xref: /vim-8.2.3635/src/undo.c (revision df1bdc92)
1 /* vi:set ts=8 sts=4 sw=4:
2  *
3  * VIM - Vi IMproved	by Bram Moolenaar
4  *
5  * Do ":help uganda"  in Vim to read copying and usage conditions.
6  * Do ":help credits" in Vim to see a list of people who contributed.
7  * See README.txt for an overview of the Vim source code.
8  */
9 
10 /*
11  * undo.c: multi level undo facility
12  *
13  * The saved lines are stored in a list of lists (one for each buffer):
14  *
15  * b_u_oldhead------------------------------------------------+
16  *							      |
17  *							      V
18  *		  +--------------+    +--------------+	  +--------------+
19  * b_u_newhead--->| u_header	 |    | u_header     |	  | u_header	 |
20  *		  |	uh_next------>|     uh_next------>|	uh_next---->NULL
21  *	   NULL<--------uh_prev  |<---------uh_prev  |<---------uh_prev  |
22  *		  |	uh_entry |    |     uh_entry |	  |	uh_entry |
23  *		  +--------|-----+    +--------|-----+	  +--------|-----+
24  *			   |		       |		   |
25  *			   V		       V		   V
26  *		  +--------------+    +--------------+	  +--------------+
27  *		  | u_entry	 |    | u_entry      |	  | u_entry	 |
28  *		  |	ue_next  |    |     ue_next  |	  |	ue_next  |
29  *		  +--------|-----+    +--------|-----+	  +--------|-----+
30  *			   |		       |		   |
31  *			   V		       V		   V
32  *		  +--------------+	      NULL		  NULL
33  *		  | u_entry	 |
34  *		  |	ue_next  |
35  *		  +--------|-----+
36  *			   |
37  *			   V
38  *			  etc.
39  *
40  * Each u_entry list contains the information for one undo or redo.
41  * curbuf->b_u_curhead points to the header of the last undo (the next redo),
42  * or is NULL if nothing has been undone.
43  *
44  * All data is allocated with U_ALLOC_LINE(), it will be freed as soon as the
45  * buffer is unloaded.
46  */
47 
48 #include "vim.h"
49 
50 /* See below: use malloc()/free() for memory management. */
51 #define U_USE_MALLOC 1
52 
53 static u_entry_T *u_get_headentry __ARGS((void));
54 static void u_getbot __ARGS((void));
55 static int undo_allowed __ARGS((void));
56 static int u_savecommon __ARGS((linenr_T, linenr_T, linenr_T));
57 static void u_doit __ARGS((int count));
58 static void u_undoredo __ARGS((void));
59 static void u_undo_end __ARGS((void));
60 static void u_freelist __ARGS((buf_T *buf, struct u_header *));
61 static void u_freeentry __ARGS((u_entry_T *, long));
62 
63 #ifdef U_USE_MALLOC
64 # define U_FREE_LINE(ptr) vim_free(ptr)
65 # define U_ALLOC_LINE(size) lalloc((long_u)((size) + 1), FALSE)
66 #else
67 static void u_free_line __ARGS((char_u *ptr, int keep));
68 static char_u *u_alloc_line __ARGS((unsigned size));
69 # define U_FREE_LINE(ptr) u_free_line((ptr), FALSE)
70 # define U_ALLOC_LINE(size) u_alloc_line(size)
71 #endif
72 static char_u *u_save_line __ARGS((linenr_T));
73 
74 static long	u_newcount, u_oldcount;
75 
76 /*
77  * When 'u' flag included in 'cpoptions', we behave like vi.  Need to remember
78  * the action that "u" should do.
79  */
80 static int	undo_undoes = FALSE;
81 
82 /*
83  * Save the current line for both the "u" and "U" command.
84  * Returns OK or FAIL.
85  */
86     int
87 u_save_cursor()
88 {
89     return (u_save((linenr_T)(curwin->w_cursor.lnum - 1),
90 				      (linenr_T)(curwin->w_cursor.lnum + 1)));
91 }
92 
93 /*
94  * Save the lines between "top" and "bot" for both the "u" and "U" command.
95  * "top" may be 0 and bot may be curbuf->b_ml.ml_line_count + 1.
96  * Returns FAIL when lines could not be saved, OK otherwise.
97  */
98     int
99 u_save(top, bot)
100     linenr_T top, bot;
101 {
102     if (undo_off)
103 	return OK;
104 
105     if (top > curbuf->b_ml.ml_line_count ||
106 			    top >= bot || bot > curbuf->b_ml.ml_line_count + 1)
107 	return FALSE;	/* rely on caller to do error messages */
108 
109     if (top + 2 == bot)
110 	u_saveline((linenr_T)(top + 1));
111 
112     return (u_savecommon(top, bot, (linenr_T)0));
113 }
114 
115 /*
116  * save the line "lnum" (used by ":s" and "~" command)
117  * The line is replaced, so the new bottom line is lnum + 1.
118  */
119     int
120 u_savesub(lnum)
121     linenr_T	lnum;
122 {
123     if (undo_off)
124 	return OK;
125 
126     return (u_savecommon(lnum - 1, lnum + 1, lnum + 1));
127 }
128 
129 /*
130  * a new line is inserted before line "lnum" (used by :s command)
131  * The line is inserted, so the new bottom line is lnum + 1.
132  */
133     int
134 u_inssub(lnum)
135     linenr_T	lnum;
136 {
137     if (undo_off)
138 	return OK;
139 
140     return (u_savecommon(lnum - 1, lnum, lnum + 1));
141 }
142 
143 /*
144  * save the lines "lnum" - "lnum" + nlines (used by delete command)
145  * The lines are deleted, so the new bottom line is lnum, unless the buffer
146  * becomes empty.
147  */
148     int
149 u_savedel(lnum, nlines)
150     linenr_T	lnum;
151     long	nlines;
152 {
153     if (undo_off)
154 	return OK;
155 
156     return (u_savecommon(lnum - 1, lnum + nlines,
157 			nlines == curbuf->b_ml.ml_line_count ? 2 : lnum));
158 }
159 
160 /*
161  * Return TRUE when undo is allowed.  Otherwise give an error message and
162  * return FALSE.
