xref: /vim-8.2.3635/src/diff.c (revision 99133038)
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 /*ARGSUSED*/
656     void
657 ex_diffupdate(eap)
658     exarg_T	*eap;	    /* can be NULL, it's not used */
659 {
660     buf_T	*buf;
661     int		idx_orig;
662     int		idx_new;
663     char_u	*tmp_orig;
664     char_u	*tmp_new;
665     char_u	*tmp_diff;
666     FILE	*fd;
667     int		ok;
668     int		io_error = FALSE;
669 
670     /* Delete all diffblocks. */
671     diff_clear(curtab);
672     curtab->tp_diff_invalid = FALSE;
673 
674     /* Use the first buffer as the original text. */
675     for (idx_orig = 0; idx_orig < DB_COUNT; ++idx_orig)
676 	if (curtab->tp_diffbuf[idx_orig] != NULL)
677 	    break;
678     if (idx_orig == DB_COUNT)
679 	return;
680 
681     /* Only need to do something when there is another buffer. */
682     for (idx_new = idx_orig + 1; idx_new < DB_COUNT; ++idx_new)
683 	if (curtab->tp_diffbuf[idx_new] != NULL)
684 	    break;
685     if (idx_new == DB_COUNT)
686 	return;
687 
688     /* We need three temp file names. */
689     tmp_orig = vim_tempname('o');
690     tmp_new = vim_tempname('n');
691     tmp_diff = vim_tempname('d');
692     if (tmp_orig == NULL || tmp_new == NULL || tmp_diff == NULL)
693 	goto theend;
694 
695     /*
696      * Do a quick test if "diff" really works.  Otherwise it looks like there
697      * are no differences.  Can't use the return value, it's non-zero when
698      * there are differences.
699      * May try twice, first with "-a" and then without.
700      */
701     for (;;)
702     {
703 	ok = FALSE;
704 	fd = mch_fopen((char *)tmp_orig, "w");
705 	if (fd == NULL)
706 	    io_error = TRUE;
707 	else
708 	{
709 	    if (fwrite("line1\n", (size_t)6, (size_t)1, fd) != 1)
710 		io_error = TRUE;
711 	    fclose(fd);
712 	    fd = mch_fopen((char *)tmp_new, "w");
713 	    if (fd == NULL)
714 		io_error = TRUE;
715 	    else
716 	    {
717 		if (fwrite("line2\n", (size_t)6, (size_t)1, fd) != 1)
718 		    io_error = TRUE;
719 		fclose(fd);
720 		diff_file(tmp_orig, tmp_new, tmp_diff);
721 		fd = mch_fopen((char *)tmp_diff, "r");
722 		if (fd == NULL)
723 		    io_error = TRUE;
724 		else
725 		{
726 		    char_u	linebuf[LBUFLEN];
727 
728 		    for (;;)
729 		    {
730 			/* There must be a line that contains "1c1". */
731 			if (tag_fgets(linebuf, LBUFLEN, fd))
732 			    break;
733 			if (STRNCMP(linebuf, "1c1", 3) == 0)
734 			    ok = TRUE;
735 		    }
736 		    fclose(fd);
737 		}
738 		mch_remove(tmp_diff);
739 		mch_remove(tmp_new);
740 	    }
741 	    mch_remove(tmp_orig);
742 	}
743 
744 #ifdef FEAT_EVAL
745 	/* When using 'diffexpr' break here. */
746 	if (*p_dex != NUL)
747 	    break;
748 #endif
749 
750 #if defined(MSWIN) || defined(MSDOS)
751 	/* If the "-a" argument works, also check if "--binary" works. */
752 	if (ok && diff_a_works == MAYBE && diff_bin_works == MAYBE)
753 	{
754 	    diff_a_works = TRUE;
755 	    diff_bin_works = TRUE;
756 	    continue;
757 	}
758 	if (!ok && diff_a_works == TRUE && diff_bin_works == TRUE)
759 	{
760 	    /* Tried --binary, but it failed. "-a" works though. */
761 	    diff_bin_works = FALSE;
762 	    ok = TRUE;
763 	}
764 #endif
765 
766 	/* If we checked if "-a" works already, break here. */
767 	if (diff_a_works != MAYBE)
768 	    break;
769 	diff_a_works = ok;
770 
771 	/* If "-a" works break here, otherwise retry without "-a". */
772 	if (ok)
773 	    break;
774     }
775     if (!ok)
776     {
777 	if (io_error)
778 	    EMSG(_("E810: Cannot read or write temp files"));
779 	EMSG(_("E97: Cannot create diffs"));
780 	diff_a_works = MAYBE;
781 #if defined(MSWIN) || defined(MSDOS)
782 	diff_bin_works = MAYBE;
783 #endif
784 	goto theend;
785     }
786 
787     /* Write the first buffer to a tempfile. */
788     buf = curtab->tp_diffbuf[idx_orig];
789     if (diff_write(buf, tmp_orig) == FAIL)
790 	goto theend;
791 
792     /* Make a difference between the first buffer and every other. */
793     for (idx_new = idx_orig + 1; idx_new < DB_COUNT; ++idx_new)
794     {
795 	buf = curtab->tp_diffbuf[idx_new];
796 	if (buf == NULL)
797 	    continue;
798 	if (diff_write(buf, tmp_new) == FAIL)
799 	    continue;
800 	diff_file(tmp_orig, tmp_new, tmp_diff);
801 
802 	/* Read the diff output and add each entry to the diff list. */
803 	diff_read(idx_orig, idx_new, tmp_diff);
804 	mch_remove(tmp_diff);
805 	mch_remove(tmp_new);
806     }
807     mch_remove(tmp_orig);
808 
809     /* force updating cursor position on screen */
810     curwin->w_valid_cursor.lnum = 0;
811 
812     diff_redraw(TRUE);
813 
814 theend:
815     vim_free(tmp_orig);
816     vim_free(tmp_new);
817     vim_free(tmp_diff);
818 }
819 
820 /*
821  * Make a diff between files "tmp_orig" and "tmp_new", results in "tmp_diff".
822  */
823     static void
824 diff_file(tmp_orig, tmp_new, tmp_diff)
825     char_u	*tmp_orig;
826     char_u	*tmp_new;
827     char_u	*tmp_diff;
828 {
829     char_u	*cmd;
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 	cmd = alloc((unsigned)(STRLEN(tmp_orig) + STRLEN(tmp_new)
839 				+ STRLEN(tmp_diff) + STRLEN(p_srr) + 27));
840 	if (cmd != NULL)
841 	{
842 	    /* We don't want $DIFF_OPTIONS to get in the way. */
843 	    if (getenv("DIFF_OPTIONS"))
844 		vim_setenv((char_u *)"DIFF_OPTIONS", (char_u *)"");
845 
846 	    /* Build the diff command and execute it.  Always use -a, binary
847 	     * differences are of no use.  Ignore errors, diff returns
848 	     * non-zero when differences have been found. */
849 	    sprintf((char *)cmd, "diff %s%s%s%s%s %s",
850 		    diff_a_works == FALSE ? "" : "-a ",
851 #if defined(MSWIN) || defined(MSDOS)
852 		    diff_bin_works == TRUE ? "--binary " : "",
853 #else
854 		    "",
855 #endif
856 		    (diff_flags & DIFF_IWHITE) ? "-b " : "",
857 		    (diff_flags & DIFF_ICASE) ? "-i " : "",
858 		    tmp_orig, tmp_new);
859 	    append_redir(cmd, p_srr, tmp_diff);
860 #ifdef FEAT_AUTOCMD
861 	    block_autocmds();	/* Avoid ShellCmdPost stuff */
862 #endif
863 	    (void)call_shell(cmd, SHELL_FILTER|SHELL_SILENT|SHELL_DOOUT);
864 #ifdef FEAT_AUTOCMD
865 	    unblock_autocmds();
866 #endif
867 	    vim_free(cmd);
868 	}
869     }
870 }
871 
872 /*
873  * Create a new version of a file from the current buffer and a diff file.
874  * The buffer is written to a file, also for unmodified buffers (the file
875  * could have been produced by autocommands, e.g. the netrw plugin).
