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textbox.c

/*
 *  textbox.c -- implements the text box
 *
 *  ORIGINAL AUTHOR: Savio Lam (lam836@cs.cuhk.hk)
 *  MODIFIED FOR LINUX KERNEL CONFIG BY: William Roadcap (roadcap@cfw.com)
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version 2
 *  of the License, or (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include "dialog.h"

static void back_lines (int n);
static void print_page (WINDOW * win, int height, int width);
static void print_line (WINDOW * win, int row, int width);
static char *get_line (void);
static void print_position (WINDOW * win, int height, int width);

static int hscroll, fd, file_size, bytes_read;
static int begin_reached = 1, end_reached, page_length;
static char *buf, *page;

/*
 * Display text from a file in a dialog box.
 */
int
dialog_textbox (const char *title, const char *file, int height, int width)
{
    int i, x, y, cur_x, cur_y, fpos, key = 0;
    int passed_end;
    char search_term[MAX_LEN + 1];
    WINDOW *dialog, *text;

    search_term[0] = '\0';    /* no search term entered yet */

    /* Open input file for reading */
    if ((fd = open (file, O_RDONLY)) == -1) {
      endwin ();
      fprintf (stderr,
             "\nCan't open input file in dialog_textbox().\n");
      exit (-1);
    }
    /* Get file size. Actually, 'file_size' is the real file size - 1,
       since it's only the last byte offset from the beginning */
    if ((file_size = lseek (fd, 0, SEEK_END)) == -1) {
      endwin ();
      fprintf (stderr, "\nError getting file size in dialog_textbox().\n");
      exit (-1);
    }
    /* Restore file pointer to beginning of file after getting file size */
    if (lseek (fd, 0, SEEK_SET) == -1) {
      endwin ();
      fprintf (stderr, "\nError moving file pointer in dialog_textbox().\n");
      exit (-1);
    }
    /* Allocate space for read buffer */
    if ((buf = malloc (BUF_SIZE + 1)) == NULL) {
      endwin ();
      fprintf (stderr, "\nCan't allocate memory in dialog_textbox().\n");
      exit (-1);
    }
    if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {
      endwin ();
      fprintf (stderr, "\nError reading file in dialog_textbox().\n");
      exit (-1);
    }
    buf[bytes_read] = '\0';   /* mark end of valid data */
    page = buf;               /* page is pointer to start of page to be displayed */

    /* center dialog box on screen */
    x = (COLS - width) / 2;
    y = (LINES - height) / 2;


    draw_shadow (stdscr, y, x, height, width);

    dialog = newwin (height, width, y, x);
    keypad (dialog, TRUE);

    /* Create window for text region, used for scrolling text */
    text = subwin (dialog, height - 4, width - 2, y + 1, x + 1);
    wattrset (text, dialog_attr);
    wbkgdset (text, dialog_attr & A_COLOR);

    keypad (text, TRUE);

    /* register the new window, along with its borders */
    draw_box (dialog, 0, 0, height, width, dialog_attr, border_attr);

    wattrset (dialog, border_attr);
    mvwaddch (dialog, height-3, 0, ACS_LTEE);
    for (i = 0; i < width - 2; i++)
      waddch (dialog, ACS_HLINE);
    wattrset (dialog, dialog_attr);
    wbkgdset (dialog, dialog_attr & A_COLOR);
    waddch (dialog, ACS_RTEE);

    if (title != NULL && strlen(title) >= width-2 ) {
      /* truncate long title -- mec */
      char * title2 = malloc(width-2+1);
      memcpy( title2, title, width-2 );
      title2[width-2] = '\0';
      title = title2;
    }

    if (title != NULL) {
      wattrset (dialog, title_attr);
      mvwaddch (dialog, 0, (width - strlen(title))/2 - 1, ' ');
      waddstr (dialog, (char *)title);
      waddch (dialog, ' ');
    }
    print_button (dialog, " Exit ", height - 2, width / 2 - 4, TRUE);
    wnoutrefresh (dialog);
    getyx (dialog, cur_y, cur_x);   /* Save cursor position */

