xref: /vim-8.2.3635/src/diff.c (revision c0880db6)
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     wp->w_p_diff = TRUE;
1121     wp->w_p_scb = TRUE;
1122     wp->w_p_wrap = FALSE;
1123 # ifdef FEAT_FOLDING
1124     {
1125 	win_T	    *old_curwin = curwin;
1126 
1127 	curwin = wp;
1128 	curbuf = curwin->w_buffer;
1129 	set_string_option_direct((char_u *)"fdm", -1, (char_u *)"diff",
1130 						       OPT_LOCAL|OPT_FREE, 0);
1131 	curwin = old_curwin;
1132 	curbuf = curwin->w_buffer;
1133 	wp->w_p_fdc = diff_foldcolumn;
1134 	wp->w_p_fen = TRUE;
1135 	wp->w_p_fdl = 0;
1136 	foldUpdateAll(wp);
1137 	/* make sure topline is not halfway a fold */
1138 	changed_window_setting_win(wp);
1139     }
1140 # endif
1141 #ifdef FEAT_SCROLLBIND
1142     if (vim_strchr(p_sbo, 'h') == NULL)
1143 	do_cmdline_cmd((char_u *)"set sbo+=hor");
1144 #endif
1145 
1146     if (addbuf)
1147 	diff_buf_add(wp->w_buffer);
1148     redraw_win_later(wp, NOT_VALID);
1149 }
1150 
1151 /*
1152  * Set options not to show diffs.  For the current window or all windows.
1153  * Only in the current tab page.
1154  */
1155     void
1156 ex_diffoff(eap)
1157     exarg_T	*eap;
1158 {
1159     win_T	*wp;
1160     win_T	*old_curwin = curwin;
1161 #ifdef FEAT_SCROLLBIND
1162     int		diffwin = FALSE;
1163 #endif
1164 
1165     for (wp = firstwin; wp != NULL; wp = wp->w_next)
1166     {
1167 	if (wp == curwin || (eap->forceit && wp->w_p_diff))
1168 	{
1169 	    /* Set 'diff', 'scrollbind' off and 'wrap' on. */
1170 	    wp->w_p_diff = FALSE;
1171 	    wp->w_p_scb = FALSE;
1172 	    wp->w_p_wrap = TRUE;
1173 #ifdef FEAT_FOLDING
1174 	    curwin = wp;
1175 	    curbuf = curwin->w_buffer;
1176 	    set_string_option_direct((char_u *)"fdm", -1,
1177 				   (char_u *)"manual", OPT_LOCAL|OPT_FREE, 0);
1178 	    curwin = old_curwin;
1179 	    curbuf = curwin->w_buffer;
1180 	    wp->w_p_fdc = 0;
1181 	    wp->w_p_fen = FALSE;
1182 	    wp->w_p_fdl = 0;
1183 	    foldUpdateAll(wp);
1184 	    /* make sure topline is not halfway a fold */
1185 	    changed_window_setting_win(wp);
1186 #endif
1187 	    diff_buf_adjust(wp);
1188 	}
1189 #ifdef FEAT_SCROLLBIND
1190 	diffwin |= wp->w_p_diff;
1191 #endif
1192     }
1193 
1194 #ifdef FEAT_SCROLLBIND
1195     /* Remove "hor" from from 'scrollopt' if there are no diff windows left. */
1196     if (!diffwin && vim_strchr(p_sbo, 'h') != NULL)
1197 	do_cmdline_cmd((char_u *)"set sbo-=hor");
1198 #endif
1199 }
1200 
1201 /*
1202  * Read the diff output and add each entry to the diff list.
1203  */
1204     static void
1205 diff_read(idx_orig, idx_new, fname)
1206     int		idx_orig;	/* idx of original file */
1207     int		idx_new;	/* idx of new file */
1208     char_u	*fname;		/* name of diff output file */
1209 {
1210     FILE	*fd;
1211     diff_T	*dprev = NULL;
1212     diff_T	*dp = curtab->tp_first_diff;
1213     diff_T	*dn, *dpl;
1214     long	f1, l1, f2, l2;
1215     char_u	linebuf[LBUFLEN];   /* only need to hold the diff line */
1216     int		difftype;
1217     char_u	*p;
1218     long	off;
1219     int		i;
1220     linenr_T	lnum_orig, lnum_new;
1221     long	count_orig, count_new;
1222     int		notset = TRUE;	    /* block "*dp" not set yet */
1223 
1224     fd = mch_fopen((char *)fname, "r");
1225     if (fd == NULL)
1226     {
1227 	EMSG(_("E98: Cannot read diff output"));
1228 	return;
1229     }
1230 
1231     for (;;)
1232     {
1233 	if (tag_fgets(linebuf, LBUFLEN, fd))
1234 	    break;		/* end of file */
1235 	if (!isdigit(*linebuf))
1236 	    continue;		/* not the start of a diff block */
1237 
1238 	/* This line must be one of three formats:
1239 	 * {first}[,{last}]c{first}[,{last}]
1240 	 * {first}a{first}[,{last}]
1241 	 * {first}[,{last}]d{first}
1242 	 */
1243 	p = linebuf;
1244 	f1 = getdigits(&p);
1245 	if (*p == ',')
1246 	{
1247 	    ++p;
1248 	    l1 = getdigits(&p);
1249 	}
1250 	else
1251 	    l1 = f1;
1252 	if (*p != 'a' && *p != 'c' && *p != 'd')
1253 	    continue;		/* invalid diff format */
1254 	difftype = *p++;
1255 	f2 = getdigits(&p);
1256 	if (*p == ',')
1257 	{
1258 	    ++p;
1259 	    l2 = getdigits(&p);
1260 	}
1261 	else
1262 	    l2 = f2;
1263 	if (l1 < f1 || l2 < f2)
1264 	    continue;		/* invalid line range */
1265 
1266 	if (difftype == 'a')
1267 	{
1268 	    lnum_orig = f1 + 1;
1269 	    count_orig = 0;
1270 	}
1271 	else
1272 	{
1273 	    lnum_orig = f1;
1274 	    count_orig = l1 - f1 + 1;
1275 	}
1276 	if (difftype == 'd')
1277 	{
1278 	    lnum_new = f2 + 1;
1279 	    count_new = 0;
1280 	}
1281 	else
1282 	{
1283 	    lnum_new = f2;
1284 	    count_new = l2 - f2 + 1;
1285 	}
1286 
1287 	/* Go over blocks before the change, for which orig and new are equal.
