remote-helpers: Support custom transport options
[git] / combine-diff.c
1 #include "cache.h"
2 #include "commit.h"
3 #include "blob.h"
4 #include "diff.h"
5 #include "diffcore.h"
6 #include "quote.h"
7 #include "xdiff-interface.h"
8 #include "log-tree.h"
9 #include "refs.h"
10
11 static struct combine_diff_path *intersect_paths(struct combine_diff_path *curr, int n, int num_parent)
12 {
13         struct diff_queue_struct *q = &diff_queued_diff;
14         struct combine_diff_path *p;
15         int i;
16
17         if (!n) {
18                 struct combine_diff_path *list = NULL, **tail = &list;
19                 for (i = 0; i < q->nr; i++) {
20                         int len;
21                         const char *path;
22                         if (diff_unmodified_pair(q->queue[i]))
23                                 continue;
24                         path = q->queue[i]->two->path;
25                         len = strlen(path);
26                         p = xmalloc(combine_diff_path_size(num_parent, len));
27                         p->path = (char *) &(p->parent[num_parent]);
28                         memcpy(p->path, path, len);
29                         p->path[len] = 0;
30                         p->len = len;
31                         p->next = NULL;
32                         memset(p->parent, 0,
33                                sizeof(p->parent[0]) * num_parent);
34
35                         hashcpy(p->sha1, q->queue[i]->two->sha1);
36                         p->mode = q->queue[i]->two->mode;
37                         hashcpy(p->parent[n].sha1, q->queue[i]->one->sha1);
38                         p->parent[n].mode = q->queue[i]->one->mode;
39                         p->parent[n].status = q->queue[i]->status;
40                         *tail = p;
41                         tail = &p->next;
42                 }
43                 return list;
44         }
45
46         for (p = curr; p; p = p->next) {
47                 int found = 0;
48                 if (!p->len)
49                         continue;
50                 for (i = 0; i < q->nr; i++) {
51                         const char *path;
52                         int len;
53
54                         if (diff_unmodified_pair(q->queue[i]))
55                                 continue;
56                         path = q->queue[i]->two->path;
57                         len = strlen(path);
58                         if (len == p->len && !memcmp(path, p->path, len)) {
59                                 found = 1;
60                                 hashcpy(p->parent[n].sha1, q->queue[i]->one->sha1);
61                                 p->parent[n].mode = q->queue[i]->one->mode;
62                                 p->parent[n].status = q->queue[i]->status;
63                                 break;
64                         }
65                 }
66                 if (!found)
67                         p->len = 0;
68         }
69         return curr;
70 }
71
72 /* Lines lost from parent */
73 struct lline {
74         struct lline *next;
75         int len;
76         unsigned long parent_map;
77         char line[FLEX_ARRAY];
78 };
79
80 /* Lines surviving in the merge result */
81 struct sline {
82         struct lline *lost_head, **lost_tail;
83         struct lline *next_lost;
84         char *bol;
85         int len;
86         /* bit 0 up to (N-1) are on if the parent has this line (i.e.
87          * we did not change it).
88          * bit N is used for "interesting" lines, including context.
89          * bit (N+1) is used for "do not show deletion before this".
90          */
91         unsigned long flag;
92         unsigned long *p_lno;
93 };
94
95 static char *grab_blob(const unsigned char *sha1, unsigned int mode, unsigned long *size)
96 {
97         char *blob;
98         enum object_type type;
99
100         if (S_ISGITLINK(mode)) {
101                 blob = xmalloc(100);
102                 *size = snprintf(blob, 100,
103                                  "Subproject commit %s\n", sha1_to_hex(sha1));
104         } else if (is_null_sha1(sha1)) {
105                 /* deleted blob */
106                 *size = 0;
107                 return xcalloc(1, 1);
108         } else {
109                 blob = read_sha1_file(sha1, &type, size);
110                 if (type != OBJ_BLOB)
111                         die("object '%s' is not a blob!", sha1_to_hex(sha1));
112         }
113         return blob;
114 }
115
116 static void append_lost(struct sline *sline, int n, const char *line, int len)
117 {
118         struct lline *lline;
119         unsigned long this_mask = (1UL<<n);
120         if (line[len-1] == '\n')
121                 len--;
122
123         /* Check to see if we can squash things */
124         if (sline->lost_head) {
125                 lline = sline->next_lost;
126                 while (lline) {
127                         if (lline->len == len &&
128                             !memcmp(lline->line, line, len)) {
129                                 lline->parent_map |= this_mask;
130                                 sline->next_lost = lline->next;
131                                 return;
132                         }
133                         lline = lline->next;
134                 }
135         }
136
137         lline = xmalloc(sizeof(*lline) + len + 1);
138         lline->len = len;
139         lline->next = NULL;
140         lline->parent_map = this_mask;
141         memcpy(lline->line, line, len);
142         lline->line[len] = 0;
143         *sline->lost_tail = lline;
144         sline->lost_tail = &lline->next;
145         sline->next_lost = NULL;
146 }
147
148 struct combine_diff_state {
149         unsigned int lno;
150         int ob, on, nb, nn;
151         unsigned long nmask;
152         int num_parent;
153         int n;
154         struct sline *sline;
155         struct sline *lost_bucket;
156 };
157
158 static void consume_line(void *state_, char *line, unsigned long len)
159 {
160         struct combine_diff_state *state = state_;
161         if (5 < len && !memcmp("@@ -", line, 4)) {
162                 if (parse_hunk_header(line, len,
163                                       &state->ob, &state->on,
164                                       &state->nb, &state->nn))
165                         return;
166                 state->lno = state->nb;
167                 if (state->nn == 0) {
168                         /* @@ -X,Y +N,0 @@ removed Y lines
169                          * that would have come *after* line N
170                          * in the result.  Our lost buckets hang
171                          * to the line after the removed lines,
172                          *
173                          * Note that this is correct even when N == 0,
174                          * in which case the hunk removes the first
175                          * line in the file.
