xref: /vim-8.2.3635/src/diff.c (revision 00a927d6)
1 /* vim: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  * diff.c: code for diff'ing two, three or four buffers.
12  */
13 
14 #include "vim.h"
15 
16 #if defined(FEAT_DIFF) || defined(PROTO)
17 
18 static int	diff_busy = FALSE;	/* ex_diffgetput() is busy */
19 
20 /* flags obtained from the 'diffopt' option */
21 #define DIFF_FILLER	1	/* display filler lines */
22 #define DIFF_ICASE	2	/* ignore case */
23 #define DIFF_IWHITE	4	/* ignore change in white space */
24 #define DIFF_HORIZONTAL	8	/* horizontal splits */
25 #define DIFF_VERTICAL	16	/* vertical splits */
26 static int	diff_flags = DIFF_FILLER;
27 
28 #define LBUFLEN 50		/* length of line in diff file */
29 
30 static int diff_a_works = MAYBE; /* TRUE when "diff -a" works, FALSE when it
31 				    doesn't work, MAYBE when not checked yet */
32 #if defined(MSWIN) || defined(MSDOS)
33 static int diff_bin_works = MAYBE; /* TRUE when "diff --binary" works, FALSE
34 				      when it doesn't work, MAYBE when not
35 				      checked yet */
36 #endif
37 
38 static int diff_buf_idx __ARGS((buf_T *buf));
39 static int diff_buf_idx_tp __ARGS((buf_T *buf, tabpage_T *tp));
40 static void diff_mark_adjust_tp __ARGS((tabpage_T *tp, int idx, linenr_T line1, linenr_T line2, long amount, long amount_after));
41 static void diff_check_unchanged __ARGS((tabpage_T *tp, diff_T *dp));
42 static int diff_check_sanity __ARGS((tabpage_T *tp, diff_T *dp));
43 static void diff_redraw __ARGS((int dofold));
44 static int diff_write __ARGS((buf_T *buf, char_u *fname));
45 static void diff_file __ARGS((char_u *tmp_orig, char_u *tmp_new, char_u *tmp_diff));
46 static int diff_equal_entry __ARGS((diff_T *dp, int idx1, int idx2));
47 static int diff_cmp __ARGS((char_u *s1, char_u *s2));
48 #ifdef FEAT_FOLDING
49 static void diff_fold_update __ARGS((diff_T *dp, int skip_idx));
50 #endif
51 static void diff_read __ARGS((int idx_orig, int idx_new, char_u *fname));
52 static void diff_copy_entry __ARGS((diff_T *dprev, diff_T *dp, int idx_orig, int idx_new));
53 static diff_T *diff_alloc_new __ARGS((tabpage_T *tp, diff_T *dprev, diff_T *dp));
54 
55 #ifndef USE_CR
56 # define tag_fgets vim_fgets
57 #endif
58 
59 /*
60  * Called when deleting or unloading a buffer: No longer make a diff with it.
61  */
62     void
63 diff_buf_delete(buf)
64     buf_T	*buf;
65 {
66     int		i;
67     tabpage_T	*tp;
68 
69     for (tp = first_tabpage; tp != NULL; tp = tp->tp_next)
70     {
71 	i = diff_buf_idx_tp(buf, tp);
72 	if (i != DB_COUNT)
73 	{
74 	    tp->tp_diffbuf[i] = NULL;
75 	    tp->tp_diff_invalid = TRUE;
76 	    if (tp == curtab)
77 		diff_redraw(TRUE);
78 	}
79     }
80 }
81 
82 /*
83  * Check if the current buffer should be added to or removed from the list of
84  * diff buffers.
85  */
86     void
87 diff_buf_adjust(win)
88     win_T	*win;
89 {
90     win_T	*wp;
91     int		i;
92 
93     if (!win->w_p_diff)
94     {
95 	/* When there is no window showing a diff for this buffer, remove
96 	 * it from the diffs. */
97 	for (wp = firstwin; wp != NULL; wp = wp->w_next)
98 	    if (wp->w_buffer == win->w_buffer && wp->w_p_diff)
99 		break;
100 	if (wp == NULL)
101 	{
102 	    i = diff_buf_idx(win->w_buffer);
103 	    if (i != DB_COUNT)
104 	    {
105 		curtab->tp_diffbuf[i] = NULL;
106 		curtab->tp_diff_invalid = TRUE;
107 		diff_redraw(TRUE);
108 	    }
109 	}
110     }
111     else
112 	diff_buf_add(win->w_buffer);
113 }
114 
115 /*
116  * Add a buffer to make diffs for.
117  * Call this when a new buffer is being edited in the current window where
118  * 'diff' is set.
119  * Marks the current buffer as being part of the diff and requiring updating.
120  * This must be done before any autocmd, because a command may use info
121  * about the screen contents.
122  */
123     void
124 diff_buf_add(buf)
125     buf_T	*buf;
126 {
127     int		i;
128 
129     if (diff_buf_idx(buf) != DB_COUNT)
130 	return;		/* It's already there. */
131 
132     for (i = 0; i < DB_COUNT; ++i)
133 	if (curtab->tp_diffbuf[i] == NULL)
134 	{
135 	    curtab->tp_diffbuf[i] = buf;
136 	    curtab->tp_diff_invalid = TRUE;
137 	    diff_redraw(TRUE);
138 	    return;
139 	}
140 
141     EMSGN(_("E96: Can not diff more than %ld buffers"), DB_COUNT);
142 }
143 
144 /*
145  * Find buffer "buf" in the list of diff buffers for the current tab page.
146  * Return its index or DB_COUNT if not found.
147  */
148     static int
149 diff_buf_idx(buf)
150     buf_T	*buf;
151 {
152     int		idx;
153 
154     for (idx = 0; idx < DB_COUNT; ++idx)
155 	if (curtab->tp_diffbuf[idx] == buf)
156 	    break;
157     return idx;
158 }
159 
160 /*
161  * Find buffer "buf" in the list of diff buffers for tab page "tp".
162  * Return its index or DB_COUNT if not found.
163  */
164     static int
165 diff_buf_idx_tp(buf, tp)
166     buf_T	*buf;
167     tabpage_T	*tp;
168 {
169     int		idx;
170 
171     for (idx = 0; idx < DB_COUNT; ++idx)
172 	if (tp->tp_diffbuf[idx] == buf)
173 	    break;
174     return idx;
175 }
176 
177 /*
178  * Mark the diff info involving buffer "buf" as invalid, it will be updated
179  * when info is requested.
180  */
181     void
182 diff_invalidate(buf)
183     buf_T	*buf;
184 {
185     tabpage_T	*tp;
186     int		i;
187 
188     for (tp = first_tabpage; tp != NULL; tp = tp->tp_next)
189     {
190 	i = diff_buf_idx_tp(buf, tp);
191 	if (i != DB_COUNT)
192 	{
193 	    tp->tp_diff_invalid = TRUE;
194 	    if (tp == curtab)
195 		diff_redraw(TRUE);
196 	}
197     }
198 }
199 
200 /*
201  * Called by mark_adjust(): update line numbers in "curbuf".
202  */
203     void
204 diff_mark_adjust(line1, line2, amount, amount_after)
205     linenr_T	line1;
206     linenr_T	line2;
207     long	amount;
208     long	amount_after;
209 {
210     int		idx;
211     tabpage_T	*tp;
212 
213     /* Handle all tab pages that use the current buffer in a diff. */
214     for (tp = first_tabpage; tp != NULL; tp = tp->tp_next)
215     {
216 	idx = diff_buf_idx_tp(curbuf, tp);
217 	if (idx != DB_COUNT)
218 	    diff_mark_adjust_tp(tp, idx, line1, line2, amount, amount_after);
219     }
220 }
221 
222 /*
223  * Update line numbers in tab page "tp" for "curbuf" with index "idx".
224  * This attempts to update the changes as much as possible:
225  * When inserting/deleting lines outside of existing change blocks, create a
226  * new change block and update the line numbers in following blocks.
227  * When inserting/deleting lines in existing change blocks, update them.
228  */
229     static void
230 diff_mark_adjust_tp(tp, idx, line1, line2, amount, amount_after)
231     tabpage_T	*tp;
232     int		idx;
233     linenr_T	line1;
234     linenr_T	line2;
235     long	amount;
236     long	amount_after;
237 {
238     diff_T	*dp;
239     diff_T	*dprev;
240     diff_T	*dnext;
241     int		i;
242     int		inserted, deleted;
243     int		n, off;
244     linenr_T	last;
245     linenr_T	lnum_deleted = line1;	/* lnum of remaining deletion */
246     int		check_unchanged;
247 
248     if (line2 == MAXLNUM)
249     {
250 	/* mark_adjust(99, MAXLNUM, 9, 0): insert lines */
251 	inserted = amount;
252 	deleted = 0;
253     }
254     else if (amount_after > 0)
255     {
256 	/* mark_adjust(99, 98, MAXLNUM, 9): a change that inserts lines*/
257 	inserted = amount_after;
258 	deleted = 0;
259     }
260     else
261     {
262 	/* mark_adjust(98, 99, MAXLNUM, -2): delete lines */
263 	inserted = 0;
264 	deleted = -amount_after;
265     }
266 
267     dprev = NULL;
268     dp = tp->tp_first_diff;
269     for (;;)
270     {
271 	/* If the change is after the previous diff block and before the next
272 	 * diff block, thus not touching an existing change, create a new diff
273 	 * block.  Don't do this when ex_diffgetput() is busy. */
274 	if ((dp == NULL || dp->df_lnum[idx] - 1 > line2
275 		    || (line2 == MAXLNUM && dp->df_lnum[idx] > line1))
276 		&& (dprev == NULL
277 		    || dprev->df_lnum[idx] + dprev->df_count[idx] < line1)
278 		&& !diff_busy)
279 	{
280 	    dnext = diff_alloc_new(tp, dprev, dp);
281 	    if (dnext == NULL)
282 		return;
283 
284 	    dnext->df_lnum[idx] = line1;
285 	    dnext->df_count[idx] = inserted;
286 	    for (i = 0; i < DB_COUNT; ++i)
287 		if (tp->tp_diffbuf[i] != NULL && i != idx)
288 		{
289 		    if (dprev == NULL)
290 			dnext->df_lnum[i] = line1;
291 		    else
292 			dnext->df_lnum[i] = line1
293 			    + (dprev->df_lnum[i] + dprev->df_count[i])
294 			    - (dprev->df_lnum[idx] + dprev->df_count[idx]);
295 		    dnext->df_count[i] = deleted;
296 		}
297 	}
298 
299 	/* if at end of the list, quit */
300 	if (dp == NULL)
301 	    break;
302 
303 	/*
304 	 * Check for these situations:
305 	 *	  1  2	3
306 	 *	  1  2	3
307 	 * line1     2	3  4  5
308 	 *	     2	3  4  5
309 	 *	     2	3  4  5
310 	 * line2     2	3  4  5
311 	 *		3     5  6
312 	 *		3     5  6
313 	 */
314 	/* compute last line of this change */
315 	last = dp->df_lnum[idx] + dp->df_count[idx] - 1;
316 
317 	/* 1. change completely above line1: nothing to do */
318 	if (last >= line1 - 1)
319 	{
320 	    /* 6. change below line2: only adjust for amount_after; also when
321 	     * "deleted" became zero when deleted all lines between two diffs */
322 	    if (dp->df_lnum[idx] - (deleted + inserted != 0) > line2)
323 	    {