876  */
877     void
878 ex_diffpatch(eap)
879     exarg_T	*eap;
880 {
881     char_u	*tmp_orig;	/* name of original temp file */
882     char_u	*tmp_new;	/* name of patched temp file */
883     char_u	*buf = NULL;
884     win_T	*old_curwin = curwin;
885     char_u	*newname = NULL;	/* name of patched file buffer */
886 #ifdef UNIX
887     char_u	dirbuf[MAXPATHL];
888     char_u	*fullname = NULL;
889 #endif
890 #ifdef FEAT_BROWSE
891     char_u	*browseFile = NULL;
892     int		browse_flag = cmdmod.browse;
893 #endif
894 
895 #ifdef FEAT_BROWSE
896     if (cmdmod.browse)
897     {
898 	browseFile = do_browse(0, (char_u *)_("Patch file"),
899 			 eap->arg, NULL, NULL, BROWSE_FILTER_ALL_FILES, NULL);
900 	if (browseFile == NULL)
901 	    return;		/* operation cancelled */
902 	eap->arg = browseFile;
903 	cmdmod.browse = FALSE;	/* don't let do_ecmd() browse again */
904     }
905 #endif
906 
907     /* We need two temp file names. */
908     tmp_orig = vim_tempname('o');
909     tmp_new = vim_tempname('n');
910     if (tmp_orig == NULL || tmp_new == NULL)
911 	goto theend;
912 
913     /* Write the current buffer to "tmp_orig". */
914     if (buf_write(curbuf, tmp_orig, NULL,
915 		(linenr_T)1, curbuf->b_ml.ml_line_count,
916 				     NULL, FALSE, FALSE, FALSE, TRUE) == FAIL)
917 	goto theend;
918 
919 #ifdef UNIX
920     /* Get the absolute path of the patchfile, changing directory below. */
921     fullname = FullName_save(eap->arg, FALSE);
922 #endif
923     buf = alloc((unsigned)(STRLEN(tmp_orig) + (
924 # ifdef UNIX
925 		    fullname != NULL ? STRLEN(fullname) :
926 # endif
927 		    STRLEN(eap->arg)) + STRLEN(tmp_new) + 16));
928     if (buf == NULL)
929 	goto theend;
930 
931 #ifdef UNIX
932     /* Temporarily chdir to /tmp, to avoid patching files in the current
933      * directory when the patch file contains more than one patch.  When we
934      * have our own temp dir use that instead, it will be cleaned up when we
935      * exit (any .rej files created).  Don't change directory if we can't
936      * return to the current. */
937     if (mch_dirname(dirbuf, MAXPATHL) != OK || mch_chdir((char *)dirbuf) != 0)
938 	dirbuf[0] = NUL;
939     else
940     {
941 # ifdef TEMPDIRNAMES
942 	if (vim_tempdir != NULL)
943 	    ignored = mch_chdir((char *)vim_tempdir);
944 	else
945 # endif
946 	    ignored = mch_chdir("/tmp");
947 	shorten_fnames(TRUE);
948     }
949 #endif
950 
951 #ifdef FEAT_EVAL
952     if (*p_pex != NUL)
953 	/* Use 'patchexpr' to generate the new file. */
954 	eval_patch(tmp_orig,
955 # ifdef UNIX
956 		fullname != NULL ? fullname :
957 # endif
958 		eap->arg, tmp_new);
959     else
960 #endif
961     {
962 	/* Build the patch command and execute it.  Ignore errors.  Switch to
963 	 * cooked mode to allow the user to respond to prompts. */
964 	sprintf((char *)buf, "patch -o %s %s < \"%s\"", tmp_new, tmp_orig,
965 # ifdef UNIX
966 		fullname != NULL ? fullname :
967 # endif
968 		eap->arg);
969 #ifdef FEAT_AUTOCMD
970 	block_autocmds();	/* Avoid ShellCmdPost stuff */
971 #endif
972 	(void)call_shell(buf, SHELL_FILTER | SHELL_COOKED);
973 #ifdef FEAT_AUTOCMD
974 	unblock_autocmds();
975 #endif
976     }
977 
978 #ifdef UNIX
979     if (dirbuf[0] != NUL)
980     {
981 	if (mch_chdir((char *)dirbuf) != 0)
982 	    EMSG(_(e_prev_dir));
983 	shorten_fnames(TRUE);
984     }
985 #endif
986 
987     /* patch probably has written over the screen */
988     redraw_later(CLEAR);
989 
990     /* Delete any .orig or .rej file created. */
991     STRCPY(buf, tmp_new);
992     STRCAT(buf, ".orig");
993     mch_remove(buf);
994     STRCPY(buf, tmp_new);
995     STRCAT(buf, ".rej");
996     mch_remove(buf);
997 
998     if (curbuf->b_fname != NULL)
999     {
1000 	newname = vim_strnsave(curbuf->b_fname,
1001 					  (int)(STRLEN(curbuf->b_fname) + 4));
1002 	if (newname != NULL)
1003 	    STRCAT(newname, ".new");
1004     }
1005 
1006 #ifdef FEAT_GUI
1007     need_mouse_correct = TRUE;
1008 #endif
1009     /* don't use a new tab page, each tab page has its own diffs */
1010     cmdmod.tab = 0;
1011 
1012     if (win_split(0, (diff_flags & DIFF_VERTICAL) ? WSP_VERT : 0) != FAIL)
1013     {
1014 	/* Pretend it was a ":split fname" command */
1015 	eap->cmdidx = CMD_split;
1016 	eap->arg = tmp_new;
1017 	do_exedit(eap, old_curwin);
1018 
1019 	if (curwin != old_curwin)		/* split must have worked */
1020 	{
1021 	    /* Set 'diff', 'scrollbind' on and 'wrap' off. */
1022 	    diff_win_options(curwin, TRUE);
1023 	    diff_win_options(old_curwin, TRUE);
1024 
1025 	    if (newname != NULL)
1026 	    {
1027 		/* do a ":file filename.new" on the patched buffer */
1028 		eap->arg = newname;
1029 		ex_file(eap);
1030 
1031 #ifdef FEAT_AUTOCMD
1032 		/* Do filetype detection with the new name. */
1033 		if (au_has_group((char_u *)"filetypedetect"))
1034 		    do_cmdline_cmd((char_u *)":doau filetypedetect BufRead");
1035 #endif
1036 	    }
1037 	}
1038     }
1039 
1040 theend:
1041     if (tmp_orig != NULL)
1042 	mch_remove(tmp_orig);
1043     vim_free(tmp_orig);
1044     if (tmp_new != NULL)
1045 	mch_remove(tmp_new);
1046     vim_free(tmp_new);
1047     vim_free(newname);
1048     vim_free(buf);
1049 #ifdef UNIX
1050     vim_free(fullname);
1051 #endif
1052 #ifdef FEAT_BROWSE
1053     vim_free(browseFile);
1054     cmdmod.browse = browse_flag;
1055 #endif
1056 }
1057 
1058 /*
1059  * Split the window and edit another file, setting options to show the diffs.
1060  */
1061     void
1062 ex_diffsplit(eap)
1063     exarg_T	*eap;
1064 {
1065     win_T	*old_curwin = curwin;
1066 
1067 #ifdef FEAT_GUI
1068     need_mouse_correct = TRUE;
1069 #endif
1070     /* don't use a new tab page, each tab page has its own diffs */
1071     cmdmod.tab = 0;
1072 
1073     if (win_split(0, (diff_flags & DIFF_VERTICAL) ? WSP_VERT : 0) != FAIL)
1074     {
1075 	/* Pretend it was a ":split fname" command */
1076 	eap->cmdidx = CMD_split;
1077 	curwin->w_p_diff = TRUE;
1078 	do_exedit(eap, old_curwin);
1079 
1080 	if (curwin != old_curwin)		/* split must have worked */
1081 	{
1082 	    /* Set 'diff', 'scrollbind' on and 'wrap' off. */
1083 	    diff_win_options(curwin, TRUE);
1084 	    diff_win_options(old_curwin, TRUE);
1085 	}
1086     }
1087 }
1088 
1089 /*
1090  * Set options to show difs for the current window.
1091  */
1092 /*ARGSUSED*/
1093     void
1094 ex_diffthis(eap)
1095     exarg_T	*eap;
1096 {
1097     /* Set 'diff', 'scrollbind' on and 'wrap' off. */
1098     diff_win_options(curwin, TRUE);
1099 }
1100 
1101 /*
1102  * Set options in window "wp" for diff mode.
1103  */
1104     void
1105 diff_win_options(wp, addbuf)
1106     win_T	*wp;
1107     int		addbuf;		/* Add buffer to diff. */
1108 {
1109     wp->w_p_diff = TRUE;
1110     wp->w_p_scb = TRUE;
1111     wp->w_p_wrap = FALSE;
1112 # ifdef FEAT_FOLDING
1113     {
1114 	win_T	    *old_curwin = curwin;
1115 
1116 	curwin = wp;
1117 	curbuf = curwin->w_buffer;
1118 	set_string_option_direct((char_u *)"fdm", -1, (char_u *)"diff",
1119 						       OPT_LOCAL|OPT_FREE, 0);
1120 	curwin = old_curwin;
1121 	curbuf = curwin->w_buffer;
1122 	wp->w_p_fdc = diff_foldcolumn;
1123 	wp->w_p_fen = TRUE;
1124 	wp->w_p_fdl = 0;
1125 	foldUpdateAll(wp);
1126 	/* make sure topline is not halfway a fold */
1127 	changed_window_setting_win(wp);
1128     }
1129 # endif
1130 #ifdef FEAT_SCROLLBIND
1131     if (vim_strchr(p_sbo, 'h') == NULL)
1132 	do_cmdline_cmd((char_u *)"set sbo+=hor");
1133 #endif
1134 
1135     if (addbuf)
1136 	diff_buf_add(wp->w_buffer);
1137     redraw_win_later(wp, NOT_VALID);
1138 }
1139 
1140 /*
1141  * Set options not to show diffs.  For the current window or all windows.