    /* Print first page of text */
    attr_clear (text, height - 4, width - 2, dialog_attr);
    print_page (text, height - 4, width - 2);
    print_position (dialog, height, width);
    wmove (dialog, cur_y, cur_x);   /* Restore cursor position */
    wrefresh (dialog);

    while ((key != ESC) && (key != '\n')) {
      key = wgetch (dialog);
      switch (key) {
      case 'E':         /* Exit */
      case 'e':
      case 'X':
      case 'x':
          delwin (dialog);
          free (buf);
          close (fd);
          return 0;
      case 'g':         /* First page */
      case KEY_HOME:
          if (!begin_reached) {
            begin_reached = 1;
            /* First page not in buffer? */
            if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {
                endwin ();
                fprintf (stderr,
                  "\nError moving file pointer in dialog_textbox().\n");
                exit (-1);
            }
            if (fpos > bytes_read) {      /* Yes, we have to read it in */
                if (lseek (fd, 0, SEEK_SET) == -1) {
                  endwin ();
                  fprintf (stderr, "\nError moving file pointer in "
                         "dialog_textbox().\n");
                  exit (-1);
                }
                if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {
                  endwin ();
                  fprintf (stderr,
                       "\nError reading file in dialog_textbox().\n");
                  exit (-1);
                }
                buf[bytes_read] = '\0';
            }
            page = buf;
            print_page (text, height - 4, width - 2);
            print_position (dialog, height, width);
            wmove (dialog, cur_y, cur_x); /* Restore cursor position */
            wrefresh (dialog);
          }
          break;
      case 'G':         /* Last page */
      case KEY_END:

          end_reached = 1;
          /* Last page not in buffer? */
          if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {
            endwin ();
            fprintf (stderr,
                  "\nError moving file pointer in dialog_textbox().\n");
            exit (-1);
          }
          if (fpos < file_size) {   /* Yes, we have to read it in */
            if (lseek (fd, -BUF_SIZE, SEEK_END) == -1) {
                endwin ();
                fprintf (stderr,
                  "\nError moving file pointer in dialog_textbox().\n");
                exit (-1);
            }
            if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {
                endwin ();
                fprintf (stderr,
                       "\nError reading file in dialog_textbox().\n");
                exit (-1);
            }
            buf[bytes_read] = '\0';
          }
          page = buf + bytes_read;
          back_lines (height - 4);
          print_page (text, height - 4, width - 2);
          print_position (dialog, height, width);
          wmove (dialog, cur_y, cur_x);   /* Restore cursor position */
          wrefresh (dialog);
          break;
      case 'K':         /* Previous line */
      case 'k':
      case KEY_UP:
          if (!begin_reached) {
            back_lines (page_length + 1);

            /* We don't call print_page() here but use scrolling to ensure
               faster screen update. However, 'end_reached' and
               'page_length' should still be updated, and 'page' should
               point to start of next page. This is done by calling
               get_line() in the following 'for' loop. */
            scrollok (text, TRUE);
            wscrl (text, -1); /* Scroll text region down one line */
            scrollok (text, FALSE);
            page_length = 0;
            passed_end = 0;
            for (i = 0; i < height - 4; i++) {
                if (!i) {
                  /* print first line of page */
                  print_line (text, 0, width - 2);
                  wnoutrefresh (text);
                } else
                  /* Called to update 'end_reached' and 'page' */
                  get_line ();
                if (!passed_end)
                  page_length++;
                if (end_reached && !passed_end)
                  passed_end = 1;
            }

            print_position (dialog, height, width);
            wmove (dialog, cur_y, cur_x); /* Restore cursor position */
            wrefresh (dialog);
          }
          break;
      case 'B':         /* Previous page */
      case 'b':
      case KEY_PPAGE:
          if (begin_reached)
            break;
          back_lines (page_length + height - 4);
          print_page (text, height - 4, width - 2);
          print_position (dialog, height, width);
          wmove (dialog, cur_y, cur_x);
          wrefresh (dialog);
          break;
      case 'J':         /* Next line */
      case 'j':
      case KEY_DOWN:
          if (!end_reached) {
            begin_reached = 0;
            scrollok (text, TRUE);
            scroll (text);    /* Scroll text region up one line */
            scrollok (text, FALSE);
            print_line (text, height - 5, width - 2);
            wnoutrefresh (text);
            print_position (dialog, height, width);
            wmove (dialog, cur_y, cur_x); /* Restore cursor position */
            wrefresh (dialog);
          }
          break;
      case KEY_NPAGE:         /* Next page */
      case ' ':
          if (end_reached)
            break;

