mined2.c

操作系统源代码

/* Decrement nlines */
  nlines--;

  return next_line;
}

/*
 * Delete() deletes all the characters (including newlines) between the
 * startposition and endposition and fixes the screen accordingly. It
 * returns the number of lines deleted.
 */
void delete(start_line, start_textp, end_line, end_textp)
register LINE *start_line;
LINE *end_line;
char *start_textp, *end_textp;
{
  register char *textp = start_line->text;
  register char *bufp = text_buffer;	/* Storage for new line->text */
  LINE *line, *stop;
  int line_cnt = 0;			/* Nr of lines deleted */
  int count = 0;
  int shift = 0;				/* Used in shift calculation */
  int nx = x;

  modified = TRUE;			/* File has been modified */

/* Set up new line. Copy first part of start line until start_position. */
  while (textp < start_textp) {
  	*bufp++ = *textp++;
  	count++;
  }

/* Check if line doesn't exceed MAX_CHARS */
  if (count + length_of(end_textp) >= MAX_CHARS) {
  	error("Line too long", NIL_PTR);
  	return;
  }

/* Copy last part of end_line if end_line is not tail */
  copy_string(bufp, (end_textp != NIL_PTR) ? end_textp : "\n");

/* Delete all lines between start and end_position (including end_line) */
  line = start_line->next;
  stop = end_line->next;
  while (line != stop && line != tail) {
  	line = line_delete(line);
  	line_cnt++;
  }

/* Check if last line of file should be deleted */
  if (end_textp == NIL_PTR && length_of(start_line->text) == 1 && nlines > 1) {
  	start_line = start_line->prev;
  	(void) line_delete(start_line->next);
  	line_cnt++;
  }
  else {	/* Install new text */
  	free_space(start_line->text);
  	start_line->text = alloc(length_of(text_buffer) + 1);
  	copy_string(start_line->text, text_buffer);
  }

/* Fix screen. First check if line is shifted. Perhaps we should shift it back*/
  if (get_shift(start_line->shift_count)) {
  	shift = (XBREAK - count_chars(start_line)) / SHIFT_SIZE;
  	if (shift > 0) {		/* Shift line `shift' back */
  		if (shift >= get_shift(start_line->shift_count))
  			start_line->shift_count = 0;
  		else
  			start_line->shift_count -= shift;
  		nx += shift * SHIFT_SIZE;/* Reset x value */
  	}
  }

  if (line_cnt == 0) {		    /* Check if only one line changed */
  	if (shift > 0) {	    /* Reprint whole line */
  		set_cursor(0, y);
  		line_print(start_line);
  	}
  	else {			    /* Just display last part of line */
  		set_cursor(x, y);
  		put_line(start_line, x, TRUE);
  	}
  	move_to(nx, y);	   /* Reset cur_text */
  	return;
  }

  shift = last_y;	   /* Save value */
  reset(top_line, y);
  display(0, y, start_line, shift - y);
  move_to((line_cnt == 1) ? nx : 0, y);
}

/*  ========================================================================  *
 *				Yank Commands				      *	
 *  ========================================================================  */

LINE *mark_line;			/* For marking position. */
char *mark_text;
int lines_saved;			/* Nr of lines in buffer */

/*
 * PT() inserts the buffer at the current location.
 */
void PT()
{
  register int fd;		/* File descriptor for buffer */

  if ((fd = scratch_file(READ)) == ERRORS)
  	error("Buffer is empty.", NIL_PTR);
  else {
  	file_insert(fd, FALSE);/* Insert the buffer */
  	(void) close(fd);
  }
}

/*
 * IF() prompt for a filename and inserts the file at the current location 
 * in the file.
 */
void IF()
{
  register int fd;		/* File descriptor of file */
  char name[LINE_LEN];		/* Buffer for file name */

/* Get the file name */
  if (get_file("Get and insert file:", name) != FINE)
  	return;
  
  if ((fd = open(name, 0)) < 0)
  	error("Cannot open ", name);
  else {
  	file_insert(fd, TRUE);	/* Insert the file */
  	(void) close(fd);
  }
}

/*
 * File_insert() inserts a an opened file (as given by filedescriptor fd)
 * at the current location.
 */
void file_insert(fd, old_pos)
int fd;
FLAG old_pos;
{
  char line_buffer[MAX_CHARS];		/* Buffer for next line */
  register LINE *line = cur_line;
  register int line_count = nlines;	/* Nr of lines inserted */
  LINE *page = cur_line;
  int ret = ERRORS;
  