1142  * Only in the current tab page.
1143  */
1144     void
1145 ex_diffoff(eap)
1146     exarg_T	*eap;
1147 {
1148     win_T	*wp;
1149     win_T	*old_curwin = curwin;
1150 #ifdef FEAT_SCROLLBIND
1151     int		diffwin = FALSE;
1152 #endif
1153 
1154     for (wp = firstwin; wp != NULL; wp = wp->w_next)
1155     {
1156 	if (wp == curwin || (eap->forceit && wp->w_p_diff))
1157 	{
1158 	    /* Set 'diff', 'scrollbind' off and 'wrap' on. */
1159 	    wp->w_p_diff = FALSE;
1160 	    wp->w_p_scb = FALSE;
1161 	    wp->w_p_wrap = TRUE;
1162 #ifdef FEAT_FOLDING
1163 	    curwin = wp;
1164 	    curbuf = curwin->w_buffer;
1165 	    set_string_option_direct((char_u *)"fdm", -1,
1166 				   (char_u *)"manual", OPT_LOCAL|OPT_FREE, 0);
1167 	    curwin = old_curwin;
1168 	    curbuf = curwin->w_buffer;
1169 	    wp->w_p_fdc = 0;
1170 	    wp->w_p_fen = FALSE;
1171 	    wp->w_p_fdl = 0;
1172 	    foldUpdateAll(wp);
1173 	    /* make sure topline is not halfway a fold */
1174 	    changed_window_setting_win(wp);
1175 #endif
1176 	    diff_buf_adjust(wp);
1177 	}
1178 #ifdef FEAT_SCROLLBIND
1179 	diffwin |= wp->w_p_diff;
1180 #endif
1181     }
1182 
1183 #ifdef FEAT_SCROLLBIND
1184     /* Remove "hor" from from 'scrollopt' if there are no diff windows left. */
1185     if (!diffwin && vim_strchr(p_sbo, 'h') != NULL)
1186 	do_cmdline_cmd((char_u *)"set sbo-=hor");
1187 #endif
1188 }
1189 
1190 /*
1191  * Read the diff output and add each entry to the diff list.
1192  */
1193     static void
1194 diff_read(idx_orig, idx_new, fname)
1195     int		idx_orig;	/* idx of original file */
1196     int		idx_new;	/* idx of new file */
1197     char_u	*fname;		/* name of diff output file */
1198 {
1199     FILE	*fd;
1200     diff_T	*dprev = NULL;
1201     diff_T	*dp = curtab->tp_first_diff;
1202     diff_T	*dn, *dpl;
1203     long	f1, l1, f2, l2;
1204     char_u	linebuf[LBUFLEN];   /* only need to hold the diff line */
1205     int		difftype;
1206     char_u	*p;
1207     long	off;
1208     int		i;
1209     linenr_T	lnum_orig, lnum_new;
1210     long	count_orig, count_new;
1211     int		notset = TRUE;	    /* block "*dp" not set yet */
1212 
1213     fd = mch_fopen((char *)fname, "r");
1214     if (fd == NULL)
1215     {
1216 	EMSG(_("E98: Cannot read diff output"));
1217 	return;
1218     }
1219 
1220     for (;;)
1221     {
1222 	if (tag_fgets(linebuf, LBUFLEN, fd))
1223 	    break;		/* end of file */
1224 	if (!isdigit(*linebuf))
1225 	    continue;		/* not the start of a diff block */
1226 
1227 	/* This line must be one of three formats:
1228 	 * {first}[,{last}]c{first}[,{last}]
1229 	 * {first}a{first}[,{last}]
1230 	 * {first}[,{last}]d{first}
1231 	 */
1232 	p = linebuf;
1233 	f1 = getdigits(&p);
1234 	if (*p == ',')
1235 	{
1236 	    ++p;
1237 	    l1 = getdigits(&p);
1238 	}
1239 	else
1240 	    l1 = f1;
1241 	if (*p != 'a' && *p != 'c' && *p != 'd')
1242 	    continue;		/* invalid diff format */
1243 	difftype = *p++;
1244 	f2 = getdigits(&p);
1245 	if (*p == ',')
1246 	{
1247 	    ++p;
1248 	    l2 = getdigits(&p);
1249 	}
1250 	else
1251 	    l2 = f2;
1252 	if (l1 < f1 || l2 < f2)
1253 	    continue;		/* invalid line range */
1254 
1255 	if (difftype == 'a')
1256 	{
1257 	    lnum_orig = f1 + 1;
1258 	    count_orig = 0;
1259 	}
1260 	else
1261 	{
1262 	    lnum_orig = f1;
1263 	    count_orig = l1 - f1 + 1;
1264 	}
1265 	if (difftype == 'd')
1266 	{
1267 	    lnum_new = f2 + 1;
1268 	    count_new = 0;
1269 	}
1270 	else
1271 	{
1272 	    lnum_new = f2;
1273 	    count_new = l2 - f2 + 1;
1274 	}
1275 
1276 	/* Go over blocks before the change, for which orig and new are equal.
1277 	 * Copy blocks from orig to new. */
1278 	while (dp != NULL
1279 		&& lnum_orig > dp->df_lnum[idx_orig] + dp->df_count[idx_orig])
1280 	{
1281 	    if (notset)
1282 		diff_copy_entry(dprev, dp, idx_orig, idx_new);
1283 	    dprev = dp;
1284 	    dp = dp->df_next;
1285 	    notset = TRUE;
1286 	}
1287 
1288 	if (dp != NULL
1289 		&& lnum_orig <= dp->df_lnum[idx_orig] + dp->df_count[idx_orig]
1290 		&& lnum_orig + count_orig >= dp->df_lnum[idx_orig])
1291 	{
1292 	    /* New block overlaps with existing block(s).
1293 	     * First find last block that overlaps. */
1294 	    for (dpl = dp; dpl->df_next != NULL; dpl = dpl->df_next)
1295 		if (lnum_orig + count_orig < dpl->df_next->df_lnum[idx_orig])
1296 		    break;
1297 
1298 	    /* If the newly found block starts before the old one, set the
1299 	     * start back a number of lines. */
1300 	    off = dp->df_lnum[idx_orig] - lnum_orig;
1301 	    if (off > 0)
1302 	    {
1303 		for (i = idx_orig; i < idx_new; ++i)
1304 		    if (curtab->tp_diffbuf[i] != NULL)
1305 			dp->df_lnum[i] -= off;
1306 		dp->df_lnum[idx_new] = lnum_new;
1307 		dp->df_count[idx_new] = count_new;
1308 	    }
1309 	    else if (notset)
1310 	    {
1311 		/* new block inside existing one, adjust new block */
1312 		dp->df_lnum[idx_new] = lnum_new + off;
1313 		dp->df_count[idx_new] = count_new - off;
1314 	    }
1315 	    else
1316 		/* second overlap of new block with existing block */
1317 		dp->df_count[idx_new] += count_new - count_orig
1318 		    + dpl->df_lnum[idx_orig] + dpl->df_count[idx_orig]
1319 		    - (dp->df_lnum[idx_orig] + dp->df_count[idx_orig]);
1320 
1321 	    /* Adjust the size of the block to include all the lines to the
1322 	     * end of the existing block or the new diff, whatever ends last. */
1323 	    off = (lnum_orig + count_orig)
1324 			 - (dpl->df_lnum[idx_orig] + dpl->df_count[idx_orig]);
1325 	    if (off < 0)
1326 	    {
1327 		/* new change ends in existing block, adjust the end if not
1328 		 * done already */
1329 		if (notset)
1330 		    dp->df_count[idx_new] += -off;
1331 		off = 0;
1332 	    }
1333 	    for (i = idx_orig; i < idx_new; ++i)
1334 		if (curtab->tp_diffbuf[i] != NULL)
1335 		    dp->df_count[i] = dpl->df_lnum[i] + dpl->df_count[i]
1336 						       - dp->df_lnum[i] + off;
1337 
1338 	    /* Delete the diff blocks that have been merged into one. */
1339 	    dn = dp->df_next;
1340 	    dp->df_next = dpl->df_next;
1341 	    while (dn != dp->df_next)
1342 	    {
1343 		dpl = dn->df_next;
1344 		vim_free(dn);
1345 		dn = dpl;
1346 	    }
1347 	}
1348 	else
1349 	{
1350 	    /* Allocate a new diffblock. */
1351 	    dp = diff_alloc_new(curtab, dprev, dp);
1352 	    if (dp == NULL)
1353 		goto done;
1354 
1355 	    dp->df_lnum[idx_orig] = lnum_orig;
1356 	    dp->df_count[idx_orig] = count_orig;
1357 	    dp->df_lnum[idx_new] = lnum_new;
1358 	    dp->df_count[idx_new] = count_new;
1359 
1360 	    /* Set values for other buffers, these must be equal to the
1361 	     * original buffer, otherwise there would have been a change
1362 	     * already. */
1363 	    for (i = idx_orig + 1; i < idx_new; ++i)
1364 		if (curtab->tp_diffbuf[i] != NULL)
1365 		    diff_copy_entry(dprev, dp, idx_orig, i);
1366 	}
1367 	notset = FALSE;		/* "*dp" has been set */
1368     }
1369 
1370     /* for remaining diff blocks orig and new are equal */
1371     while (dp != NULL)
1372     {
1373 	if (notset)
1374 	    diff_copy_entry(dprev, dp, idx_orig, idx_new);
1375 	dprev = dp;
1376 	dp = dp->df_next;
1377 	notset = TRUE;
1378     }
1379 
1380 done:
1381     fclose(fd);
1382 }
1383 
1384 /*
1385  * Copy an entry at "dp" from "idx_orig" to "idx_new".