176                          */
177                         state->lost_bucket = &state->sline[state->nb];
178                         if (!state->nb)
179                                 state->nb = 1;
180                 } else {
181                         state->lost_bucket = &state->sline[state->nb-1];
182                 }
183                 if (!state->sline[state->nb-1].p_lno)
184                         state->sline[state->nb-1].p_lno =
185                                 xcalloc(state->num_parent,
186                                         sizeof(unsigned long));
187                 state->sline[state->nb-1].p_lno[state->n] = state->ob;
188                 state->lost_bucket->next_lost = state->lost_bucket->lost_head;
189                 return;
190         }
191         if (!state->lost_bucket)
192                 return; /* not in any hunk yet */
193         switch (line[0]) {
194         case '-':
195                 append_lost(state->lost_bucket, state->n, line+1, len-1);
196                 break;
197         case '+':
198                 state->sline[state->lno-1].flag |= state->nmask;
199                 state->lno++;
200                 break;
201         }
202 }
203
204 static void combine_diff(const unsigned char *parent, unsigned int mode,
205                          mmfile_t *result_file,
206                          struct sline *sline, unsigned int cnt, int n,
207                          int num_parent)
208 {
209         unsigned int p_lno, lno;
210         unsigned long nmask = (1UL << n);
211         xpparam_t xpp;
212         xdemitconf_t xecfg;
213         mmfile_t parent_file;
214         xdemitcb_t ecb;
215         struct combine_diff_state state;
216         unsigned long sz;
217
218         if (!cnt)
219                 return; /* result deleted */
220
221         parent_file.ptr = grab_blob(parent, mode, &sz);
222         parent_file.size = sz;
223         memset(&xpp, 0, sizeof(xpp));
224         xpp.flags = XDF_NEED_MINIMAL;
225         memset(&xecfg, 0, sizeof(xecfg));
226         memset(&state, 0, sizeof(state));
227         state.nmask = nmask;
228         state.sline = sline;
229         state.lno = 1;
230         state.num_parent = num_parent;
231         state.n = n;
232
233         xdi_diff_outf(&parent_file, result_file, consume_line, &state,
234                       &xpp, &xecfg, &ecb);
235         free(parent_file.ptr);
236
237         /* Assign line numbers for this parent.
238          *
239          * sline[lno].p_lno[n] records the first line number
240          * (counting from 1) for parent N if the final hunk display
241          * started by showing sline[lno] (possibly showing the lost
242          * lines attached to it first).
243          */
244         for (lno = 0,  p_lno = 1; lno <= cnt; lno++) {
245                 struct lline *ll;
246                 sline[lno].p_lno[n] = p_lno;
247
248                 /* How many lines would this sline advance the p_lno? */
249                 ll = sline[lno].lost_head;
250                 while (ll) {
251                         if (ll->parent_map & nmask)
252                                 p_lno++; /* '-' means parent had it */
253                         ll = ll->next;
254                 }
255                 if (lno < cnt && !(sline[lno].flag & nmask))
256                         p_lno++; /* no '+' means parent had it */
257         }
258         sline[lno].p_lno[n] = p_lno; /* trailer */
259 }
260
261 static unsigned long context = 3;
262 static char combine_marker = '@';
263
264 static int interesting(struct sline *sline, unsigned long all_mask)
265 {
266         /* If some parents lost lines here, or if we have added to
267          * some parent, it is interesting.
268          */
269         return ((sline->flag & all_mask) || sline->lost_head);
270 }
271
272 static unsigned long adjust_hunk_tail(struct sline *sline,
273                                       unsigned long all_mask,
274                                       unsigned long hunk_begin,
275                                       unsigned long i)
276 {
277         /* i points at the first uninteresting line.  If the last line
278          * of the hunk was interesting only because it has some
279          * deletion, then it is not all that interesting for the
280          * purpose of giving trailing context lines.  This is because
281          * we output '-' line and then unmodified sline[i-1] itself in
282          * that case which gives us one extra context line.