1288 	 * Copy blocks from orig to new. */
1289 	while (dp != NULL
1290 		&& lnum_orig > dp->df_lnum[idx_orig] + dp->df_count[idx_orig])
1291 	{
1292 	    if (notset)
1293 		diff_copy_entry(dprev, dp, idx_orig, idx_new);
1294 	    dprev = dp;
1295 	    dp = dp->df_next;
1296 	    notset = TRUE;
1297 	}
1298 
1299 	if (dp != NULL
1300 		&& lnum_orig <= dp->df_lnum[idx_orig] + dp->df_count[idx_orig]
1301 		&& lnum_orig + count_orig >= dp->df_lnum[idx_orig])
1302 	{
1303 	    /* New block overlaps with existing block(s).
1304 	     * First find last block that overlaps. */
1305 	    for (dpl = dp; dpl->df_next != NULL; dpl = dpl->df_next)
1306 		if (lnum_orig + count_orig < dpl->df_next->df_lnum[idx_orig])
1307 		    break;
1308 
1309 	    /* If the newly found block starts before the old one, set the
1310 	     * start back a number of lines. */
1311 	    off = dp->df_lnum[idx_orig] - lnum_orig;
1312 	    if (off > 0)
1313 	    {
1314 		for (i = idx_orig; i < idx_new; ++i)
1315 		    if (curtab->tp_diffbuf[i] != NULL)
1316 			dp->df_lnum[i] -= off;
1317 		dp->df_lnum[idx_new] = lnum_new;
1318 		dp->df_count[idx_new] = count_new;
1319 	    }
1320 	    else if (notset)
1321 	    {
1322 		/* new block inside existing one, adjust new block */
1323 		dp->df_lnum[idx_new] = lnum_new + off;
1324 		dp->df_count[idx_new] = count_new - off;
1325 	    }
1326 	    else
1327 		/* second overlap of new block with existing block */
1328 		dp->df_count[idx_new] += count_new - count_orig
1329 		    + dpl->df_lnum[idx_orig] + dpl->df_count[idx_orig]
1330 		    - (dp->df_lnum[idx_orig] + dp->df_count[idx_orig]);
1331 
1332 	    /* Adjust the size of the block to include all the lines to the
1333 	     * end of the existing block or the new diff, whatever ends last. */
1334 	    off = (lnum_orig + count_orig)
1335 			 - (dpl->df_lnum[idx_orig] + dpl->df_count[idx_orig]);
1336 	    if (off < 0)
1337 	    {
1338 		/* new change ends in existing block, adjust the end if not
1339 		 * done already */
1340 		if (notset)
1341 		    dp->df_count[idx_new] += -off;
1342 		off = 0;
1343 	    }
1344 	    for (i = idx_orig; i < idx_new; ++i)
1345 		if (curtab->tp_diffbuf[i] != NULL)
1346 		    dp->df_count[i] = dpl->df_lnum[i] + dpl->df_count[i]
1347 						       - dp->df_lnum[i] + off;
1348 
1349 	    /* Delete the diff blocks that have been merged into one. */
1350 	    dn = dp->df_next;
1351 	    dp->df_next = dpl->df_next;
1352 	    while (dn != dp->df_next)
1353 	    {
1354 		dpl = dn->df_next;
1355 		vim_free(dn);
1356 		dn = dpl;
1357 	    }
1358 	}
1359 	else
1360 	{
1361 	    /* Allocate a new diffblock. */
1362 	    dp = diff_alloc_new(curtab, dprev, dp);
1363 	    if (dp == NULL)
1364 		goto done;
1365 
1366 	    dp->df_lnum[idx_orig] = lnum_orig;
1367 	    dp->df_count[idx_orig] = count_orig;
1368 	    dp->df_lnum[idx_new] = lnum_new;
1369 	    dp->df_count[idx_new] = count_new;
1370 
1371 	    /* Set values for other buffers, these must be equal to the
1372 	     * original buffer, otherwise there would have been a change
1373 	     * already. */
1374 	    for (i = idx_orig + 1; i < idx_new; ++i)
1375 		if (curtab->tp_diffbuf[i] != NULL)
1376 		    diff_copy_entry(dprev, dp, idx_orig, i);
1377 	}
1378 	notset = FALSE;		/* "*dp" has been set */
1379     }
1380 
1381     /* for remaining diff blocks orig and new are equal */
1382     while (dp != NULL)
1383     {
1384 	if (notset)
1385 	    diff_copy_entry(dprev, dp, idx_orig, idx_new);
1386 	dprev = dp;
1387 	dp = dp->df_next;
1388 	notset = TRUE;
1389     }
1390 
1391 done:
1392     fclose(fd);
1393 }
1394 
1395 /*
1396  * Copy an entry at "dp" from "idx_orig" to "idx_new".
1397  */
1398     static void
1399 diff_copy_entry(dprev, dp, idx_orig, idx_new)
1400     diff_T	*dprev;
1401     diff_T	*dp;
1402     int		idx_orig;
1403     int		idx_new;
1404 {
1405     long	off;
1406 
1407     if (dprev == NULL)
1408 	off = 0;
1409     else
1410 	off = (dprev->df_lnum[idx_orig] + dprev->df_count[idx_orig])
1411 	    - (dprev->df_lnum[idx_new] + dprev->df_count[idx_new]);
1412     dp->df_lnum[idx_new] = dp->df_lnum[idx_orig] - off;
1413     dp->df_count[idx_new] = dp->df_count[idx_orig];
1414 }
1415 
1416 /*
1417  * Clear the list of diffblocks for tab page "tp".
1418  */
1419     void
1420 diff_clear(tp)
1421     tabpage_T	*tp;
1422 {
1423     diff_T	*p, *next_p;
1424 
1425     for (p = tp->tp_first_diff; p != NULL; p = next_p)
1426     {
1427 	next_p = p->df_next;
1428 	vim_free(p);
1429     }
1430     tp->tp_first_diff = NULL;
1431 }
1432 
1433 /*
1434  * Check diff status for line "lnum" in buffer "buf":
1435  * Returns 0 for nothing special
1436  * Returns -1 for a line that should be highlighted as changed.
1437  * Returns -2 for a line that should be highlighted as added/deleted.
1438  * Returns > 0 for inserting that many filler lines above it (never happens
1439  * when 'diffopt' doesn't contain "filler").
1440  * This should only be used for windows where 'diff' is set.