324 		if (amount_after == 0)
325 		    break;	/* nothing left to change */
326 		dp->df_lnum[idx] += amount_after;
327 	    }
328 	    else
329 	    {
330 		check_unchanged = FALSE;
331 
332 		/* 2. 3. 4. 5.: inserted/deleted lines touching this diff. */
333 		if (deleted > 0)
334 		{
335 		    if (dp->df_lnum[idx] >= line1)
336 		    {
337 			off = dp->df_lnum[idx] - lnum_deleted;
338 			if (last <= line2)
339 			{
340 			    /* 4. delete all lines of diff */
341 			    if (dp->df_next != NULL
342 				    && dp->df_next->df_lnum[idx] - 1 <= line2)
343 			    {
344 				/* delete continues in next diff, only do
345 				 * lines until that one */
346 				n = dp->df_next->df_lnum[idx] - lnum_deleted;
347 				deleted -= n;
348 				n -= dp->df_count[idx];
349 				lnum_deleted = dp->df_next->df_lnum[idx];
350 			    }
351 			    else
352 				n = deleted - dp->df_count[idx];
353 			    dp->df_count[idx] = 0;
354 			}
355 			else
356 			{
357 			    /* 5. delete lines at or just before top of diff */
358 			    n = off;
359 			    dp->df_count[idx] -= line2 - dp->df_lnum[idx] + 1;
360 			    check_unchanged = TRUE;
361 			}
362 			dp->df_lnum[idx] = line1;
363 		    }
364 		    else
365 		    {
366 			off = 0;
367 			if (last < line2)
368 			{
369 			    /* 2. delete at end of of diff */
370 			    dp->df_count[idx] -= last - lnum_deleted + 1;
371 			    if (dp->df_next != NULL
372 				    && dp->df_next->df_lnum[idx] - 1 <= line2)
373 			    {
374 				/* delete continues in next diff, only do
375 				 * lines until that one */
376 				n = dp->df_next->df_lnum[idx] - 1 - last;
377 				deleted -= dp->df_next->df_lnum[idx]
378 							       - lnum_deleted;
379 				lnum_deleted = dp->df_next->df_lnum[idx];
380 			    }
381 			    else
382 				n = line2 - last;
383 			    check_unchanged = TRUE;
384 			}
385 			else
386 			{
387 			    /* 3. delete lines inside the diff */
388 			    n = 0;
389 			    dp->df_count[idx] -= deleted;
390 			}
391 		    }
392 
393 		    for (i = 0; i < DB_COUNT; ++i)
394 			if (tp->tp_diffbuf[i] != NULL && i != idx)
395 			{
396 			    dp->df_lnum[i] -= off;
397 			    dp->df_count[i] += n;
398 			}
399 		}
400 		else
401 		{
402 		    if (dp->df_lnum[idx] <= line1)
403 		    {
404 			/* inserted lines somewhere in this diff */
405 			dp->df_count[idx] += inserted;
406 			check_unchanged = TRUE;
407 		    }
408 		    else
409 			/* inserted lines somewhere above this diff */
410 			dp->df_lnum[idx] += inserted;
411 		}
412 
413 		if (check_unchanged)
414 		    /* Check if inserted lines are equal, may reduce the
415 		     * size of the diff.  TODO: also check for equal lines
416 		     * in the middle and perhaps split the block. */
417 		    diff_check_unchanged(tp, dp);
418 	    }
419 	}
420 
421 	/* check if this block touches the previous one, may merge them. */
422 	if (dprev != NULL && dprev->df_lnum[idx] + dprev->df_count[idx]
423 							  == dp->df_lnum[idx])
424 	{
425 	    for (i = 0; i < DB_COUNT; ++i)
426 		if (tp->tp_diffbuf[i] != NULL)
427 		    dprev->df_count[i] += dp->df_count[i];
428 	    dprev->df_next = dp->df_next;
429 	    vim_free(dp);
430 	    dp = dprev->df_next;
431 	}
432 	else
433 	{
434 	    /* Advance to next entry. */
435 	    dprev = dp;
436 	    dp = dp->df_next;
437 	}
438     }
439 
440     dprev = NULL;
441     dp = tp->tp_first_diff;
442     while (dp != NULL)
443     {
444 	/* All counts are zero, remove this entry. */
445 	for (i = 0; i < DB_COUNT; ++i)
446 	    if (tp->tp_diffbuf[i] != NULL && dp->df_count[i] != 0)
447 		break;
448 	if (i == DB_COUNT)
449 	{
450 	    dnext = dp->df_next;
451 	    vim_free(dp);
452 	    dp = dnext;
453 	    if (dprev == NULL)
454 		tp->tp_first_diff = dnext;
455 	    else
456 		dprev->df_next = dnext;
457 	}
458 	else
459 	{
460 	    /* Advance to next entry. */
461 	    dprev = dp;
462 	    dp = dp->df_next;
463 	}
464 
465     }
466 
467     if (tp == curtab)
468     {
469 	diff_redraw(TRUE);
470 
471 	/* Need to recompute the scroll binding, may remove or add filler
472 	 * lines (e.g., when adding lines above w_topline). But it's slow when
473 	 * making many changes, postpone until redrawing. */
474 	diff_need_scrollbind = TRUE;
475     }
476 }
477 
478 /*
479  * Allocate a new diff block and link it between "dprev" and "dp".
480  */
481     static diff_T *
482 diff_alloc_new(tp, dprev, dp)
483     tabpage_T	*tp;
484     diff_T	*dprev;
485     diff_T	*dp;
486 {
487     diff_T	*dnew;
488 
489     dnew = (diff_T *)alloc((unsigned)sizeof(diff_T));
490     if (dnew != NULL)
491     {
492 	dnew->df_next = dp;
493 	if (dprev == NULL)
494 	    tp->tp_first_diff = dnew;
495 	else
496 	    dprev->df_next = dnew;
497     }
498     return dnew;
499 }
500 
501 /*
502  * Check if the diff block "dp" can be made smaller for lines at the start and
503  * end that are equal.  Called after inserting lines.
504  * This may result in a change where all buffers have zero lines, the caller
505  * must take care of removing it.
506  */
507     static void
508 diff_check_unchanged(tp, dp)
509     tabpage_T	*tp;
510     diff_T	*dp;
511 {
512     int		i_org;
513     int		i_new;
514     int		off_org, off_new;
515     char_u	*line_org;
516     int		dir = FORWARD;
517 
518     /* Find the first buffers, use it as the original, compare the other
519      * buffer lines against this one. */
520     for (i_org = 0; i_org < DB_COUNT; ++i_org)
521 	if (tp->tp_diffbuf[i_org] != NULL)
522 	    break;
523     if (i_org == DB_COUNT)	/* safety check */
524 	return;
525 
526     if (diff_check_sanity(tp, dp) == FAIL)
527 	return;
528 
529     /* First check lines at the top, then at the bottom. */
530     off_org = 0;
531     off_new = 0;
532     for (;;)
533     {
534 	/* Repeat until a line is found which is different or the number of
535 	 * lines has become zero. */
536 	while (dp->df_count[i_org] > 0)
537 	{
538 	    /* Copy the line, the next ml_get() will invalidate it.  */
539 	    if (dir == BACKWARD)
540 		off_org = dp->df_count[i_org] - 1;
541 	    line_org = vim_strsave(ml_get_buf(tp->tp_diffbuf[i_org],
542 					dp->df_lnum[i_org] + off_org, FALSE));
543 	    if (line_org == NULL)
544 		return;
545 	    for (i_new = i_org + 1; i_new < DB_COUNT; ++i_new)
546 	    {
547 		if (tp->tp_diffbuf[i_new] == NULL)
548 		    continue;
549 		if (dir == BACKWARD)
550 		    off_new = dp->df_count[i_new] - 1;
551 		/* if other buffer doesn't have this line, it was inserted */
552 		if (off_new < 0 || off_new >= dp->df_count[i_new])
553 		    break;
554 		if (diff_cmp(line_org, ml_get_buf(tp->tp_diffbuf[i_new],
555 				   dp->df_lnum[i_new] + off_new, FALSE)) != 0)
556 		    break;
557 	    }
558 	    vim_free(line_org);
559 
560 	    /* Stop when a line isn't equal in all diff buffers. */
561 	    if (i_new != DB_COUNT)
562 		break;
563 
564 	    /* Line matched in all buffers, remove it from the diff. */
565 	    for (i_new = i_org; i_new < DB_COUNT; ++i_new)
566 		if (tp->tp_diffbuf[i_new] != NULL)
567 		{
568 		    if (dir == FORWARD)
569 			++dp->df_lnum[i_new];
570 		    --dp->df_count[i_new];
571 		}
572 	}
573 	if (dir == BACKWARD)
574 	    break;
575 	dir = BACKWARD;
576     }
577 }
578 
579 /*
580  * Check if a diff block doesn't contain invalid line numbers.
581  * This can happen when the diff program returns invalid results.
582  */
583     static int
584 diff_check_sanity(tp, dp)
585     tabpage_T	*tp;
586     diff_T	*dp;
587 {
588     int		i;
589 
590     for (i = 0; i < DB_COUNT; ++i)
591 	if (tp->tp_diffbuf[i] != NULL)
592 	    if (dp->df_lnum[i] + dp->df_count[i] - 1
593 				      > tp->tp_diffbuf[i]->b_ml.ml_line_count)
594 		return FAIL;
595     return OK;
596 }
597 
598 /*
599  * Mark all diff buffers in the current tab page for redraw.
600  */
601     static void
602 diff_redraw(dofold)
603     int		dofold;	    /* also recompute the folds */
604 {
605     win_T	*wp;
606     int		n;
607 
608     for (wp = firstwin; wp != NULL; wp = wp->w_next)
609 	if (wp->w_p_diff)
610 	{
611 	    redraw_win_later(wp, SOME_VALID);
612 #ifdef FEAT_FOLDING
613 	    if (dofold && foldmethodIsDiff(wp))
614 		foldUpdateAll(wp);
615 #endif
616 	    /* A change may have made filler lines invalid, need to take care
617 	     * of that for other windows. */
618 	    if (wp != curwin && wp->w_topfill > 0)
619 	    {
620 		n = diff_check(wp, wp->w_topline);
621 		if (wp->w_topfill > n)
622 		    wp->w_topfill = (n < 0 ? 0 : n);
623 	    }
624 	}
625 }
626 
627 /*
628  * Write buffer "buf" to file "name".
629  * Always use 'fileformat' set to "unix".
630  * Return FAIL for failure
631  */
632     static int
633 diff_write(buf, fname)
634     buf_T	*buf;
635     char_u	*fname;
636 {
637     int		r;
638     char_u	*save_ff;
639 
640     save_ff = buf->b_p_ff;
641     buf->b_p_ff = vim_strsave((char_u *)FF_UNIX);
642     r = buf_write(buf, fname, NULL, (linenr_T)1, buf->b_ml.ml_line_count,
643 					     NULL, FALSE, FALSE, FALSE, TRUE);
644     free_string_option(buf->b_p_ff);
645     buf->b_p_ff = save_ff;
646     return r;
647 }
648 
649 /*
650  * Completely update the diffs for the buffers involved.
651  * This uses the ordinary "diff" command.
652  * The buffers are written to a file, also for unmodified buffers (the file
653  * could have been produced by autocommands, e.g. the netrw plugin).