          begin_reached = 0;
          print_page (text, height - 4, width - 2);
          print_position (dialog, height, width);
          wmove (dialog, cur_y, cur_x);
          wrefresh (dialog);
          break;
      case '0':         /* Beginning of line */
      case 'H':         /* Scroll left */
      case 'h':
      case KEY_LEFT:
          if (hscroll <= 0)
            break;

          if (key == '0')
            hscroll = 0;
          else
            hscroll--;
          /* Reprint current page to scroll horizontally */
          back_lines (page_length);
          print_page (text, height - 4, width - 2);
          wmove (dialog, cur_y, cur_x);
          wrefresh (dialog);
          break;
      case 'L':         /* Scroll right */
      case 'l':
      case KEY_RIGHT:
          if (hscroll >= MAX_LEN)
            break;
          hscroll++;
          /* Reprint current page to scroll horizontally */
          back_lines (page_length);
          print_page (text, height - 4, width - 2);
          wmove (dialog, cur_y, cur_x);
          wrefresh (dialog);
          break;
      case ESC:
          break;
      }
    }

    delwin (dialog);
    free (buf);
    close (fd);
    return 1;                 /* ESC pressed */
}

/*
 * Go back 'n' lines in text file. Called by dialog_textbox().
 * 'page' will be updated to point to the desired line in 'buf'.
 */
static void
back_lines (int n)
{
    int i, fpos;

    begin_reached = 0;
    /* We have to distinguish between end_reached and !end_reached
       since at end of file, the line is not ended by a '\n'.
       The code inside 'if' basically does a '--page' to move one
       character backward so as to skip '\n' of the previous line */
    if (!end_reached) {
      /* Either beginning of buffer or beginning of file reached? */
      if (page == buf) {
          if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {
            endwin ();
            fprintf (stderr, "\nError moving file pointer in "
                   "back_lines().\n");
            exit (-1);
          }
          if (fpos > bytes_read) {  /* Not beginning of file yet */
            /* We've reached beginning of buffer, but not beginning of
               file yet, so read previous part of file into buffer.
               Note that we only move backward for BUF_SIZE/2 bytes,
               but not BUF_SIZE bytes to avoid re-reading again in
               print_page() later */
            /* Really possible to move backward BUF_SIZE/2 bytes? */
            if (fpos < BUF_SIZE / 2 + bytes_read) {
                /* No, move less then */
                if (lseek (fd, 0, SEEK_SET) == -1) {
                  endwin ();
                  fprintf (stderr, "\nError moving file pointer in "
                         "back_lines().\n");
                  exit (-1);
                }
                page = buf + fpos - bytes_read;
            } else {    /* Move backward BUF_SIZE/2 bytes */
                if (lseek (fd, -(BUF_SIZE / 2 + bytes_read), SEEK_CUR)
                  == -1) {
                  endwin ();
                  fprintf (stderr, "\nError moving file pointer "
                         "in back_lines().\n");
                  exit (-1);
                }
                page = buf + BUF_SIZE / 2;
            }
            if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {
                endwin ();
                fprintf (stderr, "\nError reading file in back_lines().\n");
                exit (-1);
            }
            buf[bytes_read] = '\0';
          } else {            /* Beginning of file reached */
            begin_reached = 1;
            return;
          }
      }
      if (*(--page) != '\n') {      /* '--page' here */
          /* Something's wrong... */
          endwin ();
          fprintf (stderr, "\nInternal error in back_lines().\n");
          exit (-1);
      }
    }
    /* Go back 'n' lines */
    for (i = 0; i < n; i++)
      do {
          if (page == buf) {
            if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {
                endwin ();
                fprintf (stderr,
                    "\nError moving file pointer in back_lines().\n");
                exit (-1);
            }
            if (fpos > bytes_read) {
                /* Really possible to move backward BUF_SIZE/2 bytes? */
                if (fpos < BUF_SIZE / 2 + bytes_read) {
                  /* No, move less then */
                  if (lseek (fd, 0, SEEK_SET) == -1) {
                      endwin ();
                      fprintf (stderr, "\nError moving file pointer "
                             "in back_lines().\n");
                      exit (-1);
                  }
                  page = buf + fpos - bytes_read;
                } else {      /* Move backward BUF_SIZE/2 bytes */
                  if (lseek (fd, -(BUF_SIZE / 2 + bytes_read),
                           SEEK_CUR) == -1) {
                      endwin ();
                      fprintf (stderr, "\nError moving file pointer"
                             " in back_lines().\n");
                      exit (-1);
                  }
                  page = buf + BUF_SIZE / 2;
                }
                if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {
                  endwin ();
                  fprintf (stderr, "\nError reading file in "
                         "back_lines().\n");
                  exit (-1);
                }
                buf[bytes_read] = '\0';
            } else {    /* Beginning of file reached */
                begin_reached = 1;
                return;
            }
          }
      } while (*(--page) != '\n');
    page++;
}