/* Get the first piece of text (might be ended with a '\n') from fd */
  if (get_line(fd, line_buffer) == ERRORS)
  	return;				/* Empty file */

/* Insert this text at the current location. */
  if (insert(line, cur_text, line_buffer) == ERRORS)
  	return;

/* Repeat getting lines (and inserting lines) until EOF is reached */
  while ((ret = get_line(fd, line_buffer)) != ERRORS && ret != NO_LINE)
  	line = line_insert(line, line_buffer, ret);
  
  if (ret == NO_LINE) {		/* Last line read not ended by a '\n' */
  	line = line->next;
  	(void) insert(line, line->text, line_buffer);
  }

/* Calculate nr of lines added */
  line_count = nlines - line_count;

/* Fix the screen */
  if (line_count == 0) {		/* Only one line changed */
  	set_cursor(0, y);
  	line_print(line);
  	move_to((old_pos == TRUE) ? x : x + length_of(line_buffer), y);
  }
  else {				/* Several lines changed */
  	reset(top_line, y);	/* Reset pointers */
  	while (page != line && page != bot_line->next)
  		page = page->next;
  	if (page != bot_line->next || old_pos == TRUE)
  		display(0, y, cur_line, screenmax - y);
  	if (old_pos == TRUE)
  		move_to(x, y);
  	else if (ret == NO_LINE)
		move_to(length_of(line_buffer), find_y(line));
	else 
		move_to(0, find_y(line->next));
  }

/* If nr of added line >= REPORT, print the count */
  if (line_count >= REPORT)
  	status_line(num_out((long) line_count), " lines added.");
}

/*
 * WB() writes the buffer (yank_file) into another file, which
 * is prompted for.
 */
void WB()
{
  register int new_fd;		/* Filedescriptor to copy file */
  int yank_fd;			/* Filedescriptor to buffer */
  register int cnt;		/* Count check for read/write */
  int ret = 0;			/* Error check for write */
  char file[LINE_LEN];		/* Output file */
  
/* Checkout the buffer */
  if ((yank_fd = scratch_file(READ)) == ERRORS) {
  	error("Buffer is empty.", NIL_PTR);
  	return;
  }

/* Get file name */
  if (get_file("Write buffer to file:", file) != FINE)
  	return;
  
/* Creat the new file */
  if ((new_fd = creat(file, 0644)) < 0) {
  	error("Cannot create ", file);
  	return;
  }

  status_line("Writing ", file);
  
/* Copy buffer into file */
  while ((cnt = read(yank_fd, text_buffer, sizeof(text_buffer))) > 0)
  	if (write(new_fd, text_buffer, cnt) != cnt) {
  		bad_write(new_fd);
  		ret = ERRORS;
  		break;
  	}

/* Clean up open files and status_line */
  (void) close(new_fd);
  (void) close(yank_fd);

  if (ret != ERRORS)			/* Bad write */
  	file_status("Wrote", chars_saved, file, lines_saved, TRUE, FALSE);
}

/*
 * MA sets mark_line (mark_text) to the current line (text pointer). 
 */
void MA()
{
  mark_line = cur_line;
  mark_text = cur_text;
  status_line("Mark set", NIL_PTR);
}

/*
 * YA() puts the text between the marked position and the current
 * in the buffer.
 */
void YA()
{
  set_up(NO_DELETE);
}

/*
 * DT() is essentially the same as YA(), but in DT() the text is deleted.
 */
void DT()
{
  set_up(DELETE);
}

/*
 * Set_up is an interface to the actual yank. It calls checkmark () to check
 * if the marked position is still valid. If it is, yank is called with the
 * arguments in the right order.
 */
void set_up(remove)
FLAG remove;				/* DELETE if text should be deleted */
{
  switch (checkmark()) {
  	case NOT_VALID :
  		error("Mark not set.", NIL_PTR);
  		return;
  	case SMALLER :
  		yank(mark_line, mark_text, cur_line, cur_text, remove);
  		break;
  	case BIGGER :
  		yank(cur_line, cur_text, mark_line, mark_text, remove);
  		break;
  	case SAME :		/* Ignore stupid behaviour */
  		yank_status = EMPTY;
  		chars_saved = 0L;
  		status_line("0 characters saved in buffer.", NIL_PTR);
  		break;
  }
}

