git-show-branch: tighten merge-base computation.
[git/git.git] / show-branch.c
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1#include <stdlib.h>
2#include "cache.h"
3#include "commit.h"
4#include "refs.h"
5
6static const char show_branch_usage[] =
1f8af483 7"git-show-branch [--all] [--heads] [--tags] [--more=count | --list | --independent | --merge-base ] [<refs>...]";
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8
9#define UNINTERESTING 01
10
11#define REV_SHIFT 2
12#define MAX_REVS 29 /* should not exceed bits_per_int - REV_SHIFT */
13
14static struct commit *interesting(struct commit_list *list)
15{
16 while (list) {
17 struct commit *commit = list->item;
18 list = list->next;
19 if (commit->object.flags & UNINTERESTING)
20 continue;
21 return commit;
22 }
23 return NULL;
24}
25
26static struct commit *pop_one_commit(struct commit_list **list_p)
27{
28 struct commit *commit;
29 struct commit_list *list;
30 list = *list_p;
31 commit = list->item;
32 *list_p = list->next;
33 free(list);
34 return commit;
35}
36
37struct commit_name {
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38 const char *head_name; /* which head's ancestor? */
39 int generation; /* how many parents away from head_name */
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40};
41
8e5dd22b 42/* Name the commit as nth generation ancestor of head_name;
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43 * we count only the first-parent relationship for naming purposes.
44 */
8e5dd22b 45static void name_commit(struct commit *commit, const char *head_name, int nth)
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46{
47 struct commit_name *name;
48 if (!commit->object.util)
49 commit->object.util = xmalloc(sizeof(struct commit_name));
50 name = commit->object.util;
8e5dd22b 51 name->head_name = head_name;
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52 name->generation = nth;
53}
54
55/* Parent is the first parent of the commit. We may name it
8e5dd22b 56 * as (n+1)th generation ancestor of the same head_name as
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57 * commit is nth generation ancestore of, if that generation
58 * number is better than the name it already has.
59 */
60static void name_parent(struct commit *commit, struct commit *parent)
61{
62 struct commit_name *commit_name = commit->object.util;
63 struct commit_name *parent_name = parent->object.util;
64 if (!commit_name)
65 return;
66 if (!parent_name ||
67 commit_name->generation + 1 < parent_name->generation)
8e5dd22b 68 name_commit(parent, commit_name->head_name,
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69 commit_name->generation + 1);
70}
71
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72static int name_first_parent_chain(struct commit *c)
73{
74 int i = 0;
75 while (c) {
76 struct commit *p;
77 if (!c->object.util)
78 break;
79 if (!c->parents)
80 break;
81 p = c->parents->item;
82 if (!p->object.util) {
83 name_parent(c, p);
84 i++;
85 }
86 c = p;
87 }
88 return i;
89}
90
91static void name_commits(struct commit_list *list,
92 struct commit **rev,
93 char **ref_name,
94 int num_rev)
95{
96 struct commit_list *cl;
97 struct commit *c;
98 int i;
99
100 /* First give names to the given heads */
101 for (cl = list; cl; cl = cl->next) {
102 c = cl->item;
103 if (c->object.util)
104 continue;
105 for (i = 0; i < num_rev; i++) {
106 if (rev[i] == c) {
107 name_commit(c, ref_name[i], 0);
108 break;
109 }
110 }
111 }
112
113 /* Then commits on the first parent ancestry chain */
114 do {
115 i = 0;
116 for (cl = list; cl; cl = cl->next) {
117 i += name_first_parent_chain(cl->item);
118 }
119 } while (i);
120
121 /* Finally, any unnamed commits */
122 do {
123 i = 0;
124 for (cl = list; cl; cl = cl->next) {
125 struct commit_list *parents;
126 struct commit_name *n;
127 int nth;
128 c = cl->item;
129 if (!c->object.util)
130 continue;
131 n = c->object.util;
132 parents = c->parents;
133 nth = 0;
134 while (parents) {
135 struct commit *p = parents->item;
013f276e 136 char newname[1000], *en;
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137 parents = parents->next;
138 nth++;
139 if (p->object.util)
140 continue;
013f276e 141 en = newname;
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142 switch (n->generation) {
143 case 0:
013f276e 144 en += sprintf(en, "%s", n->head_name);
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145 break;
146 case 1:
013f276e 147 en += sprintf(en, "%s^", n->head_name);
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148 break;
149 default:
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150 en += sprintf(en, "%s~%d",
151 n->head_name, n->generation);
152 break;
fbaf834d 153 }
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154 if (nth == 1)
155 en += sprintf(en, "^");