654  */
655     void
656 ex_diffupdate(eap)
657     exarg_T	*eap UNUSED;	    /* can be NULL */
658 {
659     buf_T	*buf;
660     int		idx_orig;
661     int		idx_new;
662     char_u	*tmp_orig;
663     char_u	*tmp_new;
664     char_u	*tmp_diff;
665     FILE	*fd;
666     int		ok;
667     int		io_error = FALSE;
668 
669     /* Delete all diffblocks. */
670     diff_clear(curtab);
671     curtab->tp_diff_invalid = FALSE;
672 
673     /* Use the first buffer as the original text. */
674     for (idx_orig = 0; idx_orig < DB_COUNT; ++idx_orig)
675 	if (curtab->tp_diffbuf[idx_orig] != NULL)
676 	    break;
677     if (idx_orig == DB_COUNT)
678 	return;
679 
680     /* Only need to do something when there is another buffer. */
681     for (idx_new = idx_orig + 1; idx_new < DB_COUNT; ++idx_new)
682 	if (curtab->tp_diffbuf[idx_new] != NULL)
683 	    break;
684     if (idx_new == DB_COUNT)
685 	return;
686 
687     /* We need three temp file names. */
688     tmp_orig = vim_tempname('o');
689     tmp_new = vim_tempname('n');
690     tmp_diff = vim_tempname('d');
691     if (tmp_orig == NULL || tmp_new == NULL || tmp_diff == NULL)
692 	goto theend;
693 
694     /*
695      * Do a quick test if "diff" really works.  Otherwise it looks like there
696      * are no differences.  Can't use the return value, it's non-zero when
697      * there are differences.
698      * May try twice, first with "-a" and then without.
699      */
700     for (;;)
701     {
702 	ok = FALSE;
703 	fd = mch_fopen((char *)tmp_orig, "w");
704 	if (fd == NULL)
705 	    io_error = TRUE;
706 	else
707 	{
708 	    if (fwrite("line1\n", (size_t)6, (size_t)1, fd) != 1)
709 		io_error = TRUE;
710 	    fclose(fd);
711 	    fd = mch_fopen((char *)tmp_new, "w");
712 	    if (fd == NULL)
713 		io_error = TRUE;
714 	    else
715 	    {
716 		if (fwrite("line2\n", (size_t)6, (size_t)1, fd) != 1)
717 		    io_error = TRUE;
718 		fclose(fd);
719 		diff_file(tmp_orig, tmp_new, tmp_diff);
720 		fd = mch_fopen((char *)tmp_diff, "r");
721 		if (fd == NULL)
722 		    io_error = TRUE;
723 		else
724 		{
725 		    char_u	linebuf[LBUFLEN];
726 
727 		    for (;;)
728 		    {
729 			/* There must be a line that contains "1c1". */
730 			if (tag_fgets(linebuf, LBUFLEN, fd))
731 			    break;
732 			if (STRNCMP(linebuf, "1c1", 3) == 0)
733 			    ok = TRUE;
734 		    }
735 		    fclose(fd);
736 		}
737 		mch_remove(tmp_diff);
738 		mch_remove(tmp_new);
739 	    }
740 	    mch_remove(tmp_orig);
741 	}
742 
743 #ifdef FEAT_EVAL
744 	/* When using 'diffexpr' break here. */
745 	if (*p_dex != NUL)
746 	    break;
747 #endif
748 
749 #if defined(MSWIN) || defined(MSDOS)
750 	/* If the "-a" argument works, also check if "--binary" works. */
751 	if (ok && diff_a_works == MAYBE && diff_bin_works == MAYBE)
752 	{
753 	    diff_a_works = TRUE;
754 	    diff_bin_works = TRUE;
755 	    continue;
756 	}
757 	if (!ok && diff_a_works == TRUE && diff_bin_works == TRUE)
758 	{
759 	    /* Tried --binary, but it failed. "-a" works though. */
760 	    diff_bin_works = FALSE;
761 	    ok = TRUE;
762 	}
763 #endif
764 
765 	/* If we checked if "-a" works already, break here. */
766 	if (diff_a_works != MAYBE)
767 	    break;
768 	diff_a_works = ok;
769 
770 	/* If "-a" works break here, otherwise retry without "-a". */
771 	if (ok)
772 	    break;
773     }
774     if (!ok)
775     {
776 	if (io_error)
777 	    EMSG(_("E810: Cannot read or write temp files"));
778 	EMSG(_("E97: Cannot create diffs"));
779 	diff_a_works = MAYBE;
780 #if defined(MSWIN) || defined(MSDOS)
781 	diff_bin_works = MAYBE;
782 #endif
783 	goto theend;
784     }
785 
786     /* Write the first buffer to a tempfile. */
787     buf = curtab->tp_diffbuf[idx_orig];
788     if (diff_write(buf, tmp_orig) == FAIL)
789 	goto theend;
790 
791     /* Make a difference between the first buffer and every other. */
792     for (idx_new = idx_orig + 1; idx_new < DB_COUNT; ++idx_new)
793     {
794 	buf = curtab->tp_diffbuf[idx_new];
795 	if (buf == NULL)
796 	    continue;
797 	if (diff_write(buf, tmp_new) == FAIL)
798 	    continue;
799 	diff_file(tmp_orig, tmp_new, tmp_diff);
800 
801 	/* Read the diff output and add each entry to the diff list. */
802 	diff_read(idx_orig, idx_new, tmp_diff);
803 	mch_remove(tmp_diff);
804 	mch_remove(tmp_new);
805     }
806     mch_remove(tmp_orig);
807 
808     /* force updating cursor position on screen */
809     curwin->w_valid_cursor.lnum = 0;
810 
811     diff_redraw(TRUE);
812 
813 theend:
814     vim_free(tmp_orig);
815     vim_free(tmp_new);
816     vim_free(tmp_diff);
817 }
818 
819 /*
820  * Make a diff between files "tmp_orig" and "tmp_new", results in "tmp_diff".
821  */
822     static void
823 diff_file(tmp_orig, tmp_new, tmp_diff)
824     char_u	*tmp_orig;
825     char_u	*tmp_new;
826     char_u	*tmp_diff;
827 {
828     char_u	*cmd;
829     size_t	len;
830 
831 #ifdef FEAT_EVAL
832     if (*p_dex != NUL)
833 	/* Use 'diffexpr' to generate the diff file. */
834 	eval_diff(tmp_orig, tmp_new, tmp_diff);
835     else
836 #endif
837     {
838 	len = STRLEN(tmp_orig) + STRLEN(tmp_new)
839 				      + STRLEN(tmp_diff) + STRLEN(p_srr) + 27;
840 	cmd = alloc((unsigned)len);
841 	if (cmd != NULL)
842 	{
843 	    /* We don't want $DIFF_OPTIONS to get in the way. */
844 	    if (getenv("DIFF_OPTIONS"))
845 		vim_setenv((char_u *)"DIFF_OPTIONS", (char_u *)"");
846 
847 	    /* Build the diff command and execute it.  Always use -a, binary
848 	     * differences are of no use.  Ignore errors, diff returns
849 	     * non-zero when differences have been found. */
850 	    vim_snprintf((char *)cmd, len, "diff %s%s%s%s%s %s",
851 		    diff_a_works == FALSE ? "" : "-a ",
852 #if defined(MSWIN) || defined(MSDOS)
853 		    diff_bin_works == TRUE ? "--binary " : "",
854 #else
855 		    "",
856 #endif
857 		    (diff_flags & DIFF_IWHITE) ? "-b " : "",
858 		    (diff_flags & DIFF_ICASE) ? "-i " : "",
859 		    tmp_orig, tmp_new);
860 	    append_redir(cmd, (int)len, p_srr, tmp_diff);
861 #ifdef FEAT_AUTOCMD
862 	    block_autocmds();	/* Avoid ShellCmdPost stuff */
863 #endif
864 	    (void)call_shell(cmd, SHELL_FILTER|SHELL_SILENT|SHELL_DOOUT);
865 #ifdef FEAT_AUTOCMD
866 	    unblock_autocmds();
867 #endif
868 	    vim_free(cmd);
869 	}
870     }
871 }
872 
873 /*
874  * Create a new version of a file from the current buffer and a diff file.
875  * The buffer is written to a file, also for unmodified buffers (the file
876  * could have been produced by autocommands, e.g. the netrw plugin).
877  */
878     void
879 ex_diffpatch(eap)
880     exarg_T	*eap;
881 {
882     char_u	*tmp_orig;	/* name of original temp file */
883     char_u	*tmp_new;	/* name of patched temp file */
884     char_u	*buf = NULL;
885     size_t	buflen;
886     win_T	*old_curwin = curwin;
887     char_u	*newname = NULL;	/* name of patched file buffer */
888 #ifdef UNIX
889     char_u	dirbuf[MAXPATHL];
890     char_u	*fullname = NULL;
891 #endif
892 #ifdef FEAT_BROWSE
893     char_u	*browseFile = NULL;
894     int		browse_flag = cmdmod.browse;
895 #endif
896     struct stat st;
897 
898 #ifdef FEAT_BROWSE
899     if (cmdmod.browse)
900     {
901 	browseFile = do_browse(0, (char_u *)_("Patch file"),
902 			 eap->arg, NULL, NULL, BROWSE_FILTER_ALL_FILES, NULL);
903 	if (browseFile == NULL)
904 	    return;		/* operation cancelled */
905 	eap->arg = browseFile;
906 	cmdmod.browse = FALSE;	/* don't let do_ecmd() browse again */
907     }
908 #endif
909 
910     /* We need two temp file names. */
911     tmp_orig = vim_tempname('o');
912     tmp_new = vim_tempname('n');
913     if (tmp_orig == NULL || tmp_new == NULL)
914 	goto theend;
915 
916     /* Write the current buffer to "tmp_orig". */
917     if (buf_write(curbuf, tmp_orig, NULL,
918 		(linenr_T)1, curbuf->b_ml.ml_line_count,
919 				     NULL, FALSE, FALSE, FALSE, TRUE) == FAIL)
920 	goto theend;
921 
922 #ifdef UNIX
923     /* Get the absolute path of the patchfile, changing directory below. */
924     fullname = FullName_save(eap->arg, FALSE);
925 #endif
926     buflen = STRLEN(tmp_orig) + (
927 # ifdef UNIX
928 		    fullname != NULL ? STRLEN(fullname) :
929 # endif
930 		    STRLEN(eap->arg)) + STRLEN(tmp_new) + 16;
931     buf = alloc((unsigned)buflen);
932     if (buf == NULL)
933 	goto theend;
934 
935 #ifdef UNIX
936     /* Temporarily chdir to /tmp, to avoid patching files in the current
937      * directory when the patch file contains more than one patch.  When we
938      * have our own temp dir use that instead, it will be cleaned up when we
939      * exit (any .rej files created).  Don't change directory if we can't
940      * return to the current. */
941     if (mch_dirname(dirbuf, MAXPATHL) != OK || mch_chdir((char *)dirbuf) != 0)
942 	dirbuf[0] = NUL;
943     else
944     {
945 # ifdef TEMPDIRNAMES
946 	if (vim_tempdir != NULL)
947 	    ignored = mch_chdir((char *)vim_tempdir);
948 	else
949 # endif
950 	    ignored = mch_chdir("/tmp");
951 	shorten_fnames(TRUE);
952     }
953 #endif
954 
955 #ifdef FEAT_EVAL
956     if (*p_pex != NUL)
957 	/* Use 'patchexpr' to generate the new file. */
958 	eval_patch(tmp_orig,
959 # ifdef UNIX
960 		fullname != NULL ? fullname :