1441  */
1442     int
1443 diff_check(wp, lnum)
1444     win_T	*wp;
1445     linenr_T	lnum;
1446 {
1447     int		idx;		/* index in tp_diffbuf[] for this buffer */
1448     diff_T	*dp;
1449     int		maxcount;
1450     int		i;
1451     buf_T	*buf = wp->w_buffer;
1452     int		cmp;
1453 
1454     if (curtab->tp_diff_invalid)
1455 	ex_diffupdate(NULL);		/* update after a big change */
1456 
1457     if (curtab->tp_first_diff == NULL || !wp->w_p_diff)	/* no diffs at all */
1458 	return 0;
1459 
1460     /* safety check: "lnum" must be a buffer line */
1461     if (lnum < 1 || lnum > buf->b_ml.ml_line_count + 1)
1462 	return 0;
1463 
1464     idx = diff_buf_idx(buf);
1465     if (idx == DB_COUNT)
1466 	return 0;		/* no diffs for buffer "buf" */
1467 
1468 #ifdef FEAT_FOLDING
1469     /* A closed fold never has filler lines. */
1470     if (hasFoldingWin(wp, lnum, NULL, NULL, TRUE, NULL))
1471 	return 0;
1472 #endif
1473 
1474     /* search for a change that includes "lnum" in the list of diffblocks. */
1475     for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next)
1476 	if (lnum <= dp->df_lnum[idx] + dp->df_count[idx])
1477 	    break;
1478     if (dp == NULL || lnum < dp->df_lnum[idx])
1479 	return 0;
1480 
1481     if (lnum < dp->df_lnum[idx] + dp->df_count[idx])
1482     {
1483 	int	zero = FALSE;
1484 
1485 	/* Changed or inserted line.  If the other buffers have a count of
1486 	 * zero, the lines were inserted.  If the other buffers have the same
1487 	 * count, check if the lines are identical. */
1488 	cmp = FALSE;
1489 	for (i = 0; i < DB_COUNT; ++i)
1490 	    if (i != idx && curtab->tp_diffbuf[i] != NULL)
1491 	    {
1492 		if (dp->df_count[i] == 0)
1493 		    zero = TRUE;
1494 		else
1495 		{
1496 		    if (dp->df_count[i] != dp->df_count[idx])
1497 			return -1;	    /* nr of lines changed. */
1498 		    cmp = TRUE;
1499 		}
1500 	    }
1501 	if (cmp)
1502 	{
1503 	    /* Compare all lines.  If they are equal the lines were inserted
1504 	     * in some buffers, deleted in others, but not changed. */
1505 	    for (i = 0; i < DB_COUNT; ++i)
1506 		if (i != idx && curtab->tp_diffbuf[i] != NULL && dp->df_count[i] != 0)
1507 		    if (!diff_equal_entry(dp, idx, i))
1508 			return -1;
1509 	}
1510 	/* If there is no buffer with zero lines then there is no difference
1511 	 * any longer.  Happens when making a change (or undo) that removes
1512 	 * the difference.  Can't remove the entry here, we might be halfway
1513 	 * updating the window.  Just report the text as unchanged.  Other
1514 	 * windows might still show the change though. */
1515 	if (zero == FALSE)
1516 	    return 0;
1517 	return -2;
1518     }
1519 
1520     /* If 'diffopt' doesn't contain "filler", return 0. */
1521     if (!(diff_flags & DIFF_FILLER))
1522 	return 0;
1523 
1524     /* Insert filler lines above the line just below the change.  Will return
1525      * 0 when this buf had the max count. */
1526     maxcount = 0;
1527     for (i = 0; i < DB_COUNT; ++i)
1528 	if (curtab->tp_diffbuf[i] != NULL && dp->df_count[i] > maxcount)
1529 	    maxcount = dp->df_count[i];
1530     return maxcount - dp->df_count[idx];
1531 }
1532 
1533 /*
1534  * Compare two entries in diff "*dp" and return TRUE if they are equal.
1535  */
1536     static int
1537 diff_equal_entry(dp, idx1, idx2)
1538     diff_T	*dp;
1539     int		idx1;
1540     int		idx2;
1541 {
1542     int		i;
1543     char_u	*line;
1544     int		cmp;
1545 
1546     if (dp->df_count[idx1] != dp->df_count[idx2])
1547 	return FALSE;
1548     if (diff_check_sanity(curtab, dp) == FAIL)
1549 	return FALSE;
1550     for (i = 0; i < dp->df_count[idx1]; ++i)
1551     {
1552 	line = vim_strsave(ml_get_buf(curtab->tp_diffbuf[idx1],
1553 					       dp->df_lnum[idx1] + i, FALSE));
1554 	if (line == NULL)
1555 	    return FALSE;
1556 	cmp = diff_cmp(line, ml_get_buf(curtab->tp_diffbuf[idx2],
1557 					       dp->df_lnum[idx2] + i, FALSE));
1558 	vim_free(line);
1559 	if (cmp != 0)
1560 	    return FALSE;
1561     }
1562     return TRUE;
1563 }
1564 
1565 /*
1566  * Compare strings "s1" and "s2" according to 'diffopt'.
1567  * Return non-zero when they are different.
1568  */
1569     static int
1570 diff_cmp(s1, s2)
1571     char_u	*s1;
1572     char_u	*s2;
1573 {
1574     char_u	*p1, *p2;
1575 #ifdef FEAT_MBYTE
1576     int		l;
1577 #endif
1578 
1579     if ((diff_flags & (DIFF_ICASE | DIFF_IWHITE)) == 0)
1580 	return STRCMP(s1, s2);
1581     if ((diff_flags & DIFF_ICASE) && !(diff_flags & DIFF_IWHITE))
1582 	return MB_STRICMP(s1, s2);
1583 
1584     /* Ignore white space changes and possibly ignore case. */
1585     p1 = s1;
1586     p2 = s2;
1587     while (*p1 != NUL && *p2 != NUL)
1588     {
1589 	if (vim_iswhite(*p1) && vim_iswhite(*p2))
1590 	{
1591 	    p1 = skipwhite(p1);
1592 	    p2 = skipwhite(p2);
1593 	}
1594 	else
1595 	{
1596 #ifdef FEAT_MBYTE
1597 	    l  = (*mb_ptr2len)(p1);
1598 	    if (l != (*mb_ptr2len)(p2))
1599 		break;
1600 	    if (l > 1)
1601 	    {
1602 		if (STRNCMP(p1, p2, l) != 0
1603 			&& (!enc_utf8
1604 			    || !(diff_flags & DIFF_ICASE)
1605 			    || utf_fold(utf_ptr2char(p1))
1606 					       != utf_fold(utf_ptr2char(p2))))
1607 		    break;
1608 		p1 += l;
1609 		p2 += l;
1610 	    }
1611 	    else
1612 #endif
1613 	    {
1614 		if (*p1 != *p2 && (!(diff_flags & DIFF_ICASE)
1615 				     || TOLOWER_LOC(*p1) != TOLOWER_LOC(*p2)))
1616 		    break;
1617 		++p1;
1618 		++p2;
1619 	    }
1620 	}
1621     }
1622 
1623     /* Ignore trailing white space. */
1624     p1 = skipwhite(p1);
1625     p2 = skipwhite(p2);
1626     if (*p1 != NUL || *p2 != NUL)
1627 	return 1;
1628     return 0;
1629 }
1630 
1631 /*
1632  * Return the number of filler lines above "lnum".
