)(ptr);
  return (int)*ptr;
}

int gchar_cursor(void)
{
  if (has_mbyte)
    return (*mb_ptr2char)(ml_get_cursor());
  return (int)*ml_get_cursor();
}

/*
 * Write a character at the current cursor position.
 * It is directly written into the block.
 */
void pchar_cursor(int c)
{
  *(ml_get_buf(curbuf, curwin->w_cursor.lnum, TRUE)
    + curwin->w_cursor.col) = c;
}

/*
 * Skip to next part of an option argument: Skip space and comma.
 */
char_u *skip_to_option_part(char_u *p)
{
  if (*p == ',')
    ++p;
  while (*p == ' ')
    ++p;
  return p;
}

/*
 * Call this function when something in the current buffer is changed.
 *
 * Most often called through changed_bytes() and changed_lines(), which also
 * mark the area of the display to be redrawn.
 *
 * Careful: may trigger autocommands that reload the buffer.
 */
void changed(void)
{

  if (!curbuf->b_changed) {
    int save_msg_scroll = msg_scroll;

    /* Give a warning about changing a read-only file.  This may also
     * check-out the file, thus change "curbuf"! */
    change_warning(0);

    /* Create a swap file if that is wanted.
     * Don't do this for "nofile" and "nowrite" buffer types. */
    if (curbuf->b_may_swap
        && !bt_dontwrite(curbuf)
        ) {
      ml_open_file(curbuf);

      /* The ml_open_file() can cause an ATTENTION message.
       * Wait two seconds, to make sure the user reads this unexpected
       * message.  Since we could be anywhere, call wait_return() now,
       * and don't let the emsg() set msg_scroll. */
      if (need_wait_return && emsg_silent == 0) {
        out_flush();
        ui_delay(2000L, TRUE);
        wait_return(TRUE);
        msg_scroll = save_msg_scroll;
      }
    }
    changed_int();
  }
  ++curbuf->b_changedtick;
}

/*
 * Internal part of changed(), no user interaction.
 */
void changed_int(void)
{
  curbuf->b_changed = TRUE;
  ml_setflags(curbuf);
  check_status(curbuf);
  redraw_tabline = TRUE;
  need_maketitle = TRUE;            /* set window title later */
}

static void changedOneline(buf_T *buf, linenr_T lnum);
static void changed_lines_buf(buf_T *buf, linenr_T lnum, linenr_T lnume,
                              long xtra);
static void changed_common(linenr_T lnum, colnr_T col, linenr_T lnume,
                           long xtra);

/*
 * Changed bytes within a single line for the current buffer.
 * - marks the windows on this buffer to be redisplayed
 * - marks the buffer changed by calling changed()
 * - invalidates cached values
 * Careful: may trigger autocommands that reload the buffer.
 */
void changed_bytes(linenr_T lnum, colnr_T col)
{
  changedOneline(curbuf, lnum);
  changed_common(lnum, col, lnum + 1, 0L);

  /* Diff highlighting in other diff windows may need to be updated too. */
  if (curwin->w_p_diff) {
    win_T       *wp;
    linenr_T wlnum;

    for (wp = firstwin; wp != NULL; wp = wp->w_next)
      if (wp->w_p_diff && wp != curwin) {
        redraw_win_later(wp, VALID);
        wlnum = diff_lnum_win(lnum, wp);
        if (wlnum > 0)
          changedOneline(wp->w_buffer, wlnum);
      }
  }
}

static void changedOneline(buf_T *buf, linenr_T lnum)
{
  if (buf->b_mod_set) {
    /* find the maximum area that must be redisplayed */
    if (lnum < buf->b_mod_top)
      buf->b_mod_top = lnum;
    else if (lnum >= buf->b_mod_bot)
      buf->b_mod_bot = lnum + 1;
  } else {
    /* set the area that must be redisplayed to one line */
    buf->b_mod_set = TRUE;
    buf->b_mod_top = lnum;
    buf->b_mod_bot = lnum + 1;
    buf->b_mod_xlines = 0;
  }
}

/*
 * Appended "count" lines below line "lnum" in the current buffer.
 * Must be called AFTER the change and after mark_adjust().
 * Takes care of marking the buffer to be redrawn and sets the changed flag.
 */
void appended_lines(linenr_T lnum, long count)
{
  changed_lines(lnum + 1, 0, lnum + 1, count);
}

/*
 * Like appended_lines(), but adjust marks first.
 */
void appended_lines_mark(linenr_T lnum, long count)
{
  mark_adjust(lnum + 1, (linenr_T)MAXLNUM, count, 0L);
  changed_lines(lnum + 1, 0, lnum + 1, count);
}

/*
 * Deleted "count" lines at line "lnum" in the current buffer.
 * Must be called AFTER the change and after mark_adjust().
 * Takes care of marking the buffer to be redrawn and sets the changed flag.
 */
void deleted_lines(linenr_T lnum, long count)
{
  changed_lines(lnum, 0, lnum + count, -count);
}

/*
 * Like deleted_lines(), but adjust marks first.
 * Make sure the cursor is on a valid line before calling, a GUI callback may
 * be triggered to display the cursor.
 */
void deleted_lines_mark(linenr_T lnum, long count)
{
  mark_adjust(lnum, (linenr_T)(lnum + count - 1), (long)MAXLNUM, -count);
  changed_lines(lnum, 0, lnum + count, -count);
}

/*
 * Changed lines for the current buffer.
 * Must be called AFTER the change and after mark_adjust().
 * - mark the buffer changed by calling changed()
 * - mark the windows on this buffer to be redisplayed
 * - invalidate cached values
 * "lnum" is the first line that needs displaying, "lnume" the first line
 * below the changed lines (BEFORE the change).
 * When only inserting lines, "lnum" and "lnume" are equal.
 * Takes care of calling changed() and updating b_mod_*.
 * Careful: may trigger autocommands that reload the buffer.
 */
void 
changed_lines (
    linenr_T lnum,              /* first line with change */
    colnr_T col,                /* column in first line with change */
    linenr_T lnume,             /* line below last changed line */
    long xtra                  /* number of extra lines (negative when deleting) */
)
{
  changed_lines_buf(curbuf, lnum, lnume, xtra);

  if (xtra == 0 && curwin->w_p_diff) {
    /* When the number of lines doesn't change then mark_adjust() isn't
     * called and other diff buffers still need to be marked for
     * displaying. */
    win_T       *wp;
    linenr_T wlnum;

    for (wp = firstwin; wp != NULL; wp = wp->w_next)
      if (wp->w_p_diff && wp != curwin) {
        redraw_win_later(wp, VALID);
        wlnum = diff_lnum_win(lnum, wp);
        if (wlnum > 0)
          changed_lines_buf(wp->w_buffer, wlnum,
              lnume - lnum + wlnum, 0L);
      }
  }