163  */
164     static int
165 undo_allowed()
166 {
167     /* Don't allow changes when 'modifiable' is off.  */
168     if (!curbuf->b_p_ma)
169     {
170 	EMSG(_(e_modifiable));
171 	return FALSE;
172     }
173 
174 #ifdef HAVE_SANDBOX
175     /* In the sandbox it's not allowed to change the text. */
176     if (sandbox != 0)
177     {
178 	EMSG(_(e_sandbox));
179 	return FALSE;
180     }
181 #endif
182 
183     /* Don't allow changes in the buffer while editing the cmdline.  The
184      * caller of getcmdline() may get confused. */
185     if (textlock != 0)
186     {
187 	EMSG(_(e_secure));
188 	return FALSE;
189     }
190 
191     return TRUE;
192 }
193 
194     static int
195 u_savecommon(top, bot, newbot)
196     linenr_T	top, bot;
197     linenr_T	newbot;
198 {
199     linenr_T		lnum;
200     long		i;
201     struct u_header	*uhp;
202     u_entry_T		*uep;
203     u_entry_T		*prev_uep;
204     long		size;
205 
206     /* When making changes is not allowed return FAIL.  It's a crude way to
207      * make all change commands fail. */
208     if (!undo_allowed())
209 	return FAIL;
210 
211 #ifdef FEAT_NETBEANS_INTG
212     /*
213      * Netbeans defines areas that cannot be modified.  Bail out here when
214      * trying to change text in a guarded area.
215      */
216     if (usingNetbeans)
217     {
218 	if (netbeans_is_guarded(top, bot))
219 	{
220 	    EMSG(_(e_guarded));
221 	    return FAIL;
222 	}
223 	if (curbuf->b_p_ro)
224 	{
225 	    EMSG(_(e_nbreadonly));
226 	    return FAIL;
227 	}
228     }
229 #endif
230 
231 #ifdef FEAT_AUTOCMD
232     /*
233      * Saving text for undo means we are going to make a change.  Give a
234      * warning for a read-only file before making the change, so that the
235      * FileChangedRO event can replace the buffer with a read-write version
236      * (e.g., obtained from a source control system).
237      */
238     change_warning(0);
239 #endif
240 
241     size = bot - top - 1;
242 
243     /*
244      * if curbuf->b_u_synced == TRUE make a new header
245      */
246     if (curbuf->b_u_synced)
247     {
248 #ifdef FEAT_JUMPLIST
249 	/* Need to create new entry in b_changelist. */
250 	curbuf->b_new_change = TRUE;
251 #endif
252 
253 	/*
254 	 * if we undid more than we redid, free the entry lists before and
255 	 * including curbuf->b_u_curhead
256 	 */
257 	while (curbuf->b_u_curhead != NULL)
258 	    u_freelist(curbuf, curbuf->b_u_newhead);
259 
260 	/*
261 	 * free headers to keep the size right
262 	 */
263 	while (curbuf->b_u_numhead > p_ul && curbuf->b_u_oldhead != NULL)
264 	    u_freelist(curbuf, curbuf->b_u_oldhead);
265 
266 	if (p_ul < 0)		/* no undo at all */
267 	{
268 	    curbuf->b_u_synced = FALSE;
269 	    return OK;
270 	}
271 
272 	/*
273 	 * make a new header entry
274 	 */
275 	uhp = (struct u_header *)U_ALLOC_LINE((unsigned)
276 						     sizeof(struct u_header));
277 	if (uhp == NULL)
278 	    goto nomem;
279 	uhp->uh_prev = NULL;
280 	uhp->uh_next = curbuf->b_u_newhead;
281 	if (curbuf->b_u_newhead != NULL)
282 	    curbuf->b_u_newhead->uh_prev = uhp;
283 	uhp->uh_entry = NULL;
284 	uhp->uh_getbot_entry = NULL;
285 	uhp->uh_cursor = curwin->w_cursor;	/* save cursor pos. for undo */
286 #ifdef FEAT_VIRTUALEDIT
287 	if (virtual_active() && curwin->w_cursor.coladd > 0)
288 	    uhp->uh_cursor_vcol = getviscol();
289 	else
290 	    uhp->uh_cursor_vcol = -1;
291 #endif
292 
293 	/* save changed and buffer empty flag for undo */
294 	uhp->uh_flags = (curbuf->b_changed ? UH_CHANGED : 0) +
295 		       ((curbuf->b_ml.ml_flags & ML_EMPTY) ? UH_EMPTYBUF : 0);
296 
297 	/* save named marks for undo */
298 	mch_memmove(uhp->uh_namedm, curbuf->b_namedm, sizeof(pos_T) * NMARKS);
299 	curbuf->b_u_newhead = uhp;
300 	if (curbuf->b_u_oldhead == NULL)
301 	    curbuf->b_u_oldhead = uhp;
302 	++curbuf->b_u_numhead;
303     }
304     else
305     {
306 	if (p_ul < 0)		/* no undo at all */
307 	    return OK;
308 
309 	/*
310 	 * When saving a single line, and it has been saved just before, it
311 	 * doesn't make sense saving it again.  Saves a lot of memory when
312 	 * making lots of changes inside the same line.
313 	 * This is only possible if the previous change didn't increase or
314 	 * decrease the number of lines.
315 	 * Check the ten last changes.  More doesn't make sense and takes too
316 	 * long.
317 	 */
318 	if (size == 1)
319 	{
320 	    uep = u_get_headentry();
321 	    prev_uep = NULL;
322 	    for (i = 0; i < 10; ++i)
323 	    {
324 		if (uep == NULL)
325 		    break;
326 
327 		/* If lines have been inserted/deleted we give up.
328 		 * Also when the line was included in a multi-line save. */
329 		if ((curbuf->b_u_newhead->uh_getbot_entry != uep
330 			    ? (uep->ue_top + uep->ue_size + 1
331 				!= (uep->ue_bot == 0
332 				    ? curbuf->b_ml.ml_line_count + 1
333 				    : uep->ue_bot))
334 			    : uep->ue_lcount != curbuf->b_ml.ml_line_count)
335 			|| (uep->ue_size > 1
336 			    && top >= uep->ue_top
337 			    && top + 2 <= uep->ue_top + uep->ue_size + 1))
338 		    break;
339 
340 		/* If it's the same line we can skip saving it again. */
341 		if (uep->ue_size == 1 && uep->ue_top == top)
342 		{
343 		    if (i > 0)
344 		    {
345 			/* It's not the last entry: get ue_bot for the last
346 			 * entry now.  Following deleted/inserted lines go to
347 			 * the re-used entry. */
348 			u_getbot();
349 			curbuf->b_u_synced = FALSE;
350 
351 			/* Move the found entry to become the last entry.  The
352 			 * order of undo/redo doesn't matter for the entries
353 			 * we move it over, since they don't change the line
354 			 * count and don't include this line.  It does matter
355 			 * for the found entry if the line count is changed by
356 			 * the executed command. */
357 			prev_uep->ue_next = uep->ue_next;
358 			uep->ue_next = curbuf->b_u_newhead->uh_entry;
359 			curbuf->b_u_newhead->uh_entry = uep;
360 		    }
361 
362 		    /* The executed command may change the line count. */
363 		    if (newbot != 0)
364 			uep->ue_bot = newbot;
365 		    else if (bot > curbuf->b_ml.ml_line_count)
366 			uep->ue_bot = 0;
367 		    else
368 		    {
369 			uep->ue_lcount = curbuf->b_ml.ml_line_count;
370 			curbuf->b_u_newhead->uh_getbot_entry = uep;
371 		    }
372 		    return OK;
373 		}
374 		prev_uep = uep;
375 		uep = uep->ue_next;
376 	    }
377 	}
378 
379 	/* find line number for ue_bot for previous u_save() */
380 	u_getbot();
381     }
382 
383 #if !defined(UNIX) && !defined(DJGPP) && !defined(WIN32) && !defined(__EMX__)
384 	/*
385 	 * With Amiga and MSDOS 16 bit we can't handle big undo's, because
386 	 * then u_alloc_line would have to allocate a block larger than 32K
387 	 */
388     if (size >= 8000)
389 	goto nomem;
390 #endif
391 
392     /*
393      * add lines in front of entry list
394      */
395     uep = (u_entry_T *)U_ALLOC_LINE((unsigned)sizeof(u_entry_T));
396     if (uep == NULL)
397 	goto nomem;
398 
399     uep->ue_size = size;
400     uep->ue_top = top;
401     if (newbot != 0)
402 	uep->ue_bot = newbot;
403     /*
404      * Use 0 for ue_bot if bot is below last line.