1633  */
1634     int
1635 diff_check_fill(wp, lnum)
1636     win_T	*wp;
1637     linenr_T	lnum;
1638 {
1639     int		n;
1640 
1641     /* be quick when there are no filler lines */
1642     if (!(diff_flags & DIFF_FILLER))
1643 	return 0;
1644     n = diff_check(wp, lnum);
1645     if (n <= 0)
1646 	return 0;
1647     return n;
1648 }
1649 
1650 /*
1651  * Set the topline of "towin" to match the position in "fromwin", so that they
1652  * show the same diff'ed lines.
1653  */
1654     void
1655 diff_set_topline(fromwin, towin)
1656     win_T	*fromwin;
1657     win_T	*towin;
1658 {
1659     buf_T	*frombuf = fromwin->w_buffer;
1660     linenr_T	lnum = fromwin->w_topline;
1661     int		fromidx;
1662     int		toidx;
1663     diff_T	*dp;
1664     int		max_count;
1665     int		i;
1666 
1667     fromidx = diff_buf_idx(frombuf);
1668     if (fromidx == DB_COUNT)
1669 	return;		/* safety check */
1670 
1671     if (curtab->tp_diff_invalid)
1672 	ex_diffupdate(NULL);		/* update after a big change */
1673 
1674     towin->w_topfill = 0;
1675 
1676     /* search for a change that includes "lnum" in the list of diffblocks. */
1677     for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next)
1678 	if (lnum <= dp->df_lnum[fromidx] + dp->df_count[fromidx])
1679 	    break;
1680     if (dp == NULL)
1681     {
1682 	/* After last change, compute topline relative to end of file; no
1683 	 * filler lines. */
1684 	towin->w_topline = towin->w_buffer->b_ml.ml_line_count
1685 				       - (frombuf->b_ml.ml_line_count - lnum);
1686     }
1687     else
1688     {
1689 	/* Find index for "towin". */
1690 	toidx = diff_buf_idx(towin->w_buffer);
1691 	if (toidx == DB_COUNT)
1692 	    return;		/* safety check */
1693 
1694 	towin->w_topline = lnum + (dp->df_lnum[toidx] - dp->df_lnum[fromidx]);
1695 	if (lnum >= dp->df_lnum[fromidx])
1696 	{
1697 	    /* Inside a change: compute filler lines. With three or more
1698 	     * buffers we need to know the largest count. */
1699 	    max_count = 0;
1700 	    for (i = 0; i < DB_COUNT; ++i)
1701 		if (curtab->tp_diffbuf[i] != NULL
1702 					       && max_count < dp->df_count[i])
1703 		    max_count = dp->df_count[i];
1704 
1705 	    if (dp->df_count[toidx] == dp->df_count[fromidx])
1706 	    {
1707 		/* same number of lines: use same filler count */
1708 		towin->w_topfill = fromwin->w_topfill;
1709 	    }
1710 	    else if (dp->df_count[toidx] > dp->df_count[fromidx])
1711 	    {
1712 		if (lnum == dp->df_lnum[fromidx] + dp->df_count[fromidx])
1713 		{
1714 		    /* more lines in towin and fromwin doesn't show diff
1715 		     * lines, only filler lines */
1716 		    if (max_count - fromwin->w_topfill >= dp->df_count[toidx])
1717 		    {
1718 			/* towin also only shows filler lines */
1719 			towin->w_topline = dp->df_lnum[toidx]
1720 						       + dp->df_count[toidx];
1721 			towin->w_topfill = fromwin->w_topfill;
1722 		    }
1723 		    else
1724 			/* towin still has some diff lines to show */
1725 			towin->w_topline = dp->df_lnum[toidx]
1726 					     + max_count - fromwin->w_topfill;
1727 		}
1728 	    }
1729 	    else if (towin->w_topline >= dp->df_lnum[toidx]
1730 							+ dp->df_count[toidx])
1731 	    {
1732 		/* less lines in towin and no diff lines to show: compute
1733 		 * filler lines */
1734 		towin->w_topline = dp->df_lnum[toidx] + dp->df_count[toidx];
1735 		if (diff_flags & DIFF_FILLER)
1736 		{
1737 		    if (lnum == dp->df_lnum[fromidx] + dp->df_count[fromidx])
1738 			/* fromwin is also out of diff lines */
1739 			towin->w_topfill = fromwin->w_topfill;
1740 		    else
1741 			/* fromwin has some diff lines */
1742 			towin->w_topfill = dp->df_lnum[fromidx]
1743 							   + max_count - lnum;
1744 		}
1745 	    }
1746 	}
1747     }
1748 
1749     /* safety check (if diff info gets outdated strange things may happen) */
1750     towin->w_botfill = FALSE;
1751     if (towin->w_topline > towin->w_buffer->b_ml.ml_line_count)
1752     {
1753 	towin->w_topline = towin->w_buffer->b_ml.ml_line_count;
1754 	towin->w_botfill = TRUE;
1755     }
1756     if (towin->w_topline < 1)
1757     {
1758 	towin->w_topline = 1;
1759 	towin->w_topfill = 0;
1760     }
1761 
1762     /* When w_topline changes need to recompute w_botline and cursor position */
1763     invalidate_botline_win(towin);
1764     changed_line_abv_curs_win(towin);
1765 
1766     check_topfill(towin, FALSE);
1767 #ifdef FEAT_FOLDING
1768     (void)hasFoldingWin(towin, towin->w_topline, &towin->w_topline,
1769 							    NULL, TRUE, NULL);
1770 #endif
1771 }
1772 
1773 /*
1774  * This is called when 'diffopt' is changed.