  changed_common(lnum, col, lnume, xtra);
}

static void 
changed_lines_buf (
    buf_T *buf,
    linenr_T lnum,              /* first line with change */
    linenr_T lnume,             /* line below last changed line */
    long xtra                  /* number of extra lines (negative when deleting) */
)
{
  if (buf->b_mod_set) {
    /* find the maximum area that must be redisplayed */
    if (lnum < buf->b_mod_top)
      buf->b_mod_top = lnum;
    if (lnum < buf->b_mod_bot) {
      /* adjust old bot position for xtra lines */
      buf->b_mod_bot += xtra;
      if (buf->b_mod_bot < lnum)
        buf->b_mod_bot = lnum;
    }
    if (lnume + xtra > buf->b_mod_bot)
      buf->b_mod_bot = lnume + xtra;
    buf->b_mod_xlines += xtra;
  } else {
    /* set the area that must be redisplayed */
    buf->b_mod_set = TRUE;
    buf->b_mod_top = lnum;
    buf->b_mod_bot = lnume + xtra;
    buf->b_mod_xlines = xtra;
  }
}

/*
 * Common code for when a change is was made.
 * See changed_lines() for the arguments.
 * Careful: may trigger autocommands that reload the buffer.
 */
static void changed_common(linenr_T lnum, colnr_T col, linenr_T lnume, long xtra)
{
  win_T       *wp;
  tabpage_T   *tp;
  int i;
  int cols;
  pos_T       *p;
  int add;

  /* mark the buffer as modified */
  changed();

  /* set the '. mark */
  if (!cmdmod.keepjumps) {
    curbuf->b_last_change.lnum = lnum;
    curbuf->b_last_change.col = col;

    /* Create a new entry if a new undo-able change was started or we
     * don't have an entry yet. */
    if (curbuf->b_new_change || curbuf->b_changelistlen == 0) {
      if (curbuf->b_changelistlen == 0)
        add = TRUE;
      else {
        /* Don't create a new entry when the line number is the same
         * as the last one and the column is not too far away.  Avoids
         * creating many entries for typing "xxxxx". */
        p = &curbuf->b_changelist[curbuf->b_changelistlen - 1];
        if (p->lnum != lnum)
          add = TRUE;
        else {
          cols = comp_textwidth(FALSE);
          if (cols == 0)
            cols = 79;
          add = (p->col + cols < col || col + cols < p->col);
        }
      }
      if (add) {
        /* This is the first of a new sequence of undo-able changes
         * and it's at some distance of the last change.  Use a new
         * position in the changelist. */
        curbuf->b_new_change = FALSE;

        if (curbuf->b_changelistlen == JUMPLISTSIZE) {
          /* changelist is full: remove oldest entry */
          curbuf->b_changelistlen = JUMPLISTSIZE - 1;
          memmove(curbuf->b_changelist, curbuf->b_changelist + 1,
              sizeof(pos_T) * (JUMPLISTSIZE - 1));
          FOR_ALL_TAB_WINDOWS(tp, wp)
          {
            /* Correct position in changelist for other windows on
             * this buffer. */
            if (wp->w_buffer == curbuf && wp->w_changelistidx > 0)
              --wp->w_changelistidx;
          }
        }
        FOR_ALL_TAB_WINDOWS(tp, wp)
        {
          /* For other windows, if the position in the changelist is
           * at the end it stays at the end. */
          if (wp->w_buffer == curbuf
              && wp->w_changelistidx == curbuf->b_changelistlen)
            ++wp->w_changelistidx;
        }
        ++curbuf->b_changelistlen;
      }
    }
    curbuf->b_changelist[curbuf->b_changelistlen - 1] =
      curbuf->b_last_change;
    /* The current window is always after the last change, so that "g,"
     * takes you back to it. */
    curwin->w_changelistidx = curbuf->b_changelistlen;
  }

  FOR_ALL_TAB_WINDOWS(tp, wp)
  {
    if (wp->w_buffer == curbuf) {
      /* Mark this window to be redrawn later. */
      if (wp->w_redr_type < VALID)
        wp->w_redr_type = VALID;

      /* Check if a change in the buffer has invalidated the cached
       * values for the cursor. */
      /*
       * Update the folds for this window.  Can't postpone this, because
       * a following operator might work on the whole fold: ">>dd".
       */
      foldUpdate(wp, lnum, lnume + xtra - 1);

      /* The change may cause lines above or below the change to become
       * included in a fold.  Set lnum/lnume to the first/last line that
       * might be displayed differently.
       * Set w_cline_folded here as an efficient way to update it when
       * inserting lines just above a closed fold. */
      i = hasFoldingWin(wp, lnum, &lnum, NULL, FALSE, NULL);
      if (wp->w_cursor.lnum == lnum)
        wp->w_cline_folded = i;
      i = hasFoldingWin(wp, lnume, NULL, &lnume, FALSE, NULL);
      if (wp->w_cursor.lnum == lnume)
        wp->w_cline_folded = i;

      /* If the changed line is in a range of previously folded lines,
       * compare with the first line in that range. */
      if (wp->w_cursor.lnum <= lnum) {
        i = find_wl_entry(wp, lnum);
        if (i >= 0 && wp->w_cursor.lnum > wp->w_lines[i].wl_lnum)
          changed_line_abv_curs_win(wp);
      }

      if (wp->w_cursor.lnum > lnum)
        changed_line_abv_curs_win(wp);
      else if (wp->w_cursor.lnum == lnum && wp->w_cursor.col >= col)
        changed_cline_bef_curs_win(wp);
      if (wp->w_botline >= lnum) {
        /* Assume that botline doesn't change (inserted lines make
         * other lines scroll down below botline). */
        approximate_botline_win(wp);
      }

      /* Check if any w_lines[] entries have become invalid.
       * For entries below the change: Correct the lnums for
       * inserted/deleted lines.  Makes it possible to stop displaying
       * after the change. */
      for (i = 0; i < wp->w_lines_valid; ++i)
        if (wp->w_lines[i].wl_valid) {
          if (wp->w_lines[i].wl_lnum >= lnum) {
            if (wp->w_lines[i].wl_lnum < lnume) {
              /* line included in change */
              wp->w_lines[i].wl_valid = FALSE;
            } else if (xtra != 0) {
              /* line below change */
              wp->w_lines[i].wl_lnum += xtra;
              wp->w_lines[i].wl_lastlnum += xtra;
            }
          } else if (wp->w_lines[i].wl_lastlnum >= lnum) {
            /* change somewhere inside this range of folded lines,
             * may need to be redrawn */
            wp->w_lines[i].wl_valid = FALSE;
          }
        }