/*
 * Print a new page of text. Called by dialog_textbox().
 */
static void
print_page (WINDOW * win, int height, int width)
{
    int i, passed_end = 0;

    page_length = 0;
    for (i = 0; i < height; i++) {
      print_line (win, i, width);
      if (!passed_end)
          page_length++;
      if (end_reached && !passed_end)
          passed_end = 1;
    }
    wnoutrefresh (win);
}

/*
 * Print a new line of text. Called by dialog_textbox() and print_page().
 */
static void
print_line (WINDOW * win, int row, int width)
{
    int y, x;
    char *line;

    line = get_line ();
    line += MIN (strlen (line), hscroll); /* Scroll horizontally */
    wmove (win, row, 0);      /* move cursor to correct line */
    waddch (win, ' ');
    waddnstr (win, line, MIN (strlen (line), width - 2));

    getyx (win, y, x);
    /* Clear 'residue' of previous line */
#if OLD_NCURSES
    {
        int i;
        for (i = 0; i < width - x; i++)
          waddch (win, ' ');
    }
#else
    wclrtoeol(win);
#endif
}

/*
 * Return current line of text. Called by dialog_textbox() and print_line().
 * 'page' should point to start of current line before calling, and will be
 * updated to point to start of next line.
 */
static char *
get_line (void)
{
    int i = 0, fpos;
    static char line[MAX_LEN + 1];

    end_reached = 0;
    while (*page != '\n') {
      if (*page == '\0') {
          /* Either end of file or end of buffer reached */
          if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {
            endwin ();
            fprintf (stderr, "\nError moving file pointer in "
                   "get_line().\n");
            exit (-1);
          }
          if (fpos < file_size) {   /* Not end of file yet */
            /* We've reached end of buffer, but not end of file yet,
               so read next part of file into buffer */
            if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {
                endwin ();
                fprintf (stderr, "\nError reading file in get_line().\n");
                exit (-1);
            }
            buf[bytes_read] = '\0';
            page = buf;
          } else {
            if (!end_reached)
                end_reached = 1;
            break;
          }
      } else if (i < MAX_LEN)
          line[i++] = *(page++);
      else {
          /* Truncate lines longer than MAX_LEN characters */
          if (i == MAX_LEN)
            line[i++] = '\0';
          page++;
      }
    }
    if (i <= MAX_LEN)
      line[i] = '\0';
    if (!end_reached)
      page++;                 /* move pass '\n' */

    return line;
}

/*
 * Print current position
 */
static void
print_position (WINDOW * win, int height, int width)
{
    int fpos, percent;

    if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {
      endwin ();
      fprintf (stderr, "\nError moving file pointer in print_position().\n");
      exit (-1);
    }
    wattrset (win, position_indicator_attr);
    wbkgdset (win, position_indicator_attr & A_COLOR);
    percent = !file_size ?
      100 : ((fpos - bytes_read + page - buf) * 100) / file_size;
    wmove (win, height - 3, width - 9);
    wprintw (win, "(%3d%%)", percent);
}

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