156 else
157 en += sprintf(en, "^%d", nth);
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158 name_commit(p, strdup(newname), 0);
159 i++;
160 name_first_parent_chain(p);
161 }
162 }
163 } while (i);
164}
165
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166static int mark_seen(struct commit *commit, struct commit_list **seen_p)
167{
168 if (!commit->object.flags) {
169 insert_by_date(commit, seen_p);
170 return 1;
171 }
172 return 0;
173}
174
175static void join_revs(struct commit_list **list_p,
176 struct commit_list **seen_p,
177 int num_rev, int extra)
178{
179 int all_mask = ((1u << (REV_SHIFT + num_rev)) - 1);
180 int all_revs = all_mask & ~((1u << REV_SHIFT) - 1);
181
182 while (*list_p) {
183 struct commit_list *parents;
9ce70285 184 int still_interesting = !!interesting(*list_p);
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185 struct commit *commit = pop_one_commit(list_p);
186 int flags = commit->object.flags & all_mask;
f76412ed 187
9ce70285 188 if (!still_interesting && extra <= 0)
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189 break;
190
191 mark_seen(commit, seen_p);
192 if ((flags & all_revs) == all_revs)
193 flags |= UNINTERESTING;
194 parents = commit->parents;
195
196 while (parents) {
197 struct commit *p = parents->item;
198 int this_flag = p->object.flags;
199 parents = parents->next;
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200 if ((this_flag & flags) == flags)
201 continue;
202 parse_commit(p);
203 if (mark_seen(p, seen_p) && !still_interesting)
204 extra--;
205 p->object.flags |= flags;
206 insert_by_date(p, list_p);
207 }
208 }
209}
210
013f276e 211static void show_one_commit(struct commit *commit, int no_name)
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212{
213 char pretty[128], *cp;
214 struct commit_name *name = commit->object.util;
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215 if (commit->object.parsed)
216 pretty_print_commit(CMIT_FMT_ONELINE, commit->buffer, ~0,
217 pretty, sizeof(pretty));
218 else
219 strcpy(pretty, "(unavailable)");
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220 if (!strncmp(pretty, "[PATCH] ", 8))
221 cp = pretty + 8;
222 else
223 cp = pretty;
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224
225 if (!no_name) {
226 if (name && name->head_name) {
227 printf("[%s", name->head_name);
228 if (name->generation) {
229 if (name->generation == 1)
230 printf("^");
231 else
232 printf("~%d", name->generation);
233 }
234 printf("] ");
235 }
236 else
237 printf("[%s] ",
238 find_unique_abbrev(commit->object.sha1, 7));
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239 }
240 puts(cp);
241}
242
243static char *ref_name[MAX_REVS + 1];
244static int ref_name_cnt;
245
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246static int compare_ref_name(const void *a_, const void *b_)
247{
248 const char * const*a = a_, * const*b = b_;
249 return strcmp(*a, *b);
250}
251
252static void sort_ref_range(int bottom, int top)
253{
254 qsort(ref_name + bottom, top - bottom, sizeof(ref_name[0]),
255 compare_ref_name);
256}
257
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258static int append_ref(const char *refname, const unsigned char *sha1)
259{
260 struct commit *commit = lookup_commit_reference_gently(sha1, 1);
261 if (!commit)
262 return 0;
79778e46 263 if (MAX_REVS <= ref_name_cnt) {
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264 fprintf(stderr, "warning: ignoring %s; "
265 "cannot handle more than %d refs",
266 refname, MAX_REVS);
267 return 0;
268 }
269 ref_name[ref_name_cnt++] = strdup(refname);
270 ref_name[ref_name_cnt] = NULL;
271 return 0;
272}
273
274static int append_head_ref(const char *refname, const unsigned char *sha1)
275{
276 if (strncmp(refname, "refs/heads/", 11))
277 return 0;
628894b2 278 return append_ref(refname + 11, sha1);
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279}
280
281static int append_tag_ref(const char *refname, const unsigned char *sha1)
282{
283 if (strncmp(refname, "refs/tags/", 10))
284 return 0;
285 return append_ref(refname + 5, sha1);
286}
287
288static void snarf_refs(int head, int tag)
289{
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290 if (head) {
291 int orig_cnt = ref_name_cnt;
f76412ed 292 for_each_ref(append_head_ref);
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293 sort_ref_range(orig_cnt, ref_name_cnt);
294 }
295 if (tag) {
296 int orig_cnt = ref_name_cnt;
f76412ed 297 for_each_ref(append_tag_ref);
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298 sort_ref_range(orig_cnt, ref_name_cnt);
299 }
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300}
301
302static int rev_is_head(char *head_path, int headlen,
303 char *name,
304 unsigned char *head_sha1, unsigned char *sha1)
305{
306 int namelen;