      /* Take care of side effects for setting w_topline when folds have
      * changed.  Esp. when the buffer was changed in another window. */
      if (hasAnyFolding(wp))
        set_topline(wp, wp->w_topline);
    }
  }

  /* Call update_screen() later, which checks out what needs to be redrawn,
   * since it notices b_mod_set and then uses b_mod_*. */
  if (must_redraw < VALID)
    must_redraw = VALID;

  /* when the cursor line is changed always trigger CursorMoved */
  if (lnum <= curwin->w_cursor.lnum
      && lnume + (xtra < 0 ? -xtra : xtra) > curwin->w_cursor.lnum)
    last_cursormoved.lnum = 0;
}

/*
 * unchanged() is called when the changed flag must be reset for buffer 'buf'
 */
void 
unchanged (
    buf_T *buf,
    int ff                 /* also reset 'fileformat' */
)
{
  if (buf->b_changed || (ff && file_ff_differs(buf, FALSE))) {
    buf->b_changed = 0;
    ml_setflags(buf);
    if (ff)
      save_file_ff(buf);
    check_status(buf);
    redraw_tabline = TRUE;
    need_maketitle = TRUE;          /* set window title later */
  }
  ++buf->b_changedtick;
}

/*
 * check_status: called when the status bars for the buffer 'buf'
 *		 need to be updated
 */
void check_status(buf_T *buf)
{
  win_T       *wp;

  for (wp = firstwin; wp != NULL; wp = wp->w_next)
    if (wp->w_buffer == buf && wp->w_status_height) {
      wp->w_redr_status = TRUE;
      if (must_redraw < VALID)
        must_redraw = VALID;
    }
}

/*
 * If the file is readonly, give a warning message with the first change.
 * Don't do this for autocommands.
 * Don't use emsg(), because it flushes the macro buffer.
 * If we have undone all changes b_changed will be FALSE, but "b_did_warn"
 * will be TRUE.
 * Careful: may trigger autocommands that reload the buffer.
 */
void 
change_warning (
    int col                        /* column for message; non-zero when in insert
                                   mode and 'showmode' is on */
)
{
  static char *w_readonly = N_("W10: Warning: Changing a readonly file");

  if (curbuf->b_did_warn == FALSE
      && curbufIsChanged() == 0
      && !autocmd_busy
      && curbuf->b_p_ro) {
    ++curbuf_lock;
    apply_autocmds(EVENT_FILECHANGEDRO, NULL, NULL, FALSE, curbuf);
    --curbuf_lock;
    if (!curbuf->b_p_ro)
      return;
    /*
     * Do what msg() does, but with a column offset if the warning should
     * be after the mode message.
     */
    msg_start();
    if (msg_row == Rows - 1)
      msg_col = col;
    msg_source(hl_attr(HLF_W));
    MSG_PUTS_ATTR(_(w_readonly), hl_attr(HLF_W) | MSG_HIST);
    set_vim_var_string(VV_WARNINGMSG, (char_u *)_(w_readonly), -1);
    msg_clr_eos();
    (void)msg_end();
    if (msg_silent == 0 && !silent_mode) {
      out_flush();
      ui_delay(1000L, TRUE);       /* give the user time to think about it */
    }
    curbuf->b_did_warn = TRUE;
    redraw_cmdline = FALSE;     /* don't redraw and erase the message */
    if (msg_row < Rows - 1)
      showmode();
  }
}

/*
 * Ask for a reply from the user, a 'y' or a 'n'.
 * No other characters are accepted, the message is repeated until a valid
 * reply is entered or CTRL-C is hit.
 * If direct is TRUE, don't use vgetc() but ui_inchar(), don't get characters
 * from any buffers but directly from the user.
 *
 * return the 'y' or 'n'
 */
int ask_yesno(char_u *str, int direct)
{
  int r = ' ';
  int save_State = State;

  if (exiting)                  /* put terminal in raw mode for this question */
    settmode(TMODE_RAW);
  ++no_wait_return;
#ifdef USE_ON_FLY_SCROLL
  dont_scroll = TRUE;           /* disallow scrolling here */
#endif
  State = CONFIRM;              /* mouse behaves like with :confirm */
  setmouse();                   /* disables mouse for xterm */
  ++no_mapping;
  ++allow_keys;                 /* no mapping here, but recognize keys */

  while (r != 'y' && r != 'n') {
    /* same highlighting as for wait_return */
    smsg_attr(hl_attr(HLF_R), (char_u *)"%s (y/n)?", str);
    if (direct)
      r = get_keystroke();
    else
      r = plain_vgetc();
    if (r == Ctrl_C || r == ESC)
      r = 'n';
    msg_putchar(r);         /* show what you typed */
    out_flush();
  }
  --no_wait_return;
  State = save_State;
  setmouse();
  --no_mapping;
  --allow_keys;

  return r;
}

/*
 * Return TRUE if "c" is a mouse key.
 */
int is_mouse_key(int c)
{
  return c == K_LEFTMOUSE
         || c == K_LEFTMOUSE_NM
         || c == K_LEFTDRAG
         || c == K_LEFTRELEASE
         || c == K_LEFTRELEASE_NM
         || c == K_MIDDLEMOUSE
         || c == K_MIDDLEDRAG
         || c == K_MIDDLERELEASE
         || c == K_RIGHTMOUSE
         || c == K_RIGHTDRAG
         || c == K_RIGHTRELEASE
         || c == K_MOUSEDOWN
         || c == K_MOUSEUP
         || c == K_MOUSELEFT
         || c == K_MOUSERIGHT
         || c == K_X1MOUSE
         || c == K_X1DRAG
         || c == K_X1RELEASE
         || c == K_X2MOUSE
         || c == K_X2DRAG
         || c == K_X2RELEASE;
}

/*
 * Get a key stroke directly from the user.
 * Ignores mouse clicks and scrollbar events, except a click for the left
 * button (used at the more prompt).
 * Doesn't use vgetc(), because it syncs undo and eats mapped characters.
 * Disadvantage: typeahead is ignored.
 * Translates the interrupt character for unix to ESC.
 */
int get_keystroke(void)
{
  char_u      *buf = NULL;
  int buflen = 150;
  int maxlen;
  int len = 0;
  int n;
  int save_mapped_ctrl_c = mapped_ctrl_c;
  int waited = 0;

  mapped_ctrl_c = FALSE;        /* mappings are not used here */
  for (;; ) {
    cursor_on();
    out_flush();

    /* Leave some room for check_termcode() to insert a key code into (max
     * 5 chars plus NUL).  And fix_input_buffer() can triple the number of
     * bytes. */
    maxlen = (buflen - 6 - len) / 3;
    if (buf == NULL)
      buf = alloc(buflen);
    else if (maxlen < 10) {
      /* Need some more space. This might happen when receiving a long
       * escape sequence. */
      buflen += 100;
      buf = xrealloc(buf, buflen);
      maxlen = (buflen - 6 - len) / 3;
    }

