Accumulated documentation updates.
[git.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] [<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                                 sprintf(newname, "%s^%d", n->head_name, nth);
142                                 name_commit(p, strdup(newname), 0);
143                                 i++;
144                                 name_first_parent_chain(p);
145                         }
146                 }
147         } while (i);
148 }
149
150 static int mark_seen(struct commit *commit, struct commit_list **seen_p)
151 {
152         if (!commit->object.flags) {
153                 insert_by_date(commit, seen_p);
154                 return 1;
155         }
156         return 0;
157 }
158
159 static void join_revs(struct commit_list **list_p,
160                       struct commit_list **seen_p,
161                       int num_rev, int extra)
162 {
163         int all_mask = ((1u << (REV_SHIFT + num_rev)) - 1);
164         int all_revs = all_mask & ~((1u << REV_SHIFT) - 1);
165
166         while (*list_p) {
167                 struct commit_list *parents;
168                 struct commit *commit = pop_one_commit(list_p);
169                 int flags = commit->object.flags & all_mask;
170                 int still_interesting = !!interesting(*list_p);
171
172                 if (!still_interesting && extra < 0)
173                         break;
174
175                 mark_seen(commit, seen_p);
176                 if ((flags & all_revs) == all_revs)
177                         flags |= UNINTERESTING;
178                 parents = commit->parents;
179
180                 while (parents) {
181                         struct commit *p = parents->item;
182                         int this_flag = p->object.flags;
183                         parents = parents->next;
184                         if ((this_flag & flags) == flags)
185                                 continue;
186                         parse_commit(p);
187                         if (mark_seen(p, seen_p) && !still_interesting)
188                                 extra--;
189                         p->object.flags |= flags;
190                         insert_by_date(p, list_p);
191                 }
192         }
193 }
194
195 static void show_one_commit(struct commit *commit)
196 {
197         char pretty[128], *cp;
198         struct commit_name *name = commit->object.util;
199         pretty_print_commit(CMIT_FMT_ONELINE, commit->buffer, ~0,
200                             pretty, sizeof(pretty));
201         if (!strncmp(pretty, "[PATCH] ", 8))
202                 cp = pretty + 8;
203         else
204                 cp = pretty;
205         if (name && name->head_name) {
206                 printf("[%s", name->head_name);
207                 if (name->generation)
208                         printf("~%d", name->generation);
209                 printf("] ");
210         }
211         puts(cp);
212 }
213
214 static char *ref_name[MAX_REVS + 1];
215 static int ref_name_cnt;
216
217 static int compare_ref_name(const void *a_, const void *b_)
218 {
219         const char * const*a = a_, * const*b = b_;
220         return strcmp(*a, *b);
221 }
222
223 static void sort_ref_range(int bottom, int top)
224 {
225         qsort(ref_name + bottom, top - bottom, sizeof(ref_name[0]),
226               compare_ref_name);
227 }
228
229 static int append_ref(const char *refname, const unsigned char *sha1)
230 {
231         struct commit *commit = lookup_commit_reference_gently(sha1, 1);
232         if (!commit)
233                 return 0;
234         if (MAX_REVS < ref_name_cnt) {
235                 fprintf(stderr, "warning: ignoring %s; "
236                         "cannot handle more than %d refs",
237                         refname, MAX_REVS);
238                 return 0;
239         }
240         ref_name[ref_name_cnt++] = strdup(refname);
241         ref_name[ref_name_cnt] = NULL;
242         return 0;
243 }
244
245 static int append_head_ref(const char *refname, const unsigned char *sha1)
246 {
247         if (strncmp(refname, "refs/heads/", 11))
248                 return 0;
249         return append_ref(refname + 11, sha1);
250 }
251
252 static int append_tag_ref(const char *refname, const unsigned char *sha1)
253 {
254         if (strncmp(refname, "refs/tags/", 10))
255                 return 0;
256         return append_ref(refname + 5, sha1);
257 }
258
259 static void snarf_refs(int head, int tag)
260 {
261         if (head) {
262                 int orig_cnt = ref_name_cnt;
263                 for_each_ref(append_head_ref);
264                 sort_ref_range(orig_cnt, ref_name_cnt);
265         }
266         if (tag) {
267                 int orig_cnt = ref_name_cnt;
268                 for_each_ref(append_tag_ref);
269                 sort_ref_range(orig_cnt, ref_name_cnt);
270         }
271 }
272
273 static int rev_is_head(char *head_path, int headlen,
274                        char *name,
275                        unsigned char *head_sha1, unsigned char *sha1)
276 {
277         int namelen;
278         if ((!head_path[0]) || memcmp(head_sha1, sha1, 20))
279                 return 0;
280         namelen = strlen(name);
281         if ((headlen < namelen) ||
282             memcmp(head_path + headlen - namelen, name, namelen))
283                 return 0;
284         if (headlen == namelen ||
285             head_path[headlen - namelen - 1] == '/')
286                 return 1;
287         return 0;
288 }
289
290 static int show_merge_base(struct commit_list *seen, int num_rev)
291 {
292         int all_mask = ((1u << (REV_SHIFT + num_rev)) - 1);
293         int all_revs = all_mask & ~((1u << REV_SHIFT) - 1);
294
295         while (seen) {
296                 struct commit *commit = pop_one_commit(&seen);
297                 int flags = commit->object.flags & all_mask;