307 if ((!head_path[0]) || memcmp(head_sha1, sha1, 20))
308 return 0;
309 namelen = strlen(name);
310 if ((headlen < namelen) ||
311 memcmp(head_path + headlen - namelen, name, namelen))
312 return 0;
313 if (headlen == namelen ||
314 head_path[headlen - namelen - 1] == '/')
315 return 1;
316 return 0;
317}
318
319static int show_merge_base(struct commit_list *seen, int num_rev)
320{
321 int all_mask = ((1u << (REV_SHIFT + num_rev)) - 1);
322 int all_revs = all_mask & ~((1u << REV_SHIFT) - 1);
2f0f8b71 323 int exit_status = 1;
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324
325 while (seen) {
326 struct commit *commit = pop_one_commit(&seen);
327 int flags = commit->object.flags & all_mask;
328 if (!(flags & UNINTERESTING) &&
329 ((flags & all_revs) == all_revs)) {
330 puts(sha1_to_hex(commit->object.sha1));
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331 exit_status = 0;
332 commit->object.flags |= UNINTERESTING;
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333 }
334 }
2f0f8b71 335 return exit_status;
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336}
337
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338static int show_independent(struct commit **rev,
339 int num_rev,
340 char **ref_name,
341 unsigned int *rev_mask)
342{
343 int i;
344
345 for (i = 0; i < num_rev; i++) {
346 struct commit *commit = rev[i];
347 unsigned int flag = rev_mask[i];
348
349 if (commit->object.flags == flag)
350 puts(sha1_to_hex(commit->object.sha1));
351 commit->object.flags |= UNINTERESTING;
352 }
353 return 0;
354}
355
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356int main(int ac, char **av)
357{
358 struct commit *rev[MAX_REVS], *commit;
359 struct commit_list *list = NULL, *seen = NULL;
1f8af483 360 unsigned int rev_mask[MAX_REVS];
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361 int num_rev, i, extra = 0;
362 int all_heads = 0, all_tags = 0;
8e5dd22b 363 int all_mask, all_revs, shown_merge_point;
f76412ed 364 char head_path[128];
8098a178 365 const char *head_path_p;
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366 int head_path_len;
367 unsigned char head_sha1[20];
368 int merge_base = 0;
1f8af483 369 int independent = 0;
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370 int no_name = 0;
371 int sha1_name = 0;
f76412ed 372
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373 setup_git_directory();
374
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375 while (1 < ac && av[1][0] == '-') {
376 char *arg = av[1];
377 if (!strcmp(arg, "--all"))
378 all_heads = all_tags = 1;
379 else if (!strcmp(arg, "--heads"))
380 all_heads = 1;
381 else if (!strcmp(arg, "--tags"))
382 all_tags = 1;
383 else if (!strcmp(arg, "--more"))
384 extra = 1;
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385 else if (!strcmp(arg, "--list"))
386 extra = -1;
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387 else if (!strcmp(arg, "--no-name"))
388 no_name = 1;
389 else if (!strcmp(arg, "--sha1-name"))
390 sha1_name = 1;
1f8af483 391 else if (!strncmp(arg, "--more=", 7))
f76412ed 392 extra = atoi(arg + 7);
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393 else if (!strcmp(arg, "--merge-base"))
394 merge_base = 1;
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395 else if (!strcmp(arg, "--independent"))
396 independent = 1;
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397 else
398 usage(show_branch_usage);
399 ac--; av++;
400 }
401 ac--; av++;
402
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403 /* Only one of these is allowed */
404 if (1 < independent + merge_base + (extra != 0))
405 usage(show_branch_usage);
406
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407 if (all_heads + all_tags)
408 snarf_refs(all_heads, all_tags);
409
410 while (0 < ac) {
411 unsigned char revkey[20];
412 if (get_sha1(*av, revkey))
413 die("bad sha1 reference %s", *av);
414 append_ref(*av, revkey);
415 ac--; av++;
416 }
417
418 /* If still no revs, then add heads */
419 if (!ref_name_cnt)
420 snarf_refs(1, 0);
421
422 for (num_rev = 0; ref_name[num_rev]; num_rev++) {
423 unsigned char revkey[20];
1f8af483 424 unsigned int flag = 1u << (num_rev + REV_SHIFT);
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425
426 if (MAX_REVS <= num_rev)
427 die("cannot handle more than %d revs.", MAX_REVS);
428 if (get_sha1(ref_name[num_rev], revkey))
429 usage(show_branch_usage);
430 commit = lookup_commit_reference(revkey);
431 if (!commit)
432 die("cannot find commit %s (%s)",
433 ref_name[num_rev], revkey);
434 parse_commit(commit);
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435 mark_seen(commit, &seen);
436
437 /* rev#0 uses bit REV_SHIFT, rev#1 uses bit REV_SHIFT+1,
438 * and so on. REV_SHIFT bits from bit 0 are used for
439 * internal bookkeeping.