    /* First time: blocking wait.  Second time: wait up to 100ms for a
     * terminal code to complete. */
    n = ui_inchar(buf + len, maxlen, len == 0 ? -1L : 100L, 0);
    if (n > 0) {
      /* Replace zero and CSI by a special key code. */
      n = fix_input_buffer(buf + len, n, FALSE);
      len += n;
      waited = 0;
    } else if (len > 0)
      ++waited;             /* keep track of the waiting time */

    /* Incomplete termcode and not timed out yet: get more characters */
    if ((n = check_termcode(1, buf, buflen, &len)) < 0
        && (!p_ttimeout || waited * 100L < (p_ttm < 0 ? p_tm : p_ttm)))
      continue;

    if (n == KEYLEN_REMOVED) {    /* key code removed */
      if (must_redraw != 0 && !need_wait_return && (State & CMDLINE) == 0) {
        /* Redrawing was postponed, do it now. */
        update_screen(0);
        setcursor();         /* put cursor back where it belongs */
      }
      continue;
    }
    if (n > 0)                  /* found a termcode: adjust length */
      len = n;
    if (len == 0)               /* nothing typed yet */
      continue;

    /* Handle modifier and/or special key code. */
    n = buf[0];
    if (n == K_SPECIAL) {
      n = TO_SPECIAL(buf[1], buf[2]);
      if (buf[1] == KS_MODIFIER
          || n == K_IGNORE
          || (is_mouse_key(n) && n != K_LEFTMOUSE)
          ) {
        if (buf[1] == KS_MODIFIER)
          mod_mask = buf[2];
        len -= 3;
        if (len > 0)
          memmove(buf, buf + 3, (size_t)len);
        continue;
      }
      break;
    }
    if (has_mbyte) {
      if (MB_BYTE2LEN(n) > len)
        continue;               /* more bytes to get */
      buf[len >= buflen ? buflen - 1 : len] = NUL;
      n = (*mb_ptr2char)(buf);
    }
#ifdef UNIX
    if (n == intr_char)
      n = ESC;
#endif
    break;
  }
  vim_free(buf);

  mapped_ctrl_c = save_mapped_ctrl_c;
  return n;
}

/*
 * Get a number from the user.
 * When "mouse_used" is not NULL allow using the mouse.
 */
int 
get_number (
    int colon,                              /* allow colon to abort */
    int *mouse_used
)
{
  int n = 0;
  int c;
  int typed = 0;

  if (mouse_used != NULL)
    *mouse_used = FALSE;

  /* When not printing messages, the user won't know what to type, return a
   * zero (as if CR was hit). */
  if (msg_silent != 0)
    return 0;

#ifdef USE_ON_FLY_SCROLL
  dont_scroll = TRUE;           /* disallow scrolling here */
#endif
  ++no_mapping;
  ++allow_keys;                 /* no mapping here, but recognize keys */
  for (;; ) {
    windgoto(msg_row, msg_col);
    c = safe_vgetc();
    if (VIM_ISDIGIT(c)) {
      n = n * 10 + c - '0';
      msg_putchar(c);
      ++typed;
    } else if (c == K_DEL || c == K_KDEL || c == K_BS || c == Ctrl_H) {
      if (typed > 0) {
        MSG_PUTS("\b \b");
        --typed;
      }
      n /= 10;
    } else if (mouse_used != NULL && c == K_LEFTMOUSE) {
      *mouse_used = TRUE;
      n = mouse_row + 1;
      break;
    } else if (n == 0 && c == ':' && colon) {
      stuffcharReadbuff(':');
      if (!exmode_active)
        cmdline_row = msg_row;
      skip_redraw = TRUE;           /* skip redraw once */
      do_redraw = FALSE;
      break;
    } else if (c == CAR || c == NL || c == Ctrl_C || c == ESC)
      break;
  }
  --no_mapping;
  --allow_keys;
  return n;
}

/*
 * Ask the user to enter a number.
 * When "mouse_used" is not NULL allow using the mouse and in that case return
 * the line number.
 */
int prompt_for_number(int *mouse_used)
{
  int i;
  int save_cmdline_row;
  int save_State;

  /* When using ":silent" assume that <CR> was entered. */
  if (mouse_used != NULL)
    MSG_PUTS(_("Type number and <Enter> or click with mouse (empty cancels): "));
  else
    MSG_PUTS(_("Type number and <Enter> (empty cancels): "));

  /* Set the state such that text can be selected/copied/pasted and we still
   * get mouse events. */
  save_cmdline_row = cmdline_row;
  cmdline_row = 0;
  save_State = State;
  State = CMDLINE;

  i = get_number(TRUE, mouse_used);
  if (KeyTyped) {
    /* don't call wait_return() now */
    /* msg_putchar('\n'); */
    cmdline_row = msg_row - 1;
    need_wait_return = FALSE;
    msg_didany = FALSE;
    msg_didout = FALSE;
  } else
    cmdline_row = save_cmdline_row;
  State = save_State;

  return i;
}

void msgmore(long n)
{
  long pn;

  if (global_busy           /* no messages now, wait until global is finished */
      || !messaging())        /* 'lazyredraw' set, don't do messages now */
    return;

  /* We don't want to overwrite another important message, but do overwrite
   * a previous "more lines" or "fewer lines" message, so that "5dd" and
   * then "put" reports the last action. */
  if (keep_msg != NULL && !keep_msg_more)
    return;

  if (n > 0)
    pn = n;
  else
    pn = -n;

  if (pn > p_report) {
    if (pn == 1) {
      if (n > 0)
        vim_strncpy(msg_buf, (char_u *)_("1 more line"),
            MSG_BUF_LEN - 1);
      else
        vim_strncpy(msg_buf, (char_u *)_("1 line less"),
            MSG_BUF_LEN - 1);
    } else {
      if (n > 0)
        vim_snprintf((char *)msg_buf, MSG_BUF_LEN,
            _("%ld more lines"), pn);
      else
        vim_snprintf((char *)msg_buf, MSG_BUF_LEN,
            _("%ld fewer lines"), pn);
    }
    if (got_int)
      vim_strcat(msg_buf, (char_u *)_(" (Interrupted)"), MSG_BUF_LEN);
    if (msg(msg_buf)) {
      set_keep_msg(msg_buf, 0);
      keep_msg_more = TRUE;
    }
  }
}

/*
 * flush map and typeahead buffers and give a warning for an error
 */
void beep_flush(void)
{
  if (emsg_silent == 0) {
    flush_buffers(FALSE);
    vim_beep();
  }
}