/*
 * Check_mark() checks if mark_line and mark_text are still valid pointers. If
 * they are it returns SMALLER if the marked position is before the current,
 * BIGGER if it isn't or SAME if somebody didn't get the point.
 * NOT_VALID is returned when mark_line and/or mark_text are no longer valid.
 * Legal() checks if mark_text is valid on the mark_line.
 */
FLAG checkmark()
{
  register LINE *line;
  FLAG cur_seen = FALSE;

/* Special case: check is mark_line and cur_line are the same. */
  if (mark_line == cur_line) {
  	if (mark_text == cur_text)	/* Even same place */
  		return SAME;
  	if (legal() == ERRORS)		/* mark_text out of range */
  		return NOT_VALID;
  	return (mark_text < cur_text) ? SMALLER : BIGGER;
  }

/* Start looking for mark_line in the line structure */
  for (line = header->next; line != tail; line = line->next) {
  	if (line == cur_line)
  		cur_seen = TRUE;
  	else if (line == mark_line)
  		break;
  }

/* If we found mark_line (line != tail) check for legality of mark_text */
  if (line == tail || legal() == ERRORS)
  	return NOT_VALID;

/* cur_seen is TRUE if cur_line is before mark_line */
  return (cur_seen == TRUE) ? BIGGER : SMALLER;
}

/*
 * Legal() checks if mark_text is still a valid pointer.
 */
int legal()
{
  register char *textp = mark_line->text;

/* Locate mark_text on mark_line */
  while (textp != mark_text && *textp++ != '\0')
  	;
  return (*textp == '\0') ? ERRORS : FINE;
}

/*
 * Yank puts all the text between start_position and end_position into
 * the buffer.
 * The caller must check that the arguments to yank() are valid. (E.g. in
 * the right order)
 */
void yank(start_line, start_textp, end_line, end_textp, remove)
LINE *start_line, *end_line;
char *start_textp, *end_textp;
FLAG remove;				/* DELETE if text should be deleted */
{
  register LINE *line = start_line;
  register char *textp = start_textp;
  int fd;

/* Creat file to hold buffer */
  if ((fd = scratch_file(WRITE)) == ERRORS)
  	return;
  
  chars_saved = 0L;
  lines_saved = 0;
  status_line("Saving text.", NIL_PTR);

/* Keep writing chars until the end_location is reached. */
  while (textp != end_textp) {
  	if (write_char(fd, *textp) == ERRORS) {
  		(void) close(fd);
  		return;
  	}
  	if (*textp++ == '\n') {	/* Move to the next line */
  		line = line->next;
  		textp = line->text;
  		lines_saved++;
  	}
  	chars_saved++;
  }

/* Flush the I/O buffer and close file */
  if (flush_buffer(fd) == ERRORS) {
  	(void) close(fd);
  	return;
  }
  (void) close(fd);
  yank_status = VALID;

/*
 * Check if the text should be deleted as well. If it should, the following
 * hack is used to save a lot of code. First move back to the start_position.
 * (This might be the location we're on now!) and them delete the text.
 * It might be a bit confusing the first time somebody uses it.
 * Delete() will fix the screen.
 */
  if (remove == DELETE) {
  	move_to(find_x(start_line, start_textp), find_y(start_line));
  	delete(start_line, start_textp, end_line, end_textp);
  }

  status_line(num_out(chars_saved), " characters saved in buffer.");
}

/*
 * Scratch_file() creates a uniq file in /usr/tmp. If the file couldn't
 * be created other combinations of files are tried until a maximum
 * of MAXTRAILS times. After MAXTRAILS times, an error message is given
 * and ERRORS is returned.
 */

#define MAXTRAILS	26

int scratch_file(mode)
FLAG mode;				/* Can be READ or WRITE permission */
{
  static int trials = 0;		/* Keep track of trails */
  register char *y_ptr, *n_ptr;
  int fd;				/* Filedescriptor to buffer */

/* If yank_status == NOT_VALID, scratch_file is called for the first time */
  if (yank_status == NOT_VALID && mode == WRITE) { /* Create new file */
  	/* Generate file name. */
	y_ptr = &yank_file[11];
	n_ptr = num_out((long) getpid());
	while ((*y_ptr = *n_ptr++) != '\0')
		y_ptr++;
	*y_ptr++ = 'a' + trials;
	*y_ptr = '\0';
  	/* Check file existence */
  	if (access(yank_file, 0) == 0 || (fd = creat(yank_file, 0644)) < 0) {
  		if (trials++ >= MAXTRAILS) {
  			error("Unable to creat scratchfile.", NIL_PTR);
  			return ERRORS;
  		}
  		else
  			return scratch_file(mode);/* Have another go */
  	}
  }
  else if ((mode == READ && (fd = open(yank_file, 0)) < 0) ||
			(mode == WRITE && (fd = creat(yank_file, 0644)) < 0)) {
  	yank_status = NOT_VALID;
  	return ERRORS;
  }

  clear_buffer();
  return fd;
}

/*  ========================================================================  *
 *				Search Routines				      *	
 *  ========================================================================  */