961 # endif
962 		eap->arg, tmp_new);
963     else
964 #endif
965     {
966 	/* Build the patch command and execute it.  Ignore errors.  Switch to
967 	 * cooked mode to allow the user to respond to prompts. */
968 	vim_snprintf((char *)buf, buflen, "patch -o %s %s < \"%s\"",
969 		tmp_new, tmp_orig,
970 # ifdef UNIX
971 		fullname != NULL ? fullname :
972 # endif
973 		eap->arg);
974 #ifdef FEAT_AUTOCMD
975 	block_autocmds();	/* Avoid ShellCmdPost stuff */
976 #endif
977 	(void)call_shell(buf, SHELL_FILTER | SHELL_COOKED);
978 #ifdef FEAT_AUTOCMD
979 	unblock_autocmds();
980 #endif
981     }
982 
983 #ifdef UNIX
984     if (dirbuf[0] != NUL)
985     {
986 	if (mch_chdir((char *)dirbuf) != 0)
987 	    EMSG(_(e_prev_dir));
988 	shorten_fnames(TRUE);
989     }
990 #endif
991 
992     /* patch probably has written over the screen */
993     redraw_later(CLEAR);
994 
995     /* Delete any .orig or .rej file created. */
996     STRCPY(buf, tmp_new);
997     STRCAT(buf, ".orig");
998     mch_remove(buf);
999     STRCPY(buf, tmp_new);
1000     STRCAT(buf, ".rej");
1001     mch_remove(buf);
1002 
1003     /* Only continue if the output file was created. */
1004     if (mch_stat((char *)tmp_new, &st) < 0 || st.st_size == 0)
1005 	EMSG(_("E816: Cannot read patch output"));
1006     else
1007     {
1008 	if (curbuf->b_fname != NULL)
1009 	{
1010 	    newname = vim_strnsave(curbuf->b_fname,
1011 					  (int)(STRLEN(curbuf->b_fname) + 4));
1012 	    if (newname != NULL)
1013 		STRCAT(newname, ".new");
1014 	}
1015 
1016 #ifdef FEAT_GUI
1017 	need_mouse_correct = TRUE;
1018 #endif
1019 	/* don't use a new tab page, each tab page has its own diffs */
1020 	cmdmod.tab = 0;
1021 
1022 	if (win_split(0, (diff_flags & DIFF_VERTICAL) ? WSP_VERT : 0) != FAIL)
1023 	{
1024 	    /* Pretend it was a ":split fname" command */
1025 	    eap->cmdidx = CMD_split;
1026 	    eap->arg = tmp_new;
1027 	    do_exedit(eap, old_curwin);
1028 
1029 	    /* check that split worked and editing tmp_new */
1030 	    if (curwin != old_curwin && win_valid(old_curwin))
1031 	    {
1032 		/* Set 'diff', 'scrollbind' on and 'wrap' off. */
1033 		diff_win_options(curwin, TRUE);
1034 		diff_win_options(old_curwin, TRUE);
1035 
1036 		if (newname != NULL)
1037 		{
1038 		    /* do a ":file filename.new" on the patched buffer */
1039 		    eap->arg = newname;
1040 		    ex_file(eap);
1041 
1042 #ifdef FEAT_AUTOCMD
1043 		    /* Do filetype detection with the new name. */
1044 		    if (au_has_group((char_u *)"filetypedetect"))
1045 			do_cmdline_cmd((char_u *)":doau filetypedetect BufRead");
1046 #endif
1047 		}
1048 	    }
1049 	}
1050     }
1051 
1052 theend:
1053     if (tmp_orig != NULL)
1054 	mch_remove(tmp_orig);
1055     vim_free(tmp_orig);
1056     if (tmp_new != NULL)
1057 	mch_remove(tmp_new);
1058     vim_free(tmp_new);
1059     vim_free(newname);
1060     vim_free(buf);
1061 #ifdef UNIX
1062     vim_free(fullname);
1063 #endif
1064 #ifdef FEAT_BROWSE
1065     vim_free(browseFile);
1066     cmdmod.browse = browse_flag;
1067 #endif
1068 }
1069 
1070 /*
1071  * Split the window and edit another file, setting options to show the diffs.
1072  */
1073     void
1074 ex_diffsplit(eap)
1075     exarg_T	*eap;
1076 {
1077     win_T	*old_curwin = curwin;
1078 
1079 #ifdef FEAT_GUI
1080     need_mouse_correct = TRUE;
1081 #endif
1082     /* don't use a new tab page, each tab page has its own diffs */
1083     cmdmod.tab = 0;
1084 
1085     if (win_split(0, (diff_flags & DIFF_VERTICAL) ? WSP_VERT : 0) != FAIL)
1086     {
1087 	/* Pretend it was a ":split fname" command */
1088 	eap->cmdidx = CMD_split;
1089 	curwin->w_p_diff = TRUE;
1090 	do_exedit(eap, old_curwin);
1091 
1092 	if (curwin != old_curwin)		/* split must have worked */
1093 	{
1094 	    /* Set 'diff', 'scrollbind' on and 'wrap' off. */
1095 	    diff_win_options(curwin, TRUE);
1096 	    diff_win_options(old_curwin, TRUE);
1097 	}
1098     }
1099 }
1100 
1101 /*
1102  * Set options to show difs for the current window.
1103  */
1104     void
1105 ex_diffthis(eap)
1106     exarg_T	*eap UNUSED;
1107 {
1108     /* Set 'diff', 'scrollbind' on and 'wrap' off. */
1109     diff_win_options(curwin, TRUE);
1110 }
1111 
1112 /*
1113  * Set options in window "wp" for diff mode.
1114  */
1115     void
1116 diff_win_options(wp, addbuf)
1117     win_T	*wp;
1118     int		addbuf;		/* Add buffer to diff. */
1119 {
1120 # ifdef FEAT_FOLDING
1121     win_T *old_curwin = curwin;
1122 
1123     /* close the manually opened folds */
1124     curwin = wp;
1125     newFoldLevel();
1126     curwin = old_curwin;
1127 # endif
1128 
1129     wp->w_p_diff = TRUE;
1130     wp->w_p_scb = TRUE;
1131     wp->w_p_wrap = FALSE;
1132 # ifdef FEAT_FOLDING
1133     curwin = wp;
1134     curbuf = curwin->w_buffer;
1135     set_string_option_direct((char_u *)"fdm", -1, (char_u *)"diff",
1136 						       OPT_LOCAL|OPT_FREE, 0);
1137     curwin = old_curwin;
1138     curbuf = curwin->w_buffer;
1139     wp->w_p_fdc = diff_foldcolumn;
1140     wp->w_p_fen = TRUE;
1141     wp->w_p_fdl = 0;
1142     foldUpdateAll(wp);
1143     /* make sure topline is not halfway a fold */
1144     changed_window_setting_win(wp);
1145 # endif
1146 #ifdef FEAT_SCROLLBIND
1147     if (vim_strchr(p_sbo, 'h') == NULL)
1148 	do_cmdline_cmd((char_u *)"set sbo+=hor");
1149 #endif
1150 
1151     if (addbuf)
1152 	diff_buf_add(wp->w_buffer);
1153     redraw_win_later(wp, NOT_VALID);
1154 }
1155 
1156 /*
1157  * Set options not to show diffs.  For the current window or all windows.
1158  * Only in the current tab page.
1159  */
1160     void
1161 ex_diffoff(eap)
1162     exarg_T	*eap;
1163 {
1164     win_T	*wp;
1165     win_T	*old_curwin = curwin;
1166 #ifdef FEAT_SCROLLBIND
1167     int		diffwin = FALSE;
1168 #endif
1169 
1170     for (wp = firstwin; wp != NULL; wp = wp->w_next)
1171     {
1172 	if (wp == curwin || (eap->forceit && wp->w_p_diff))
1173 	{
1174 	    /* Set 'diff', 'scrollbind' off and 'wrap' on. */
1175 	    wp->w_p_diff = FALSE;
1176 	    wp->w_p_scb = FALSE;
1177 	    wp->w_p_wrap = TRUE;
1178 #ifdef FEAT_FOLDING
1179 	    curwin = wp;
1180 	    curbuf = curwin->w_buffer;
1181 	    set_string_option_direct((char_u *)"fdm", -1,
1182 				   (char_u *)"manual", OPT_LOCAL|OPT_FREE, 0);
1183 	    curwin = old_curwin;
1184 	    curbuf = curwin->w_buffer;
1185 	    wp->w_p_fdc = 0;
1186 	    wp->w_p_fen = FALSE;
1187 	    wp->w_p_fdl = 0;
1188 	    foldUpdateAll(wp);
1189 	    /* make sure topline is not halfway a fold */
1190 	    changed_window_setting_win(wp);
1191 #endif
1192 	    diff_buf_adjust(wp);
1193 	}
1194 #ifdef FEAT_SCROLLBIND
1195 	diffwin |= wp->w_p_diff;
1196 #endif
1197     }
1198 
1199 #ifdef FEAT_SCROLLBIND
1200     /* Remove "hor" from from 'scrollopt' if there are no diff windows left. */
1201     if (!diffwin && vim_strchr(p_sbo, 'h') != NULL)
1202 	do_cmdline_cmd((char_u *)"set sbo-=hor");
1203 #endif
1204 }
1205 
1206 /*
1207  * Read the diff output and add each entry to the diff list.
1208  */
1209     static void
1210 diff_read(idx_orig, idx_new, fname)
1211     int		idx_orig;	/* idx of original file */
1212     int		idx_new;	/* idx of new file */
1213     char_u	*fname;		/* name of diff output file */
1214 {
1215     FILE	*fd;
1216     diff_T	*dprev = NULL;
1217     diff_T	*dp = curtab->tp_first_diff;
1218     diff_T	*dn, *dpl;
1219     long	f1, l1, f2, l2;
1220     char_u	linebuf[LBUFLEN];   /* only need to hold the diff line */
1221     int		difftype;
1222     char_u	*p;
1223     long	off;
1224     int		i;
1225     linenr_T	lnum_orig, lnum_new;
1226     long	count_orig, count_new;
1227     int		notset = TRUE;	    /* block "*dp" not set yet */
1228 
1229     fd = mch_fopen((char *)fname, "r");
1230     if (fd == NULL)
1231     {
1232 	EMSG(_("E98: Cannot read diff output"));
1233 	return;
1234     }
1235 
1236     for (;;)
1237     {
1238 	if (tag_fgets(linebuf, LBUFLEN, fd))
1239 	    break;		/* end of file */
1240 	if (!isdigit(*linebuf))
1241 	    continue;		/* not the start of a diff block */
1242 
1243 	/* This line must be one of three formats:
1244 	 * {first}[,{last}]c{first}[,{last}]
1245 	 * {first}a{first}[,{last}]
1246 	 * {first}[,{last}]d{first}
1247 	 */
1248 	p = linebuf;
1249 	f1 = getdigits(&p);
1250 	if (*p == ',')
1251 	{
1252 	    ++p;
1253 	    l1 = getdigits(&p);
1254 	}
1255 	else
1256 	    l1 = f1;
1257 	if (*p != 'a' && *p != 'c' && *p != 'd')
1258 	    continue;		/* invalid diff format */
1259 	difftype = *p++;
1260 	f2 = getdigits(&p);
1261 	if (*p == ',')
1262 	{
1263 	    ++p;
1264 	    l2 = getdigits(&p);
1265 	}
1266 	else
1267 	    l2 = f2;
1268 	if (l1 < f1 || l2 < f2)
1269 	    continue;		/* invalid line range */
1270 
1271 	if (difftype == 'a')
1272 	{
1273 	    lnum_orig = f1 + 1;
1274 	    count_orig = 0;
1275 	}
1276 	else
1277 	{
1278 	    lnum_orig = f1;
1279 	    count_orig = l1 - f1 + 1;
1280 	}
1281 	if (difftype == 'd')
1282 	{
1283 	    lnum_new = f2 + 1;
1284 	    count_new = 0;
1285 	}
1286 	else
1287 	{
1288 	    lnum_new = f2;
1289 	    count_new = l2 - f2 + 1;
1290 	}
1291 
1292 	/* Go over blocks before the change, for which orig and new are equal.