405      * Otherwise we have to compute ue_bot later.
406      */
407     else if (bot > curbuf->b_ml.ml_line_count)
408 	uep->ue_bot = 0;
409     else
410     {
411 	uep->ue_lcount = curbuf->b_ml.ml_line_count;
412 	curbuf->b_u_newhead->uh_getbot_entry = uep;
413     }
414 
415     if (size > 0)
416     {
417 	if ((uep->ue_array = (char_u **)U_ALLOC_LINE(
418 				(unsigned)(sizeof(char_u *) * size))) == NULL)
419 	{
420 	    u_freeentry(uep, 0L);
421 	    goto nomem;
422 	}
423 	for (i = 0, lnum = top + 1; i < size; ++i)
424 	{
425 	    fast_breakcheck();
426 	    if (got_int)
427 	    {
428 		u_freeentry(uep, i);
429 		return FAIL;
430 	    }
431 	    if ((uep->ue_array[i] = u_save_line(lnum++)) == NULL)
432 	    {
433 		u_freeentry(uep, i);
434 		goto nomem;
435 	    }
436 	}
437     }
438     else
439 	uep->ue_array = NULL;
440     uep->ue_next = curbuf->b_u_newhead->uh_entry;
441     curbuf->b_u_newhead->uh_entry = uep;
442     curbuf->b_u_synced = FALSE;
443     undo_undoes = FALSE;
444 
445     return OK;
446 
447 nomem:
448     msg_silent = 0;	/* must display the prompt */
449     if (ask_yesno((char_u *)_("No undo possible; continue anyway"), TRUE)
450 								       == 'y')
451     {
452 	undo_off = TRUE;	    /* will be reset when character typed */
453 	return OK;
454     }
455     do_outofmem_msg((long_u)0);
456     return FAIL;
457 }
458 
459 /*
460  * If 'cpoptions' contains 'u': Undo the previous undo or redo (vi compatible).
461  * If 'cpoptions' does not contain 'u': Always undo.
462  */
463     void
464 u_undo(count)
465     int count;
466 {
467     /*
468      * If we get an undo command while executing a macro, we behave like the
469      * original vi. If this happens twice in one macro the result will not
470      * be compatible.
471      */
472     if (curbuf->b_u_synced == FALSE)
473     {
474 	u_sync();
475 	count = 1;
476     }
477 
478     if (vim_strchr(p_cpo, CPO_UNDO) == NULL)
479 	undo_undoes = TRUE;
480     else
481 	undo_undoes = !undo_undoes;
482     u_doit(count);
483 }
484 
485 /*
486  * If 'cpoptions' contains 'u': Repeat the previous undo or redo.
487  * If 'cpoptions' does not contain 'u': Always redo.
488  */
489     void
490 u_redo(count)
491     int count;
492 {
493     if (vim_strchr(p_cpo, CPO_UNDO) == NULL)
494 	undo_undoes = FALSE;
495     u_doit(count);
496 }
497 
498 /*
499  * Undo or redo, depending on 'undo_undoes', 'count' times.
500  */
501     static void
502 u_doit(count)
503     int count;
504 {
505     if (!undo_allowed())
506 	return;
507 
508     u_newcount = 0;
509     u_oldcount = 0;
510     if (curbuf->b_ml.ml_flags & ML_EMPTY)
511 	u_oldcount = -1;
512     while (count--)
513     {
514 	if (undo_undoes)
515 	{
516 	    if (curbuf->b_u_curhead == NULL)		/* first undo */
517 		curbuf->b_u_curhead = curbuf->b_u_newhead;
518 	    else if (p_ul > 0)				/* multi level undo */
519 		/* get next undo */
520 		curbuf->b_u_curhead = curbuf->b_u_curhead->uh_next;
521 	    /* nothing to undo */
522 	    if (curbuf->b_u_numhead == 0 || curbuf->b_u_curhead == NULL)
523 	    {
524 		/* stick curbuf->b_u_curhead at end */
525 		curbuf->b_u_curhead = curbuf->b_u_oldhead;
526 		beep_flush();
527 		break;
528 	    }
529 
530 	    u_undoredo();
531 	}
532 	else
533 	{
534 	    if (curbuf->b_u_curhead == NULL || p_ul <= 0)
535 	    {
536 		beep_flush();	/* nothing to redo */
537 		break;
538 	    }
539 
540 	    u_undoredo();
541 	    /* advance for next redo */
542 	    curbuf->b_u_curhead = curbuf->b_u_curhead->uh_prev;
543 	}
544     }
545     if (curbuf->b_ml.ml_flags & ML_EMPTY)
546 	--u_newcount;
547     u_undo_end();
548 }
549 
550 /*
551  * u_undoredo: common code for undo and redo
552  *
553  * The lines in the file are replaced by the lines in the entry list at
554  * curbuf->b_u_curhead. The replaced lines in the file are saved in the entry
555  * list for the next undo/redo.