/*
 * give a warning for an error
 */
void vim_beep(void)
{
  if (emsg_silent == 0) {
    if (p_vb
        ) {
      out_str(T_VB);
    } else {
      out_char(BELL);
    }

    /* When 'verbose' is set and we are sourcing a script or executing a
     * function give the user a hint where the beep comes from. */
    if (vim_strchr(p_debug, 'e') != NULL) {
      msg_source(hl_attr(HLF_W));
      msg_attr((char_u *)_("Beep!"), hl_attr(HLF_W));
    }
  }
}

/*
 * To get the "real" home directory:
 * - get value of $HOME
 * For Unix:
 *  - go to that directory
 *  - do os_dirname() to get the real name of that directory.
 *  This also works with mounts and links.
 *  Don't do this for MS-DOS, it will change the "current dir" for a drive.
 */
static char_u   *homedir = NULL;

void init_homedir(void)
{
  char_u  *var;

  /* In case we are called a second time (when 'encoding' changes). */
  vim_free(homedir);
  homedir = NULL;

  var = (char_u *)os_getenv("HOME");

  if (var != NULL && *var == NUL)       /* empty is same as not set */
    var = NULL;


  if (var != NULL) {
#ifdef UNIX
    /*
     * Change to the directory and get the actual path.  This resolves
     * links.  Don't do it when we can't return.
     */
    if (os_dirname(NameBuff, MAXPATHL) == OK
        && os_chdir((char *)NameBuff) == 0) {
      if (!os_chdir((char *)var) && os_dirname(IObuff, IOSIZE) == OK)
        var = IObuff;
      if (os_chdir((char *)NameBuff) != 0)
        EMSG(_(e_prev_dir));
    }
#endif
    homedir = vim_strsave(var);
  }
}

#if defined(EXITFREE) || defined(PROTO)
void free_homedir(void)
{
  vim_free(homedir);
}

void free_users(void)
{
  ga_clear_strings(&ga_users);
}

#endif

/*
 * Call expand_env() and store the result in an allocated string.
 * This is not very memory efficient, this expects the result to be freed
 * again soon.
 */
char_u *expand_env_save(char_u *src)
{
  return expand_env_save_opt(src, FALSE);
}

/*
 * Idem, but when "one" is TRUE handle the string as one file name, only
 * expand "~" at the start.
 */
char_u *expand_env_save_opt(char_u *src, int one)
{
  char_u      *p;

  p = alloc(MAXPATHL);
  expand_env_esc(src, p, MAXPATHL, FALSE, one, NULL);
  return p;
}

/*
 * Expand environment variable with path name.
 * "~/" is also expanded, using $HOME.	For Unix "~user/" is expanded.
 * Skips over "\ ", "\~" and "\$" (not for Win32 though).
 * If anything fails no expansion is done and dst equals src.
 */
void 
expand_env (
    char_u *src,               /* input string e.g. "$HOME/vim.hlp" */
    char_u *dst,               /* where to put the result */
    int dstlen                     /* maximum length of the result */
)
{
  expand_env_esc(src, dst, dstlen, FALSE, FALSE, NULL);
}

void 
expand_env_esc (
    char_u *srcp,              /* input string e.g. "$HOME/vim.hlp" */
    char_u *dst,               /* where to put the result */
    int dstlen,                     /* maximum length of the result */
    int esc,                        /* escape spaces in expanded variables */
    int one,                        /* "srcp" is one file name */
    char_u *startstr          /* start again after this (can be NULL) */
)
{
  char_u      *src;
  char_u      *tail;
  int c;
  char_u      *var;
  int copy_char;
  int mustfree;                 /* var was allocated, need to free it later */
  int at_start = TRUE;           /* at start of a name */
  int startstr_len = 0;

  if (startstr != NULL)
    startstr_len = (int)STRLEN(startstr);

  src = skipwhite(srcp);
  --dstlen;                 /* leave one char space for "\," */
  while (*src && dstlen > 0) {
    copy_char = TRUE;
    if ((*src == '$'
         )
        || (*src == '~' && at_start)) {
      mustfree = FALSE;

      /*
       * The variable name is copied into dst temporarily, because it may
       * be a string in read-only memory and a NUL needs to be appended.
       */
      if (*src != '~') {                                /* environment var */
        tail = src + 1;
        var = dst;
        c = dstlen - 1;

#ifdef UNIX
        /* Unix has ${var-name} type environment vars */
        if (*tail == '{' && !vim_isIDc('{')) {
          tail++;               /* ignore '{' */
          while (c-- > 0 && *tail && *tail != '}')
            *var++ = *tail++;
        } else
#endif
        {
          while (c-- > 0 && *tail != NUL && ((vim_isIDc(*tail))
                                             )) {
            *var++ = *tail++;
          }
        }

#if defined(MSDOS) || defined(MSWIN) || defined(OS2) || defined(UNIX)
# ifdef UNIX
        if (src[1] == '{' && *tail != '}')
# else
        if (*src == '%' && *tail != '%')
# endif
          var = NULL;
        else {
# ifdef UNIX
          if (src[1] == '{')
# else
          if (*src == '%')
#endif
            ++tail;
#endif
        *var = NUL;
        var = vim_getenv(dst, &mustfree);
#if defined(MSDOS) || defined(MSWIN) || defined(OS2) || defined(UNIX)
      }
#endif
      }
      /* home directory */
      else if (  src[1] == NUL
                 || vim_ispathsep(src[1])
                 || vim_strchr((char_u *)" ,\t\n", src[1]) != NULL) {
        var = homedir;
        tail = src + 1;
      } else {                                        /* user directory */
#if defined(UNIX) || (defined(VMS) && defined(USER_HOME))
        /*
         * Copy ~user to dst[], so we can put a NUL after it.
         */
        tail = src;
        var = dst;
        c = dstlen - 1;
        while (    c-- > 0
                   && *tail
                   && vim_isfilec(*tail)
                   && !vim_ispathsep(*tail))
          *var++ = *tail++;
        *var = NUL;
# ifdef UNIX
        /*
         * Use os_get_user_directory() to get the user directory.
         * If this function fails, the shell is used to
         * expand ~user. This is slower and may fail if the shell
         * does not support ~user (old versions of /bin/sh).
         */
        var = (char_u *)os_get_user_directory((char *)dst + 1);
        mustfree = TRUE;
        if (var == NULL)
        {
          expand_T xpc;

          ExpandInit(&xpc);
          xpc.xp_context = EXPAND_FILES;
          var = ExpandOne(&xpc, dst, NULL,
              WILD_ADD_SLASH|WILD_SILENT, WILD_EXPAND_FREE);
          mustfree = TRUE;
        }

# else  /* !UNIX, thus VMS */
        /*
         * USER_HOME is a comma-separated list of
         * directories to search for the user account in.
         */
        {
          char_u test[MAXPATHL], paths[MAXPATHL];
          char_u      *path, *next_path, *ptr;
          struct stat st;