1293 	 * Copy blocks from orig to new. */
1294 	while (dp != NULL
1295 		&& lnum_orig > dp->df_lnum[idx_orig] + dp->df_count[idx_orig])
1296 	{
1297 	    if (notset)
1298 		diff_copy_entry(dprev, dp, idx_orig, idx_new);
1299 	    dprev = dp;
1300 	    dp = dp->df_next;
1301 	    notset = TRUE;
1302 	}
1303 
1304 	if (dp != NULL
1305 		&& lnum_orig <= dp->df_lnum[idx_orig] + dp->df_count[idx_orig]
1306 		&& lnum_orig + count_orig >= dp->df_lnum[idx_orig])
1307 	{
1308 	    /* New block overlaps with existing block(s).
1309 	     * First find last block that overlaps. */
1310 	    for (dpl = dp; dpl->df_next != NULL; dpl = dpl->df_next)
1311 		if (lnum_orig + count_orig < dpl->df_next->df_lnum[idx_orig])
1312 		    break;
1313 
1314 	    /* If the newly found block starts before the old one, set the
1315 	     * start back a number of lines. */
1316 	    off = dp->df_lnum[idx_orig] - lnum_orig;
1317 	    if (off > 0)
1318 	    {
1319 		for (i = idx_orig; i < idx_new; ++i)
1320 		    if (curtab->tp_diffbuf[i] != NULL)
1321 			dp->df_lnum[i] -= off;
1322 		dp->df_lnum[idx_new] = lnum_new;
1323 		dp->df_count[idx_new] = count_new;
1324 	    }
1325 	    else if (notset)
1326 	    {
1327 		/* new block inside existing one, adjust new block */
1328 		dp->df_lnum[idx_new] = lnum_new + off;
1329 		dp->df_count[idx_new] = count_new - off;
1330 	    }
1331 	    else
1332 		/* second overlap of new block with existing block */
1333 		dp->df_count[idx_new] += count_new - count_orig
1334 		    + dpl->df_lnum[idx_orig] + dpl->df_count[idx_orig]
1335 		    - (dp->df_lnum[idx_orig] + dp->df_count[idx_orig]);
1336 
1337 	    /* Adjust the size of the block to include all the lines to the
1338 	     * end of the existing block or the new diff, whatever ends last. */
1339 	    off = (lnum_orig + count_orig)
1340 			 - (dpl->df_lnum[idx_orig] + dpl->df_count[idx_orig]);
1341 	    if (off < 0)
1342 	    {
1343 		/* new change ends in existing block, adjust the end if not
1344 		 * done already */
1345 		if (notset)
1346 		    dp->df_count[idx_new] += -off;
1347 		off = 0;
1348 	    }
1349 	    for (i = idx_orig; i < idx_new; ++i)
1350 		if (curtab->tp_diffbuf[i] != NULL)
1351 		    dp->df_count[i] = dpl->df_lnum[i] + dpl->df_count[i]
1352 						       - dp->df_lnum[i] + off;
1353 
1354 	    /* Delete the diff blocks that have been merged into one. */
1355 	    dn = dp->df_next;
1356 	    dp->df_next = dpl->df_next;
1357 	    while (dn != dp->df_next)
1358 	    {
1359 		dpl = dn->df_next;
1360 		vim_free(dn);
1361 		dn = dpl;
1362 	    }
1363 	}
1364 	else
1365 	{
1366 	    /* Allocate a new diffblock. */
1367 	    dp = diff_alloc_new(curtab, dprev, dp);
1368 	    if (dp == NULL)
1369 		goto done;
1370 
1371 	    dp->df_lnum[idx_orig] = lnum_orig;
1372 	    dp->df_count[idx_orig] = count_orig;
1373 	    dp->df_lnum[idx_new] = lnum_new;
1374 	    dp->df_count[idx_new] = count_new;
1375 
1376 	    /* Set values for other buffers, these must be equal to the
1377 	     * original buffer, otherwise there would have been a change
1378 	     * already. */
1379 	    for (i = idx_orig + 1; i < idx_new; ++i)
1380 		if (curtab->tp_diffbuf[i] != NULL)
1381 		    diff_copy_entry(dprev, dp, idx_orig, i);
1382 	}
1383 	notset = FALSE;		/* "*dp" has been set */
1384     }
1385 
1386     /* for remaining diff blocks orig and new are equal */
1387     while (dp != NULL)
1388     {
1389 	if (notset)
1390 	    diff_copy_entry(dprev, dp, idx_orig, idx_new);
1391 	dprev = dp;
1392 	dp = dp->df_next;
1393 	notset = TRUE;
1394     }
1395 
1396 done:
1397     fclose(fd);
1398 }
1399 
1400 /*
1401  * Copy an entry at "dp" from "idx_orig" to "idx_new".
1402  */
1403     static void
1404 diff_copy_entry(dprev, dp, idx_orig, idx_new)
1405     diff_T	*dprev;
1406     diff_T	*dp;
1407     int		idx_orig;
1408     int		idx_new;
1409 {
1410     long	off;
1411 
1412     if (dprev == NULL)
1413 	off = 0;
1414     else
1415 	off = (dprev->df_lnum[idx_orig] + dprev->df_count[idx_orig])
1416 	    - (dprev->df_lnum[idx_new] + dprev->df_count[idx_new]);
1417     dp->df_lnum[idx_new] = dp->df_lnum[idx_orig] - off;
1418     dp->df_count[idx_new] = dp->df_count[idx_orig];
1419 }
1420 
1421 /*
1422  * Clear the list of diffblocks for tab page "tp".
1423  */
1424     void
1425 diff_clear(tp)
1426     tabpage_T	*tp;
1427 {
1428     diff_T	*p, *next_p;
1429 
1430     for (p = tp->tp_first_diff; p != NULL; p = next_p)
1431     {
1432 	next_p = p->df_next;
1433 	vim_free(p);
1434     }
1435     tp->tp_first_diff = NULL;
1436 }
1437 
1438 /*
1439  * Check diff status for line "lnum" in buffer "buf":
1440  * Returns 0 for nothing special
1441  * Returns -1 for a line that should be highlighted as changed.
1442  * Returns -2 for a line that should be highlighted as added/deleted.
1443  * Returns > 0 for inserting that many filler lines above it (never happens
1444  * when 'diffopt' doesn't contain "filler").
1445  * This should only be used for windows where 'diff' is set.
1446  */
1447     int
1448 diff_check(wp, lnum)
1449     win_T	*wp;
1450     linenr_T	lnum;
1451 {
1452     int		idx;		/* index in tp_diffbuf[] for this buffer */
1453     diff_T	*dp;
1454     int		maxcount;
1455     int		i;
1456     buf_T	*buf = wp->w_buffer;
1457     int		cmp;
1458 
1459     if (curtab->tp_diff_invalid)
1460 	ex_diffupdate(NULL);		/* update after a big change */
1461 
1462     if (curtab->tp_first_diff == NULL || !wp->w_p_diff)	/* no diffs at all */
1463 	return 0;
1464 
1465     /* safety check: "lnum" must be a buffer line */
1466     if (lnum < 1 || lnum > buf->b_ml.ml_line_count + 1)
1467 	return 0;
1468 
1469     idx = diff_buf_idx(buf);
1470     if (idx == DB_COUNT)
1471 	return 0;		/* no diffs for buffer "buf" */
1472 
1473 #ifdef FEAT_FOLDING
1474     /* A closed fold never has filler lines. */
1475     if (hasFoldingWin(wp, lnum, NULL, NULL, TRUE, NULL))
1476 	return 0;
1477 #endif
1478 
1479     /* search for a change that includes "lnum" in the list of diffblocks. */
1480     for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next)
1481 	if (lnum <= dp->df_lnum[idx] + dp->df_count[idx])
1482 	    break;
1483     if (dp == NULL || lnum < dp->df_lnum[idx])
1484 	return 0;
1485 
1486     if (lnum < dp->df_lnum[idx] + dp->df_count[idx])
1487     {
1488 	int	zero = FALSE;
1489 
1490 	/* Changed or inserted line.  If the other buffers have a count of
1491 	 * zero, the lines were inserted.  If the other buffers have the same
1492 	 * count, check if the lines are identical. */
1493 	cmp = FALSE;
1494 	for (i = 0; i < DB_COUNT; ++i)
1495 	    if (i != idx && curtab->tp_diffbuf[i] != NULL)
1496 	    {
1497 		if (dp->df_count[i] == 0)
1498 		    zero = TRUE;
1499 		else
1500 		{
1501 		    if (dp->df_count[i] != dp->df_count[idx])
1502 			return -1;	    /* nr of lines changed. */
1503 		    cmp = TRUE;
1504 		}
1505 	    }
1506 	if (cmp)
1507 	{
1508 	    /* Compare all lines.  If they are equal the lines were inserted
1509 	     * in some buffers, deleted in others, but not changed. */
1510 	    for (i = 0; i < DB_COUNT; ++i)
1511 		if (i != idx && curtab->tp_diffbuf[i] != NULL && dp->df_count[i] != 0)
1512 		    if (!diff_equal_entry(dp, idx, i))
1513 			return -1;
1514 	}
1515 	/* If there is no buffer with zero lines then there is no difference
1516 	 * any longer.  Happens when making a change (or undo) that removes
1517 	 * the difference.  Can't remove the entry here, we might be halfway
1518 	 * updating the window.  Just report the text as unchanged.  Other
1519 	 * windows might still show the change though. */
1520 	if (zero == FALSE)
1521 	    return 0;
1522 	return -2;
1523     }
1524 
1525     /* If 'diffopt' doesn't contain "filler", return 0. */
1526     if (!(diff_flags & DIFF_FILLER))
1527 	return 0;
1528 
1529     /* Insert filler lines above the line just below the change.  Will return
1530      * 0 when this buf had the max count. */
1531     maxcount = 0;
1532     for (i = 0; i < DB_COUNT; ++i)
1533 	if (curtab->tp_diffbuf[i] != NULL && dp->df_count[i] > maxcount)
1534 	    maxcount = dp->df_count[i];
1535     return maxcount - dp->df_count[idx];
1536 }
1537 
1538 /*
1539  * Compare two entries in diff "*dp" and return TRUE if they are equal.
1540  */
1541     static int
1542 diff_equal_entry(dp, idx1, idx2)
1543     diff_T	*dp;
1544     int		idx1;
1545     int		idx2;
1546 {
1547     int		i;
1548     char_u	*line;
1549     int		cmp;
1550 
1551     if (dp->df_count[idx1] != dp->df_count[idx2])
1552 	return FALSE;
1553     if (diff_check_sanity(curtab, dp) == FAIL)
1554 	return FALSE;
1555     for (i = 0; i < dp->df_count[idx1]; ++i)
1556     {
1557 	line = vim_strsave(ml_get_buf(curtab->tp_diffbuf[idx1],
1558 					       dp->df_lnum[idx1] + i, FALSE));
1559 	if (line == NULL)
1560 	    return FALSE;
1561 	cmp = diff_cmp(line, ml_get_buf(curtab->tp_diffbuf[idx2],
1562 					       dp->df_lnum[idx2] + i, FALSE));
1563 	vim_free(line);
1564 	if (cmp != 0)
1565 	    return FALSE;
1566     }
1567     return TRUE;
1568 }
1569 
1570 /*
1571  * Compare strings "s1" and "s2" according to 'diffopt'.
1572  * Return non-zero when they are different.