556  */
557     static void
558 u_undoredo()
559 {
560     char_u	**newarray = NULL;
561     linenr_T	oldsize;
562     linenr_T	newsize;
563     linenr_T	top, bot;
564     linenr_T	lnum;
565     linenr_T	newlnum = MAXLNUM;
566     long	i;
567     u_entry_T	*uep, *nuep;
568     u_entry_T	*newlist = NULL;
569     int		old_flags;
570     int		new_flags;
571     pos_T	namedm[NMARKS];
572     int		empty_buffer;		    /* buffer became empty */
573 
574     old_flags = curbuf->b_u_curhead->uh_flags;
575     new_flags = (curbuf->b_changed ? UH_CHANGED : 0) +
576 	       ((curbuf->b_ml.ml_flags & ML_EMPTY) ? UH_EMPTYBUF : 0);
577     setpcmark();
578 
579     /*
580      * save marks before undo/redo
581      */
582     mch_memmove(namedm, curbuf->b_namedm, sizeof(pos_T) * NMARKS);
583     curbuf->b_op_start.lnum = curbuf->b_ml.ml_line_count;
584     curbuf->b_op_start.col = 0;
585     curbuf->b_op_end.lnum = 0;
586     curbuf->b_op_end.col = 0;
587 
588     for (uep = curbuf->b_u_curhead->uh_entry; uep != NULL; uep = nuep)
589     {
590 	top = uep->ue_top;
591 	bot = uep->ue_bot;
592 	if (bot == 0)
593 	    bot = curbuf->b_ml.ml_line_count + 1;
594 	if (top > curbuf->b_ml.ml_line_count || top >= bot
595 				      || bot > curbuf->b_ml.ml_line_count + 1)
596 	{
597 	    EMSG(_("E438: u_undo: line numbers wrong"));
598 	    changed();		/* don't want UNCHANGED now */
599 	    return;
600 	}
601 
602 	oldsize = bot - top - 1;    /* number of lines before undo */
603 	newsize = uep->ue_size;	    /* number of lines after undo */
604 
605 	if (top < newlnum)
606 	{
607 	    /* If the saved cursor is somewhere in this undo block, move it to
608 	     * the remembered position.  Makes "gwap" put the cursor back
609 	     * where it was. */
610 	    lnum = curbuf->b_u_curhead->uh_cursor.lnum;
611 	    if (lnum >= top && lnum <= top + newsize + 1)
612 	    {
613 		curwin->w_cursor = curbuf->b_u_curhead->uh_cursor;
614 		newlnum = curwin->w_cursor.lnum - 1;
615 	    }
616 	    else
617 	    {
618 		/* Use the first line that actually changed.  Avoids that
619 		 * undoing auto-formatting puts the cursor in the previous
620 		 * line. */
621 		for (i = 0; i < newsize && i < oldsize; ++i)
622 		    if (STRCMP(uep->ue_array[i], ml_get(top + 1 + i)) != 0)
623 			break;
624 		if (i == newsize && newlnum == MAXLNUM && uep->ue_next == NULL)
625 		{
626 		    newlnum = top;
627 		    curwin->w_cursor.lnum = newlnum + 1;
628 		}
629 		else if (i < newsize)
630 		{
631 		    newlnum = top + i;
632 		    curwin->w_cursor.lnum = newlnum + 1;
633 		}
634 	    }
635 	}
636 
637 	empty_buffer = FALSE;
638 
639 	/* delete the lines between top and bot and save them in newarray */
640 	if (oldsize > 0)
641 	{
642 	    if ((newarray = (char_u **)U_ALLOC_LINE(
643 			    (unsigned)(sizeof(char_u *) * oldsize))) == NULL)
644 	    {
645 		do_outofmem_msg((long_u)(sizeof(char_u *) * oldsize));
646 		/*
647 		 * We have messed up the entry list, repair is impossible.
648 		 * we have to free the rest of the list.
649 		 */
650 		while (uep != NULL)
651 		{
652 		    nuep = uep->ue_next;
653 		    u_freeentry(uep, uep->ue_size);
654 		    uep = nuep;
655 		}
656 		break;
657 	    }
658 	    /* delete backwards, it goes faster in most cases */
659 	    for (lnum = bot - 1, i = oldsize; --i >= 0; --lnum)
660 	    {
661 		/* what can we do when we run out of memory? */
662 		if ((newarray[i] = u_save_line(lnum)) == NULL)
663 		    do_outofmem_msg((long_u)0);
664 		/* remember we deleted the last line in the buffer, and a
665 		 * dummy empty line will be inserted */
666 		if (curbuf->b_ml.ml_line_count == 1)
667 		    empty_buffer = TRUE;
668 		ml_delete(lnum, FALSE);
669 	    }
670 	}
671 	else
672 	    newarray = NULL;
673 
674 	/* insert the lines in u_array between top and bot */
675 	if (newsize)
676 	{
677 	    for (lnum = top, i = 0; i < newsize; ++i, ++lnum)
678 	    {
679 		/*
680 		 * If the file is empty, there is an empty line 1 that we
681 		 * should get rid of, by replacing it with the new line
682 		 */
683 		if (empty_buffer && lnum == 0)
684 		    ml_replace((linenr_T)1, uep->ue_array[i], TRUE);
685 		else
686 		    ml_append(lnum, uep->ue_array[i], (colnr_T)0, FALSE);
687 		U_FREE_LINE(uep->ue_array[i]);
688 	    }
689 	    U_FREE_LINE((char_u *)uep->ue_array);
690 	}
691 
692 	/* adjust marks */
693 	if (oldsize != newsize)
694 	{
695 	    mark_adjust(top + 1, top + oldsize, (long)MAXLNUM,
696 					       (long)newsize - (long)oldsize);
697 	    if (curbuf->b_op_start.lnum > top + oldsize)
698 		curbuf->b_op_start.lnum += newsize - oldsize;
699 	    if (curbuf->b_op_end.lnum > top + oldsize)
700 		curbuf->b_op_end.lnum += newsize - oldsize;
701 	}
702 
703 	changed_lines(top + 1, 0, bot, newsize - oldsize);
704 
705 	/* set '[ and '] mark */
706 	if (top + 1 < curbuf->b_op_start.lnum)
707 	    curbuf->b_op_start.lnum = top + 1;
708 	if (newsize == 0 && top + 1 > curbuf->b_op_end.lnum)
709 	    curbuf->b_op_end.lnum = top + 1;
710 	else if (top + newsize > curbuf->b_op_end.lnum)
711 	    curbuf->b_op_end.lnum = top + newsize;
712 
713 	u_newcount += newsize;
714 	u_oldcount += oldsize;
715 	uep->ue_size = oldsize;
716 	uep->ue_array = newarray;
717 	uep->ue_bot = top + newsize + 1;
718 
719 	/*
720 	 * insert this entry in front of the new entry list
721 	 */
722 	nuep = uep->ue_next;
723 	uep->ue_next = newlist;
724 	newlist = uep;
725     }
726 
727     curbuf->b_u_curhead->uh_entry = newlist;
728     curbuf->b_u_curhead->uh_flags = new_flags;
729     if ((old_flags & UH_EMPTYBUF) && bufempty())
730 	curbuf->b_ml.ml_flags |= ML_EMPTY;
731     if (old_flags & UH_CHANGED)
732 	changed();
733     else
734 #ifdef FEAT_NETBEANS_INTG
735 	/* per netbeans undo rules, keep it as modified */
736 	if (!isNetbeansModified(curbuf))
737 #endif
738 	unchanged(curbuf, FALSE);
739 
740     /*
741      * restore marks from before undo/redo
742      */
743     for (i = 0; i < NMARKS; ++i)
744 	if (curbuf->b_u_curhead->uh_namedm[i].lnum)
745 	{
746 	    curbuf->b_namedm[i] = curbuf->b_u_curhead->uh_namedm[i];
747 	    curbuf->b_u_curhead->uh_namedm[i] = namedm[i];
748 	}
749 
750     /*
751      * If the cursor is only off by one line, put it at the same position as
752      * before starting the change (for the "o" command).