1386  */
1387     static void
1388 diff_copy_entry(dprev, dp, idx_orig, idx_new)
1389     diff_T	*dprev;
1390     diff_T	*dp;
1391     int		idx_orig;
1392     int		idx_new;
1393 {
1394     long	off;
1395 
1396     if (dprev == NULL)
1397 	off = 0;
1398     else
1399 	off = (dprev->df_lnum[idx_orig] + dprev->df_count[idx_orig])
1400 	    - (dprev->df_lnum[idx_new] + dprev->df_count[idx_new]);
1401     dp->df_lnum[idx_new] = dp->df_lnum[idx_orig] - off;
1402     dp->df_count[idx_new] = dp->df_count[idx_orig];
1403 }
1404 
1405 /*
1406  * Clear the list of diffblocks for tab page "tp".
1407  */
1408     void
1409 diff_clear(tp)
1410     tabpage_T	*tp;
1411 {
1412     diff_T	*p, *next_p;
1413 
1414     for (p = tp->tp_first_diff; p != NULL; p = next_p)
1415     {
1416 	next_p = p->df_next;
1417 	vim_free(p);
1418     }
1419     tp->tp_first_diff = NULL;
1420 }
1421 
1422 /*
1423  * Check diff status for line "lnum" in buffer "buf":
1424  * Returns 0 for nothing special
1425  * Returns -1 for a line that should be highlighted as changed.
1426  * Returns -2 for a line that should be highlighted as added/deleted.
1427  * Returns > 0 for inserting that many filler lines above it (never happens
1428  * when 'diffopt' doesn't contain "filler").
1429  * This should only be used for windows where 'diff' is set.
1430  */
1431     int
1432 diff_check(wp, lnum)
1433     win_T	*wp;
1434     linenr_T	lnum;
1435 {
1436     int		idx;		/* index in tp_diffbuf[] for this buffer */
1437     diff_T	*dp;
1438     int		maxcount;
1439     int		i;
1440     buf_T	*buf = wp->w_buffer;
1441     int		cmp;
1442 
1443     if (curtab->tp_diff_invalid)
1444 	ex_diffupdate(NULL);		/* update after a big change */
1445 
1446     if (curtab->tp_first_diff == NULL || !wp->w_p_diff)	/* no diffs at all */
1447 	return 0;
1448 
1449     /* safety check: "lnum" must be a buffer line */
1450     if (lnum < 1 || lnum > buf->b_ml.ml_line_count + 1)
1451 	return 0;
1452 
1453     idx = diff_buf_idx(buf);
1454     if (idx == DB_COUNT)
1455 	return 0;		/* no diffs for buffer "buf" */
1456 
1457 #ifdef FEAT_FOLDING
1458     /* A closed fold never has filler lines. */
1459     if (hasFoldingWin(wp, lnum, NULL, NULL, TRUE, NULL))
1460 	return 0;
1461 #endif
1462 
1463     /* search for a change that includes "lnum" in the list of diffblocks. */
1464     for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next)
1465 	if (lnum <= dp->df_lnum[idx] + dp->df_count[idx])
1466 	    break;
1467     if (dp == NULL || lnum < dp->df_lnum[idx])
1468 	return 0;
1469 
1470     if (lnum < dp->df_lnum[idx] + dp->df_count[idx])
1471     {
1472 	int	zero = FALSE;
1473 
1474 	/* Changed or inserted line.  If the other buffers have a count of
1475 	 * zero, the lines were inserted.  If the other buffers have the same
1476 	 * count, check if the lines are identical. */
1477 	cmp = FALSE;
1478 	for (i = 0; i < DB_COUNT; ++i)
1479 	    if (i != idx && curtab->tp_diffbuf[i] != NULL)
1480 	    {
1481 		if (dp->df_count[i] == 0)
1482 		    zero = TRUE;
1483 		else
1484 		{
1485 		    if (dp->df_count[i] != dp->df_count[idx])
1486 			return -1;	    /* nr of lines changed. */
1487 		    cmp = TRUE;
1488 		}
1489 	    }
1490 	if (cmp)
1491 	{
1492 	    /* Compare all lines.  If they are equal the lines were inserted
1493 	     * in some buffers, deleted in others, but not changed. */
1494 	    for (i = 0; i < DB_COUNT; ++i)
1495 		if (i != idx && curtab->tp_diffbuf[i] != NULL && dp->df_count[i] != 0)
1496 		    if (!diff_equal_entry(dp, idx, i))
1497 			return -1;
1498 	}
1499 	/* If there is no buffer with zero lines then there is no difference
1500 	 * any longer.  Happens when making a change (or undo) that removes
1501 	 * the difference.  Can't remove the entry here, we might be halfway
1502 	 * updating the window.  Just report the text as unchanged.  Other
1503 	 * windows might still show the change though. */
1504 	if (zero == FALSE)
1505 	    return 0;
1506 	return -2;
1507     }
1508 
1509     /* If 'diffopt' doesn't contain "filler", return 0. */
1510     if (!(diff_flags & DIFF_FILLER))
1511 	return 0;
1512 
1513     /* Insert filler lines above the line just below the change.  Will return
1514      * 0 when this buf had the max count. */
1515     maxcount = 0;
1516     for (i = 0; i < DB_COUNT; ++i)
1517 	if (curtab->tp_diffbuf[i] != NULL && dp->df_count[i] > maxcount)
1518 	    maxcount = dp->df_count[i];
1519     return maxcount - dp->df_count[idx];
1520 }
1521 
1522 /*
1523  * Compare two entries in diff "*dp" and return TRUE if they are equal.
1524  */
1525     static int
1526 diff_equal_entry(dp, idx1, idx2)
1527     diff_T	*dp;
1528     int		idx1;
1529     int		idx2;
1530 {
1531     int		i;
1532     char_u	*line;
1533     int		cmp;
1534 
1535     if (dp->df_count[idx1] != dp->df_count[idx2])
1536 	return FALSE;
1537     if (diff_check_sanity(curtab, dp) == FAIL)
1538 	return FALSE;
1539     for (i = 0; i < dp->df_count[idx1]; ++i)
1540     {
1541 	line = vim_strsave(ml_get_buf(curtab->tp_diffbuf[idx1],
1542 					       dp->df_lnum[idx1] + i, FALSE));
1543 	if (line == NULL)
1544 	    return FALSE;
1545 	cmp = diff_cmp(line, ml_get_buf(curtab->tp_diffbuf[idx2],
1546 					       dp->df_lnum[idx2] + i, FALSE));
1547 	vim_free(line);
1548 	if (cmp != 0)
1549 	    return FALSE;
1550     }
1551     return TRUE;
1552 }
1553 
1554 /*
1555  * Compare strings "s1" and "s2" according to 'diffopt'.
1556  * Return non-zero when they are different.