283          */
284         if ((hunk_begin + 1 <= i) && !(sline[i-1].flag & all_mask))
285                 i--;
286         return i;
287 }
288
289 static unsigned long find_next(struct sline *sline,
290                                unsigned long mark,
291                                unsigned long i,
292                                unsigned long cnt,
293                                int look_for_uninteresting)
294 {
295         /* We have examined up to i-1 and are about to look at i.
296          * Find next interesting or uninteresting line.  Here,
297          * "interesting" does not mean interesting(), but marked by
298          * the give_context() function below (i.e. it includes context
299          * lines that are not interesting to interesting() function
300          * that are surrounded by interesting() ones.
301          */
302         while (i <= cnt)
303                 if (look_for_uninteresting
304                     ? !(sline[i].flag & mark)
305                     : (sline[i].flag & mark))
306                         return i;
307                 else
308                         i++;
309         return i;
310 }
311
312 static int give_context(struct sline *sline, unsigned long cnt, int num_parent)
313 {
314         unsigned long all_mask = (1UL<<num_parent) - 1;
315         unsigned long mark = (1UL<<num_parent);
316         unsigned long no_pre_delete = (2UL<<num_parent);
317         unsigned long i;
318
319         /* Two groups of interesting lines may have a short gap of
320          * uninteresting lines.  Connect such groups to give them a
321          * bit of context.
322          *
323          * We first start from what the interesting() function says,
324          * and mark them with "mark", and paint context lines with the
325          * mark.  So interesting() would still say false for such context
326          * lines but they are treated as "interesting" in the end.
327          */
328         i = find_next(sline, mark, 0, cnt, 0);
329         if (cnt < i)
330                 return 0;
331
332         while (i <= cnt) {
333                 unsigned long j = (context < i) ? (i - context) : 0;
334                 unsigned long k;
335
336                 /* Paint a few lines before the first interesting line. */
337                 while (j < i)
338                         sline[j++].flag |= mark | no_pre_delete;
339
340         again:
341                 /* we know up to i is to be included.  where does the
342                  * next uninteresting one start?
343                  */
344                 j = find_next(sline, mark, i, cnt, 1);
345                 if (cnt < j)
346                         break; /* the rest are all interesting */
347
348                 /* lookahead context lines */
349                 k = find_next(sline, mark, j, cnt, 0);
350                 j = adjust_hunk_tail(sline, all_mask, i, j);
351
352                 if (k < j + context) {
353                         /* k is interesting and [j,k) are not, but
354                          * paint them interesting because the gap is small.
355                          */
356                         while (j < k)
357                                 sline[j++].flag |= mark;
358                         i = k;
359                         goto again;
360                 }
361
362                 /* j is the first uninteresting line and there is
363                  * no overlap beyond it within context lines.  Paint
364                  * the trailing edge a bit.
365                  */
366                 i = k;
367                 k = (j + context < cnt+1) ? j + context : cnt+1;
368                 while (j < k)
369                         sline[j++].flag |= mark;
370         }
371         return 1;
372 }
373
374 static int make_hunks(struct sline *sline, unsigned long cnt,
375                        int num_parent, int dense)
376 {
377         unsigned long all_mask = (1UL<<num_parent) - 1;
378         unsigned long mark = (1UL<<num_parent);
379         unsigned long i;
380         int has_interesting = 0;
381
382         for (i = 0; i <= cnt; i++) {
383                 if (interesting(&sline[i], all_mask))
384                         sline[i].flag |= mark;
385                 else
386                         sline[i].flag &= ~mark;
387         }
388         if (!dense)
389                 return give_context(sline, cnt, num_parent);
390
391         /* Look at each hunk, and if we have changes from only one
392          * parent, or the changes are the same from all but one
393          * parent, mark that uninteresting.
394          */
395         i = 0;
396         while (i <= cnt) {
397                 unsigned long j, hunk_begin, hunk_end;
398                 unsigned long same_diff;
399                 while (i <= cnt && !(sline[i].flag & mark))
400                         i++;
401                 if (cnt < i)
402                         break; /* No more interesting hunks */
403                 hunk_begin = i;
404                 for (j = i + 1; j <= cnt; j++) {
405                         if (!(sline[j].flag & mark)) {
406                                 /* Look beyond the end to see if there
407                                  * is an interesting line after this
408                                  * hunk within context span.
409                                  */
410                                 unsigned long la; /* lookahead */
411                                 int contin = 0;
412                                 la = adjust_hunk_tail(sline, all_mask,
413                                                      hunk_begin, j);
414                                 la = (la + context < cnt + 1) ?