753      * Otherwise the cursor should go to the first undone line.
754      */
755     if (curbuf->b_u_curhead->uh_cursor.lnum + 1 == curwin->w_cursor.lnum
756 						 && curwin->w_cursor.lnum > 1)
757 	--curwin->w_cursor.lnum;
758     if (curbuf->b_u_curhead->uh_cursor.lnum == curwin->w_cursor.lnum)
759     {
760 	curwin->w_cursor.col = curbuf->b_u_curhead->uh_cursor.col;
761 #ifdef FEAT_VIRTUALEDIT
762 	if (virtual_active() && curbuf->b_u_curhead->uh_cursor_vcol >= 0)
763 	    coladvance((colnr_T)curbuf->b_u_curhead->uh_cursor_vcol);
764 	else
765 	    curwin->w_cursor.coladd = 0;
766 #endif
767     }
768     else if (curwin->w_cursor.lnum <= curbuf->b_ml.ml_line_count)
769 	beginline(BL_SOL | BL_FIX);
770     else
771     {
772 	/* We get here with the current cursor line being past the end (eg
773 	 * after adding lines at the end of the file, and then undoing it).
774 	 * check_cursor() will move the cursor to the last line.  Move it to
775 	 * the first column here. */
776 	curwin->w_cursor.col = 0;
777 #ifdef FEAT_VIRTUALEDIT
778 	curwin->w_cursor.coladd = 0;
779 #endif
780     }
781 
782     /* Make sure the cursor is on an existing line and column. */
783     check_cursor();
784 }
785 
786 /*
787  * If we deleted or added lines, report the number of less/more lines.
788  * Otherwise, report the number of changes (this may be incorrect
789  * in some cases, but it's better than nothing).
790  */
791     static void
792 u_undo_end()
793 {
794     if ((u_oldcount -= u_newcount) != 0)
795 	msgmore(-u_oldcount);
796     else if (u_newcount > p_report)
797     {
798 	if (u_newcount == 1)
799 	    MSG(_("1 change"));
800 	else
801 	    smsg((char_u *)_("%ld changes"), u_newcount);
802     }
803 #ifdef FEAT_FOLDING
804     if ((fdo_flags & FDO_UNDO) && KeyTyped)
805 	foldOpenCursor();
806 #endif
807 }
808 
809 /*
810  * u_sync: stop adding to the current entry list
811  */
812     void
813 u_sync()
814 {
815     if (curbuf->b_u_synced)
816 	return;		    /* already synced */
817 #if defined(FEAT_XIM) && defined(FEAT_GUI_GTK)
818     if (im_is_preediting())
819 	return;		    /* XIM is busy, don't break an undo sequence */
820 #endif
821     if (p_ul < 0)
822 	curbuf->b_u_synced = TRUE;  /* no entries, nothing to do */
823     else
824     {
825 	u_getbot();		    /* compute ue_bot of previous u_save */
826 	curbuf->b_u_curhead = NULL;
827     }
828 }
829 
830 /*
831  * Called after writing the file and setting b_changed to FALSE.
832  * Now an undo means that the buffer is modified.
833  */
834     void
835 u_unchanged(buf)
836     buf_T	*buf;
837 {
838     struct u_header	*uh;
839 
840     for (uh = buf->b_u_newhead; uh; uh = uh->uh_next)
841 	uh->uh_flags |= UH_CHANGED;
842     buf->b_did_warn = FALSE;
843 }
844 
845 /*
846  * Get pointer to last added entry.
847  * If it's not valid, give an error message and return NULL.
848  */
849     static u_entry_T *
850 u_get_headentry()
851 {
852     if (curbuf->b_u_newhead == NULL || curbuf->b_u_newhead->uh_entry == NULL)
853     {
854 	EMSG(_("E439: undo list corrupt"));
855 	return NULL;
856     }
857     return curbuf->b_u_newhead->uh_entry;
858 }
859 
860 /*
861  * u_getbot(): compute the line number of the previous u_save
862  *		It is called only when b_u_synced is FALSE.
863  */
864     static void
865 u_getbot()
866 {
867     u_entry_T	*uep;
868     linenr_T	extra;
869 
870     uep = u_get_headentry();	/* check for corrupt undo list */
871     if (uep == NULL)
872 	return;
873 
874     uep = curbuf->b_u_newhead->uh_getbot_entry;
875     if (uep != NULL)
876     {
877 	/*
878 	 * the new ue_bot is computed from the number of lines that has been
879 	 * inserted (0 - deleted) since calling u_save. This is equal to the
880 	 * old line count subtracted from the current line count.
881 	 */
882 	extra = curbuf->b_ml.ml_line_count - uep->ue_lcount;
883 	uep->ue_bot = uep->ue_top + uep->ue_size + 1 + extra;
884 	if (uep->ue_bot < 1 || uep->ue_bot > curbuf->b_ml.ml_line_count)
885 	{
886 	    EMSG(_("E440: undo line missing"));
887 	    uep->ue_bot = uep->ue_top + 1;  /* assume all lines deleted, will
888 					     * get all the old lines back
889 					     * without deleting the current
890 					     * ones */
891 	}
892 
893 	curbuf->b_u_newhead->uh_getbot_entry = NULL;
894     }
895 
896     curbuf->b_u_synced = TRUE;
897 }
898 
899 /*
900  * u_freelist: free one entry list and adjust the pointers
901  */
902     static void
903 u_freelist(buf, uhp)
904     buf_T	    *buf;
905     struct u_header *uhp;
906 {
907     u_entry_T	*uep, *nuep;
908 
909     for (uep = uhp->uh_entry; uep != NULL; uep = nuep)
910     {
911 	nuep = uep->ue_next;
912 	u_freeentry(uep, uep->ue_size);
913     }
914 
915     if (buf->b_u_curhead == uhp)
916 	buf->b_u_curhead = NULL;
917 
918     if (uhp->uh_next == NULL)
919 	buf->b_u_oldhead = uhp->uh_prev;
920     else
921 	uhp->uh_next->uh_prev = uhp->uh_prev;
922 
923     if (uhp->uh_prev == NULL)
924 	buf->b_u_newhead = uhp->uh_next;
925     else
926 	uhp->uh_prev->uh_next = uhp->uh_next;
927 
928     U_FREE_LINE((char_u *)uhp);
929     --buf->b_u_numhead;
930 }
931 
932 /*
933  * free entry 'uep' and 'n' lines in uep->ue_array[]
934  */
935     static void
936 u_freeentry(uep, n)
937     u_entry_T	*uep;
938     long	    n;
939 {
940     while (n > 0)
941 	U_FREE_LINE(uep->ue_array[--n]);
942     U_FREE_LINE((char_u *)uep->ue_array);
943     U_FREE_LINE((char_u *)uep);
944 }
945 
946 /*
947  * invalidate the undo buffer; called when storage has already been released
948  */
949     void
950 u_clearall(buf)
951     buf_T	*buf;
952 {
953     buf->b_u_newhead = buf->b_u_oldhead = buf->b_u_curhead = NULL;
954     buf->b_u_synced = TRUE;
955     buf->b_u_numhead = 0;
956     buf->b_u_line_ptr = NULL;
957     buf->b_u_line_lnum = 0;
958 }
959 
960 /*
961  * save the line "lnum" for the "U" command
962  */
963     void
964 u_saveline(lnum)
965     linenr_T lnum;
966 {
967     if (lnum == curbuf->b_u_line_lnum)	    /* line is already saved */
968 	return;
969     if (lnum < 1 || lnum > curbuf->b_ml.ml_line_count) /* should never happen */
970 	return;
971     u_clearline();
972     curbuf->b_u_line_lnum = lnum;
973     if (curwin->w_cursor.lnum == lnum)
974 	curbuf->b_u_line_colnr = curwin->w_cursor.col;
975     else
976 	curbuf->b_u_line_colnr = 0;
977     if ((curbuf->b_u_line_ptr = u_save_line(lnum)) == NULL)
978 	do_outofmem_msg((long_u)0);
979 }
980 
981 /*
982  * clear the line saved for the "U" command
983  * (this is used externally for crossing a line while in insert mode)
984  */
985     void
986 u_clearline()
987 {
988     if (curbuf->b_u_line_ptr != NULL)
989     {
990 	U_FREE_LINE(curbuf->b_u_line_ptr);
991 	curbuf->b_u_line_ptr = NULL;
992 	curbuf->b_u_line_lnum = 0;
993     }
994 }
995 
996 /*
997  * Implementation of the "U" command.