1557  */
1558     static int
1559 diff_cmp(s1, s2)
1560     char_u	*s1;
1561     char_u	*s2;
1562 {
1563     char_u	*p1, *p2;
1564 #ifdef FEAT_MBYTE
1565     int		l;
1566 #endif
1567 
1568     if ((diff_flags & (DIFF_ICASE | DIFF_IWHITE)) == 0)
1569 	return STRCMP(s1, s2);
1570     if ((diff_flags & DIFF_ICASE) && !(diff_flags & DIFF_IWHITE))
1571 	return MB_STRICMP(s1, s2);
1572 
1573     /* Ignore white space changes and possibly ignore case. */
1574     p1 = s1;
1575     p2 = s2;
1576     while (*p1 != NUL && *p2 != NUL)
1577     {
1578 	if (vim_iswhite(*p1) && vim_iswhite(*p2))
1579 	{
1580 	    p1 = skipwhite(p1);
1581 	    p2 = skipwhite(p2);
1582 	}
1583 	else
1584 	{
1585 #ifdef FEAT_MBYTE
1586 	    l  = (*mb_ptr2len)(p1);
1587 	    if (l != (*mb_ptr2len)(p2))
1588 		break;
1589 	    if (l > 1)
1590 	    {
1591 		if (STRNCMP(p1, p2, l) != 0
1592 			&& (!enc_utf8
1593 			    || !(diff_flags & DIFF_ICASE)
1594 			    || utf_fold(utf_ptr2char(p1))
1595 					       != utf_fold(utf_ptr2char(p2))))
1596 		    break;
1597 		p1 += l;
1598 		p2 += l;
1599 	    }
1600 	    else
1601 #endif
1602 	    {
1603 		if (*p1 != *p2 && (!(diff_flags & DIFF_ICASE)
1604 				     || TOLOWER_LOC(*p1) != TOLOWER_LOC(*p2)))
1605 		    break;
1606 		++p1;
1607 		++p2;
1608 	    }
1609 	}
1610     }
1611 
1612     /* Ignore trailing white space. */
1613     p1 = skipwhite(p1);
1614     p2 = skipwhite(p2);
1615     if (*p1 != NUL || *p2 != NUL)
1616 	return 1;
1617     return 0;
1618 }
1619 
1620 /*
1621  * Return the number of filler lines above "lnum".
1622  */
1623     int
1624 diff_check_fill(wp, lnum)
1625     win_T	*wp;
1626     linenr_T	lnum;
1627 {
1628     int		n;
1629 
1630     /* be quick when there are no filler lines */
1631     if (!(diff_flags & DIFF_FILLER))
1632 	return 0;
1633     n = diff_check(wp, lnum);
1634     if (n <= 0)
1635 	return 0;
1636     return n;
1637 }
1638 
1639 /*
1640  * Set the topline of "towin" to match the position in "fromwin", so that they
1641  * show the same diff'ed lines.
1642  */
1643     void
1644 diff_set_topline(fromwin, towin)
1645     win_T	*fromwin;
1646     win_T	*towin;
1647 {
1648     buf_T	*frombuf = fromwin->w_buffer;
1649     linenr_T	lnum = fromwin->w_topline;
1650     int		fromidx;
1651     int		toidx;
1652     diff_T	*dp;
1653     int		max_count;
1654     int		i;
1655 
1656     fromidx = diff_buf_idx(frombuf);
1657     if (fromidx == DB_COUNT)
1658 	return;		/* safety check */
1659 
1660     if (curtab->tp_diff_invalid)
1661 	ex_diffupdate(NULL);		/* update after a big change */
1662 
1663     towin->w_topfill = 0;
1664 
1665     /* search for a change that includes "lnum" in the list of diffblocks. */
1666     for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next)
1667 	if (lnum <= dp->df_lnum[fromidx] + dp->df_count[fromidx])
1668 	    break;
1669     if (dp == NULL)
1670     {
1671 	/* After last change, compute topline relative to end of file; no
1672 	 * filler lines. */
1673 	towin->w_topline = towin->w_buffer->b_ml.ml_line_count
1674 				       - (frombuf->b_ml.ml_line_count - lnum);
1675     }
1676     else
1677     {
1678 	/* Find index for "towin". */
1679 	toidx = diff_buf_idx(towin->w_buffer);
1680 	if (toidx == DB_COUNT)
1681 	    return;		/* safety check */
1682 
1683 	towin->w_topline = lnum + (dp->df_lnum[toidx] - dp->df_lnum[fromidx]);
1684 	if (lnum >= dp->df_lnum[fromidx])
1685 	{
1686 	    /* Inside a change: compute filler lines. With three or more
1687 	     * buffers we need to know the largest count. */
1688 	    max_count = 0;
1689 	    for (i = 0; i < DB_COUNT; ++i)
1690 		if (curtab->tp_diffbuf[i] != NULL
1691 					       && max_count < dp->df_count[i])
1692 		    max_count = dp->df_count[i];
1693 
1694 	    if (dp->df_count[toidx] == dp->df_count[fromidx])
1695 	    {
1696 		/* same number of lines: use same filler count */
1697 		towin->w_topfill = fromwin->w_topfill;
1698 	    }
1699 	    else if (dp->df_count[toidx] > dp->df_count[fromidx])
1700 	    {
1701 		if (lnum == dp->df_lnum[fromidx] + dp->df_count[fromidx])
1702 		{
1703 		    /* more lines in towin and fromwin doesn't show diff
1704 		     * lines, only filler lines */
1705 		    if (max_count - fromwin->w_topfill >= dp->df_count[toidx])
1706 		    {
1707 			/* towin also only shows filler lines */
1708 			towin->w_topline = dp->df_lnum[toidx]
1709 						       + dp->df_count[toidx];
1710 			towin->w_topfill = fromwin->w_topfill;
1711 		    }
1712 		    else
1713 			/* towin still has some diff lines to show */
1714 			towin->w_topline = dp->df_lnum[toidx]
1715 					     + max_count - fromwin->w_topfill;
1716 		}
1717 	    }
1718 	    else if (towin->w_topline >= dp->df_lnum[toidx]
1719 							+ dp->df_count[toidx])
1720 	    {
1721 		/* less lines in towin and no diff lines to show: compute
1722 		 * filler lines */
1723 		towin->w_topline = dp->df_lnum[toidx] + dp->df_count[toidx];
1724 		if (diff_flags & DIFF_FILLER)
1725 		{
1726 		    if (lnum == dp->df_lnum[fromidx] + dp->df_count[fromidx])
1727 			/* fromwin is also out of diff lines */
1728 			towin->w_topfill = fromwin->w_topfill;
1729 		    else
1730 			/* fromwin has some diff lines */
1731 			towin->w_topfill = dp->df_lnum[fromidx]
1732 							   + max_count - lnum;
1733 		}
1734 	    }
1735 	}
1736     }
1737 
1738     /* safety check (if diff info gets outdated strange things may happen) */
1739     towin->w_botfill = FALSE;
1740     if (towin->w_topline > towin->w_buffer->b_ml.ml_line_count)
1741     {
1742 	towin->w_topline = towin->w_buffer->b_ml.ml_line_count;
1743 	towin->w_botfill = TRUE;
1744     }
1745     if (towin->w_topline < 1)
1746     {
1747 	towin->w_topline = 1;
1748 	towin->w_topfill = 0;
1749     }
1750 
1751     /* When w_topline changes need to recompute w_botline and cursor position */
1752     invalidate_botline_win(towin);
1753     changed_line_abv_curs_win(towin);
1754 
1755     check_topfill(towin, FALSE);
1756 #ifdef FEAT_FOLDING
1757     (void)hasFoldingWin(towin, towin->w_topline, &towin->w_topline,
1758 							    NULL, TRUE, NULL);
1759 #endif
1760 }
1761 
1762 /*
1763  * This is called when 'diffopt' is changed.