1775  */
1776     int
1777 diffopt_changed()
1778 {
1779     char_u	*p;
1780     int		diff_context_new = 6;
1781     int		diff_flags_new = 0;
1782     int		diff_foldcolumn_new = 2;
1783     tabpage_T	*tp;
1784 
1785     p = p_dip;
1786     while (*p != NUL)
1787     {
1788 	if (STRNCMP(p, "filler", 6) == 0)
1789 	{
1790 	    p += 6;
1791 	    diff_flags_new |= DIFF_FILLER;
1792 	}
1793 	else if (STRNCMP(p, "context:", 8) == 0 && VIM_ISDIGIT(p[8]))
1794 	{
1795 	    p += 8;
1796 	    diff_context_new = getdigits(&p);
1797 	}
1798 	else if (STRNCMP(p, "icase", 5) == 0)
1799 	{
1800 	    p += 5;
1801 	    diff_flags_new |= DIFF_ICASE;
1802 	}
1803 	else if (STRNCMP(p, "iwhite", 6) == 0)
1804 	{
1805 	    p += 6;
1806 	    diff_flags_new |= DIFF_IWHITE;
1807 	}
1808 	else if (STRNCMP(p, "horizontal", 10) == 0)
1809 	{
1810 	    p += 10;
1811 	    diff_flags_new |= DIFF_HORIZONTAL;
1812 	}
1813 	else if (STRNCMP(p, "vertical", 8) == 0)
1814 	{
1815 	    p += 8;
1816 	    diff_flags_new |= DIFF_VERTICAL;
1817 	}
1818 	else if (STRNCMP(p, "foldcolumn:", 11) == 0 && VIM_ISDIGIT(p[11]))
1819 	{
1820 	    p += 11;
1821 	    diff_foldcolumn_new = getdigits(&p);
1822 	}
1823 	if (*p != ',' && *p != NUL)
1824 	    return FAIL;
1825 	if (*p == ',')
1826 	    ++p;
1827     }
1828 
1829     /* Can't have both "horizontal" and "vertical". */
1830     if ((diff_flags_new & DIFF_HORIZONTAL) && (diff_flags_new & DIFF_VERTICAL))
1831 	return FAIL;
1832 
1833     /* If "icase" or "iwhite" was added or removed, need to update the diff. */
1834     if (diff_flags != diff_flags_new)
1835 	for (tp = first_tabpage; tp != NULL; tp = tp->tp_next)
1836 	    tp->tp_diff_invalid = TRUE;
1837 
1838     diff_flags = diff_flags_new;
1839     diff_context = diff_context_new;
1840     diff_foldcolumn = diff_foldcolumn_new;
1841 
1842     diff_redraw(TRUE);
1843 
1844     /* recompute the scroll binding with the new option value, may
1845      * remove or add filler lines */
1846     check_scrollbind((linenr_T)0, 0L);
1847 
1848     return OK;
1849 }
1850 
1851 /*
1852  * Return TRUE if 'diffopt' contains "horizontal".
1853  */
1854     int
1855 diffopt_horizontal()
1856 {
1857     return (diff_flags & DIFF_HORIZONTAL) != 0;
1858 }
1859 
1860 /*
1861  * Find the difference within a changed line.
1862  * Returns TRUE if the line was added, no other buffer has it.
1863  */
1864     int
1865 diff_find_change(wp, lnum, startp, endp)
1866     win_T	*wp;
1867     linenr_T	lnum;
1868     int		*startp;	/* first char of the change */
1869     int		*endp;		/* last char of the change */
1870 {
1871     char_u	*line_org;
1872     char_u	*line_new;
1873     int		i;
1874     int		si_org, si_new;
1875     int		ei_org, ei_new;
1876     diff_T	*dp;
1877     int		idx;
1878     int		off;
1879     int		added = TRUE;
1880 
1881     /* Make a copy of the line, the next ml_get() will invalidate it. */
1882     line_org = vim_strsave(ml_get_buf(wp->w_buffer, lnum, FALSE));
1883     if (line_org == NULL)
1884 	return FALSE;
1885 
1886     idx = diff_buf_idx(wp->w_buffer);
1887     if (idx == DB_COUNT)	/* cannot happen */
1888     {
1889 	vim_free(line_org);
1890 	return FALSE;
1891     }
1892 
1893     /* search for a change that includes "lnum" in the list of diffblocks. */
1894     for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next)
1895 	if (lnum <= dp->df_lnum[idx] + dp->df_count[idx])
1896 	    break;
1897     if (dp == NULL || diff_check_sanity(curtab, dp) == FAIL)
1898     {
1899 	vim_free(line_org);
1900 	return FALSE;
1901     }
1902 
1903     off = lnum - dp->df_lnum[idx];
1904 
1905     for (i = 0; i < DB_COUNT; ++i)
1906 	if (curtab->tp_diffbuf[i] != NULL && i != idx)
1907 	{
1908 	    /* Skip lines that are not in the other change (filler lines). */
1909 	    if (off >= dp->df_count[i])
1910 		continue;
1911 	    added = FALSE;
1912 	    line_new = ml_get_buf(curtab->tp_diffbuf[i],
1913 						 dp->df_lnum[i] + off, FALSE);
1914 
1915 	    /* Search for start of difference */
1916 	    si_org = si_new = 0;
1917 	    while (line_org[si_org] != NUL)
1918 	    {
1919 		if ((diff_flags & DIFF_IWHITE)
1920 			&& vim_iswhite(line_org[si_org])
1921 			&& vim_iswhite(line_new[si_new]))
1922 		{
1923 		    si_org = (int)(skipwhite(line_org + si_org) - line_org);
1924 		    si_new = (int)(skipwhite(line_new + si_new) - line_new);
1925 		}
1926 		else
1927 		{
1928 		    if (line_org[si_org] != line_new[si_new])
1929 			break;
1930 		    ++si_org;
1931 		    ++si_new;
1932 		}
1933 	    }
1934 #ifdef FEAT_MBYTE
1935 	    if (has_mbyte)
1936 	    {
1937 		/* Move back to first byte of character in both lines (may
1938 		 * have "nn^" in line_org and "n^ in line_new). */
1939 		si_org -= (*mb_head_off)(line_org, line_org + si_org);
1940 		si_new -= (*mb_head_off)(line_new, line_new + si_new);
1941 	    }
1942 #endif
1943 	    if (*startp > si_org)
1944 		*startp = si_org;
1945 
1946 	    /* Search for end of difference, if any. */
1947 	    if (line_org[si_org] != NUL || line_new[si_new] != NUL)
1948 	    {
1949 		ei_org = (int)STRLEN(line_org);
1950 		ei_new = (int)STRLEN(line_new);
1951 		while (ei_org >= *startp && ei_new >= si_new
1952 						&& ei_org >= 0 && ei_new >= 0)
1953 		{
1954 		    if ((diff_flags & DIFF_IWHITE)
1955 			    && vim_iswhite(line_org[ei_org])
1956 			    && vim_iswhite(line_new[ei_new]))
1957 		    {
1958 			while (ei_org >= *startp
1959 					     && vim_iswhite(line_org[ei_org]))
1960 			    --ei_org;
1961 			while (ei_new >= si_new
1962 					     && vim_iswhite(line_new[ei_new]))
1963 			    --ei_new;
1964 		    }
1965 		    else
1966 		    {
1967 			if (line_org[ei_org] != line_new[ei_new])
1968 			    break;
1969 			--ei_org;
1970 			--ei_new;
1971 		    }
1972 		}
1973 		if (*endp < ei_org)
1974 		    *endp = ei_org;
1975 	    }
1976 	}
1977 
1978     vim_free(line_org);
1979     return added;
1980 }
1981 
1982 #if defined(FEAT_FOLDING) || defined(PROTO)
1983 /*
1984  * Return TRUE if line "lnum" is not close to a diff block, this line should
1985  * be in a fold.