998  * Differentiation from vi: "U" can be undone with the next "U".
999  * We also allow the cursor to be in another line.
1000  */
1001     void
1002 u_undoline()
1003 {
1004     colnr_T t;
1005     char_u  *oldp;
1006 
1007     if (undo_off)
1008 	return;
1009 
1010     if (curbuf->b_u_line_ptr == NULL ||
1011 			curbuf->b_u_line_lnum > curbuf->b_ml.ml_line_count)
1012     {
1013 	beep_flush();
1014 	return;
1015     }
1016 	/* first save the line for the 'u' command */
1017     if (u_savecommon(curbuf->b_u_line_lnum - 1,
1018 				curbuf->b_u_line_lnum + 1, (linenr_T)0) == FAIL)
1019 	return;
1020     oldp = u_save_line(curbuf->b_u_line_lnum);
1021     if (oldp == NULL)
1022     {
1023 	do_outofmem_msg((long_u)0);
1024 	return;
1025     }
1026     ml_replace(curbuf->b_u_line_lnum, curbuf->b_u_line_ptr, TRUE);
1027     changed_bytes(curbuf->b_u_line_lnum, 0);
1028     U_FREE_LINE(curbuf->b_u_line_ptr);
1029     curbuf->b_u_line_ptr = oldp;
1030 
1031     t = curbuf->b_u_line_colnr;
1032     if (curwin->w_cursor.lnum == curbuf->b_u_line_lnum)
1033 	curbuf->b_u_line_colnr = curwin->w_cursor.col;
1034     curwin->w_cursor.col = t;
1035     curwin->w_cursor.lnum = curbuf->b_u_line_lnum;
1036 }
1037 
1038 /*
1039  * There are two implementations of the memory management for undo:
1040  * 1. Use the standard malloc()/free() functions.
1041  *    This should be fast for allocating memory, but when a buffer is
1042  *    abandoned every single allocated chunk must be freed, which may be slow.
1043  * 2. Allocate larger blocks of memory and keep track of chunks ourselves.
1044  *    This is fast for abandoning, but the use of linked lists is slow for
1045  *    finding a free chunk.  Esp. when a lot of lines are changed or deleted.
1046  * A bit of profiling showed that the first method is faster, especially when
1047  * making a large number of changes, under the condition that malloc()/free()
1048  * is implemented efficiently.
1049  */
1050 #ifdef U_USE_MALLOC
1051 /*
1052  * Version of undo memory allocation using malloc()/free()
1053  *
1054  * U_FREE_LINE() and U_ALLOC_LINE() are macros that invoke vim_free() and
1055  * lalloc() directly.
1056  */
1057 
1058 /*
1059  * Free all allocated memory blocks for the buffer 'buf'.
1060  */
1061     void
1062 u_blockfree(buf)
1063     buf_T	*buf;
1064 {
1065     while (buf->b_u_newhead != NULL)
1066 	u_freelist(buf, buf->b_u_newhead);
1067     U_FREE_LINE(buf->b_u_line_ptr);
1068 }
1069 
1070 #else
1071 /*
1072  * Storage allocation for the undo lines and blocks of the current file.
1073  * Version where Vim keeps track of the available memory.
1074  */
1075 
1076 /*
1077  * Memory is allocated in relatively large blocks. These blocks are linked
1078  * in the allocated block list, headed by curbuf->b_block_head. They are all
1079  * freed when abandoning a file, so we don't have to free every single line.
1080  * The list is kept sorted on memory address.
1081  * block_alloc() allocates a block.
1082  * m_blockfree() frees all blocks.
1083  *
1084  * The available chunks of memory are kept in free chunk lists. There is
1085  * one free list for each block of allocated memory. The list is kept sorted
1086  * on memory address.
1087  * u_alloc_line() gets a chunk from the free lists.
1088  * u_free_line() returns a chunk to the free lists.
1089  * curbuf->b_m_search points to the chunk before the chunk that was
1090  * freed/allocated the last time.
1091  * curbuf->b_mb_current points to the b_head where curbuf->b_m_search
1092  * points into the free list.
1093  *
1094  *
1095  *  b_block_head     /---> block #1	/---> block #2
1096  *	 mb_next ---/	    mb_next ---/       mb_next ---> NULL
1097  *	 mb_info	    mb_info	       mb_info
1098  *	    |		       |		  |
1099  *	    V		       V		  V
1100  *	  NULL		free chunk #1.1      free chunk #2.1
1101  *			       |		  |
1102  *			       V		  V
1103  *			free chunk #1.2		 NULL
1104  *			       |
1105  *			       V
1106  *			      NULL
1107  *
1108  * When a single free chunk list would have been used, it could take a lot
1109  * of time in u_free_line() to find the correct place to insert a chunk in the
1110  * free list. The single free list would become very long when many lines are
1111  * changed (e.g. with :%s/^M$//).
