builtin-describe.c

   1 #include "cache.h"
   2 #include "commit.h"
   3 #include "tag.h"
   4 #include "refs.h"
   5 #include "builtin.h"
   6
   7 #define SEEN            (1u<<0)
   8 #define MAX_TAGS        (FLAG_BITS - 1)
   9
  10 static const char describe_usage[] =
  11 "git-describe [--all] [--tags] [--abbrev=<n>] <committish>*";
  12
  13 static int debug;       /* Display lots of verbose info */
  14 static int all; /* Default to annotated tags only */
  15 static int tags;        /* But allow any tags if --tags is specified */
  16 static int abbrev = DEFAULT_ABBREV;
  17 static int max_candidates = 10;
  18
  19 static unsigned int names[256], allocs[256];
  20 static struct commit_name {
  21         struct commit *commit;
  22         int prio; /* annotated tag = 2, tag = 1, head = 0 */
  23         char path[FLEX_ARRAY]; /* more */
  24 } **name_array[256];
  25 static const char *prio_names[] = {
  26         "head", "lightweight", "annotated",
  27 };
  28
  29 static struct commit_name *match(struct commit *cmit)
  30 {
  31         unsigned char level0 = cmit->object.sha1[0];
  32         struct commit_name **p = name_array[level0];
  33         unsigned int hi = names[level0];
  34         unsigned int lo = 0;
  35
  36         while (lo < hi) {
  37                 unsigned int mi = (lo + hi) / 2;
  38                 int cmp = hashcmp(p[mi]->commit->object.sha1,
  39                         cmit->object.sha1);
  40                 if (!cmp) {
  41                         while (mi && p[mi - 1]->commit == cmit)
  42                                 mi--;
  43                         return p[mi];
  44                 }
  45                 if (cmp > 0)
  46                         hi = mi;
  47                 else
  48                         lo = mi+1;
  49         }
  50         return NULL;
  51 }
  52
  53 static void add_to_known_names(const char *path,
  54                                struct commit *commit,
  55                                int prio)
  56 {
  57         int idx;
  58         int len = strlen(path)+1;
  59         struct commit_name *name = xmalloc(sizeof(struct commit_name) + len);
  60         unsigned char m = commit->object.sha1[0];
  61
  62         name->commit = commit;
  63         name->prio = prio;
  64         memcpy(name->path, path, len);
  65         idx = names[m];
  66         if (idx >= allocs[m]) {
  67                 allocs[m] = (idx + 50) * 3 / 2;
  68                 name_array[m] = xrealloc(name_array[m],
  69                         allocs[m] * sizeof(*name_array));
  70         }
  71         name_array[m][idx] = name;
  72         names[m] = ++idx;
  73 }
  74
  75 static int get_name(const char *path, const unsigned char *sha1, int flag, void *cb_data)
  76 {
  77         struct commit *commit = lookup_commit_reference_gently(sha1, 1);
  78         struct object *object;
  79         int prio;
  80
  81         if (!commit)
  82                 return 0;
  83         object = parse_object(sha1);
  84         /* If --all, then any refs are used.
  85          * If --tags, then any tags are used.
  86          * Otherwise only annotated tags are used.
  87          */
  88         if (!strncmp(path, "refs/tags/", 10)) {
  89                 if (object->type == OBJ_TAG)
  90                         prio = 2;
  91                 else
  92                         prio = 1;
  93         }
  94         else
  95                 prio = 0;
  96
  97         if (!all) {
  98                 if (!prio)
  99                         return 0;
 100                 if (!tags && prio < 2)
 101                         return 0;
 102         }
 103         add_to_known_names(all ? path + 5 : path + 10, commit, prio);
 104         return 0;
 105 }
 106
 107 static int compare_names(const void *_a, const void *_b)
 108 {
 109         struct commit_name *a = *(struct commit_name **)_a;
 110         struct commit_name *b = *(struct commit_name **)_b;
 111         unsigned long a_date = a->commit->date;
 112         unsigned long b_date = b->commit->date;
 113         int cmp = hashcmp(a->commit->object.sha1, b->commit->object.sha1);
 114
 115         if (cmp)
 116                 return cmp;
 117         if (a->prio != b->prio)
 118                 return b->prio - a->prio;
 119         return (a_date > b_date) ? -1 : (a_date == b_date) ? 0 : 1;
 120 }
 121
 122 struct possible_tag {
 123         struct commit_name *name;
 124         int depth;
 125         int found_order;
 126         unsigned flag_within;
 127 };
 128
 129 static int compare_pt(const void *a_, const void *b_)
 130 {
 131         struct possible_tag *a = (struct possible_tag *)a_;
 132         struct possible_tag *b = (struct possible_tag *)b_;
 133         if (a->name->prio != b->name->prio)
 134                 return b->name->prio - a->name->prio;
 135         if (a->depth != b->depth)
 136                 return a->depth - b->depth;
 137         if (a->found_order != b->found_order)
 138                 return a->found_order - b->found_order;
 139         return 0;
 140 }
 141
 142 static void describe(const char *arg, int last_one)
 143 {
 144         unsigned char sha1[20];
 145         struct commit *cmit, *gave_up_on = NULL;
 146         struct commit_list *list;
 147         static int initialized = 0;
 148         struct commit_name *n;
 149         struct possible_tag all_matches[MAX_TAGS];
 150         unsigned int match_cnt = 0, annotated_cnt = 0, cur_match;
 151         unsigned long seen_commits = 0;
 152         int found = 0;
 153
 154         if (get_sha1(arg, sha1))
 155                 die("Not a valid object name %s", arg);
 156         cmit = lookup_commit_reference(sha1);
 157         if (!cmit)
 158                 die("%s is not a valid '%s' object", arg, commit_type);
 159