          STRCPY(paths, USER_HOME);
          next_path = paths;
          while (*next_path) {
            for (path = next_path; *next_path && *next_path != ',';
                 next_path++) ;
            if (*next_path)
              *next_path++ = NUL;
            STRCPY(test, path);
            STRCAT(test, "/");
            STRCAT(test, dst + 1);
            if (mch_stat(test, &st) == 0) {
              var = alloc(STRLEN(test) + 1);
              STRCPY(var, test);
              mustfree = TRUE;
              break;
            }
          }
        }
# endif /* UNIX */
#else
        /* cannot expand user's home directory, so don't try */
        var = NULL;
        tail = (char_u *)"";            /* for gcc */
#endif /* UNIX || VMS */
      }

#ifdef BACKSLASH_IN_FILENAME
      /* If 'shellslash' is set change backslashes to forward slashes.
       * Can't use slash_adjust(), p_ssl may be set temporarily. */
      if (p_ssl && var != NULL && vim_strchr(var, '\\') != NULL) {
        char_u  *p = vim_strsave(var);

        if (p != NULL) {
          if (mustfree)
            vim_free(var);
          var = p;
          mustfree = TRUE;
          forward_slash(var);
        }
      }
#endif

      /* If "var" contains white space, escape it with a backslash.
       * Required for ":e ~/tt" when $HOME includes a space. */
      if (esc && var != NULL && vim_strpbrk(var, (char_u *)" \t") != NULL) {
        char_u  *p = vim_strsave_escaped(var, (char_u *)" \t");

        if (p != NULL) {
          if (mustfree)
            vim_free(var);
          var = p;
          mustfree = TRUE;
        }
      }

      if (var != NULL && *var != NUL
          && (STRLEN(var) + STRLEN(tail) + 1 < (unsigned)dstlen)) {
        STRCPY(dst, var);
        dstlen -= (int)STRLEN(var);
        c = (int)STRLEN(var);
        /* if var[] ends in a path separator and tail[] starts
         * with it, skip a character */
        if (*var != NUL && after_pathsep(dst, dst + c)
#if defined(BACKSLASH_IN_FILENAME)
            && dst[-1] != ':'
#endif
            && vim_ispathsep(*tail))
          ++tail;
        dst += c;
        src = tail;
        copy_char = FALSE;
      }
      if (mustfree)
        vim_free(var);
    }

    if (copy_char) {        /* copy at least one char */
      /*
       * Recognize the start of a new name, for '~'.
       * Don't do this when "one" is TRUE, to avoid expanding "~" in
       * ":edit foo ~ foo".
       */
      at_start = FALSE;
      if (src[0] == '\\' && src[1] != NUL) {
        *dst++ = *src++;
        --dstlen;
      } else if ((src[0] == ' ' || src[0] == ',') && !one)
        at_start = TRUE;
      *dst++ = *src++;
      --dstlen;

      if (startstr != NULL && src - startstr_len >= srcp
          && STRNCMP(src - startstr_len, startstr, startstr_len) == 0)
        at_start = TRUE;
    }
  }
  *dst = NUL;
}

/*
 * Vim's version of getenv().
 * Special handling of $HOME, $VIM and $VIMRUNTIME.
 * Also does ACP to 'enc' conversion for Win32.
 * "mustfree" is set to TRUE when returned is allocated, it must be
 * initialized to FALSE by the caller.
 */
char_u *vim_getenv(char_u *name, int *mustfree)
{
  char_u      *p;
  char_u      *pend;
  int vimruntime;


  p = (char_u *)os_getenv((char *)name);
  if (p != NULL && *p == NUL)       /* empty is the same as not set */
    p = NULL;

  if (p != NULL) {
    return p;
  }

  vimruntime = (STRCMP(name, "VIMRUNTIME") == 0);
  if (!vimruntime && STRCMP(name, "VIM") != 0)
    return NULL;

  /*
   * When expanding $VIMRUNTIME fails, try using $VIM/vim<version> or $VIM.
   * Don't do this when default_vimruntime_dir is non-empty.
   */
  if (vimruntime
#ifdef HAVE_PATHDEF
      && *default_vimruntime_dir == NUL
#endif
      ) {
    p = (char_u *)os_getenv("VIM");
    if (p != NULL && *p == NUL)             /* empty is the same as not set */
      p = NULL;
    if (p != NULL) {
      p = vim_version_dir(p);
      if (p != NULL)
        *mustfree = TRUE;
      else
        p = (char_u *)os_getenv("VIM");

    }
  }

  /*
   * When expanding $VIM or $VIMRUNTIME fails, try using:
   * - the directory name from 'helpfile' (unless it contains '$')
   * - the executable name from argv[0]
   */
  if (p == NULL) {
    if (p_hf != NULL && vim_strchr(p_hf, '$') == NULL)
      p = p_hf;
#ifdef USE_EXE_NAME
    /*
     * Use the name of the executable, obtained from argv[0].
     */
    else
      p = exe_name;
#endif
    if (p != NULL) {
      /* remove the file name */
      pend = path_tail(p);

      /* remove "doc/" from 'helpfile', if present */
      if (p == p_hf)
        pend = remove_tail(p, pend, (char_u *)"doc");

#ifdef USE_EXE_NAME
      /* remove "src/" from exe_name, if present */
      if (p == exe_name)
        pend = remove_tail(p, pend, (char_u *)"src");
#endif

      /* for $VIM, remove "runtime/" or "vim54/", if present */
      if (!vimruntime) {
        pend = remove_tail(p, pend, (char_u *)RUNTIME_DIRNAME);
        pend = remove_tail(p, pend, (char_u *)VIM_VERSION_NODOT);
      }

      /* remove trailing path separator */
      /* With MacOS path (with  colons) the final colon is required */
      /* to avoid confusion between absolute and relative path */
      if (pend > p && after_pathsep(p, pend))
        --pend;

      /* check that the result is a directory name */
      p = vim_strnsave(p, (int)(pend - p));

      if (p != NULL && !os_isdir(p)) {
        vim_free(p);
        p = NULL;
      } else {
#ifdef USE_EXE_NAME
        /* may add "/vim54" or "/runtime" if it exists */
        if (vimruntime && (pend = vim_version_dir(p)) != NULL) {
          vim_free(p);
          p = pend;
        }
#endif
        *mustfree = TRUE;
      }
    }
  }

#ifdef HAVE_PATHDEF
  /* When there is a pathdef.c file we can use default_vim_dir and
   * default_vimruntime_dir */
  if (p == NULL) {
    /* Only use default_vimruntime_dir when it is not empty */
    if (vimruntime && *default_vimruntime_dir != NUL) {
      p = default_vimruntime_dir;
      *mustfree = FALSE;
    } else if (*default_vim_dir != NUL) {
      if (vimruntime && (p = vim_version_dir(default_vim_dir)) != NULL)
        *mustfree = TRUE;
      else {
        p = default_vim_dir;
        *mustfree = FALSE;
      }
    }
  }
#endif