1112  */
1113 
1114  /*
1115   * this blocksize is used when allocating new lines
1116   */
1117 #define MEMBLOCKSIZE 2044
1118 
1119 /*
1120  * The size field contains the size of the chunk, including the size field
1121  * itself.
1122  *
1123  * When the chunk is not in-use it is preceded with the m_info structure.
1124  * The m_next field links it in one of the free chunk lists.
1125  *
1126  * On most unix systems structures have to be longword (32 or 64 bit) aligned.
1127  * On most other systems they are short (16 bit) aligned.
1128  */
1129 
1130 /* the structure definitions are now in structs.h */
1131 
1132 #ifdef ALIGN_LONG
1133     /* size of m_size */
1134 # define M_OFFSET (sizeof(long_u))
1135 #else
1136     /* size of m_size */
1137 # define M_OFFSET (sizeof(short_u))
1138 #endif
1139 
1140 static char_u *u_blockalloc __ARGS((long_u));
1141 
1142 /*
1143  * Allocate a block of memory and link it in the allocated block list.
1144  */
1145     static char_u *
1146 u_blockalloc(size)
1147     long_u	size;
1148 {
1149     mblock_T	*p;
1150     mblock_T	*mp, *next;
1151 
1152     p = (mblock_T *)lalloc(size + sizeof(mblock_T), FALSE);
1153     if (p != NULL)
1154     {
1155 	 /* Insert the block into the allocated block list, keeping it
1156 		    sorted on address. */
1157 	for (mp = &curbuf->b_block_head;
1158 		(next = mp->mb_next) != NULL && next < p;
1159 			mp = next)
1160 	    ;
1161 	p->mb_next = next;		/* link in block list */
1162 	p->mb_size = size;
1163 	p->mb_maxsize = 0;		/* nothing free yet */
1164 	mp->mb_next = p;
1165 	p->mb_info.m_next = NULL;	/* clear free list */
1166 	p->mb_info.m_size = 0;
1167 	curbuf->b_mb_current = p;	/* remember current block */
1168 	curbuf->b_m_search = NULL;
1169 	p++;				/* return usable memory */
1170     }
1171     return (char_u *)p;
1172 }
1173 
1174 /*
1175  * free all allocated memory blocks for the buffer 'buf'
1176  */
1177     void
1178 u_blockfree(buf)
1179     buf_T	*buf;
1180 {
1181     mblock_T	*p, *np;
1182 
1183     for (p = buf->b_block_head.mb_next; p != NULL; p = np)
1184     {
1185 	np = p->mb_next;
1186 	vim_free(p);
1187     }
1188     buf->b_block_head.mb_next = NULL;
1189     buf->b_m_search = NULL;
1190     buf->b_mb_current = NULL;
1191 }
1192 
1193 /*
1194  * Free a chunk of memory for the current buffer.
1195  * Insert the chunk into the correct free list, keeping it sorted on address.
1196  */
1197     static void
1198 u_free_line(ptr, keep)
1199     char_u	*ptr;
1200     int		keep;	/* don't free the block when it's empty */
1201 {
1202     minfo_T	*next;
1203     minfo_T	*prev, *curr;
1204     minfo_T	*mp;
1205     mblock_T	*nextb;
1206     mblock_T	*prevb;
1207     long_u	maxsize;
1208 
1209     if (ptr == NULL || ptr == IObuff)
1210 	return;	/* illegal address can happen in out-of-memory situations */
1211 
1212     mp = (minfo_T *)(ptr - M_OFFSET);
1213 
1214     /* find block where chunk could be a part off */
1215     /* if we change curbuf->b_mb_current, curbuf->b_m_search is set to NULL */
1216     if (curbuf->b_mb_current == NULL || mp < (minfo_T *)curbuf->b_mb_current)
1217     {
1218 	curbuf->b_mb_current = curbuf->b_block_head.mb_next;
1219 	curbuf->b_m_search = NULL;
1220     }
1221     if ((nextb = curbuf->b_mb_current->mb_next) != NULL
1222 						     && (minfo_T *)nextb < mp)
1223     {
1224 	curbuf->b_mb_current = nextb;
1225 	curbuf->b_m_search = NULL;
1226     }
1227     while ((nextb = curbuf->b_mb_current->mb_next) != NULL
1228 						     && (minfo_T *)nextb < mp)
1229 	curbuf->b_mb_current = nextb;
1230 
1231     curr = NULL;
1232     /*
1233      * If mp is smaller than curbuf->b_m_search->m_next go to the start of
1234      * the free list
1235      */
1236     if (curbuf->b_m_search == NULL || mp < (curbuf->b_m_search->m_next))
1237 	next = &(curbuf->b_mb_current->mb_info);
1238     else
1239 	next = curbuf->b_m_search;
1240     /*
1241      * The following loop is executed very often.
1242      * Therefore it has been optimized at the cost of readability.
1243      * Keep it fast!
1244      */
1245 #ifdef SLOW_BUT_EASY_TO_READ
1246     do
1247     {
1248 	prev = curr;
1249 	curr = next;
1250 	next = next->m_next;
1251     }
1252     while (mp > next && next != NULL);
1253 #else
1254     do					    /* first, middle, last */
1255     {
1256 	prev = next->m_next;		    /* curr, next, prev */
1257 	if (prev == NULL || mp <= prev)
1258 	{
1259 	    prev = curr;
1260 	    curr = next;
1261 	    next = next->m_next;
1262 	    break;
1263 	}
1264 	curr = prev->m_next;		    /* next, prev, curr */
1265 	if (curr == NULL || mp <= curr)
1266 	{
1267 	    prev = next;
1268 	    curr = prev->m_next;
1269 	    next = curr->m_next;
1270 	    break;
1271 	}
1272 	next = curr->m_next;		    /* prev, curr, next */
1273     }
1274     while (mp > next && next != NULL);
1275 #endif
1276 
1277     /* if *mp and *next are concatenated, join them into one chunk */
1278     if ((char_u *)mp + mp->m_size == (char_u *)next)
1279     {
1280 	mp->m_size += next->m_size;
1281 	mp->m_next = next->m_next;
1282     }
1283     else
1284 	mp->m_next = next;
1285     maxsize = mp->m_size;
1286 
1287     /* if *curr and *mp are concatenated, join them */
1288     if (prev != NULL && (char_u *)curr + curr->m_size == (char_u *)mp)
1289     {
1290 	curr->m_size += mp->m_size;
1291 	maxsize = curr->m_size;
1292 	curr->m_next = mp->m_next;
1293 	curbuf->b_m_search = prev;
1294     }
1295     else
1296     {
1297 	curr->m_next = mp;
1298 	curbuf->b_m_search = curr;  /* put curbuf->b_m_search before freed
1299 				       chunk */
1300     }
1301 
1302     /*
1303      * If the block only containes free memory now, release it.