1986  * Return FALSE if there are no diff blocks at all in this window.
1987  */
1988     int
1989 diff_infold(wp, lnum)
1990     win_T	*wp;
1991     linenr_T	lnum;
1992 {
1993     int		i;
1994     int		idx = -1;
1995     int		other = FALSE;
1996     diff_T	*dp;
1997 
1998     /* Return if 'diff' isn't set. */
1999     if (!wp->w_p_diff)
2000 	return FALSE;
2001 
2002     for (i = 0; i < DB_COUNT; ++i)
2003     {
2004 	if (curtab->tp_diffbuf[i] == wp->w_buffer)
2005 	    idx = i;
2006 	else if (curtab->tp_diffbuf[i] != NULL)
2007 	    other = TRUE;
2008     }
2009 
2010     /* return here if there are no diffs in the window */
2011     if (idx == -1 || !other)
2012 	return FALSE;
2013 
2014     if (curtab->tp_diff_invalid)
2015 	ex_diffupdate(NULL);		/* update after a big change */
2016 
2017     /* Return if there are no diff blocks.  All lines will be folded. */
2018     if (curtab->tp_first_diff == NULL)
2019 	return TRUE;
2020 
2021     for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next)
2022     {
2023 	/* If this change is below the line there can't be any further match. */
2024 	if (dp->df_lnum[idx] - diff_context > lnum)
2025 	    break;
2026 	/* If this change ends before the line we have a match. */
2027 	if (dp->df_lnum[idx] + dp->df_count[idx] + diff_context > lnum)
2028 	    return FALSE;
2029     }
2030     return TRUE;
2031 }
2032 #endif
2033 
2034 /*
2035  * "dp" and "do" commands.
2036  */
2037     void
2038 nv_diffgetput(put)
2039     int		put;
2040 {
2041     exarg_T	ea;
2042 
2043     ea.arg = (char_u *)"";
2044     if (put)
2045 	ea.cmdidx = CMD_diffput;
2046     else
2047 	ea.cmdidx = CMD_diffget;
2048     ea.addr_count = 0;
2049     ea.line1 = curwin->w_cursor.lnum;
2050     ea.line2 = curwin->w_cursor.lnum;
2051     ex_diffgetput(&ea);
2052 }
2053 
2054 /*
2055  * ":diffget"
2056  * ":diffput"
2057  */
2058     void
2059 ex_diffgetput(eap)
2060     exarg_T	*eap;
2061 {
2062     linenr_T	lnum;
2063     int		count;
2064     linenr_T	off = 0;
2065     diff_T	*dp;
2066     diff_T	*dprev;
2067     diff_T	*dfree;
2068     int		idx_cur;
2069     int		idx_other;
2070     int		idx_from;
2071     int		idx_to;
2072     int		i;
2073     int		added;
2074     char_u	*p;
2075     aco_save_T	aco;
2076     buf_T	*buf;
2077     int		start_skip, end_skip;
2078     int		new_count;
2079     int		buf_empty;
2080     int		found_not_ma = FALSE;
2081 
2082     /* Find the current buffer in the list of diff buffers. */
2083     idx_cur = diff_buf_idx(curbuf);
2084     if (idx_cur == DB_COUNT)
2085     {
2086 	EMSG(_("E99: Current buffer is not in diff mode"));
2087 	return;
2088     }
2089 
2090     if (*eap->arg == NUL)
2091     {
2092 	/* No argument: Find the other buffer in the list of diff buffers. */
2093 	for (idx_other = 0; idx_other < DB_COUNT; ++idx_other)
2094 	    if (curtab->tp_diffbuf[idx_other] != curbuf
2095 		    && curtab->tp_diffbuf[idx_other] != NULL)
2096 	    {
2097 		if (eap->cmdidx != CMD_diffput
2098 				     || curtab->tp_diffbuf[idx_other]->b_p_ma)
2099 		    break;
2100 		found_not_ma = TRUE;
2101 	    }
2102 	if (idx_other == DB_COUNT)
2103 	{
2104 	    if (found_not_ma)
2105 		EMSG(_("E793: No other buffer in diff mode is modifiable"));
2106 	    else
2107 		EMSG(_("E100: No other buffer in diff mode"));
2108 	    return;
2109 	}
2110 
2111 	/* Check that there isn't a third buffer in the list */
2112 	for (i = idx_other + 1; i < DB_COUNT; ++i)
2113 	    if (curtab->tp_diffbuf[i] != curbuf
2114 		    && curtab->tp_diffbuf[i] != NULL
2115 		    && (eap->cmdidx != CMD_diffput || curtab->tp_diffbuf[i]->b_p_ma))
2116 	    {
2117 		EMSG(_("E101: More than two buffers in diff mode, don't know which one to use"));
2118 		return;
2119 	    }
2120     }
2121     else
2122     {
2123 	/* Buffer number or pattern given.  Ignore trailing white space. */
2124 	p = eap->arg + STRLEN(eap->arg);
2125 	while (p > eap->arg && vim_iswhite(p[-1]))
2126 	    --p;
2127 	for (i = 0; vim_isdigit(eap->arg[i]) && eap->arg + i < p; ++i)
2128 	    ;
2129 	if (eap->arg + i == p)	    /* digits only */
2130 	    i = atol((char *)eap->arg);
2131 	else
2132 	{
2133 	    i = buflist_findpat(eap->arg, p, FALSE, TRUE);
2134 	    if (i < 0)
2135 		return;		/* error message already given */
2136 	}
2137 	buf = buflist_findnr(i);
2138 	if (buf == NULL)
2139 	{
2140 	    EMSG2(_("E102: Can't find buffer \"%s\""), eap->arg);
2141 	    return;
2142 	}
2143 	if (buf == curbuf)
2144 	    return;		/* nothing to do */
2145 	idx_other = diff_buf_idx(buf);
2146 	if (idx_other == DB_COUNT)
2147 	{
2148 	    EMSG2(_("E103: Buffer \"%s\" is not in diff mode"), eap->arg);
2149 	    return;
2150 	}
2151     }
2152 
2153     diff_busy = TRUE;
2154 
2155     /* When no range given include the line above or below the cursor. */
2156     if (eap->addr_count == 0)
2157     {
2158 	/* Make it possible that ":diffget" on the last line gets line below
2159 	 * the cursor line when there is no difference above the cursor. */
2160 	if (eap->cmdidx == CMD_diffget
2161 		&& eap->line1 == curbuf->b_ml.ml_line_count
2162 		&& diff_check(curwin, eap->line1) == 0
2163 		&& (eap->line1 == 1 || diff_check(curwin, eap->line1 - 1) == 0))
2164 	    ++eap->line2;
2165 	else if (eap->line1 > 0)
2166 	    --eap->line1;
2167     }
2168 
2169     if (eap->cmdidx == CMD_diffget)
2170     {
2171 	idx_from = idx_other;
2172 	idx_to = idx_cur;
2173     }
2174     else
2175     {
2176 	idx_from = idx_cur;
2177 	idx_to = idx_other;
2178 	/* Need to make the other buffer the current buffer to be able to make
2179 	 * changes in it. */
2180 	/* set curwin/curbuf to buf and save a few things */
2181 	aucmd_prepbuf(&aco, curtab->tp_diffbuf[idx_other]);
