Teach update-ref about a symbolic ref stored in a textfile.
[git] / show-branch.c
1 #include <stdlib.h>
2 #include "cache.h"
3 #include "commit.h"
4 #include "refs.h"
5
6 static const char show_branch_usage[] =
7 "git-show-branch [--all] [--heads] [--tags] [--more=count | --list | --independent | --merge-base ] [<refs>...]";
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
14 static 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
26 static 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
37 struct commit_name {
38         const char *head_name; /* which head's ancestor? */
39         int generation; /* how many parents away from head_name */
40 };
41
42 /* Name the commit as nth generation ancestor of head_name;
43  * we count only the first-parent relationship for naming purposes.
44  */
45 static void name_commit(struct commit *commit, const char *head_name, int nth)
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;
51         name->head_name = head_name;
52         name->generation = nth;
53 }
54
55 /* Parent is the first parent of the commit.  We may name it
56  * as (n+1)th generation ancestor of the same head_name as
57  * commit is nth generation ancestore of, if that generation
58  * number is better than the name it already has.
59  */
60 static 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)
68                 name_commit(parent, commit_name->head_name,
69                             commit_name->generation + 1);
70 }
71
72 static 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
91 static 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;
136                                 char newname[1000];
137                                 parents = parents->next;
138                                 nth++;
139                                 if (p->object.util)
140                                         continue;
141                                 switch (n->generation) {
142                                 case 0:
143                                         sprintf(newname, "%s^%d",
144                                                 n->head_name, nth);
145                                         break;
146                                 case 1:
147                                         sprintf(newname, "%s^^%d",
148                                                 n->head_name, nth);
149                                         break;
150                                 default:
151                                         sprintf(newname, "%s~%d^%d",
152                                                 n->head_name, n->generation,
153                                                 nth);
154                                 }
155                                 name_commit(p, strdup(newname), 0);
156                                 i++;
157                                 name_first_parent_chain(p);
158                         }
159                 }
160         } while (i);
161 }
162
163 static int mark_seen(struct commit *commit, struct commit_list **seen_p)
164 {
165         if (!commit->object.flags) {
166                 insert_by_date(commit, seen_p);
167                 return 1;
168         }
169         return 0;
170 }
171
172 static void join_revs(struct commit_list **list_p,
173                       struct commit_list **seen_p,
174                       int num_rev, int extra)
175 {
176         int all_mask = ((1u << (REV_SHIFT + num_rev)) - 1);
177         int all_revs = all_mask & ~((1u << REV_SHIFT) - 1);
178
179         while (*list_p) {
180                 struct commit_list *parents;
181                 struct commit *commit = pop_one_commit(list_p);
182                 int flags = commit->object.flags & all_mask;
183                 int still_interesting = !!interesting(*list_p);
184
185                 if (!still_interesting && extra < 0)
186                         break;
187
188                 mark_seen(commit, seen_p);
189                 if ((flags & all_revs) == all_revs)
190                         flags |= UNINTERESTING;
191                 parents = commit->parents;
192
193                 while (parents) {
194                         struct commit *p = parents->item;
195                         int this_flag = p->object.flags;
196                         parents = parents->next;
197                         if ((this_flag & flags) == flags)
198                                 continue;
199                         parse_commit(p);
200                         if (mark_seen(p, seen_p) && !still_interesting)
201                                 extra--;
202                         p->object.flags |= flags;
203                         insert_by_date(p, list_p);
204                 }
205         }
206 }
207
208 static void show_one_commit(struct commit *commit)
209 {
210         char pretty[128], *cp;
211         struct commit_name *name = commit->object.util;
212         if (commit->object.parsed)
213                 pretty_print_commit(CMIT_FMT_ONELINE, commit->buffer, ~0,
214                                     pretty, sizeof(pretty));
215         else
216                 strcpy(pretty, "(unavailable)");
217         if (!strncmp(pretty, "[PATCH] ", 8))
218                 cp = pretty + 8;
219         else
220                 cp = pretty;
221         if (name && name->head_name) {
222                 printf("[%s", name->head_name);
223                 if (name->generation)