440 */
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441 commit->object.flags |= flag;
442 if (commit->object.flags == flag)
443 insert_by_date(commit, &list);
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444 rev[num_rev] = commit;
445 }
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446 for (i = 0; i < num_rev; i++)
447 rev_mask[i] = rev[i]->object.flags;
448
449 if (0 <= extra)
450 join_revs(&list, &seen, num_rev, extra);
f76412ed 451
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452 head_path_p = resolve_ref(git_path("HEAD"), head_sha1, 1);
453 if (head_path_p) {
454 head_path_len = strlen(head_path_p);
455 memcpy(head_path, head_path_p, head_path_len + 1);
456 }
457 else {
458 head_path_len = 0;
f76412ed 459 head_path[0] = 0;
8098a178 460 }
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461
462 if (merge_base)
463 return show_merge_base(seen, num_rev);
464
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465 if (independent)
466 return show_independent(rev, num_rev, ref_name, rev_mask);
467
468 /* Show list; --more=-1 means list-only */
c9d023b2 469 if (1 < num_rev || extra < 0) {
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470 for (i = 0; i < num_rev; i++) {
471 int j;
472 int is_head = rev_is_head(head_path,
473 head_path_len,
474 ref_name[i],
475 head_sha1,
476 rev[i]->object.sha1);
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477 if (extra < 0)
478 printf("%c [%s] ",
479 is_head ? '*' : ' ', ref_name[i]);
480 else {
481 for (j = 0; j < i; j++)
482 putchar(' ');
483 printf("%c [%s] ",
484 is_head ? '*' : '!', ref_name[i]);
485 }
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486 /* header lines never need name */
487 show_one_commit(rev[i], 1);
f76412ed 488 }
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489 if (0 <= extra) {
490 for (i = 0; i < num_rev; i++)
491 putchar('-');
492 putchar('\n');
493 }
f5e375c9 494 }
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495 if (extra < 0)
496 exit(0);
f5e375c9 497
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498 /* Sort topologically */
499 sort_in_topological_order(&seen);
500
501 /* Give names to commits */
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502 if (!sha1_name && !no_name)
503 name_commits(seen, rev, ref_name, num_rev);
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504
505 all_mask = ((1u << (REV_SHIFT + num_rev)) - 1);
506 all_revs = all_mask & ~((1u << REV_SHIFT) - 1);
507 shown_merge_point = 0;
508
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509 while (seen) {
510 struct commit *commit = pop_one_commit(&seen);
511 int this_flag = commit->object.flags;
8e5dd22b 512 int is_merge_point = (this_flag & all_revs) == all_revs;
f5e375c9 513
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514 if (is_merge_point)
515 shown_merge_point = 1;
516
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517 if (1 < num_rev) {
518 for (i = 0; i < num_rev; i++)
519 putchar((this_flag & (1u << (i + REV_SHIFT)))
520 ? '+' : ' ');
521 putchar(' ');
522 }
013f276e 523 show_one_commit(commit, no_name);
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524 if (shown_merge_point && is_merge_point)
525 if (--extra < 0)
526 break;
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527 }
528 return 0;
529}