/*
 * A regular expression consists of a sequence of:
 * 	1. A normal character matching that character.
 * 	2. A . matching any character.
 * 	3. A ^ matching the begin of a line.
 * 	4. A $ (as last character of the pattern) mathing the end of a line.
 * 	5. A \<character> matching <character>.
 * 	6. A number of characters enclosed in [] pairs matching any of these
 * 	   characters. A list of characters can be indicated by a '-'. So
 * 	   [a-z] matches any letter of the alphabet. If the first character
 * 	   after the '[' is a '^' then the set is negated (matching none of
 * 	   the characters). 
 * 	   A ']', '^' or '-' can be escaped by putting a '\' in front of it.
 * 	7. If one of the expressions as described in 1-6 is followed by a
 * 	   '*' than that expressions matches a sequence of 0 or more of
 * 	   that expression.
 */

char typed_expression[LINE_LEN];	/* Holds previous expr. */

/*
 * SF searches forward for an expression.
 */
void SF()
{
  search("Search forward:", FORWARD);
}

/*
 * SF searches backwards for an expression.
 */
void SR()
{
  search("Search reverse:", REVERSE);
}

/*
 * Get_expression() prompts for an expression. If just a return is typed, the
 * old expression is used. If the expression changed, compile() is called and
 * the returning REGEX structure is returned. It returns NIL_REG upon error.
 * The save flag indicates whether the expression should be appended at the
 * message pointer.
 */
REGEX *get_expression(message)
char *message;
{
  static REGEX program;			/* Program of expression */
  char exp_buf[LINE_LEN];			/* Buffer for new expr. */

  if (get_string(message, exp_buf, FALSE) == ERRORS)
  	return NIL_REG;
  
  if (exp_buf[0] == '\0' && typed_expression[0] == '\0') {
  	error("No previous expression.", NIL_PTR);
  	return NIL_REG;
  }

  if (exp_buf[0] != '\0') {		/* A new expr. is typed */
  	copy_string(typed_expression, exp_buf);/* Save expr. */
  	compile(exp_buf, &program);	/* Compile new expression */
  }

  if (program.status == REG_ERROR) {	/* Error during compiling */
  	error(program.result.err_mess, NIL_PTR);
  	return NIL_REG;
  }
  return &program;
}

/*
 * GR() a replaces all matches from the current position until the end
 * of the file.
 */
void GR()
{
  change("Global replace:", VALID);
}

/*
 * LR() replaces all matches on the current line.
 */
void LR()
{
  change("Line replace:", NOT_VALID);
}

/*
 * Change() prompts for an expression and a substitution pattern and changes
 * all matches of the expression into the substitution. change() start looking
 * for expressions at the current line and continues until the end of the file
 * if the FLAG file is VALID.
 */
void change(message, file)
char *message;				/* Message to prompt for expression */
FLAG file;
{
  char mess_buf[LINE_LEN];	/* Buffer to hold message */
  char replacement[LINE_LEN];	/* Buffer to hold subst. pattern */
  REGEX *program;			/* Program resulting from compilation */
  register LINE *line = cur_line;
  register char *textp;
  long lines = 0L;		/* Nr of lines on which subs occurred */
  long subs = 0L;			/* Nr of subs made */
  int page = y;			/* Index to check if line is on screen*/

/* Save message and get expression */
  copy_string(mess_buf, message);
  if ((program = get_expression(mess_buf)) == NIL_REG)
  	return;
  
/* Get substitution pattern */
  build_string(mess_buf, "%s %s by:", mess_buf, typed_expression);
  if (get_string(mess_buf, replacement, FALSE) == ERRORS)
  	return;
  
  set_cursor(0, ymax);
  flush();
/* Substitute until end of file */
  do {
  	if (line_check(program, line->text, FORWARD)) {
  		lines++;
  		/* Repeat sub. on this line as long as we find a match*/