224                         printf("~%d", name->generation);
225                 printf("] ");
226         }
227         puts(cp);
228 }
229
230 static char *ref_name[MAX_REVS + 1];
231 static int ref_name_cnt;
232
233 static int compare_ref_name(const void *a_, const void *b_)
234 {
235         const char * const*a = a_, * const*b = b_;
236         return strcmp(*a, *b);
237 }
238
239 static void sort_ref_range(int bottom, int top)
240 {
241         qsort(ref_name + bottom, top - bottom, sizeof(ref_name[0]),
242               compare_ref_name);
243 }
244
245 static int append_ref(const char *refname, const unsigned char *sha1)
246 {
247         struct commit *commit = lookup_commit_reference_gently(sha1, 1);
248         if (!commit)
249                 return 0;
250         if (MAX_REVS < ref_name_cnt) {
251                 fprintf(stderr, "warning: ignoring %s; "
252                         "cannot handle more than %d refs",
253                         refname, MAX_REVS);
254                 return 0;
255         }
256         ref_name[ref_name_cnt++] = strdup(refname);
257         ref_name[ref_name_cnt] = NULL;
258         return 0;
259 }
260
261 static int append_head_ref(const char *refname, const unsigned char *sha1)
262 {
263         if (strncmp(refname, "refs/heads/", 11))
264                 return 0;
265         return append_ref(refname + 11, sha1);
266 }
267
268 static int append_tag_ref(const char *refname, const unsigned char *sha1)
269 {
270         if (strncmp(refname, "refs/tags/", 10))
271                 return 0;
272         return append_ref(refname + 5, sha1);
273 }
274
275 static void snarf_refs(int head, int tag)
276 {
277         if (head) {
278                 int orig_cnt = ref_name_cnt;
279                 for_each_ref(append_head_ref);
280                 sort_ref_range(orig_cnt, ref_name_cnt);
281         }
282         if (tag) {
283                 int orig_cnt = ref_name_cnt;
284                 for_each_ref(append_tag_ref);
285                 sort_ref_range(orig_cnt, ref_name_cnt);
286         }
287 }
288
289 static int rev_is_head(char *head_path, int headlen,
290                        char *name,
291                        unsigned char *head_sha1, unsigned char *sha1)
292 {
293         int namelen;
294         if ((!head_path[0]) || memcmp(head_sha1, sha1, 20))
295                 return 0;
296         namelen = strlen(name);
297         if ((headlen < namelen) ||
298             memcmp(head_path + headlen - namelen, name, namelen))
299                 return 0;
300         if (headlen == namelen ||
301             head_path[headlen - namelen - 1] == '/')
302                 return 1;
303         return 0;
304 }
305
306 static int show_merge_base(struct commit_list *seen, int num_rev)
307 {
308         int all_mask = ((1u << (REV_SHIFT + num_rev)) - 1);
309         int all_revs = all_mask & ~((1u << REV_SHIFT) - 1);
310         int exit_status = 1;
311
312         while (seen) {
313                 struct commit *commit = pop_one_commit(&seen);
314                 int flags = commit->object.flags & all_mask;
315                 if (!(flags & UNINTERESTING) &&
316                     ((flags & all_revs) == all_revs)) {
317                         puts(sha1_to_hex(commit->object.sha1));
318                         exit_status = 0;
319                         commit->object.flags |= UNINTERESTING;
320                 }
321         }
322         return exit_status;
323 }
324
325 static int show_independent(struct commit **rev,
326                             int num_rev,
327                             char **ref_name,
328                             unsigned int *rev_mask)
329 {
330         int i;
331
332         for (i = 0; i < num_rev; i++) {
333                 struct commit *commit = rev[i];
334                 unsigned int flag = rev_mask[i];
335
336                 if (commit->object.flags == flag)
337                         puts(sha1_to_hex(commit->object.sha1));
338                 commit->object.flags |= UNINTERESTING;
339         }
340         return 0;
341 }
342
343 int main(int ac, char **av)
344 {
345         struct commit *rev[MAX_REVS], *commit;
346         struct commit_list *list = NULL, *seen = NULL;
347         unsigned int rev_mask[MAX_REVS];
348         int num_rev, i, extra = 0;
349         int all_heads = 0, all_tags = 0;
350         int all_mask, all_revs, shown_merge_point;
351         char head_path[128];
352         int head_path_len;
353         unsigned char head_sha1[20];
354         int merge_base = 0;
355         int independent = 0;
356         char **label;
357
358         setup_git_directory();
359
360         while (1 < ac && av[1][0] == '-') {
361                 char *arg = av[1];
362                 if (!strcmp(arg, "--all"))
363                         all_heads = all_tags = 1;
364                 else if (!strcmp(arg, "--heads"))
365                         all_heads = 1;
366                 else if (!strcmp(arg, "--tags"))
367                         all_tags = 1;
368                 else if (!strcmp(arg, "--more"))
369                         extra = 1;
370                 else if (!strcmp(arg, "--list"))
371                         extra = -1;
372                 else if (!strncmp(arg, "--more=", 7))
373                         extra = atoi(arg + 7);
374                 else if (!strcmp(arg, "--merge-base"))
375                         merge_base = 1;