2182     }
2183 
2184     /* May give the warning for a changed buffer here, which can trigger the
2185      * FileChangedRO autocommand, which may do nasty things and mess
2186      * everything up. */
2187     if (!curbuf->b_changed)
2188     {
2189 	change_warning(0);
2190 	if (diff_buf_idx(curbuf) != idx_to)
2191 	{
2192 	    EMSG(_("E787: Buffer changed unexpectedly"));
2193 	    return;
2194 	}
2195     }
2196 
2197     dprev = NULL;
2198     for (dp = curtab->tp_first_diff; dp != NULL; )
2199     {
2200 	if (dp->df_lnum[idx_cur] > eap->line2 + off)
2201 	    break;	/* past the range that was specified */
2202 
2203 	dfree = NULL;
2204 	lnum = dp->df_lnum[idx_to];
2205 	count = dp->df_count[idx_to];
2206 	if (dp->df_lnum[idx_cur] + dp->df_count[idx_cur] > eap->line1 + off
2207 		&& u_save(lnum - 1, lnum + count) != FAIL)
2208 	{
2209 	    /* Inside the specified range and saving for undo worked. */
2210 	    start_skip = 0;
2211 	    end_skip = 0;
2212 	    if (eap->addr_count > 0)
2213 	    {
2214 		/* A range was specified: check if lines need to be skipped. */
2215 		start_skip = eap->line1 + off - dp->df_lnum[idx_cur];
2216 		if (start_skip > 0)
2217 		{
2218 		    /* range starts below start of current diff block */
2219 		    if (start_skip > count)
2220 		    {
2221 			lnum += count;
2222 			count = 0;
2223 		    }
2224 		    else
2225 		    {
2226 			count -= start_skip;
2227 			lnum += start_skip;
2228 		    }
2229 		}
2230 		else
2231 		    start_skip = 0;
2232 
2233 		end_skip = dp->df_lnum[idx_cur] + dp->df_count[idx_cur] - 1
2234 							 - (eap->line2 + off);
2235 		if (end_skip > 0)
2236 		{
2237 		    /* range ends above end of current/from diff block */
2238 		    if (idx_cur == idx_from)	/* :diffput */
2239 		    {
2240 			i = dp->df_count[idx_cur] - start_skip - end_skip;
2241 			if (count > i)
2242 			    count = i;
2243 		    }
2244 		    else			/* :diffget */
2245 		    {
2246 			count -= end_skip;
2247 			end_skip = dp->df_count[idx_from] - start_skip - count;
2248 			if (end_skip < 0)
2249 			    end_skip = 0;
2250 		    }
2251 		}
2252 		else
2253 		    end_skip = 0;
2254 	    }
2255 
2256 	    buf_empty = FALSE;
2257 	    added = 0;
2258 	    for (i = 0; i < count; ++i)
2259 	    {
2260 		/* remember deleting the last line of the buffer */
2261 		buf_empty = curbuf->b_ml.ml_line_count == 1;
2262 		ml_delete(lnum, FALSE);
2263 		--added;
2264 	    }
2265 	    for (i = 0; i < dp->df_count[idx_from] - start_skip - end_skip; ++i)
2266 	    {
2267 		linenr_T nr;
2268 
2269 		nr = dp->df_lnum[idx_from] + start_skip + i;
2270 		if (nr > curtab->tp_diffbuf[idx_from]->b_ml.ml_line_count)
2271 		    break;
2272 		p = vim_strsave(ml_get_buf(curtab->tp_diffbuf[idx_from],
2273 								  nr, FALSE));
2274 		if (p != NULL)
2275 		{
2276 		    ml_append(lnum + i - 1, p, 0, FALSE);
2277 		    vim_free(p);
2278 		    ++added;
2279 		    if (buf_empty && curbuf->b_ml.ml_line_count == 2)
2280 		    {
2281 			/* Added the first line into an empty buffer, need to
2282 			 * delete the dummy empty line. */
2283 			buf_empty = FALSE;
2284 			ml_delete((linenr_T)2, FALSE);
2285 		    }
2286 		}
2287 	    }
2288 	    new_count = dp->df_count[idx_to] + added;
2289 	    dp->df_count[idx_to] = new_count;
2290 
2291 	    if (start_skip == 0 && end_skip == 0)
2292 	    {
2293 		/* Check if there are any other buffers and if the diff is
2294 		 * equal in them. */
2295 		for (i = 0; i < DB_COUNT; ++i)
2296 		    if (curtab->tp_diffbuf[i] != NULL && i != idx_from
2297 								&& i != idx_to
2298 			    && !diff_equal_entry(dp, idx_from, i))
2299 			break;
2300 		if (i == DB_COUNT)
2301 		{
2302 		    /* delete the diff entry, the buffers are now equal here */
2303 		    dfree = dp;
2304 		    dp = dp->df_next;
2305 		    if (dprev == NULL)
2306 			curtab->tp_first_diff = dp;
2307 		    else
2308 			dprev->df_next = dp;
2309 		}
2310 	    }
2311 
2312 	    /* Adjust marks.  This will change the following entries! */
2313 	    if (added != 0)
2314 	    {
2315 		mark_adjust(lnum, lnum + count - 1, (long)MAXLNUM, (long)added);
2316 		if (curwin->w_cursor.lnum >= lnum)
2317 		{
2318 		    /* Adjust the cursor position if it's in/after the changed
2319 		     * lines. */
2320 		    if (curwin->w_cursor.lnum >= lnum + count)
2321 			curwin->w_cursor.lnum += added;
2322 		    else if (added < 0)
2323 			curwin->w_cursor.lnum = lnum;
2324 		}
2325 	    }
2326 	    changed_lines(lnum, 0, lnum + count, (long)added);
2327 
2328 	    if (dfree != NULL)
2329 	    {
2330 		/* Diff is deleted, update folds in other windows. */
2331 #ifdef FEAT_FOLDING
2332 		diff_fold_update(dfree, idx_to);
2333 #endif
2334 		vim_free(dfree);
2335 	    }
2336 	    else
2337 		/* mark_adjust() may have changed the count in a wrong way */
2338 		dp->df_count[idx_to] = new_count;
2339 
2340 	    /* When changing the current buffer, keep track of line numbers */
2341 	    if (idx_cur == idx_to)
2342 		off += added;
2343 	}
2344 
2345 	/* If before the range or not deleted, go to next diff. */
2346 	if (dfree == NULL)
2347 	{
2348 	    dprev = dp;
2349 	    dp = dp->df_next;
2350 	}
2351     }
2352 
2353     /* restore curwin/curbuf and a few other things */
2354     if (idx_other == idx_to)
2355     {
2356 	/* Syncing undo only works for the current buffer, but we change
2357 	 * another buffer.  Sync undo if the command was typed.  This isn't
2358 	 * 100% right when ":diffput" is used in a function or mapping. */
2359 	if (KeyTyped)
2360 	    u_sync(FALSE);
2361 	aucmd_restbuf(&aco);
2362     }
2363 
2364     diff_busy = FALSE;
2365 
2366     /* Check that the cursor is on a valid character and update it's position.