1304      */
1305     if (!keep && curbuf->b_mb_current->mb_size
1306 			      == curbuf->b_mb_current->mb_info.m_next->m_size)
1307     {
1308 	/* Find the block before the current one to be able to unlink it from
1309 	 * the list of blocks. */
1310 	prevb = &curbuf->b_block_head;
1311 	for (nextb = prevb->mb_next; nextb != curbuf->b_mb_current;
1312 						       nextb = nextb->mb_next)
1313 	    prevb = nextb;
1314 	prevb->mb_next = nextb->mb_next;
1315 	vim_free(nextb);
1316 	curbuf->b_mb_current = NULL;
1317 	curbuf->b_m_search = NULL;
1318     }
1319     else if (curbuf->b_mb_current->mb_maxsize < maxsize)
1320 	curbuf->b_mb_current->mb_maxsize = maxsize;
1321 }
1322 
1323 /*
1324  * Allocate and initialize a new line structure with room for at least
1325  * 'size' characters plus a terminating NUL.
1326  */
1327     static char_u *
1328 u_alloc_line(size)
1329     unsigned	size;
1330 {
1331     minfo_T	*mp, *mprev, *mp2;
1332     mblock_T	*mbp;
1333     int		size_align;
1334 
1335     /*
1336      * Add room for size field and trailing NUL byte.
1337      * Adjust for minimal size (must be able to store minfo_T
1338      * plus a trailing NUL, so the chunk can be released again)
1339      */
1340     size += M_OFFSET + 1;
1341     if (size < sizeof(minfo_T) + 1)
1342 	size = sizeof(minfo_T) + 1;
1343 
1344     /*
1345      * round size up for alignment
1346      */
1347     size_align = (size + ALIGN_MASK) & ~ALIGN_MASK;
1348 
1349     /*
1350      * If curbuf->b_m_search is NULL (uninitialized free list) start at
1351      * curbuf->b_block_head
1352      */
1353     if (curbuf->b_mb_current == NULL || curbuf->b_m_search == NULL)
1354     {
1355 	curbuf->b_mb_current = &curbuf->b_block_head;
1356 	curbuf->b_m_search = &(curbuf->b_block_head.mb_info);
1357     }
1358 
1359     /* Search for a block with enough space. */
1360     mbp = curbuf->b_mb_current;
1361     while (mbp->mb_maxsize < size_align)
1362     {
1363 	if (mbp->mb_next != NULL)
1364 	    mbp = mbp->mb_next;
1365 	else
1366 	    mbp = &curbuf->b_block_head;
1367 	if (mbp == curbuf->b_mb_current)
1368 	{
1369 	    int	n = (size_align > (MEMBLOCKSIZE / 4)
1370 					     ? size_align : MEMBLOCKSIZE);
1371 
1372 	    /* Back where we started in block list: need to add a new block
1373 	     * with enough space. */
1374 	    mp = (minfo_T *)u_blockalloc((long_u)n);
1375 	    if (mp == NULL)
1376 		return (NULL);
1377 	    mp->m_size = n;
1378 	    u_free_line((char_u *)mp + M_OFFSET, TRUE);
1379 	    mbp = curbuf->b_mb_current;
1380 	    break;
1381 	}
1382     }
1383     if (mbp != curbuf->b_mb_current)
1384 	curbuf->b_m_search = &(mbp->mb_info);
1385 
1386     /* In this block find a chunk with enough space. */
1387     mprev = curbuf->b_m_search;
1388     mp = curbuf->b_m_search->m_next;
1389     for (;;)
1390     {
1391 	if (mp == NULL)			    /* at end of the list */
1392 	    mp = &(mbp->mb_info);	    /* wrap around to begin */
1393 	if (mp->m_size >= size)
1394 	    break;
1395 	if (mp == curbuf->b_m_search)
1396 	{
1397 	    /* back where we started in free chunk list: "cannot happen" */
1398 	    EMSG2(_(e_intern2), "u_alloc_line()");
1399 	    return NULL;
1400 	}
1401 	mprev = mp;
1402 	mp = mp->m_next;
1403     }
1404 
1405     /* when using the largest chunk adjust mb_maxsize */
1406     if (mp->m_size >= mbp->mb_maxsize)
1407 	mbp->mb_maxsize = 0;
1408 
1409     /* if the chunk we found is large enough, split it up in two */
1410     if ((long)mp->m_size - size_align >= (long)(sizeof(minfo_T) + 1))
1411     {
1412 	mp2 = (minfo_T *)((char_u *)mp + size_align);
1413 	mp2->m_size = mp->m_size - size_align;
1414 	mp2->m_next = mp->m_next;
1415 	mprev->m_next = mp2;
1416 	mp->m_size = size_align;
1417     }
1418     else		    /* remove *mp from the free list */
1419     {
1420 	mprev->m_next = mp->m_next;
1421     }
1422     curbuf->b_m_search = mprev;
1423     curbuf->b_mb_current = mbp;
1424 
1425     /* If using the largest chunk need to find the new largest chunk */
1426     if (mbp->mb_maxsize == 0)
1427 	for (mp2 = &(mbp->mb_info); mp2 != NULL; mp2 = mp2->m_next)
1428 	    if (mbp->mb_maxsize < mp2->m_size)
1429 		mbp->mb_maxsize = mp2->m_size;
1430 
1431     mp = (minfo_T *)((char_u *)mp + M_OFFSET);
1432     *(char_u *)mp = NUL;		    /* set the first byte to NUL */
1433 
1434     return ((char_u *)mp);
1435 }
1436 #endif
1437 
1438 /*
1439  * u_save_line(): allocate memory with u_alloc_line() and copy line 'lnum'
1440  * into it.
1441  */
1442     static char_u *
1443 u_save_line(lnum)
1444     linenr_T	lnum;
1445 {
1446     char_u	*src;
1447     char_u	*dst;
1448     unsigned	len;
1449 
1450     src = ml_get(lnum);
1451     len = (unsigned)STRLEN(src);
1452     if ((dst = U_ALLOC_LINE(len)) != NULL)
1453 	mch_memmove(dst, src, (size_t)(len + 1));
1454     return (dst);
1455 }
1456 
1457 /*
1458  * Check if the 'modified' flag is set, or 'ff' has changed (only need to
1459  * check the first character, because it can only be "dos", "unix" or "mac").
1460  * "nofile" and "scratch" type buffers are considered to always be unchanged.
1461  */
1462     int
1463 bufIsChanged(buf)
1464     buf_T	*buf;
1465 {
1466     return
1467 #ifdef FEAT_QUICKFIX
1468 	    !bt_dontwrite(buf) &&
1469 #endif
1470 	    (buf->b_changed || file_ff_differs(buf));
1471 }
1472 
1473     int
1474 curbufIsChanged()
1475 {
1476     return
1477 #ifdef FEAT_QUICKFIX
1478 	!bt_dontwrite(curbuf) &&
1479 #endif
1480 	(curbuf->b_changed || file_ff_differs(curbuf));
1481 }
1482