1573  */
1574     static int
1575 diff_cmp(s1, s2)
1576     char_u	*s1;
1577     char_u	*s2;
1578 {
1579     char_u	*p1, *p2;
1580 #ifdef FEAT_MBYTE
1581     int		l;
1582 #endif
1583 
1584     if ((diff_flags & (DIFF_ICASE | DIFF_IWHITE)) == 0)
1585 	return STRCMP(s1, s2);
1586     if ((diff_flags & DIFF_ICASE) && !(diff_flags & DIFF_IWHITE))
1587 	return MB_STRICMP(s1, s2);
1588 
1589     /* Ignore white space changes and possibly ignore case. */
1590     p1 = s1;
1591     p2 = s2;
1592     while (*p1 != NUL && *p2 != NUL)
1593     {
1594 	if (vim_iswhite(*p1) && vim_iswhite(*p2))
1595 	{
1596 	    p1 = skipwhite(p1);
1597 	    p2 = skipwhite(p2);
1598 	}
1599 	else
1600 	{
1601 #ifdef FEAT_MBYTE
1602 	    l  = (*mb_ptr2len)(p1);
1603 	    if (l != (*mb_ptr2len)(p2))
1604 		break;
1605 	    if (l > 1)
1606 	    {
1607 		if (STRNCMP(p1, p2, l) != 0
1608 			&& (!enc_utf8
1609 			    || !(diff_flags & DIFF_ICASE)
1610 			    || utf_fold(utf_ptr2char(p1))
1611 					       != utf_fold(utf_ptr2char(p2))))
1612 		    break;
1613 		p1 += l;
1614 		p2 += l;
1615 	    }
1616 	    else
1617 #endif
1618 	    {
1619 		if (*p1 != *p2 && (!(diff_flags & DIFF_ICASE)
1620 				     || TOLOWER_LOC(*p1) != TOLOWER_LOC(*p2)))
1621 		    break;
1622 		++p1;
1623 		++p2;
1624 	    }
1625 	}
1626     }
1627 
1628     /* Ignore trailing white space. */
1629     p1 = skipwhite(p1);
1630     p2 = skipwhite(p2);
1631     if (*p1 != NUL || *p2 != NUL)
1632 	return 1;
1633     return 0;
1634 }
1635 
1636 /*
1637  * Return the number of filler lines above "lnum".
1638  */
1639     int
1640 diff_check_fill(wp, lnum)
1641     win_T	*wp;
1642     linenr_T	lnum;
1643 {
1644     int		n;
1645 
1646     /* be quick when there are no filler lines */
1647     if (!(diff_flags & DIFF_FILLER))
1648 	return 0;
1649     n = diff_check(wp, lnum);
1650     if (n <= 0)
1651 	return 0;
1652     return n;
1653 }
1654 
1655 /*
1656  * Set the topline of "towin" to match the position in "fromwin", so that they
1657  * show the same diff'ed lines.
1658  */
1659     void
1660 diff_set_topline(fromwin, towin)
1661     win_T	*fromwin;
1662     win_T	*towin;
1663 {
1664     buf_T	*frombuf = fromwin->w_buffer;
1665     linenr_T	lnum = fromwin->w_topline;
1666     int		fromidx;
1667     int		toidx;
1668     diff_T	*dp;
1669     int		max_count;
1670     int		i;
1671 
1672     fromidx = diff_buf_idx(frombuf);
1673     if (fromidx == DB_COUNT)
1674 	return;		/* safety check */
1675 
1676     if (curtab->tp_diff_invalid)
1677 	ex_diffupdate(NULL);		/* update after a big change */
1678 
1679     towin->w_topfill = 0;
1680 
1681     /* search for a change that includes "lnum" in the list of diffblocks. */
1682     for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next)
1683 	if (lnum <= dp->df_lnum[fromidx] + dp->df_count[fromidx])
1684 	    break;
1685     if (dp == NULL)
1686     {
1687 	/* After last change, compute topline relative to end of file; no
1688 	 * filler lines. */
1689 	towin->w_topline = towin->w_buffer->b_ml.ml_line_count
1690 				       - (frombuf->b_ml.ml_line_count - lnum);
1691     }
1692     else
1693     {
1694 	/* Find index for "towin". */
1695 	toidx = diff_buf_idx(towin->w_buffer);
1696 	if (toidx == DB_COUNT)
1697 	    return;		/* safety check */
1698 
1699 	towin->w_topline = lnum + (dp->df_lnum[toidx] - dp->df_lnum[fromidx]);
1700 	if (lnum >= dp->df_lnum[fromidx])
1701 	{
1702 	    /* Inside a change: compute filler lines. With three or more
1703 	     * buffers we need to know the largest count. */
1704 	    max_count = 0;
1705 	    for (i = 0; i < DB_COUNT; ++i)
1706 		if (curtab->tp_diffbuf[i] != NULL
1707 					       && max_count < dp->df_count[i])
1708 		    max_count = dp->df_count[i];
1709 
1710 	    if (dp->df_count[toidx] == dp->df_count[fromidx])
1711 	    {
1712 		/* same number of lines: use same filler count */
1713 		towin->w_topfill = fromwin->w_topfill;
1714 	    }
1715 	    else if (dp->df_count[toidx] > dp->df_count[fromidx])
1716 	    {
1717 		if (lnum == dp->df_lnum[fromidx] + dp->df_count[fromidx])
1718 		{
1719 		    /* more lines in towin and fromwin doesn't show diff
1720 		     * lines, only filler lines */
1721 		    if (max_count - fromwin->w_topfill >= dp->df_count[toidx])
1722 		    {
1723 			/* towin also only shows filler lines */
1724 			towin->w_topline = dp->df_lnum[toidx]
1725 						       + dp->df_count[toidx];
1726 			towin->w_topfill = fromwin->w_topfill;
1727 		    }
1728 		    else
1729 			/* towin still has some diff lines to show */
1730 			towin->w_topline = dp->df_lnum[toidx]
1731 					     + max_count - fromwin->w_topfill;
1732 		}
1733 	    }
1734 	    else if (towin->w_topline >= dp->df_lnum[toidx]
1735 							+ dp->df_count[toidx])
1736 	    {
1737 		/* less lines in towin and no diff lines to show: compute
1738 		 * filler lines */
1739 		towin->w_topline = dp->df_lnum[toidx] + dp->df_count[toidx];
1740 		if (diff_flags & DIFF_FILLER)
1741 		{
1742 		    if (lnum == dp->df_lnum[fromidx] + dp->df_count[fromidx])
1743 			/* fromwin is also out of diff lines */
1744 			towin->w_topfill = fromwin->w_topfill;
1745 		    else
1746 			/* fromwin has some diff lines */
1747 			towin->w_topfill = dp->df_lnum[fromidx]
1748 							   + max_count - lnum;
1749 		}
1750 	    }
1751 	}
1752     }
1753 
1754     /* safety check (if diff info gets outdated strange things may happen) */
1755     towin->w_botfill = FALSE;
1756     if (towin->w_topline > towin->w_buffer->b_ml.ml_line_count)
1757     {
1758 	towin->w_topline = towin->w_buffer->b_ml.ml_line_count;
1759 	towin->w_botfill = TRUE;
1760     }
1761     if (towin->w_topline < 1)
1762     {
1763 	towin->w_topline = 1;
1764 	towin->w_topfill = 0;
1765     }
1766 
1767     /* When w_topline changes need to recompute w_botline and cursor position */
1768     invalidate_botline_win(towin);
1769     changed_line_abv_curs_win(towin);
1770 
1771     check_topfill(towin, FALSE);
1772 #ifdef FEAT_FOLDING
1773     (void)hasFoldingWin(towin, towin->w_topline, &towin->w_topline,
1774 							    NULL, TRUE, NULL);
1775 #endif
1776 }
1777 
1778 /*
1779  * This is called when 'diffopt' is changed.
1780  */
1781     int
1782 diffopt_changed()
1783 {
1784     char_u	*p;
1785     int		diff_context_new = 6;
1786     int		diff_flags_new = 0;
1787     int		diff_foldcolumn_new = 2;
1788     tabpage_T	*tp;
1789 
1790     p = p_dip;
1791     while (*p != NUL)
1792     {
1793 	if (STRNCMP(p, "filler", 6) == 0)
1794 	{
1795 	    p += 6;
1796 	    diff_flags_new |= DIFF_FILLER;
1797 	}
1798 	else if (STRNCMP(p, "context:", 8) == 0 && VIM_ISDIGIT(p[8]))
1799 	{
1800 	    p += 8;
1801 	    diff_context_new = getdigits(&p);
1802 	}
1803 	else if (STRNCMP(p, "icase", 5) == 0)
1804 	{
1805 	    p += 5;
1806 	    diff_flags_new |= DIFF_ICASE;
1807 	}
1808 	else if (STRNCMP(p, "iwhite", 6) == 0)
1809 	{
1810 	    p += 6;
1811 	    diff_flags_new |= DIFF_IWHITE;
1812 	}
1813 	else if (STRNCMP(p, "horizontal", 10) == 0)
1814 	{
1815 	    p += 10;
1816 	    diff_flags_new |= DIFF_HORIZONTAL;
1817 	}
1818 	else if (STRNCMP(p, "vertical", 8) == 0)
1819 	{
1820 	    p += 8;
1821 	    diff_flags_new |= DIFF_VERTICAL;
1822 	}
1823 	else if (STRNCMP(p, "foldcolumn:", 11) == 0 && VIM_ISDIGIT(p[11]))
1824 	{
1825 	    p += 11;
1826 	    diff_foldcolumn_new = getdigits(&p);
1827 	}
1828 	if (*p != ',' && *p != NUL)
1829 	    return FAIL;
1830 	if (*p == ',')
1831 	    ++p;
1832     }
1833 
1834     /* Can't have both "horizontal" and "vertical". */
1835     if ((diff_flags_new & DIFF_HORIZONTAL) && (diff_flags_new & DIFF_VERTICAL))
1836 	return FAIL;
1837 
1838     /* If "icase" or "iwhite" was added or removed, need to update the diff. */
1839     if (diff_flags != diff_flags_new)
1840 	for (tp = first_tabpage; tp != NULL; tp = tp->tp_next)
1841 	    tp->tp_diff_invalid = TRUE;
1842 
1843     diff_flags = diff_flags_new;
1844     diff_context = diff_context_new;
1845     diff_foldcolumn = diff_foldcolumn_new;
1846 
1847     diff_redraw(TRUE);
1848 
1849     /* recompute the scroll binding with the new option value, may
1850      * remove or add filler lines */
1851     check_scrollbind((linenr_T)0, 0L);
1852 
1853     return OK;
1854 }
1855 
1856 /*
1857  * Return TRUE if 'diffopt' contains "horizontal".
1858  */
1859     int
1860 diffopt_horizontal()
1861 {
1862     return (diff_flags & DIFF_HORIZONTAL) != 0;
1863 }
1864 
1865 /*
1866  * Find the difference within a changed line.
1867  * Returns TRUE if the line was added, no other buffer has it.