 160         if (!initialized) {
 161                 unsigned int m;
 162                 initialized = 1;
 163                 for_each_ref(get_name, NULL);
 164                 for (m = 0; m < ARRAY_SIZE(name_array); m++)
 165                         qsort(name_array[m], names[m],
 166                                 sizeof(*name_array[m]), compare_names);
 167         }
 168
 169         n = match(cmit);
 170         if (n) {
 171                 printf("%s\n", n->path);
 172                 return;
 173         }
 174
 175         if (debug)
 176                 fprintf(stderr, "searching to describe %s\n", arg);
 177
 178         list = NULL;
 179         cmit->object.flags = SEEN;
 180         commit_list_insert(cmit, &list);
 181         while (list) {
 182                 struct commit *c = pop_commit(&list);
 183                 struct commit_list *parents = c->parents;
 184                 seen_commits++;
 185                 n = match(c);
 186                 if (n) {
 187                         if (match_cnt < max_candidates) {
 188                                 struct possible_tag *t = &all_matches[match_cnt++];
 189                                 t->name = n;
 190                                 t->depth = seen_commits - 1;
 191                                 t->flag_within = 1u << match_cnt;
 192                                 t->found_order = found++;
 193                                 c->object.flags |= t->flag_within;
 194                                 if (n->prio == 2)
 195                                         annotated_cnt++;
 196                         }
 197                         else {
 198                                 gave_up_on = c;
 199                                 break;
 200                         }
 201                 }
 202                 for (cur_match = 0; cur_match < match_cnt; cur_match++) {
 203                         struct possible_tag *t = &all_matches[cur_match];
 204                         if (!(c->object.flags & t->flag_within))
 205                                 t->depth++;
 206                 }
 207                 if (annotated_cnt && !list) {
 208                         if (debug)
 209                                 fprintf(stderr, "finished search at %s\n",
 210                                         sha1_to_hex(c->object.sha1));
 211                         break;
 212                 }
 213                 while (parents) {
 214                         struct commit *p = parents->item;
 215                         parse_commit(p);
 216                         if (!(p->object.flags & SEEN))
 217                                 insert_by_date(p, &list);
 218                         p->object.flags |= c->object.flags;
 219                         parents = parents->next;
 220                 }
 221         }
 222         free_commit_list(list);
 223
 224         if (!match_cnt)
 225                 die("cannot describe '%s'", sha1_to_hex(cmit->object.sha1));
 226
 227         qsort(all_matches, match_cnt, sizeof(all_matches[0]), compare_pt);
 228         if (debug) {
 229                 for (cur_match = 0; cur_match < match_cnt; cur_match++) {
 230                         struct possible_tag *t = &all_matches[cur_match];
 231                         fprintf(stderr, " %-11s %8d %s\n",
 232                                 prio_names[t->name->prio],
 233                                 t->depth, t->name->path);
 234                 }
 235                 fprintf(stderr, "traversed %lu commits\n", seen_commits);
 236                 if (gave_up_on) {
 237                         fprintf(stderr,
 238                                 "more than %i tags found; listed %i most recent\n"
 239                                 "gave up search at %s\n",
 240                                 max_candidates, max_candidates,
 241                                 sha1_to_hex(gave_up_on->object.sha1));
 242                 }
 243         }
 244         printf("%s-g%s\n", all_matches[0].name->path,
 245                    find_unique_abbrev(cmit->object.sha1, abbrev));
 246
 247         if (!last_one)
 248                 clear_commit_marks(cmit, -1);
 249 }
 250
 251 int cmd_describe(int argc, const char **argv, const char *prefix)
 252 {
 253         int i;
 254
 255         for (i = 1; i < argc; i++) {
 256                 const char *arg = argv[i];
 257
 258                 if (*arg != '-')
 259                         break;
 260                 else if (!strcmp(arg, "--debug"))
 261                         debug = 1;
 262                 else if (!strcmp(arg, "--all"))
 263                         all = 1;
 264                 else if (!strcmp(arg, "--tags"))
 265                         tags = 1;
 266                 else if (!strncmp(arg, "--abbrev=", 9)) {
 267                         abbrev = strtoul(arg + 9, NULL, 10);
 268                         if (abbrev < MINIMUM_ABBREV || 40 < abbrev)
 269                                 abbrev = DEFAULT_ABBREV;
 270                 }
 271                 else if (!strncmp(arg, "--candidates=", 13)) {
 272                         max_candidates = strtoul(arg + 13, NULL, 10);
 273                         if (max_candidates < 1)
 274                                 max_candidates = 1;
 275                         else if (max_candidates > MAX_TAGS)
 276                                 max_candidates = MAX_TAGS;
 277                 }
 278                 else
 279                         usage(describe_usage);
 280         }
 281
 282         save_commit_buffer = 0;
 283
 284         if (argc <= i)
 285                 describe("HEAD", 1);
 286         else
 287                 while (i < argc) {
 288                         describe(argv[i], (i == argc - 1));
 289                         i++;
 290                 }
 291
 292         return 0;
 293 }