  /*
   * Set the environment variable, so that the new value can be found fast
   * next time, and others can also use it (e.g. Perl).
   */
  if (p != NULL) {
    if (vimruntime) {
      vim_setenv((char_u *)"VIMRUNTIME", p);
      didset_vimruntime = TRUE;
    } else {
      vim_setenv((char_u *)"VIM", p);
      didset_vim = TRUE;
    }
  }
  return p;
}

/*
 * Check if the directory "vimdir/<version>" or "vimdir/runtime" exists.
 * Return NULL if not, return its name in allocated memory otherwise.
 */
static char_u *vim_version_dir(char_u *vimdir)
{
  char_u      *p;

  if (vimdir == NULL || *vimdir == NUL)
    return NULL;
  p = concat_fnames(vimdir, (char_u *)VIM_VERSION_NODOT, TRUE);
  if (p != NULL && os_isdir(p))
    return p;
  vim_free(p);
  p = concat_fnames(vimdir, (char_u *)RUNTIME_DIRNAME, TRUE);
  if (p != NULL && os_isdir(p))
    return p;
  vim_free(p);
  return NULL;
}

/*
 * If the string between "p" and "pend" ends in "name/", return "pend" minus
 * the length of "name/".  Otherwise return "pend".
 */
static char_u *remove_tail(char_u *p, char_u *pend, char_u *name)
{
  int len = (int)STRLEN(name) + 1;
  char_u      *newend = pend - len;

  if (newend >= p
      && fnamencmp(newend, name, len - 1) == 0
      && (newend == p || after_pathsep(p, newend)))
    return newend;
  return pend;
}

/*
 * Our portable version of setenv.
 */
void vim_setenv(char_u *name, char_u *val)
{
  os_setenv((char *)name, (char *)val, 1);
  /*
   * When setting $VIMRUNTIME adjust the directory to find message
   * translations to $VIMRUNTIME/lang.
   */
  if (*val != NUL && STRICMP(name, "VIMRUNTIME") == 0) {
    char_u  *buf = concat_str(val, (char_u *)"/lang");

    if (buf != NULL) {
      bindtextdomain(VIMPACKAGE, (char *)buf);
      vim_free(buf);
    }
  }
}


/*
 * Function given to ExpandGeneric() to obtain an environment variable name.
 */
char_u *get_env_name(expand_T *xp, int idx)
{
# define ENVNAMELEN 100
  // this static buffer is needed to avoid a memory leak in ExpandGeneric
  static char_u name[ENVNAMELEN];
  char *envname = os_getenvname_at_index(idx);
  if (envname) {
    vim_strncpy(name, (char_u *)envname, ENVNAMELEN - 1);
    vim_free(envname);
    return name;
  } else {
    return NULL;
  }
}

/*
 * Find all user names for user completion.
 * Done only once and then cached.
 */
static void init_users(void)
{
  static int lazy_init_done = FALSE;

  if (lazy_init_done) {
    return;
  }

  lazy_init_done = TRUE;
  
  os_get_usernames(&ga_users);
}

/*
 * Function given to ExpandGeneric() to obtain an user names.
 */
char_u *get_users(expand_T *xp, int idx)
{
  init_users();
  if (idx < ga_users.ga_len)
    return ((char_u **)ga_users.ga_data)[idx];
  return NULL;
}

/*
 * Check whether name matches a user name. Return:
 * 0 if name does not match any user name.
 * 1 if name partially matches the beginning of a user name.
 * 2 is name fully matches a user name.
 */
int match_user(char_u *name)
{
  int i;
  int n = (int)STRLEN(name);
  int result = 0;

  init_users();
  for (i = 0; i < ga_users.ga_len; i++) {
    if (STRCMP(((char_u **)ga_users.ga_data)[i], name) == 0)
      return 2;       /* full match */
    if (STRNCMP(((char_u **)ga_users.ga_data)[i], name, n) == 0)
      result = 1;       /* partial match */
  }
  return result;
}

/*
 * Replace home directory by "~" in each space or comma separated file name in
 * 'src'.
 * If anything fails (except when out of space) dst equals src.
 */
void 
home_replace (
    buf_T *buf,       /* when not NULL, check for help files */
    char_u *src,       /* input file name */
    char_u *dst,       /* where to put the result */
    int dstlen,             /* maximum length of the result */
    int one                /* if TRUE, only replace one file name, include
                           spaces and commas in the file name. */
)
{
  size_t dirlen = 0, envlen = 0;
  size_t len;
  char_u      *homedir_env, *homedir_env_orig;
  char_u      *p;

  if (src == NULL) {
    *dst = NUL;
    return;
  }

  /*
   * If the file is a help file, remove the path completely.
   */
  if (buf != NULL && buf->b_help) {
    STRCPY(dst, path_tail(src));
    return;
  }

  /*
   * We check both the value of the $HOME environment variable and the
   * "real" home directory.
   */
  if (homedir != NULL)
    dirlen = STRLEN(homedir);

  homedir_env_orig = homedir_env = (char_u *)os_getenv("HOME");
  /* Empty is the same as not set. */
  if (homedir_env != NULL && *homedir_env == NUL)
    homedir_env = NULL;

  if (homedir_env != NULL && vim_strchr(homedir_env, '~') != NULL) {
    int usedlen = 0;
    int flen;
    char_u  *fbuf = NULL;

    flen = (int)STRLEN(homedir_env);
    (void)modify_fname((char_u *)":p", &usedlen,
        &homedir_env, &fbuf, &flen);
    flen = (int)STRLEN(homedir_env);
    if (flen > 0 && vim_ispathsep(homedir_env[flen - 1]))
      /* Remove the trailing / that is added to a directory. */
      homedir_env[flen - 1] = NUL;
  }

  if (homedir_env != NULL)
    envlen = STRLEN(homedir_env);

  if (!one)
    src = skipwhite(src);
  while (*src && dstlen > 0) {
    /*
     * Here we are at the beginning of a file name.
     * First, check to see if the beginning of the file name matches
     * $HOME or the "real" home directory. Check that there is a '/'
     * after the match (so that if e.g. the file is "/home/pieter/bla",
     * and the home directory is "/home/piet", the file does not end up
     * as "~er/bla" (which would seem to indicate the file "bla" in user
     * er's home directory)).
     */
    p = homedir;
    len = dirlen;
    for (;; ) {
      if (   len
             && fnamencmp(src, p, len) == 0
             && (vim_ispathsep(src[len])
                 || (!one && (src[len] == ',' || src[len] == ' '))
                 || src[len] == NUL)) {
        src += len;
        if (--dstlen > 0)
          *dst++ = '~';