415                                         (la + context) : cnt + 1;
416                                 while (j <= --la) {
417                                         if (sline[la].flag & mark) {
418                                                 contin = 1;
419                                                 break;
420                                         }
421                                 }
422                                 if (!contin)
423                                         break;
424                                 j = la;
425                         }
426                 }
427                 hunk_end = j;
428
429                 /* [i..hunk_end) are interesting.  Now is it really
430                  * interesting?  We check if there are only two versions
431                  * and the result matches one of them.  That is, we look
432                  * at:
433                  *   (+) line, which records lines added to which parents;
434                  *       this line appears in the result.
435                  *   (-) line, which records from what parents the line
436                  *       was removed; this line does not appear in the result.
437                  * then check the set of parents the result has difference
438                  * from, from all lines.  If there are lines that has
439                  * different set of parents that the result has differences
440                  * from, that means we have more than two versions.
441                  *
442                  * Even when we have only two versions, if the result does
443                  * not match any of the parents, the it should be considered
444                  * interesting.  In such a case, we would have all '+' line.
445                  * After passing the above "two versions" test, that would
446                  * appear as "the same set of parents" to be "all parents".
447                  */
448                 same_diff = 0;
449                 has_interesting = 0;
450                 for (j = i; j < hunk_end && !has_interesting; j++) {
451                         unsigned long this_diff = sline[j].flag & all_mask;
452                         struct lline *ll = sline[j].lost_head;
453                         if (this_diff) {
454                                 /* This has some changes.  Is it the
455                                  * same as others?
456                                  */
457                                 if (!same_diff)
458                                         same_diff = this_diff;
459                                 else if (same_diff != this_diff) {
460                                         has_interesting = 1;
461                                         break;
462                                 }
463                         }
464                         while (ll && !has_interesting) {
465                                 /* Lost this line from these parents;
466                                  * who are they?  Are they the same?
467                                  */
468                                 this_diff = ll->parent_map;
469                                 if (!same_diff)
470                                         same_diff = this_diff;
471                                 else if (same_diff != this_diff) {
472                                         has_interesting = 1;
473                                 }
474                                 ll = ll->next;
475                         }
476                 }
477
478                 if (!has_interesting && same_diff != all_mask) {
479                         /* This hunk is not that interesting after all */
480                         for (j = hunk_begin; j < hunk_end; j++)
481                                 sline[j].flag &= ~mark;
482                 }
483                 i = hunk_end;
484         }
485
486         has_interesting = give_context(sline, cnt, num_parent);
487         return has_interesting;
488 }
489
490 static void show_parent_lno(struct sline *sline, unsigned long l0, unsigned long l1, int n, unsigned long null_context)
491 {
492         l0 = sline[l0].p_lno[n];
493         l1 = sline[l1].p_lno[n];
494         printf(" -%lu,%lu", l0, l1-l0-null_context);
495 }
496
497 static int hunk_comment_line(const char *bol)
498 {
499         int ch;
500
501         if (!bol)
502                 return 0;
503         ch = *bol & 0xff;
504         return (isalpha(ch) || ch == '_' || ch == '$');
505 }
506
507 static void show_line_to_eol(const char *line, int len, const char *reset)
508 {
509         int saw_cr_at_eol = 0;
510         if (len < 0)
511                 len = strlen(line);
512         saw_cr_at_eol = (len && line[len-1] == '\r');
513
514         printf("%.*s%s%s\n", len - saw_cr_at_eol, line,
515                reset,
516                saw_cr_at_eol ? "\r" : "");
517 }
518
519 static void dump_sline(struct sline *sline, unsigned long cnt, int num_parent,
520                        int use_color)
521 {
522         unsigned long mark = (1UL<<num_parent);
523         unsigned long no_pre_delete = (2UL<<num_parent);
524         int i;
525         unsigned long lno = 0;
526         const char *c_frag = diff_get_color(use_color, DIFF_FRAGINFO);
527         const char *c_new = diff_get_color(use_color, DIFF_FILE_NEW);
528         const char *c_old = diff_get_color(use_color, DIFF_FILE_OLD);
529         const char *c_plain = diff_get_color(use_color, DIFF_PLAIN);
530         const char *c_reset = diff_get_color(use_color, DIFF_RESET);
531
532         if (!cnt)
533                 return; /* result deleted */
534
535         while (1) {
536                 unsigned long hunk_end;
537                 unsigned long rlines;
538                 const char *hunk_comment = NULL;
539                 unsigned long null_context = 0;
540
541                 while (lno <= cnt && !(sline[lno].flag & mark)) {
542                         if (hunk_comment_line(sline[lno].bol))
543                                 hunk_comment = sline[lno].bol;
544                         lno++;
545                 }
546                 if (cnt < lno)
547                         break;
548                 else {
549                         for (hunk_end = lno + 1; hunk_end <= cnt; hunk_end++)
550                                 if (!(sline[hunk_end].flag & mark))
551                                         break;
552                 }
553                 rlines = hunk_end - lno;
554                 if (cnt < hunk_end)
555                         rlines--; /* pointing at the last delete hunk */
556
557                 if (!context) {
558                         /*
559                          * Even when running with --unified=0, all
560                          * lines in the hunk needs to be processed in
561                          * the loop below in order to show the
562                          * deletion recorded in lost_head.  However,
563                          * we do not want to show the resulting line
564                          * with all blank context markers in such a
565                          * case.  Compensate.