1764  */
1765     int
1766 diffopt_changed()
1767 {
1768     char_u	*p;
1769     int		diff_context_new = 6;
1770     int		diff_flags_new = 0;
1771     int		diff_foldcolumn_new = 2;
1772     tabpage_T	*tp;
1773 
1774     p = p_dip;
1775     while (*p != NUL)
1776     {
1777 	if (STRNCMP(p, "filler", 6) == 0)
1778 	{
1779 	    p += 6;
1780 	    diff_flags_new |= DIFF_FILLER;
1781 	}
1782 	else if (STRNCMP(p, "context:", 8) == 0 && VIM_ISDIGIT(p[8]))
1783 	{
1784 	    p += 8;
1785 	    diff_context_new = getdigits(&p);
1786 	}
1787 	else if (STRNCMP(p, "icase", 5) == 0)
1788 	{
1789 	    p += 5;
1790 	    diff_flags_new |= DIFF_ICASE;
1791 	}
1792 	else if (STRNCMP(p, "iwhite", 6) == 0)
1793 	{
1794 	    p += 6;
1795 	    diff_flags_new |= DIFF_IWHITE;
1796 	}
1797 	else if (STRNCMP(p, "horizontal", 10) == 0)
1798 	{
1799 	    p += 10;
1800 	    diff_flags_new |= DIFF_HORIZONTAL;
1801 	}
1802 	else if (STRNCMP(p, "vertical", 8) == 0)
1803 	{
1804 	    p += 8;
1805 	    diff_flags_new |= DIFF_VERTICAL;
1806 	}
1807 	else if (STRNCMP(p, "foldcolumn:", 11) == 0 && VIM_ISDIGIT(p[11]))
1808 	{
1809 	    p += 11;
1810 	    diff_foldcolumn_new = getdigits(&p);
1811 	}
1812 	if (*p != ',' && *p != NUL)
1813 	    return FAIL;
1814 	if (*p == ',')
1815 	    ++p;
1816     }
1817 
1818     /* Can't have both "horizontal" and "vertical". */
1819     if ((diff_flags_new & DIFF_HORIZONTAL) && (diff_flags_new & DIFF_VERTICAL))
1820 	return FAIL;
1821 
1822     /* If "icase" or "iwhite" was added or removed, need to update the diff. */
1823     if (diff_flags != diff_flags_new)
1824 	for (tp = first_tabpage; tp != NULL; tp = tp->tp_next)
1825 	    tp->tp_diff_invalid = TRUE;
1826 
1827     diff_flags = diff_flags_new;
1828     diff_context = diff_context_new;
1829     diff_foldcolumn = diff_foldcolumn_new;
1830 
1831     diff_redraw(TRUE);
1832 
1833     /* recompute the scroll binding with the new option value, may
1834      * remove or add filler lines */
1835     check_scrollbind((linenr_T)0, 0L);
1836 
1837     return OK;
1838 }
1839 
1840 /*
1841  * Return TRUE if 'diffopt' contains "horizontal".
1842  */
1843     int
1844 diffopt_horizontal()
1845 {
1846     return (diff_flags & DIFF_HORIZONTAL) != 0;
1847 }
1848 
1849 /*
1850  * Find the difference within a changed line.
1851  * Returns TRUE if the line was added, no other buffer has it.
1852  */
1853     int
1854 diff_find_change(wp, lnum, startp, endp)
1855     win_T	*wp;
1856     linenr_T	lnum;
1857     int		*startp;	/* first char of the change */
1858     int		*endp;		/* last char of the change */
1859 {
1860     char_u	*line_org;
1861     char_u	*line_new;
1862     int		i;
1863     int		si_org, si_new;
1864     int		ei_org, ei_new;
1865     diff_T	*dp;
1866     int		idx;
1867     int		off;
1868     int		added = TRUE;
1869 
1870     /* Make a copy of the line, the next ml_get() will invalidate it. */
1871     line_org = vim_strsave(ml_get_buf(wp->w_buffer, lnum, FALSE));
1872     if (line_org == NULL)
1873 	return FALSE;
1874 
1875     idx = diff_buf_idx(wp->w_buffer);
1876     if (idx == DB_COUNT)	/* cannot happen */
1877     {
1878 	vim_free(line_org);
1879 	return FALSE;
1880     }
1881 
1882     /* search for a change that includes "lnum" in the list of diffblocks. */
1883     for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next)
1884 	if (lnum <= dp->df_lnum[idx] + dp->df_count[idx])
1885 	    break;
1886     if (dp == NULL || diff_check_sanity(curtab, dp) == FAIL)
1887     {
1888 	vim_free(line_org);
1889 	return FALSE;
1890     }
1891 
1892     off = lnum - dp->df_lnum[idx];
1893 
1894     for (i = 0; i < DB_COUNT; ++i)
1895 	if (curtab->tp_diffbuf[i] != NULL && i != idx)
1896 	{
1897 	    /* Skip lines that are not in the other change (filler lines). */
1898 	    if (off >= dp->df_count[i])
1899 		continue;
1900 	    added = FALSE;
1901 	    line_new = ml_get_buf(curtab->tp_diffbuf[i],
1902 						 dp->df_lnum[i] + off, FALSE);
1903 
1904 	    /* Search for start of difference */
1905 	    si_org = si_new = 0;
1906 	    while (line_org[si_org] != NUL)
1907 	    {
1908 		if ((diff_flags & DIFF_IWHITE)
1909 			&& vim_iswhite(line_org[si_org])
1910 			&& vim_iswhite(line_new[si_new]))
1911 		{
1912 		    si_org = (int)(skipwhite(line_org + si_org) - line_org);
1913 		    si_new = (int)(skipwhite(line_new + si_new) - line_new);
1914 		}
1915 		else
1916 		{
1917 		    if (line_org[si_org] != line_new[si_new])
1918 			break;
1919 		    ++si_org;
1920 		    ++si_new;
1921 		}
1922 	    }
1923 #ifdef FEAT_MBYTE
1924 	    if (has_mbyte)
1925 	    {
1926 		/* Move back to first byte of character in both lines (may
1927 		 * have "nn^" in line_org and "n^ in line_new). */
1928 		si_org -= (*mb_head_off)(line_org, line_org + si_org);
1929 		si_new -= (*mb_head_off)(line_new, line_new + si_new);
1930 	    }
1931 #endif
1932 	    if (*startp > si_org)
1933 		*startp = si_org;
1934 
1935 	    /* Search for end of difference, if any. */
1936 	    if (line_org[si_org] != NUL || line_new[si_new] != NUL)
1937 	    {
1938 		ei_org = (int)STRLEN(line_org);
1939 		ei_new = (int)STRLEN(line_new);
1940 		while (ei_org >= *startp && ei_new >= si_new
1941 						&& ei_org >= 0 && ei_new >= 0)
1942 		{
1943 		    if ((diff_flags & DIFF_IWHITE)
1944 			    && vim_iswhite(line_org[ei_org])
1945 			    && vim_iswhite(line_new[ei_new]))
1946 		    {
1947 			while (ei_org >= *startp
1948 					     && vim_iswhite(line_org[ei_org]))
1949 			    --ei_org;
1950 			while (ei_new >= si_new
1951 					     && vim_iswhite(line_new[ei_new]))
1952 			    --ei_new;
1953 		    }
1954 		    else
1955 		    {
1956 			if (line_org[ei_org] != line_new[ei_new])
1957 			    break;
1958 			--ei_org;
1959 			--ei_new;
1960 		    }
1961 		}
1962 		if (*endp < ei_org)
1963 		    *endp = ei_org;
1964 	    }
1965 	}
1966 
1967     vim_free(line_org);
1968     return added;
1969 }
1970 
1971 #if defined(FEAT_FOLDING) || defined(PROTO)
1972 /*
1973  * Return TRUE if line "lnum" is not close to a diff block, this line should
1974  * be in a fold.
1975  * Return FALSE if there are no diff blocks at all in this window.
1976  */
1977     int
1978 diff_infold(wp, lnum)
1979     win_T	*wp;
1980     linenr_T	lnum;
1981 {
1982     int		i;
1983     int		idx = -1;
1984     int		other = FALSE;
1985     diff_T	*dp;
1986 
1987     /* Return if 'diff' isn't set. */
1988     if (!wp->w_p_diff)
1989 	return FALSE;
1990 
1991     for (i = 0; i < DB_COUNT; ++i)
1992     {
1993 	if (curtab->tp_diffbuf[i] == wp->w_buffer)
1994 	    idx = i;
1995 	else if (curtab->tp_diffbuf[i] != NULL)
1996 	    other = TRUE;
1997     }
1998 
1999     /* return here if there are no diffs in the window */
2000     if (idx == -1 || !other)
2001 	return FALSE;
2002 
2003     if (curtab->tp_diff_invalid)
2004 	ex_diffupdate(NULL);		/* update after a big change */
2005 
2006     /* Return if there are no diff blocks.  All lines will be folded. */
2007     if (curtab->tp_first_diff == NULL)
2008 	return TRUE;
2009 
2010     for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next)
2011     {
2012 	/* If this change is below the line there can't be any further match. */
2013 	if (dp->df_lnum[idx] - diff_context > lnum)
2014 	    break;
2015 	/* If this change ends before the line we have a match. */
2016 	if (dp->df_lnum[idx] + dp->df_count[idx] + diff_context > lnum)
2017 	    return FALSE;
2018     }
2019     return TRUE;
2020 }
2021 #endif
2022 
2023 /*
2024  * "dp" and "do" commands.