1868  */
1869     int
1870 diff_find_change(wp, lnum, startp, endp)
1871     win_T	*wp;
1872     linenr_T	lnum;
1873     int		*startp;	/* first char of the change */
1874     int		*endp;		/* last char of the change */
1875 {
1876     char_u	*line_org;
1877     char_u	*line_new;
1878     int		i;
1879     int		si_org, si_new;
1880     int		ei_org, ei_new;
1881     diff_T	*dp;
1882     int		idx;
1883     int		off;
1884     int		added = TRUE;
1885 
1886     /* Make a copy of the line, the next ml_get() will invalidate it. */
1887     line_org = vim_strsave(ml_get_buf(wp->w_buffer, lnum, FALSE));
1888     if (line_org == NULL)
1889 	return FALSE;
1890 
1891     idx = diff_buf_idx(wp->w_buffer);
1892     if (idx == DB_COUNT)	/* cannot happen */
1893     {
1894 	vim_free(line_org);
1895 	return FALSE;
1896     }
1897 
1898     /* search for a change that includes "lnum" in the list of diffblocks. */
1899     for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next)
1900 	if (lnum <= dp->df_lnum[idx] + dp->df_count[idx])
1901 	    break;
1902     if (dp == NULL || diff_check_sanity(curtab, dp) == FAIL)
1903     {
1904 	vim_free(line_org);
1905 	return FALSE;
1906     }
1907 
1908     off = lnum - dp->df_lnum[idx];
1909 
1910     for (i = 0; i < DB_COUNT; ++i)
1911 	if (curtab->tp_diffbuf[i] != NULL && i != idx)
1912 	{
1913 	    /* Skip lines that are not in the other change (filler lines). */
1914 	    if (off >= dp->df_count[i])
1915 		continue;
1916 	    added = FALSE;
1917 	    line_new = ml_get_buf(curtab->tp_diffbuf[i],
1918 						 dp->df_lnum[i] + off, FALSE);
1919 
1920 	    /* Search for start of difference */
1921 	    si_org = si_new = 0;
1922 	    while (line_org[si_org] != NUL)
1923 	    {
1924 		if ((diff_flags & DIFF_IWHITE)
1925 			&& vim_iswhite(line_org[si_org])
1926 			&& vim_iswhite(line_new[si_new]))
1927 		{
1928 		    si_org = (int)(skipwhite(line_org + si_org) - line_org);
1929 		    si_new = (int)(skipwhite(line_new + si_new) - line_new);
1930 		}
1931 		else
1932 		{
1933 		    if (line_org[si_org] != line_new[si_new])
1934 			break;
1935 		    ++si_org;
1936 		    ++si_new;
1937 		}
1938 	    }
1939 #ifdef FEAT_MBYTE
1940 	    if (has_mbyte)
1941 	    {
1942 		/* Move back to first byte of character in both lines (may
1943 		 * have "nn^" in line_org and "n^ in line_new). */
1944 		si_org -= (*mb_head_off)(line_org, line_org + si_org);
1945 		si_new -= (*mb_head_off)(line_new, line_new + si_new);
1946 	    }
1947 #endif
1948 	    if (*startp > si_org)
1949 		*startp = si_org;
1950 
1951 	    /* Search for end of difference, if any. */
1952 	    if (line_org[si_org] != NUL || line_new[si_new] != NUL)
1953 	    {
1954 		ei_org = (int)STRLEN(line_org);
1955 		ei_new = (int)STRLEN(line_new);
1956 		while (ei_org >= *startp && ei_new >= si_new
1957 						&& ei_org >= 0 && ei_new >= 0)
1958 		{
1959 		    if ((diff_flags & DIFF_IWHITE)
1960 			    && vim_iswhite(line_org[ei_org])
1961 			    && vim_iswhite(line_new[ei_new]))
1962 		    {
1963 			while (ei_org >= *startp
1964 					     && vim_iswhite(line_org[ei_org]))
1965 			    --ei_org;
1966 			while (ei_new >= si_new
1967 					     && vim_iswhite(line_new[ei_new]))
1968 			    --ei_new;
1969 		    }
1970 		    else
1971 		    {
1972 			if (line_org[ei_org] != line_new[ei_new])
1973 			    break;
1974 			--ei_org;
1975 			--ei_new;
1976 		    }
1977 		}
1978 		if (*endp < ei_org)
1979 		    *endp = ei_org;
1980 	    }
1981 	}
1982 
1983     vim_free(line_org);
1984     return added;
1985 }
1986 
1987 #if defined(FEAT_FOLDING) || defined(PROTO)
1988 /*
1989  * Return TRUE if line "lnum" is not close to a diff block, this line should
1990  * be in a fold.
1991  * Return FALSE if there are no diff blocks at all in this window.
1992  */
1993     int
1994 diff_infold(wp, lnum)
1995     win_T	*wp;
1996     linenr_T	lnum;
1997 {
1998     int		i;
1999     int		idx = -1;
2000     int		other = FALSE;
2001     diff_T	*dp;
2002 
2003     /* Return if 'diff' isn't set. */
2004     if (!wp->w_p_diff)
2005 	return FALSE;
2006 
2007     for (i = 0; i < DB_COUNT; ++i)
2008     {
2009 	if (curtab->tp_diffbuf[i] == wp->w_buffer)
2010 	    idx = i;
2011 	else if (curtab->tp_diffbuf[i] != NULL)
2012 	    other = TRUE;
2013     }
2014 
2015     /* return here if there are no diffs in the window */
2016     if (idx == -1 || !other)
2017 	return FALSE;
2018 
2019     if (curtab->tp_diff_invalid)
2020 	ex_diffupdate(NULL);		/* update after a big change */
2021 
2022     /* Return if there are no diff blocks.  All lines will be folded. */
2023     if (curtab->tp_first_diff == NULL)
2024 	return TRUE;
2025 
2026     for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next)
2027     {
2028 	/* If this change is below the line there can't be any further match. */
2029 	if (dp->df_lnum[idx] - diff_context > lnum)
2030 	    break;
2031 	/* If this change ends before the line we have a match. */
2032 	if (dp->df_lnum[idx] + dp->df_count[idx] + diff_context > lnum)
2033 	    return FALSE;
2034     }
2035     return TRUE;
2036 }
2037 #endif
2038 
2039 /*
2040  * "dp" and "do" commands.
2041  */
2042     void
2043 nv_diffgetput(put)
2044     int		put;
2045 {
2046     exarg_T	ea;
2047 
2048     ea.arg = (char_u *)"";
2049     if (put)
2050 	ea.cmdidx = CMD_diffput;
2051     else
2052 	ea.cmdidx = CMD_diffget;
2053     ea.addr_count = 0;
2054     ea.line1 = curwin->w_cursor.lnum;
2055     ea.line2 = curwin->w_cursor.lnum;
2056     ex_diffgetput(&ea);
2057 }
2058 
2059 /*
2060  * ":diffget"
2061  * ":diffput"
2062  */
2063     void
2064 ex_diffgetput(eap)
2065     exarg_T	*eap;
2066 {
2067     linenr_T	lnum;
2068     int		count;
2069     linenr_T	off = 0;
2070     diff_T	*dp;
2071     diff_T	*dprev;
2072     diff_T	*dfree;
2073     int		idx_cur;
2074     int		idx_other;
2075     int		idx_from;
2076     int		idx_to;
2077     int		i;
2078     int		added;
2079     char_u	*p;
2080     aco_save_T	aco;
2081     buf_T	*buf;
2082     int		start_skip, end_skip;
2083     int		new_count;
2084     int		buf_empty;
2085     int		found_not_ma = FALSE;
2086 
2087     /* Find the current buffer in the list of diff buffers. */
2088     idx_cur = diff_buf_idx(curbuf);
2089     if (idx_cur == DB_COUNT)
2090     {
2091 	EMSG(_("E99: Current buffer is not in diff mode"));
2092 	return;
2093     }
2094 
2095     if (*eap->arg == NUL)
2096     {
2097 	/* No argument: Find the other buffer in the list of diff buffers. */
2098 	for (idx_other = 0; idx_other < DB_COUNT; ++idx_other)
2099 	    if (curtab->tp_diffbuf[idx_other] != curbuf
2100 		    && curtab->tp_diffbuf[idx_other] != NULL)
2101 	    {
2102 		if (eap->cmdidx != CMD_diffput
2103 				     || curtab->tp_diffbuf[idx_other]->b_p_ma)
2104 		    break;
2105 		found_not_ma = TRUE;
2106 	    }
2107 	if (idx_other == DB_COUNT)
2108 	{
2109 	    if (found_not_ma)
2110 		EMSG(_("E793: No other buffer in diff mode is modifiable"));
2111 	    else
2112 		EMSG(_("E100: No other buffer in diff mode"));
2113 	    return;
2114 	}
2115 
2116 	/* Check that there isn't a third buffer in the list */
2117 	for (i = idx_other + 1; i < DB_COUNT; ++i)
2118 	    if (curtab->tp_diffbuf[i] != curbuf
2119 		    && curtab->tp_diffbuf[i] != NULL
2120 		    && (eap->cmdidx != CMD_diffput || curtab->tp_diffbuf[i]->b_p_ma))
2121 	    {
2122 		EMSG(_("E101: More than two buffers in diff mode, don't know which one to use"));
2123 		return;
2124 	    }
2125     }
2126     else
2127     {
2128 	/* Buffer number or pattern given.  Ignore trailing white space. */
2129 	p = eap->arg + STRLEN(eap->arg);
2130 	while (p > eap->arg && vim_iswhite(p[-1]))
2131 	    --p;
2132 	for (i = 0; vim_isdigit(eap->arg[i]) && eap->arg + i < p; ++i)
2133 	    ;
2134 	if (eap->arg + i == p)	    /* digits only */
2135 	    i = atol((char *)eap->arg);
2136 	else
2137 	{
2138 	    i = buflist_findpat(eap->arg, p, FALSE, TRUE);
2139 	    if (i < 0)
2140 		return;		/* error message already given */
2141 	}
2142 	buf = buflist_findnr(i);
2143 	if (buf == NULL)
2144 	{
2145 	    EMSG2(_("E102: Can't find buffer \"%s\""), eap->arg);
2146 	    return;
2147 	}
2148 	if (buf == curbuf)
2149 	    return;		/* nothing to do */
2150 	idx_other = diff_buf_idx(buf);
2151 	if (idx_other == DB_COUNT)
2152 	{
2153 	    EMSG2(_("E103: Buffer \"%s\" is not in diff mode"), eap->arg);
2154 	    return;
2155 	}
2156     }
2157 
2158     diff_busy = TRUE;
2159 
2160     /* When no range given include the line above or below the cursor. */
2161     if (eap->addr_count == 0)
2162     {
2163 	/* Make it possible that ":diffget" on the last line gets line below
2164 	 * the cursor line when there is no difference above the cursor. */
2165 	if (eap->cmdidx == CMD_diffget
2166 		&& eap->line1 == curbuf->b_ml.ml_line_count
2167 		&& diff_check(curwin, eap->line1) == 0
2168 		&& (eap->line1 == 1 || diff_check(curwin, eap->line1 - 1) == 0))
2169 	    ++eap->line2;
2170 	else if (eap->line1 > 0)
2171 	    --eap->line1;
2172     }
2173 
2174     if (eap->cmdidx == CMD_diffget)
2175     {
2176 	idx_from = idx_other;
2177 	idx_to = idx_cur;
2178     }
2179     else
2180     {
2181 	idx_from = idx_cur;
2182 	idx_to = idx_other;
2183 	/* Need to make the other buffer the current buffer to be able to make
2184 	 * changes in it. */
2185 	/* set curwin/curbuf to buf and save a few things */
2186 	aucmd_prepbuf(&aco, curtab->tp_diffbuf[idx_other]);
2187     }
2188 
2189     /* May give the warning for a changed buffer here, which can trigger the
2190      * FileChangedRO autocommand, which may do nasty things and mess
2191      * everything up. */
2192     if (!curbuf->b_changed)
2193     {
2194 	change_warning(0);