566                          */
567                         unsigned long j;
568                         for (j = lno; j < hunk_end; j++)
569                                 if (!(sline[j].flag & (mark-1)))
570                                         null_context++;
571                         rlines -= null_context;
572                 }
573
574                 fputs(c_frag, stdout);
575                 for (i = 0; i <= num_parent; i++) putchar(combine_marker);
576                 for (i = 0; i < num_parent; i++)
577                         show_parent_lno(sline, lno, hunk_end, i, null_context);
578                 printf(" +%lu,%lu ", lno+1, rlines);
579                 for (i = 0; i <= num_parent; i++) putchar(combine_marker);
580
581                 if (hunk_comment) {
582                         int comment_end = 0;
583                         for (i = 0; i < 40; i++) {
584                                 int ch = hunk_comment[i] & 0xff;
585                                 if (!ch || ch == '\n')
586                                         break;
587                                 if (!isspace(ch))
588                                     comment_end = i;
589                         }
590                         if (comment_end)
591                                 putchar(' ');
592                         for (i = 0; i < comment_end; i++)
593                                 putchar(hunk_comment[i]);
594                 }
595
596                 printf("%s\n", c_reset);
597                 while (lno < hunk_end) {
598                         struct lline *ll;
599                         int j;
600                         unsigned long p_mask;
601                         struct sline *sl = &sline[lno++];
602                         ll = (sl->flag & no_pre_delete) ? NULL : sl->lost_head;
603                         while (ll) {
604                                 fputs(c_old, stdout);
605                                 for (j = 0; j < num_parent; j++) {
606                                         if (ll->parent_map & (1UL<<j))
607                                                 putchar('-');
608                                         else
609                                                 putchar(' ');
610                                 }
611                                 show_line_to_eol(ll->line, -1, c_reset);
612                                 ll = ll->next;
613                         }
614                         if (cnt < lno)
615                                 break;
616                         p_mask = 1;
617                         if (!(sl->flag & (mark-1))) {
618                                 /*
619                                  * This sline was here to hang the
620                                  * lost lines in front of it.
621                                  */
622                                 if (!context)
623                                         continue;
624                                 fputs(c_plain, stdout);
625                         }
626                         else
627                                 fputs(c_new, stdout);
628                         for (j = 0; j < num_parent; j++) {
629                                 if (p_mask & sl->flag)
630                                         putchar('+');
631                                 else
632                                         putchar(' ');
633                                 p_mask <<= 1;
634                         }
635                         show_line_to_eol(sl->bol, sl->len, c_reset);
636                 }
637         }
638 }
639
640 static void reuse_combine_diff(struct sline *sline, unsigned long cnt,
641                                int i, int j)
642 {
643         /* We have already examined parent j and we know parent i
644          * and parent j are the same, so reuse the combined result
645          * of parent j for parent i.
646          */
647         unsigned long lno, imask, jmask;
648         imask = (1UL<<i);
649         jmask = (1UL<<j);
650
651         for (lno = 0; lno <= cnt; lno++) {
652                 struct lline *ll = sline->lost_head;
653                 sline->p_lno[i] = sline->p_lno[j];
654                 while (ll) {
655                         if (ll->parent_map & jmask)
656                                 ll->parent_map |= imask;
657                         ll = ll->next;
658                 }
659                 if (sline->flag & jmask)
660                         sline->flag |= imask;
661                 sline++;
662         }
663         /* the overall size of the file (sline[cnt]) */
664         sline->p_lno[i] = sline->p_lno[j];
665 }
666
667 static void dump_quoted_path(const char *head,
668                              const char *prefix,
669                              const char *path,
670                              const char *c_meta, const char *c_reset)
671 {
672         static struct strbuf buf = STRBUF_INIT;
673
674         strbuf_reset(&buf);
675         strbuf_addstr(&buf, c_meta);
676         strbuf_addstr(&buf, head);
677         quote_two_c_style(&buf, prefix, path, 0);
678         strbuf_addstr(&buf, c_reset);
679         puts(buf.buf);
680 }
681
682 static void show_patch_diff(struct combine_diff_path *elem, int num_parent,
683                             int dense, struct rev_info *rev)
684 {
685         struct diff_options *opt = &rev->diffopt;