        /*
         * If it's just the home directory, add  "/".
         */
        if (!vim_ispathsep(src[0]) && --dstlen > 0)
          *dst++ = '/';
        break;
      }
      if (p == homedir_env)
        break;
      p = homedir_env;
      len = envlen;
    }

    /* if (!one) skip to separator: space or comma */
    while (*src && (one || (*src != ',' && *src != ' ')) && --dstlen > 0)
      *dst++ = *src++;
    /* skip separator */
    while ((*src == ' ' || *src == ',') && --dstlen > 0)
      *dst++ = *src++;
  }
  /* if (dstlen == 0) out of space, what to do??? */

  *dst = NUL;

  if (homedir_env != homedir_env_orig)
    vim_free(homedir_env);
}

/*
 * Like home_replace, store the replaced string in allocated memory.
 * When something fails, NULL is returned.
 */
char_u *
home_replace_save (
    buf_T *buf,       /* when not NULL, check for help files */
    char_u *src       /* input file name */
)
{
  char_u      *dst;
  unsigned len;

  len = 3;                      /* space for "~/" and trailing NUL */
  if (src != NULL)              /* just in case */
    len += (unsigned)STRLEN(src);
  dst = alloc(len);
  home_replace(buf, src, dst, len, TRUE);
  return dst;
}

void prepare_to_exit(void)
{
#if defined(SIGHUP) && defined(SIG_IGN)
  /* Ignore SIGHUP, because a dropped connection causes a read error, which
   * makes Vim exit and then handling SIGHUP causes various reentrance
   * problems. */
  signal(SIGHUP, SIG_IGN);
#endif

  {
    windgoto((int)Rows - 1, 0);

    /*
     * Switch terminal mode back now, so messages end up on the "normal"
     * screen (if there are two screens).
     */
    settmode(TMODE_COOK);
    stoptermcap();
    out_flush();
  }
}

/*
 * Preserve files and exit.
 * When called IObuff must contain a message.
 * NOTE: This may be called from deathtrap() in a signal handler, avoid unsafe
 * functions, such as allocating memory.
 */
void preserve_exit(void)
{
  buf_T       *buf;

  prepare_to_exit();

  /* Setting this will prevent free() calls.  That avoids calling free()
   * recursively when free() was invoked with a bad pointer. */
  really_exiting = TRUE;

  out_str(IObuff);
  screen_start();                   /* don't know where cursor is now */
  out_flush();

  ml_close_notmod();                /* close all not-modified buffers */

  for (buf = firstbuf; buf != NULL; buf = buf->b_next) {
    if (buf->b_ml.ml_mfp != NULL && buf->b_ml.ml_mfp->mf_fname != NULL) {
      OUT_STR("Vim: preserving files...\n");
      screen_start();               /* don't know where cursor is now */
      out_flush();
      ml_sync_all(FALSE, FALSE);        /* preserve all swap files */
      break;
    }
  }

  ml_close_all(FALSE);              /* close all memfiles, without deleting */

  OUT_STR("Vim: Finished.\n");

  getout(1);
}

/*
 * Check for CTRL-C pressed, but only once in a while.
 * Should be used instead of ui_breakcheck() for functions that check for
 * each line in the file.  Calling ui_breakcheck() each time takes too much
 * time, because it can be a system call.
 */

#ifndef BREAKCHECK_SKIP
#  define BREAKCHECK_SKIP 32
#endif

static int breakcheck_count = 0;

void line_breakcheck(void)
{
  if (++breakcheck_count >= BREAKCHECK_SKIP) {
    breakcheck_count = 0;
    ui_breakcheck();
  }
}

/*
 * Like line_breakcheck() but check 10 times less often.
 */
void fast_breakcheck(void)
{
  if (++breakcheck_count >= BREAKCHECK_SKIP * 10) {
    breakcheck_count = 0;
    ui_breakcheck();
  }
}

#ifndef SEEK_SET
# define SEEK_SET 0
#endif
#ifndef SEEK_END
# define SEEK_END 2
#endif

/*
 * Get the stdout of an external command.
 * Returns an allocated string, or NULL for error.
 */
char_u *
get_cmd_output (
    char_u *cmd,
    char_u *infile,            /* optional input file name */
    int flags                      /* can be SHELL_SILENT */
)
{
  char_u      *tempname;
  char_u      *command;
  char_u      *buffer = NULL;
  int len;
  int i = 0;
  FILE        *fd;

  if (check_restricted() || check_secure())
    return NULL;

  /* get a name for the temp file */
  if ((tempname = vim_tempname('o')) == NULL) {
    EMSG(_(e_notmp));
    return NULL;
  }

  /* Add the redirection stuff */
  command = make_filter_cmd(cmd, infile, tempname);
  if (command == NULL)
    goto done;

  /*
   * Call the shell to execute the command (errors are ignored).
   * Don't check timestamps here.
   */
  ++no_check_timestamps;
  call_shell(command, kShellOptDoOut | kShellOptExpand | flags, NULL);
  --no_check_timestamps;

  vim_free(command);

  /*
   * read the names from the file into memory
   */
  fd = mch_fopen((char *)tempname, READBIN);

  if (fd == NULL) {
    EMSG2(_(e_notopen), tempname);
    goto done;
  }

  fseek(fd, 0L, SEEK_END);
  len = ftell(fd);                  /* get size of temp file */
  fseek(fd, 0L, SEEK_SET);

  buffer = alloc(len + 1);
  i = (int)fread((char *)buffer, (size_t)1, (size_t)len, fd);
  fclose(fd);
  os_remove((char *)tempname);
  if (buffer == NULL)
    goto done;
  if (i != len) {
    EMSG2(_(e_notread), tempname);
    vim_free(buffer);
    buffer = NULL;
  } else {
    /* Change NUL into SOH, otherwise the string is truncated. */
    for (i = 0; i < len; ++i)
      if (buffer[i] == NUL)
        buffer[i] = 1;

    buffer[len] = NUL;          /* make sure the buffer is terminated */
  }

done:
  vim_free(tempname);
  return buffer;
}

/*
 * Free the list of files returned by expand_wildcards() or other expansion
 * functions.
 */
void FreeWild(int count, char_u **files)
{
  if (count <= 0 || files == NULL)
    return;
  while (count--)
    vim_free(files[count]);
  vim_free(files);
}

/*
 * Return TRUE when need to go to Insert mode because of 'insertmode'.
 * Don't do this when still processing a command or a mapping.
 * Don't do this when inside a ":normal" command.
 */
int goto_im(void)
{
  return p_im && stuff_empty() && typebuf_typed();
}