2367      * When there were filler lines the topline has become invalid. */
2368     check_cursor();
2369     changed_line_abv_curs();
2370 
2371     /* Also need to redraw the other buffers. */
2372     diff_redraw(FALSE);
2373 }
2374 
2375 #ifdef FEAT_FOLDING
2376 /*
2377  * Update folds for all diff buffers for entry "dp".
2378  * Skip buffer with index "skip_idx".
2379  * When there are no diffs, all folds are removed.
2380  */
2381     static void
2382 diff_fold_update(dp, skip_idx)
2383     diff_T	*dp;
2384     int		skip_idx;
2385 {
2386     int		i;
2387     win_T	*wp;
2388 
2389     for (wp = firstwin; wp != NULL; wp = wp->w_next)
2390 	for (i = 0; i < DB_COUNT; ++i)
2391 	    if (curtab->tp_diffbuf[i] == wp->w_buffer && i != skip_idx)
2392 		foldUpdate(wp, dp->df_lnum[i],
2393 					    dp->df_lnum[i] + dp->df_count[i]);
2394 }
2395 #endif
2396 
2397 /*
2398  * Return TRUE if buffer "buf" is in diff-mode.
2399  */
2400     int
2401 diff_mode_buf(buf)
2402     buf_T	*buf;
2403 {
2404     tabpage_T	*tp;
2405 
2406     for (tp = first_tabpage; tp != NULL; tp = tp->tp_next)
2407 	if (diff_buf_idx_tp(buf, tp) != DB_COUNT)
2408 	    return TRUE;
2409     return FALSE;
2410 }
2411 
2412 /*
2413  * Move "count" times in direction "dir" to the next diff block.
2414  * Return FAIL if there isn't such a diff block.
2415  */
2416     int
2417 diff_move_to(dir, count)
2418     int		dir;
2419     long	count;
2420 {
2421     int		idx;
2422     linenr_T	lnum = curwin->w_cursor.lnum;
2423     diff_T	*dp;
2424 
2425     idx = diff_buf_idx(curbuf);
2426     if (idx == DB_COUNT || curtab->tp_first_diff == NULL)
2427 	return FAIL;
2428 
2429     if (curtab->tp_diff_invalid)
2430 	ex_diffupdate(NULL);		/* update after a big change */
2431 
2432     if (curtab->tp_first_diff == NULL)		/* no diffs today */
2433 	return FAIL;
2434 
2435     while (--count >= 0)
2436     {
2437 	/* Check if already before first diff. */
2438 	if (dir == BACKWARD && lnum <= curtab->tp_first_diff->df_lnum[idx])
2439 	    break;
2440 
2441 	for (dp = curtab->tp_first_diff; ; dp = dp->df_next)
2442 	{
2443 	    if (dp == NULL)
2444 		break;
2445 	    if ((dir == FORWARD && lnum < dp->df_lnum[idx])
2446 		    || (dir == BACKWARD
2447 			&& (dp->df_next == NULL
2448 			    || lnum <= dp->df_next->df_lnum[idx])))
2449 	    {
2450 		lnum = dp->df_lnum[idx];
2451 		break;
2452 	    }
2453 	}
2454     }
2455 
2456     /* don't end up past the end of the file */
2457     if (lnum > curbuf->b_ml.ml_line_count)
2458 	lnum = curbuf->b_ml.ml_line_count;
2459 
2460     /* When the cursor didn't move at all we fail. */
2461     if (lnum == curwin->w_cursor.lnum)
2462 	return FAIL;
2463 
2464     setpcmark();
2465     curwin->w_cursor.lnum = lnum;
2466     curwin->w_cursor.col = 0;
2467 
2468     return OK;
2469 }
2470 
2471 #if defined(FEAT_FOLDING) || defined(PROTO)
2472 /*
2473  * For line "lnum" in the current window find the equivalent lnum in window
2474  * "wp", compensating for inserted/deleted lines.
2475  */
2476     linenr_T
2477 diff_lnum_win(lnum, wp)
2478     linenr_T	lnum;
2479     win_T	*wp;
2480 {
2481     diff_T	*dp;
2482     int		idx;
2483     int		i;
2484     linenr_T	n;
2485 
2486     idx = diff_buf_idx(curbuf);
2487     if (idx == DB_COUNT)		/* safety check */
2488 	return (linenr_T)0;
2489 
2490     if (curtab->tp_diff_invalid)
2491 	ex_diffupdate(NULL);		/* update after a big change */
2492 
2493     /* search for a change that includes "lnum" in the list of diffblocks. */
2494     for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next)
2495 	if (lnum <= dp->df_lnum[idx] + dp->df_count[idx])
2496 	    break;
2497 
2498     /* When after the last change, compute relative to the last line number. */
2499     if (dp == NULL)
2500 	return wp->w_buffer->b_ml.ml_line_count
2501 					- (curbuf->b_ml.ml_line_count - lnum);
2502 
2503     /* Find index for "wp". */
2504     i = diff_buf_idx(wp->w_buffer);
2505     if (i == DB_COUNT)			/* safety check */
2506 	return (linenr_T)0;
2507 
2508     n = lnum + (dp->df_lnum[i] - dp->df_lnum[idx]);
2509     if (n > dp->df_lnum[i] + dp->df_count[i])
2510 	n = dp->df_lnum[i] + dp->df_count[i];
2511     return n;
2512 }
2513 #endif
2514 
2515 #endif	/* FEAT_DIFF */
2516