298                 if (!(flags & UNINTERESTING) &&
299                     ((flags & all_revs) == all_revs)) {
300                         puts(sha1_to_hex(commit->object.sha1));
301                         return 0;
302                 }
303         }
304         return 1;
305 }
306
307 int main(int ac, char **av)
308 {
309         struct commit *rev[MAX_REVS], *commit;
310         struct commit_list *list = NULL, *seen = NULL;
311         int num_rev, i, extra = 0;
312         int all_heads = 0, all_tags = 0;
313         int all_mask, all_revs, shown_merge_point;
314         char head_path[128];
315         int head_path_len;
316         unsigned char head_sha1[20];
317         int merge_base = 0;
318         char **label;
319
320         while (1 < ac && av[1][0] == '-') {
321                 char *arg = av[1];
322                 if (!strcmp(arg, "--all"))
323                         all_heads = all_tags = 1;
324                 else if (!strcmp(arg, "--heads"))
325                         all_heads = 1;
326                 else if (!strcmp(arg, "--tags"))
327                         all_tags = 1;
328                 else if (!strcmp(arg, "--more"))
329                         extra = 1;
330                 else if (!strncmp(arg, "--more=", 7)) {
331                         extra = atoi(arg + 7);
332                         if (extra < 0)
333                                 usage(show_branch_usage);
334                 }
335                 else if (!strcmp(arg, "--merge-base"))
336                         merge_base = 1;
337                 else
338                         usage(show_branch_usage);
339                 ac--; av++;
340         }
341         ac--; av++;
342
343         if (all_heads + all_tags)
344                 snarf_refs(all_heads, all_tags);
345
346         while (0 < ac) {
347                 unsigned char revkey[20];
348                 if (get_sha1(*av, revkey))
349                         die("bad sha1 reference %s", *av);
350                 append_ref(*av, revkey);
351                 ac--; av++;
352         }
353
354         /* If still no revs, then add heads */
355         if (!ref_name_cnt)
356                 snarf_refs(1, 0);
357
358         for (num_rev = 0; ref_name[num_rev]; num_rev++) {
359                 unsigned char revkey[20];
360
361                 if (MAX_REVS <= num_rev)
362                         die("cannot handle more than %d revs.", MAX_REVS);
363                 if (get_sha1(ref_name[num_rev], revkey))
364                         usage(show_branch_usage);
365                 commit = lookup_commit_reference(revkey);
366                 if (!commit)
367                         die("cannot find commit %s (%s)",
368                             ref_name[num_rev], revkey);
369                 parse_commit(commit);
370                 mark_seen(commit, &seen);
371
372                 /* rev#0 uses bit REV_SHIFT, rev#1 uses bit REV_SHIFT+1,
373                  * and so on.  REV_SHIFT bits from bit 0 are used for
374                  * internal bookkeeping.
375                  */
376                 commit->object.flags |= 1u << (num_rev + REV_SHIFT);
377                 insert_by_date(commit, &list);
378                 rev[num_rev] = commit;
379         }
380         join_revs(&list, &seen, num_rev, extra);
381
382         head_path_len = readlink(".git/HEAD", head_path, sizeof(head_path)-1);
383         if ((head_path_len < 0) || get_sha1("HEAD", head_sha1))
384                 head_path[0] = 0;
385         else
386                 head_path[head_path_len] = 0;
387
388         if (merge_base)
389                 return show_merge_base(seen, num_rev);
390
391         /* Show list */
392         if (1 < num_rev) {
393                 for (i = 0; i < num_rev; i++) {
394                         int j;
395                         int is_head = rev_is_head(head_path,
396                                                   head_path_len,
397                                                   ref_name[i],
398                                                   head_sha1,
399                                                   rev[i]->object.sha1);
400                         for (j = 0; j < i; j++)
401                                 putchar(' ');
402                         printf("%c [%s] ", is_head ? '*' : '!', ref_name[i]);
403                         show_one_commit(rev[i]);
404                 }
405                 for (i = 0; i < num_rev; i++)
406                         putchar('-');
407                 putchar('\n');
408         }
409
410         /* Sort topologically */
411         sort_in_topological_order(&seen);
412
413         /* Give names to commits */
414         name_commits(seen, rev, ref_name, num_rev);
415
416         all_mask = ((1u << (REV_SHIFT + num_rev)) - 1);
417         all_revs = all_mask & ~((1u << REV_SHIFT) - 1);
418         shown_merge_point = 0;
419
420         while (seen) {
421                 struct commit *commit = pop_one_commit(&seen);
422                 int this_flag = commit->object.flags;
423                 int is_merge_point = (this_flag & all_revs) == all_revs;
424                 static char *obvious[] = { "" };
425
426                 if (is_merge_point)
427                         shown_merge_point = 1;
428
429                 if (1 < num_rev) {
430                         for (i = 0; i < num_rev; i++)
431                                 putchar((this_flag & (1u << (i + REV_SHIFT)))
432                                         ? '+' : ' ');
433                         putchar(' ');
434                 }
435                 show_one_commit(commit);
436                 if (num_rev == 1)
437                         label = obvious;
438                 if (shown_merge_point && is_merge_point)
439                         if (--extra < 0)
440                                 break;
441         }
442         return 0;
443 }