2195 	if (diff_buf_idx(curbuf) != idx_to)
2196 	{
2197 	    EMSG(_("E787: Buffer changed unexpectedly"));
2198 	    return;
2199 	}
2200     }
2201 
2202     dprev = NULL;
2203     for (dp = curtab->tp_first_diff; dp != NULL; )
2204     {
2205 	if (dp->df_lnum[idx_cur] > eap->line2 + off)
2206 	    break;	/* past the range that was specified */
2207 
2208 	dfree = NULL;
2209 	lnum = dp->df_lnum[idx_to];
2210 	count = dp->df_count[idx_to];
2211 	if (dp->df_lnum[idx_cur] + dp->df_count[idx_cur] > eap->line1 + off
2212 		&& u_save(lnum - 1, lnum + count) != FAIL)
2213 	{
2214 	    /* Inside the specified range and saving for undo worked. */
2215 	    start_skip = 0;
2216 	    end_skip = 0;
2217 	    if (eap->addr_count > 0)
2218 	    {
2219 		/* A range was specified: check if lines need to be skipped. */
2220 		start_skip = eap->line1 + off - dp->df_lnum[idx_cur];
2221 		if (start_skip > 0)
2222 		{
2223 		    /* range starts below start of current diff block */
2224 		    if (start_skip > count)
2225 		    {
2226 			lnum += count;
2227 			count = 0;
2228 		    }
2229 		    else
2230 		    {
2231 			count -= start_skip;
2232 			lnum += start_skip;
2233 		    }
2234 		}
2235 		else
2236 		    start_skip = 0;
2237 
2238 		end_skip = dp->df_lnum[idx_cur] + dp->df_count[idx_cur] - 1
2239 							 - (eap->line2 + off);
2240 		if (end_skip > 0)
2241 		{
2242 		    /* range ends above end of current/from diff block */
2243 		    if (idx_cur == idx_from)	/* :diffput */
2244 		    {
2245 			i = dp->df_count[idx_cur] - start_skip - end_skip;
2246 			if (count > i)
2247 			    count = i;
2248 		    }
2249 		    else			/* :diffget */
2250 		    {
2251 			count -= end_skip;
2252 			end_skip = dp->df_count[idx_from] - start_skip - count;
2253 			if (end_skip < 0)
2254 			    end_skip = 0;
2255 		    }
2256 		}
2257 		else
2258 		    end_skip = 0;
2259 	    }
2260 
2261 	    buf_empty = FALSE;
2262 	    added = 0;
2263 	    for (i = 0; i < count; ++i)
2264 	    {
2265 		/* remember deleting the last line of the buffer */
2266 		buf_empty = curbuf->b_ml.ml_line_count == 1;
2267 		ml_delete(lnum, FALSE);
2268 		--added;
2269 	    }
2270 	    for (i = 0; i < dp->df_count[idx_from] - start_skip - end_skip; ++i)
2271 	    {
2272 		linenr_T nr;
2273 
2274 		nr = dp->df_lnum[idx_from] + start_skip + i;
2275 		if (nr > curtab->tp_diffbuf[idx_from]->b_ml.ml_line_count)
2276 		    break;
2277 		p = vim_strsave(ml_get_buf(curtab->tp_diffbuf[idx_from],
2278 								  nr, FALSE));
2279 		if (p != NULL)
2280 		{
2281 		    ml_append(lnum + i - 1, p, 0, FALSE);
2282 		    vim_free(p);
2283 		    ++added;
2284 		    if (buf_empty && curbuf->b_ml.ml_line_count == 2)
2285 		    {
2286 			/* Added the first line into an empty buffer, need to
2287 			 * delete the dummy empty line. */
2288 			buf_empty = FALSE;
2289 			ml_delete((linenr_T)2, FALSE);
2290 		    }
2291 		}
2292 	    }
2293 	    new_count = dp->df_count[idx_to] + added;
2294 	    dp->df_count[idx_to] = new_count;
2295 
2296 	    if (start_skip == 0 && end_skip == 0)
2297 	    {
2298 		/* Check if there are any other buffers and if the diff is
2299 		 * equal in them. */
2300 		for (i = 0; i < DB_COUNT; ++i)
2301 		    if (curtab->tp_diffbuf[i] != NULL && i != idx_from
2302 								&& i != idx_to
2303 			    && !diff_equal_entry(dp, idx_from, i))
2304 			break;
2305 		if (i == DB_COUNT)
2306 		{
2307 		    /* delete the diff entry, the buffers are now equal here */
2308 		    dfree = dp;
2309 		    dp = dp->df_next;
2310 		    if (dprev == NULL)
2311 			curtab->tp_first_diff = dp;
2312 		    else
2313 			dprev->df_next = dp;
2314 		}
2315 	    }
2316 
2317 	    /* Adjust marks.  This will change the following entries! */
2318 	    if (added != 0)
2319 	    {
2320 		mark_adjust(lnum, lnum + count - 1, (long)MAXLNUM, (long)added);
2321 		if (curwin->w_cursor.lnum >= lnum)
2322 		{
2323 		    /* Adjust the cursor position if it's in/after the changed
2324 		     * lines. */
2325 		    if (curwin->w_cursor.lnum >= lnum + count)
2326 			curwin->w_cursor.lnum += added;
2327 		    else if (added < 0)
2328 			curwin->w_cursor.lnum = lnum;
2329 		}
2330 	    }
2331 	    changed_lines(lnum, 0, lnum + count, (long)added);
2332 
2333 	    if (dfree != NULL)
2334 	    {
2335 		/* Diff is deleted, update folds in other windows. */
2336 #ifdef FEAT_FOLDING
2337 		diff_fold_update(dfree, idx_to);
2338 #endif
2339 		vim_free(dfree);
2340 	    }
2341 	    else
2342 		/* mark_adjust() may have changed the count in a wrong way */
2343 		dp->df_count[idx_to] = new_count;
2344 
2345 	    /* When changing the current buffer, keep track of line numbers */
2346 	    if (idx_cur == idx_to)
2347 		off += added;
2348 	}
2349 
2350 	/* If before the range or not deleted, go to next diff. */
2351 	if (dfree == NULL)
2352 	{
2353 	    dprev = dp;
2354 	    dp = dp->df_next;
2355 	}
2356     }
2357 
2358     /* restore curwin/curbuf and a few other things */
2359     if (idx_other == idx_to)
2360     {
2361 	/* Syncing undo only works for the current buffer, but we change
2362 	 * another buffer.  Sync undo if the command was typed.  This isn't
2363 	 * 100% right when ":diffput" is used in a function or mapping. */
2364 	if (KeyTyped)
2365 	    u_sync(FALSE);
2366 	aucmd_restbuf(&aco);
2367     }
2368 
2369     diff_busy = FALSE;
2370 
2371     /* Check that the cursor is on a valid character and update it's position.
2372      * When there were filler lines the topline has become invalid. */
2373     check_cursor();
2374     changed_line_abv_curs();
2375 
2376     /* Also need to redraw the other buffers. */
2377     diff_redraw(FALSE);
2378 }
2379 
2380 #ifdef FEAT_FOLDING
2381 /*
2382  * Update folds for all diff buffers for entry "dp".
2383  * Skip buffer with index "skip_idx".
2384  * When there are no diffs, all folds are removed.
2385  */
2386     static void
2387 diff_fold_update(dp, skip_idx)
2388     diff_T	*dp;
2389     int		skip_idx;
2390 {
2391     int		i;
2392     win_T	*wp;
2393 
2394     for (wp = firstwin; wp != NULL; wp = wp->w_next)
2395 	for (i = 0; i < DB_COUNT; ++i)
2396 	    if (curtab->tp_diffbuf[i] == wp->w_buffer && i != skip_idx)
2397 		foldUpdate(wp, dp->df_lnum[i],
2398 					    dp->df_lnum[i] + dp->df_count[i]);
2399 }
2400 #endif
2401 
2402 /*
2403  * Return TRUE if buffer "buf" is in diff-mode.
2404  */
2405     int
2406 diff_mode_buf(buf)
2407     buf_T	*buf;
2408 {
2409     tabpage_T	*tp;
2410 
2411     for (tp = first_tabpage; tp != NULL; tp = tp->tp_next)
2412 	if (diff_buf_idx_tp(buf, tp) != DB_COUNT)
2413 	    return TRUE;
2414     return FALSE;
2415 }
2416 
2417 /*
2418  * Move "count" times in direction "dir" to the next diff block.
2419  * Return FAIL if there isn't such a diff block.
2420  */
2421     int
2422 diff_move_to(dir, count)
2423     int		dir;
2424     long	count;
2425 {
2426     int		idx;
2427     linenr_T	lnum = curwin->w_cursor.lnum;
2428     diff_T	*dp;
2429 
2430     idx = diff_buf_idx(curbuf);
2431     if (idx == DB_COUNT || curtab->tp_first_diff == NULL)
2432 	return FAIL;
2433 
2434     if (curtab->tp_diff_invalid)
2435 	ex_diffupdate(NULL);		/* update after a big change */
2436 
2437     if (curtab->tp_first_diff == NULL)		/* no diffs today */
2438 	return FAIL;
2439 
2440     while (--count >= 0)
2441     {
2442 	/* Check if already before first diff. */
2443 	if (dir == BACKWARD && lnum <= curtab->tp_first_diff->df_lnum[idx])
2444 	    break;
2445 
2446 	for (dp = curtab->tp_first_diff; ; dp = dp->df_next)
2447 	{
2448 	    if (dp == NULL)
2449 		break;
2450 	    if ((dir == FORWARD && lnum < dp->df_lnum[idx])
2451 		    || (dir == BACKWARD
2452 			&& (dp->df_next == NULL
2453 			    || lnum <= dp->df_next->df_lnum[idx])))
2454 	    {
2455 		lnum = dp->df_lnum[idx];
2456 		break;
2457 	    }
2458 	}
2459     }
2460 
2461     /* don't end up past the end of the file */
2462     if (lnum > curbuf->b_ml.ml_line_count)
2463 	lnum = curbuf->b_ml.ml_line_count;
2464 
2465     /* When the cursor didn't move at all we fail. */
2466     if (lnum == curwin->w_cursor.lnum)
2467 	return FAIL;
2468 
2469     setpcmark();
2470     curwin->w_cursor.lnum = lnum;
2471     curwin->w_cursor.col = 0;
2472 
2473     return OK;
2474 }
2475 
2476 #if defined(FEAT_FOLDING) || defined(PROTO)
2477 /*
2478  * For line "lnum" in the current window find the equivalent lnum in window
2479  * "wp", compensating for inserted/deleted lines.
2480  */
2481     linenr_T
2482 diff_lnum_win(lnum, wp)
2483     linenr_T	lnum;
2484     win_T	*wp;
2485 {
2486     diff_T	*dp;
2487     int		idx;
2488     int		i;
2489     linenr_T	n;
2490 
2491     idx = diff_buf_idx(curbuf);
2492     if (idx == DB_COUNT)		/* safety check */
2493 	return (linenr_T)0;
2494 
2495     if (curtab->tp_diff_invalid)
2496 	ex_diffupdate(NULL);		/* update after a big change */
2497 
2498     /* search for a change that includes "lnum" in the list of diffblocks. */
2499     for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next)
2500 	if (lnum <= dp->df_lnum[idx] + dp->df_count[idx])
2501 	    break;
2502 
2503     /* When after the last change, compute relative to the last line number. */
2504     if (dp == NULL)
2505 	return wp->w_buffer->b_ml.ml_line_count
2506 					- (curbuf->b_ml.ml_line_count - lnum);
2507 
2508     /* Find index for "wp". */
2509     i = diff_buf_idx(wp->w_buffer);
2510     if (i == DB_COUNT)			/* safety check */
2511 	return (linenr_T)0;
2512 
2513     n = lnum + (dp->df_lnum[i] - dp->df_lnum[idx]);
2514     if (n > dp->df_lnum[i] + dp->df_count[i])
2515 	n = dp->df_lnum[i] + dp->df_count[i];
2516     return n;
2517 }
2518 #endif
2519 
2520 #endif	/* FEAT_DIFF */
2521