686         unsigned long result_size, cnt, lno;
687         char *result, *cp;
688         struct sline *sline; /* survived lines */
689         int mode_differs = 0;
690         int i, show_hunks;
691         int working_tree_file = is_null_sha1(elem->sha1);
692         int abbrev = DIFF_OPT_TST(opt, FULL_INDEX) ? 40 : DEFAULT_ABBREV;
693         const char *a_prefix, *b_prefix;
694         mmfile_t result_file;
695
696         context = opt->context;
697         a_prefix = opt->a_prefix ? opt->a_prefix : "a/";
698         b_prefix = opt->b_prefix ? opt->b_prefix : "b/";
699
700         /* Read the result of merge first */
701         if (!working_tree_file)
702                 result = grab_blob(elem->sha1, elem->mode, &result_size);
703         else {
704                 /* Used by diff-tree to read from the working tree */
705                 struct stat st;
706                 int fd = -1;
707
708                 if (lstat(elem->path, &st) < 0)
709                         goto deleted_file;
710
711                 if (S_ISLNK(st.st_mode)) {
712                         struct strbuf buf = STRBUF_INIT;
713
714                         if (strbuf_readlink(&buf, elem->path, st.st_size) < 0) {
715                                 error("readlink(%s): %s", elem->path,
716                                       strerror(errno));
717                                 return;
718                         }
719                         result_size = buf.len;
720                         result = strbuf_detach(&buf, NULL);
721                         elem->mode = canon_mode(st.st_mode);
722                 } else if (S_ISDIR(st.st_mode)) {
723                         unsigned char sha1[20];
724                         if (resolve_gitlink_ref(elem->path, "HEAD", sha1) < 0)
725                                 result = grab_blob(elem->sha1, elem->mode, &result_size);
726                         else
727                                 result = grab_blob(sha1, elem->mode, &result_size);
728                 } else if (0 <= (fd = open(elem->path, O_RDONLY))) {
729                         size_t len = xsize_t(st.st_size);
730                         ssize_t done;
731                         int is_file, i;
732
733                         elem->mode = canon_mode(st.st_mode);
734                         /* if symlinks don't work, assume symlink if all parents
735                          * are symlinks
736                          */
737                         is_file = has_symlinks;
738                         for (i = 0; !is_file && i < num_parent; i++)
739                                 is_file = !S_ISLNK(elem->parent[i].mode);
740                         if (!is_file)
741                                 elem->mode = canon_mode(S_IFLNK);
742
743                         result_size = len;
744                         result = xmalloc(len + 1);
745
746                         done = read_in_full(fd, result, len);
747                         if (done < 0)
748                                 die_errno("read error '%s'", elem->path);
749                         else if (done < len)
750                                 die("early EOF '%s'", elem->path);
751
752                         result[len] = 0;
753
754                         /* If not a fake symlink, apply filters, e.g. autocrlf */
755                         if (is_file) {
756                                 struct strbuf buf = STRBUF_INIT;
757
758                                 if (convert_to_git(elem->path, result, len, &buf, safe_crlf)) {
759                                         free(result);
760                                         result = strbuf_detach(&buf, &len);
761                                         result_size = len;
762                                 }
763                         }
764                 }
765                 else {
766                 deleted_file:
767                         result_size = 0;
768                         elem->mode = 0;
769                         result = xcalloc(1, 1);
770                 }
771
772                 if (0 <= fd)
773                         close(fd);
774         }
775
776         for (cnt = 0, cp = result; cp < result + result_size; cp++) {
777                 if (*cp == '\n')
778                         cnt++;
779         }
780         if (result_size && result[result_size-1] != '\n')
781                 cnt++; /* incomplete line */
782
783         sline = xcalloc(cnt+2, sizeof(*sline));
784         sline[0].bol = result;
785         for (lno = 0; lno <= cnt + 1; lno++) {
786                 sline[lno].lost_tail = &sline[lno].lost_head;
787                 sline[lno].flag = 0;
788         }
789         for (lno = 0, cp = result; cp < result + result_size; cp++) {
790                 if (*cp == '\n') {
791                         sline[lno].len = cp - sline[lno].bol;
792                         lno++;
793                         if (lno < cnt)
794                                 sline[lno].bol = cp + 1;
795                 }
796         }
797         if (result_size && result[result_size-1] != '\n')
798                 sline[cnt-1].len = result_size - (sline[cnt-1].bol - result);
799
800         result_file.ptr = result;
801         result_file.size = result_size;
802
803         /* Even p_lno[cnt+1] is valid -- that is for the end line number
804          * for deletion hunk at the end.