376                 else if (!strcmp(arg, "--independent"))
377                         independent = 1;
378                 else
379                         usage(show_branch_usage);
380                 ac--; av++;
381         }
382         ac--; av++;
383
384         /* Only one of these is allowed */
385         if (1 < independent + merge_base + (extra != 0))
386                 usage(show_branch_usage);
387
388         if (all_heads + all_tags)
389                 snarf_refs(all_heads, all_tags);
390
391         while (0 < ac) {
392                 unsigned char revkey[20];
393                 if (get_sha1(*av, revkey))
394                         die("bad sha1 reference %s", *av);
395                 append_ref(*av, revkey);
396                 ac--; av++;
397         }
398
399         /* If still no revs, then add heads */
400         if (!ref_name_cnt)
401                 snarf_refs(1, 0);
402
403         for (num_rev = 0; ref_name[num_rev]; num_rev++) {
404                 unsigned char revkey[20];
405                 unsigned int flag = 1u << (num_rev + REV_SHIFT);
406
407                 if (MAX_REVS <= num_rev)
408                         die("cannot handle more than %d revs.", MAX_REVS);
409                 if (get_sha1(ref_name[num_rev], revkey))
410                         usage(show_branch_usage);
411                 commit = lookup_commit_reference(revkey);
412                 if (!commit)
413                         die("cannot find commit %s (%s)",
414                             ref_name[num_rev], revkey);
415                 parse_commit(commit);
416                 mark_seen(commit, &seen);
417
418                 /* rev#0 uses bit REV_SHIFT, rev#1 uses bit REV_SHIFT+1,
419                  * and so on.  REV_SHIFT bits from bit 0 are used for
420                  * internal bookkeeping.
421                  */
422                 commit->object.flags |= flag;
423                 if (commit->object.flags == flag)
424                         insert_by_date(commit, &list);
425                 rev[num_rev] = commit;
426         }
427         for (i = 0; i < num_rev; i++)
428                 rev_mask[i] = rev[i]->object.flags;
429
430         if (0 <= extra)
431                 join_revs(&list, &seen, num_rev, extra);
432
433         head_path_len = readlink(".git/HEAD", head_path, sizeof(head_path)-1);
434         if ((head_path_len < 0) || get_sha1("HEAD", head_sha1))
435                 head_path[0] = 0;
436         else
437                 head_path[head_path_len] = 0;
438
439         if (merge_base)
440                 return show_merge_base(seen, num_rev);
441
442         if (independent)
443                 return show_independent(rev, num_rev, ref_name, rev_mask);
444
445         /* Show list; --more=-1 means list-only */
446         if (1 < num_rev || extra < 0) {
447                 for (i = 0; i < num_rev; i++) {
448                         int j;
449                         int is_head = rev_is_head(head_path,
450                                                   head_path_len,
451                                                   ref_name[i],
452                                                   head_sha1,
453                                                   rev[i]->object.sha1);
454                         if (extra < 0)
455                                 printf("%c [%s] ",
456                                        is_head ? '*' : ' ', ref_name[i]);
457                         else {
458                                 for (j = 0; j < i; j++)
459                                         putchar(' ');
460                                 printf("%c [%s] ",
461                                        is_head ? '*' : '!', ref_name[i]);
462                         }
463                         show_one_commit(rev[i]);
464                 }
465                 if (0 <= extra) {
466                         for (i = 0; i < num_rev; i++)
467                                 putchar('-');
468                         putchar('\n');
469                 }
470         }
471         if (extra < 0)
472                 exit(0);
473
474         /* Sort topologically */
475         sort_in_topological_order(&seen);
476
477         /* Give names to commits */
478         name_commits(seen, rev, ref_name, num_rev);
479
480         all_mask = ((1u << (REV_SHIFT + num_rev)) - 1);
481         all_revs = all_mask & ~((1u << REV_SHIFT) - 1);
482         shown_merge_point = 0;
483
484         while (seen) {
485                 struct commit *commit = pop_one_commit(&seen);
486                 int this_flag = commit->object.flags;
487                 int is_merge_point = (this_flag & all_revs) == all_revs;
488                 static char *obvious[] = { "" };
489
490                 if (is_merge_point)
491                         shown_merge_point = 1;
492
493                 if (1 < num_rev) {
494                         for (i = 0; i < num_rev; i++)
495                                 putchar((this_flag & (1u << (i + REV_SHIFT)))
496                                         ? '+' : ' ');
497                         putchar(' ');
498                 }
499                 show_one_commit(commit);
500                 if (num_rev == 1)
501                         label = obvious;
502                 if (shown_merge_point && is_merge_point)
503                         if (--extra < 0)
504                                 break;
505         }
506         return 0;
507 }