2025  */
2026     void
2027 nv_diffgetput(put)
2028     int		put;
2029 {
2030     exarg_T	ea;
2031 
2032     ea.arg = (char_u *)"";
2033     if (put)
2034 	ea.cmdidx = CMD_diffput;
2035     else
2036 	ea.cmdidx = CMD_diffget;
2037     ea.addr_count = 0;
2038     ea.line1 = curwin->w_cursor.lnum;
2039     ea.line2 = curwin->w_cursor.lnum;
2040     ex_diffgetput(&ea);
2041 }
2042 
2043 /*
2044  * ":diffget"
2045  * ":diffput"
2046  */
2047     void
2048 ex_diffgetput(eap)
2049     exarg_T	*eap;
2050 {
2051     linenr_T	lnum;
2052     int		count;
2053     linenr_T	off = 0;
2054     diff_T	*dp;
2055     diff_T	*dprev;
2056     diff_T	*dfree;
2057     int		idx_cur;
2058     int		idx_other;
2059     int		idx_from;
2060     int		idx_to;
2061     int		i;
2062     int		added;
2063     char_u	*p;
2064     aco_save_T	aco;
2065     buf_T	*buf;
2066     int		start_skip, end_skip;
2067     int		new_count;
2068     int		buf_empty;
2069     int		found_not_ma = FALSE;
2070 
2071     /* Find the current buffer in the list of diff buffers. */
2072     idx_cur = diff_buf_idx(curbuf);
2073     if (idx_cur == DB_COUNT)
2074     {
2075 	EMSG(_("E99: Current buffer is not in diff mode"));
2076 	return;
2077     }
2078 
2079     if (*eap->arg == NUL)
2080     {
2081 	/* No argument: Find the other buffer in the list of diff buffers. */
2082 	for (idx_other = 0; idx_other < DB_COUNT; ++idx_other)
2083 	    if (curtab->tp_diffbuf[idx_other] != curbuf
2084 		    && curtab->tp_diffbuf[idx_other] != NULL)
2085 	    {
2086 		if (eap->cmdidx != CMD_diffput
2087 				     || curtab->tp_diffbuf[idx_other]->b_p_ma)
2088 		    break;
2089 		found_not_ma = TRUE;
2090 	    }
2091 	if (idx_other == DB_COUNT)
2092 	{
2093 	    if (found_not_ma)
2094 		EMSG(_("E793: No other buffer in diff mode is modifiable"));
2095 	    else
2096 		EMSG(_("E100: No other buffer in diff mode"));
2097 	    return;
2098 	}
2099 
2100 	/* Check that there isn't a third buffer in the list */
2101 	for (i = idx_other + 1; i < DB_COUNT; ++i)
2102 	    if (curtab->tp_diffbuf[i] != curbuf
2103 		    && curtab->tp_diffbuf[i] != NULL
2104 		    && (eap->cmdidx != CMD_diffput || curtab->tp_diffbuf[i]->b_p_ma))
2105 	    {
2106 		EMSG(_("E101: More than two buffers in diff mode, don't know which one to use"));
2107 		return;
2108 	    }
2109     }
2110     else
2111     {
2112 	/* Buffer number or pattern given.  Ignore trailing white space. */
2113 	p = eap->arg + STRLEN(eap->arg);
2114 	while (p > eap->arg && vim_iswhite(p[-1]))
2115 	    --p;
2116 	for (i = 0; vim_isdigit(eap->arg[i]) && eap->arg + i < p; ++i)
2117 	    ;
2118 	if (eap->arg + i == p)	    /* digits only */
2119 	    i = atol((char *)eap->arg);
2120 	else
2121 	{
2122 	    i = buflist_findpat(eap->arg, p, FALSE, TRUE);
2123 	    if (i < 0)
2124 		return;		/* error message already given */
2125 	}
2126 	buf = buflist_findnr(i);
2127 	if (buf == NULL)
2128 	{
2129 	    EMSG2(_("E102: Can't find buffer \"%s\""), eap->arg);
2130 	    return;
2131 	}
2132 	if (buf == curbuf)
2133 	    return;		/* nothing to do */
2134 	idx_other = diff_buf_idx(buf);
2135 	if (idx_other == DB_COUNT)
2136 	{
2137 	    EMSG2(_("E103: Buffer \"%s\" is not in diff mode"), eap->arg);
2138 	    return;
2139 	}
2140     }
2141 
2142     diff_busy = TRUE;
2143 
2144     /* When no range given include the line above or below the cursor. */
2145     if (eap->addr_count == 0)
2146     {
2147 	/* Make it possible that ":diffget" on the last line gets line below
2148 	 * the cursor line when there is no difference above the cursor. */
2149 	if (eap->cmdidx == CMD_diffget
2150 		&& eap->line1 == curbuf->b_ml.ml_line_count
2151 		&& diff_check(curwin, eap->line1) == 0
2152 		&& (eap->line1 == 1 || diff_check(curwin, eap->line1 - 1) == 0))
2153 	    ++eap->line2;
2154 	else if (eap->line1 > 0)
2155 	    --eap->line1;
2156     }
2157 
2158     if (eap->cmdidx == CMD_diffget)
2159     {
2160 	idx_from = idx_other;
2161 	idx_to = idx_cur;
2162     }
2163     else
2164     {
2165 	idx_from = idx_cur;
2166 	idx_to = idx_other;
2167 	/* Need to make the other buffer the current buffer to be able to make
2168 	 * changes in it. */
2169 	/* set curwin/curbuf to buf and save a few things */
2170 	aucmd_prepbuf(&aco, curtab->tp_diffbuf[idx_other]);
2171     }
2172 
2173     /* May give the warning for a changed buffer here, which can trigger the
2174      * FileChangedRO autocommand, which may do nasty things and mess
2175      * everything up. */
2176     if (!curbuf->b_changed)
2177     {
2178 	change_warning(0);
2179 	if (diff_buf_idx(curbuf) != idx_to)
2180 	{
2181 	    EMSG(_("E787: Buffer changed unexpectedly"));
2182 	    return;
2183 	}
2184     }
2185 
2186     dprev = NULL;
2187     for (dp = curtab->tp_first_diff; dp != NULL; )
2188     {
2189 	if (dp->df_lnum[idx_cur] > eap->line2 + off)
2190 	    break;	/* past the range that was specified */
2191 
2192 	dfree = NULL;
2193 	lnum = dp->df_lnum[idx_to];
2194 	count = dp->df_count[idx_to];
2195 	if (dp->df_lnum[idx_cur] + dp->df_count[idx_cur] > eap->line1 + off
2196 		&& u_save(lnum - 1, lnum + count) != FAIL)
2197 	{
2198 	    /* Inside the specified range and saving for undo worked. */
2199 	    start_skip = 0;
2200 	    end_skip = 0;
2201 	    if (eap->addr_count > 0)
2202 	    {
2203 		/* A range was specified: check if lines need to be skipped. */
2204 		start_skip = eap->line1 + off - dp->df_lnum[idx_cur];
2205 		if (start_skip > 0)
2206 		{
2207 		    /* range starts below start of current diff block */
2208 		    if (start_skip > count)
2209 		    {
2210 			lnum += count;
2211 			count = 0;
2212 		    }
2213 		    else
2214 		    {
2215 			count -= start_skip;
2216 			lnum += start_skip;
2217 		    }
2218 		}
2219 		else
2220 		    start_skip = 0;
2221 
2222 		end_skip = dp->df_lnum[idx_cur] + dp->df_count[idx_cur] - 1
2223 							 - (eap->line2 + off);
2224 		if (end_skip > 0)
2225 		{
2226 		    /* range ends above end of current/from diff block */
2227 		    if (idx_cur == idx_from)	/* :diffput */
2228 		    {
2229 			i = dp->df_count[idx_cur] - start_skip - end_skip;
2230 			if (count > i)
2231 			    count = i;
2232 		    }
2233 		    else			/* :diffget */
2234 		    {
2235 			count -= end_skip;
2236 			end_skip = dp->df_count[idx_from] - start_skip - count;
2237 			if (end_skip < 0)
2238 			    end_skip = 0;
2239 		    }
2240 		}
2241 		else
2242 		    end_skip = 0;
2243 	    }
2244 
2245 	    buf_empty = FALSE;
2246 	    added = 0;
2247 	    for (i = 0; i < count; ++i)
2248 	    {
2249 		/* remember deleting the last line of the buffer */
2250 		buf_empty = curbuf->b_ml.ml_line_count == 1;
2251 		ml_delete(lnum, FALSE);
2252 		--added;
2253 	    }
2254 	    for (i = 0; i < dp->df_count[idx_from] - start_skip - end_skip; ++i)
2255 	    {
2256 		linenr_T nr;
2257 
2258 		nr = dp->df_lnum[idx_from] + start_skip + i;
2259 		if (nr > curtab->tp_diffbuf[idx_from]->b_ml.ml_line_count)
2260 		    break;
2261 		p = vim_strsave(ml_get_buf(curtab->tp_diffbuf[idx_from],
2262 								  nr, FALSE));
2263 		if (p != NULL)
2264 		{
2265 		    ml_append(lnum + i - 1, p, 0, FALSE);