805          */
806         sline[0].p_lno = xcalloc((cnt+2) * num_parent, sizeof(unsigned long));
807         for (lno = 0; lno <= cnt; lno++)
808                 sline[lno+1].p_lno = sline[lno].p_lno + num_parent;
809
810         for (i = 0; i < num_parent; i++) {
811                 int j;
812                 for (j = 0; j < i; j++) {
813                         if (!hashcmp(elem->parent[i].sha1,
814                                      elem->parent[j].sha1)) {
815                                 reuse_combine_diff(sline, cnt, i, j);
816                                 break;
817                         }
818                 }
819                 if (i <= j)
820                         combine_diff(elem->parent[i].sha1,
821                                      elem->parent[i].mode,
822                                      &result_file, sline,
823                                      cnt, i, num_parent);
824                 if (elem->parent[i].mode != elem->mode)
825                         mode_differs = 1;
826         }
827
828         show_hunks = make_hunks(sline, cnt, num_parent, dense);
829
830         if (show_hunks || mode_differs || working_tree_file) {
831                 const char *abb;
832                 int use_color = DIFF_OPT_TST(opt, COLOR_DIFF);
833                 const char *c_meta = diff_get_color(use_color, DIFF_METAINFO);
834                 const char *c_reset = diff_get_color(use_color, DIFF_RESET);
835                 int added = 0;
836                 int deleted = 0;
837
838                 if (rev->loginfo && !rev->no_commit_id)
839                         show_log(rev);
840                 dump_quoted_path(dense ? "diff --cc " : "diff --combined ",
841                                  "", elem->path, c_meta, c_reset);
842                 printf("%sindex ", c_meta);
843                 for (i = 0; i < num_parent; i++) {
844                         abb = find_unique_abbrev(elem->parent[i].sha1,
845                                                  abbrev);
846                         printf("%s%s", i ? "," : "", abb);
847                 }
848                 abb = find_unique_abbrev(elem->sha1, abbrev);
849                 printf("..%s%s\n", abb, c_reset);
850
851                 if (mode_differs) {
852                         deleted = !elem->mode;
853
854                         /* We say it was added if nobody had it */
855                         added = !deleted;
856                         for (i = 0; added && i < num_parent; i++)
857                                 if (elem->parent[i].status !=
858                                     DIFF_STATUS_ADDED)
859                                         added = 0;
860                         if (added)
861                                 printf("%snew file mode %06o",
862                                        c_meta, elem->mode);
863                         else {
864                                 if (deleted)
865                                         printf("%sdeleted file ", c_meta);
866                                 printf("mode ");
867                                 for (i = 0; i < num_parent; i++) {
868                                         printf("%s%06o", i ? "," : "",
869                                                elem->parent[i].mode);
870                                 }
871                                 if (elem->mode)
872                                         printf("..%06o", elem->mode);
873                         }
874                         printf("%s\n", c_reset);
875                 }
876                 if (added)
877                         dump_quoted_path("--- ", "", "/dev/null",
878                                          c_meta, c_reset);
879                 else
880                         dump_quoted_path("--- ", a_prefix, elem->path,
881                                          c_meta, c_reset);
882                 if (deleted)
883                         dump_quoted_path("+++ ", "", "/dev/null",
884                                          c_meta, c_reset);
885                 else
886                         dump_quoted_path("+++ ", b_prefix, elem->path,
887                                          c_meta, c_reset);
888                 dump_sline(sline, cnt, num_parent,
889                            DIFF_OPT_TST(opt, COLOR_DIFF));
890         }
891         free(result);
892
893         for (lno = 0; lno < cnt; lno++) {
894                 if (sline[lno].lost_head) {
895                         struct lline *ll = sline[lno].lost_head;
896                         while (ll) {
897                                 struct lline *tmp = ll;
898                                 ll = ll->next;
899                                 free(tmp);
900                         }
901                 }
902         }
903         free(sline[0].p_lno);
904         free(sline);
905 }
906
907 #define COLONS "::::::::::::::::::::::::::::::::"
908
909 static void show_raw_diff(struct combine_diff_path *p, int num_parent, struct rev_info *rev)
910 {
911         struct diff_options *opt = &rev->diffopt;
912         int i, offset;
913         const char *prefix;
914         int line_termination, inter_name_termination;
915
916         line_termination = opt->line_termination;
917         inter_name_termination = '\t';
918         if (!line_termination)
919                 inter_name_termination = 0;
920
921         if (rev->loginfo && !rev->no_commit_id)
922                 show_log(rev);
923
924         if (opt->output_format & DIFF_FORMAT_RAW) {
925                 offset = strlen(COLONS) - num_parent;
926                 if (offset < 0)
927                         offset = 0;
928                 prefix = COLONS + offset;
929
930                 /* Show the modes */
931                 for (i = 0; i < num_parent; i++) {
932                         printf("%s%06o", prefix, p->parent[i].mode);