2266 		    vim_free(p);
2267 		    ++added;
2268 		    if (buf_empty && curbuf->b_ml.ml_line_count == 2)
2269 		    {
2270 			/* Added the first line into an empty buffer, need to
2271 			 * delete the dummy empty line. */
2272 			buf_empty = FALSE;
2273 			ml_delete((linenr_T)2, FALSE);
2274 		    }
2275 		}
2276 	    }
2277 	    new_count = dp->df_count[idx_to] + added;
2278 	    dp->df_count[idx_to] = new_count;
2279 
2280 	    if (start_skip == 0 && end_skip == 0)
2281 	    {
2282 		/* Check if there are any other buffers and if the diff is
2283 		 * equal in them. */
2284 		for (i = 0; i < DB_COUNT; ++i)
2285 		    if (curtab->tp_diffbuf[i] != NULL && i != idx_from
2286 								&& i != idx_to
2287 			    && !diff_equal_entry(dp, idx_from, i))
2288 			break;
2289 		if (i == DB_COUNT)
2290 		{
2291 		    /* delete the diff entry, the buffers are now equal here */
2292 		    dfree = dp;
2293 		    dp = dp->df_next;
2294 		    if (dprev == NULL)
2295 			curtab->tp_first_diff = dp;
2296 		    else
2297 			dprev->df_next = dp;
2298 		}
2299 	    }
2300 
2301 	    /* Adjust marks.  This will change the following entries! */
2302 	    if (added != 0)
2303 	    {
2304 		mark_adjust(lnum, lnum + count - 1, (long)MAXLNUM, (long)added);
2305 		if (curwin->w_cursor.lnum >= lnum)
2306 		{
2307 		    /* Adjust the cursor position if it's in/after the changed
2308 		     * lines. */
2309 		    if (curwin->w_cursor.lnum >= lnum + count)
2310 			curwin->w_cursor.lnum += added;
2311 		    else if (added < 0)
2312 			curwin->w_cursor.lnum = lnum;
2313 		}
2314 	    }
2315 	    changed_lines(lnum, 0, lnum + count, (long)added);
2316 
2317 	    if (dfree != NULL)
2318 	    {
2319 		/* Diff is deleted, update folds in other windows. */
2320 #ifdef FEAT_FOLDING
2321 		diff_fold_update(dfree, idx_to);
2322 #endif
2323 		vim_free(dfree);
2324 	    }
2325 	    else
2326 		/* mark_adjust() may have changed the count in a wrong way */
2327 		dp->df_count[idx_to] = new_count;
2328 
2329 	    /* When changing the current buffer, keep track of line numbers */
2330 	    if (idx_cur == idx_to)
2331 		off += added;
2332 	}
2333 
2334 	/* If before the range or not deleted, go to next diff. */
2335 	if (dfree == NULL)
2336 	{
2337 	    dprev = dp;
2338 	    dp = dp->df_next;
2339 	}
2340     }
2341 
2342     /* restore curwin/curbuf and a few other things */
2343     if (idx_other == idx_to)
2344     {
2345 	/* Syncing undo only works for the current buffer, but we change
2346 	 * another buffer.  Sync undo if the command was typed.  This isn't
2347 	 * 100% right when ":diffput" is used in a function or mapping. */
2348 	if (KeyTyped)
2349 	    u_sync(FALSE);
2350 	aucmd_restbuf(&aco);
2351     }
2352 
2353     diff_busy = FALSE;
2354 
2355     /* Check that the cursor is on a valid character and update it's position.
2356      * When there were filler lines the topline has become invalid. */
2357     check_cursor();
2358     changed_line_abv_curs();
2359 
2360     /* Also need to redraw the other buffers. */
2361     diff_redraw(FALSE);
2362 }
2363 
2364 #ifdef FEAT_FOLDING
2365 /*
2366  * Update folds for all diff buffers for entry "dp".
2367  * Skip buffer with index "skip_idx".
2368  * When there are no diffs, all folds are removed.
2369  */
2370     static void
2371 diff_fold_update(dp, skip_idx)
2372     diff_T	*dp;
2373     int		skip_idx;
2374 {
2375     int		i;
2376     win_T	*wp;
2377 
2378     for (wp = firstwin; wp != NULL; wp = wp->w_next)
2379 	for (i = 0; i < DB_COUNT; ++i)
2380 	    if (curtab->tp_diffbuf[i] == wp->w_buffer && i != skip_idx)
2381 		foldUpdate(wp, dp->df_lnum[i],
2382 					    dp->df_lnum[i] + dp->df_count[i]);
2383 }
2384 #endif
2385 
2386 /*
2387  * Return TRUE if buffer "buf" is in diff-mode.
2388  */
2389     int
2390 diff_mode_buf(buf)
2391     buf_T	*buf;
2392 {
2393     tabpage_T	*tp;
2394 
2395     for (tp = first_tabpage; tp != NULL; tp = tp->tp_next)
2396 	if (diff_buf_idx_tp(buf, tp) != DB_COUNT)
2397 	    return TRUE;
2398     return FALSE;
2399 }
2400 
2401 /*
2402  * Move "count" times in direction "dir" to the next diff block.
2403  * Return FAIL if there isn't such a diff block.
2404  */
2405     int
2406 diff_move_to(dir, count)
2407     int		dir;
2408     long	count;
2409 {
2410     int		idx;
2411     linenr_T	lnum = curwin->w_cursor.lnum;
2412     diff_T	*dp;
2413 
2414     idx = diff_buf_idx(curbuf);
2415     if (idx == DB_COUNT || curtab->tp_first_diff == NULL)
2416 	return FAIL;
2417 
2418     if (curtab->tp_diff_invalid)
2419 	ex_diffupdate(NULL);		/* update after a big change */
2420 
2421     if (curtab->tp_first_diff == NULL)		/* no diffs today */
2422 	return FAIL;
2423 
2424     while (--count >= 0)
2425     {
2426 	/* Check if already before first diff. */
2427 	if (dir == BACKWARD && lnum <= curtab->tp_first_diff->df_lnum[idx])
2428 	    break;
2429 
2430 	for (dp = curtab->tp_first_diff; ; dp = dp->df_next)
2431 	{
2432 	    if (dp == NULL)
2433 		break;
2434 	    if ((dir == FORWARD && lnum < dp->df_lnum[idx])
2435 		    || (dir == BACKWARD
2436 			&& (dp->df_next == NULL
2437 			    || lnum <= dp->df_next->df_lnum[idx])))
2438 	    {
2439 		lnum = dp->df_lnum[idx];
2440 		break;
2441 	    }
2442 	}
2443     }
2444 
2445     /* don't end up past the end of the file */
2446     if (lnum > curbuf->b_ml.ml_line_count)
2447 	lnum = curbuf->b_ml.ml_line_count;
2448 
2449     /* When the cursor didn't move at all we fail. */
2450     if (lnum == curwin->w_cursor.lnum)
2451 	return FAIL;
2452 
2453     setpcmark();
2454     curwin->w_cursor.lnum = lnum;
2455     curwin->w_cursor.col = 0;
2456 
2457     return OK;
2458 }
2459 
2460 #if defined(FEAT_FOLDING) || defined(PROTO)
2461 /*
2462  * For line "lnum" in the current window find the equivalent lnum in window
2463  * "wp", compensating for inserted/deleted lines.
2464  */
2465     linenr_T
2466 diff_lnum_win(lnum, wp)
2467     linenr_T	lnum;
2468     win_T	*wp;
2469 {
2470     diff_T	*dp;
2471     int		idx;
2472     int		i;
2473     linenr_T	n;
2474 
2475     idx = diff_buf_idx(curbuf);
2476     if (idx == DB_COUNT)		/* safety check */
2477 	return (linenr_T)0;
2478 
2479     if (curtab->tp_diff_invalid)
2480 	ex_diffupdate(NULL);		/* update after a big change */
2481 
2482     /* search for a change that includes "lnum" in the list of diffblocks. */
2483     for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next)
2484 	if (lnum <= dp->df_lnum[idx] + dp->df_count[idx])
2485 	    break;
2486 
2487     /* When after the last change, compute relative to the last line number. */
2488     if (dp == NULL)
2489 	return wp->w_buffer->b_ml.ml_line_count
2490 					- (curbuf->b_ml.ml_line_count - lnum);
2491 
2492     /* Find index for "wp". */
2493     i = diff_buf_idx(wp->w_buffer);
2494     if (i == DB_COUNT)			/* safety check */
2495 	return (linenr_T)0;
2496 
2497     n = lnum + (dp->df_lnum[i] - dp->df_lnum[idx]);
2498     if (n > dp->df_lnum[i] + dp->df_count[i])
2499 	n = dp->df_lnum[i] + dp->df_count[i];
2500     return n;
2501 }
2502 #endif
2503 
2504 #endif	/* FEAT_DIFF */
2505