933                         prefix = " ";
934                 }
935                 printf("%s%06o", prefix, p->mode);
936
937                 /* Show sha1's */
938                 for (i = 0; i < num_parent; i++)
939                         printf(" %s", diff_unique_abbrev(p->parent[i].sha1,
940                                                          opt->abbrev));
941                 printf(" %s ", diff_unique_abbrev(p->sha1, opt->abbrev));
942         }
943
944         if (opt->output_format & (DIFF_FORMAT_RAW | DIFF_FORMAT_NAME_STATUS)) {
945                 for (i = 0; i < num_parent; i++)
946                         putchar(p->parent[i].status);
947                 putchar(inter_name_termination);
948         }
949
950         write_name_quoted(p->path, stdout, line_termination);
951 }
952
953 void show_combined_diff(struct combine_diff_path *p,
954                        int num_parent,
955                        int dense,
956                        struct rev_info *rev)
957 {
958         struct diff_options *opt = &rev->diffopt;
959         if (!p->len)
960                 return;
961         if (opt->output_format & (DIFF_FORMAT_RAW |
962                                   DIFF_FORMAT_NAME |
963                                   DIFF_FORMAT_NAME_STATUS))
964                 show_raw_diff(p, num_parent, rev);
965         else if (opt->output_format & DIFF_FORMAT_PATCH)
966                 show_patch_diff(p, num_parent, dense, rev);
967 }
968
969 void diff_tree_combined(const unsigned char *sha1,
970                         const unsigned char parent[][20],
971                         int num_parent,
972                         int dense,
973                         struct rev_info *rev)
974 {
975         struct diff_options *opt = &rev->diffopt;
976         struct diff_options diffopts;
977         struct combine_diff_path *p, *paths = NULL;
978         int i, num_paths, needsep, show_log_first;
979
980         diffopts = *opt;
981         diffopts.output_format = DIFF_FORMAT_NO_OUTPUT;
982         DIFF_OPT_SET(&diffopts, RECURSIVE);
983         DIFF_OPT_CLR(&diffopts, ALLOW_EXTERNAL);
984
985         show_log_first = !!rev->loginfo && !rev->no_commit_id;
986         needsep = 0;
987         /* find set of paths that everybody touches */
988         for (i = 0; i < num_parent; i++) {
989                 /* show stat against the first parent even
990                  * when doing combined diff.
991                  */
992                 int stat_opt = (opt->output_format &
993                                 (DIFF_FORMAT_NUMSTAT|DIFF_FORMAT_DIFFSTAT));
994                 if (i == 0 && stat_opt)
995                         diffopts.output_format = stat_opt;
996                 else
997                         diffopts.output_format = DIFF_FORMAT_NO_OUTPUT;
998                 diff_tree_sha1(parent[i], sha1, "", &diffopts);
999                 diffcore_std(&diffopts);
1000                 paths = intersect_paths(paths, i, num_parent);
1001
1002                 if (show_log_first && i == 0) {
1003                         show_log(rev);
1004                         if (rev->verbose_header && opt->output_format)
1005                                 putchar(opt->line_termination);
1006                 }
1007                 diff_flush(&diffopts);
1008         }
1009
1010         /* find out surviving paths */
1011         for (num_paths = 0, p = paths; p; p = p->next) {
1012                 if (p->len)
1013                         num_paths++;
1014         }
1015         if (num_paths) {
1016                 if (opt->output_format & (DIFF_FORMAT_RAW |
1017                                           DIFF_FORMAT_NAME |
1018                                           DIFF_FORMAT_NAME_STATUS)) {
1019                         for (p = paths; p; p = p->next) {
1020                                 if (p->len)
1021                                         show_raw_diff(p, num_parent, rev);
1022                         }
1023                         needsep = 1;
1024                 }
1025                 else if (opt->output_format &
1026                          (DIFF_FORMAT_NUMSTAT|DIFF_FORMAT_DIFFSTAT))
1027                         needsep = 1;
1028                 if (opt->output_format & DIFF_FORMAT_PATCH) {
1029                         if (needsep)
1030                                 putchar(opt->line_termination);
1031                         for (p = paths; p; p = p->next) {
1032                                 if (p->len)
1033                                         show_patch_diff(p, num_parent, dense,
1034                                                         rev);
1035                         }
1036                 }
1037         }
1038
1039         /* Clean things up */
1040         while (paths) {
1041                 struct combine_diff_path *tmp = paths;
1042                 paths = paths->next;
1043                 free(tmp);
1044         }
1045 }
1046
1047 void diff_tree_combined_merge(const unsigned char *sha1,
1048                              int dense, struct rev_info *rev)
1049 {
1050         int num_parent;
1051         const unsigned char (*parent)[20];
1052         struct commit *commit = lookup_commit(sha1);
1053         struct commit_list *parents;
1054
1055         /* count parents */
1056         for (parents = commit->parents, num_parent = 0;
1057              parents;
1058              parents = parents->next, num_parent++)
1059                 ; /* nothing */
1060
1061         parent = xmalloc(num_parent * sizeof(*parent));
1062         for (parents = commit->parents, num_parent = 0;
1063              parents;
1064              parents = parents->next, num_parent++)
1065                 hashcpy((unsigned char *)(parent + num_parent),
1066                         parents->item->object.sha1);
1067         diff_tree_combined(sha1, parent, num_parent, dense, rev);
1068 }